Journal articles: 'Chromatin Assembly'

1

Tyler, Jessica K. "Chromatin assembly." European Journal of Biochemistry 269, no. 9 (April 22, 2002): 2268–74. http://dx.doi.org/10.1046/j.1432-1033.2002.02890.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Adkins, Melissa W., and Jessica K. Tyler. "The Histone Chaperone Asf1p Mediates Global Chromatin Disassemblyin Vivo." Journal of Biological Chemistry 279, no. 50 (September 26, 2004): 52069–74. http://dx.doi.org/10.1074/jbc.m406113200.

Full text

Abstract:

The packaging of the eukaryotic genome into chromatin is likely to be mediated by chromatin assembly factors, including histone chaperones. We investigated the function of the histone H3/H4 chaperones anti-silencing function 1 (Asf1p) and chromatin assembly factor 1 (CAF-1)in vivo. Analysis of chromatin structure by accessibility to micrococcal nuclease and DNase I digestion demonstrated that the chromatin from CAF-1 mutant yeast has increased accessibility to these enzymes. In agreement, the supercoiling of the endogenous 2μ plasmid is reduced in yeast lacking CAF-1. These results indicate that CAF-1 mutant yeast globally under-assemble their genome into chromatin, consistent with a role for CAF-1 in chromatin assemblyin vivo. By contrast,asf1mutants globally over-assemble their genome into chromatin, as suggested by decreased accessibility of their chromatin to micrococcal nuclease and DNase I digestion and increased supercoiling of the endogenous 2μ plasmid. Deletion ofASF1causes a striking loss of acetylation on histone H3 lysine 9, but this is not responsible for the altered chromatin structure inasf1mutants. These data indicate that Asf1p may have a global role in chromatin disassembly and an unexpected role in histone acetylationin vivo.

APA, Harvard, Vancouver, ISO, and other styles

3

Yadav, Rajesh K., Atsushi Matsuda, Brandon R. Lowe, Yasushi Hiraoka, and Janet F. Partridge. "Subtelomeric Chromatin in the Fission Yeast S. pombe." Microorganisms 9, no. 9 (September 17, 2021): 1977. http://dx.doi.org/10.3390/microorganisms9091977.

Full text

Abstract:

Telomeres play important roles in safeguarding the genome. The specialized repressive chromatin that assembles at telomeres and subtelomeric domains is key to this protective role. However, in many organisms, the repetitive nature of telomeric and subtelomeric sequences has hindered research efforts. The fission yeast S. pombe has provided an important model system for dissection of chromatin biology due to the relative ease of genetic manipulation and strong conservation of important regulatory proteins with higher eukaryotes. Telomeres and the telomere-binding shelterin complex are highly conserved with mammals, as is the assembly of constitutive heterochromatin at subtelomeres. In this review, we seek to summarize recent work detailing the assembly of distinct chromatin structures within subtelomeric domains in fission yeast. These include the heterochromatic SH subtelomeric domains, the telomere-associated sequences (TAS), and ST chromatin domains that assemble highly condensed chromatin clusters called knobs. Specifically, we review new insights into the sequence of subtelomeric domains, the distinct types of chromatin that assemble on these sequences and how histone H3 K36 modifications influence these chromatin structures. We address the interplay between the subdomains of chromatin structure and how subtelomeric chromatin is influenced by both the telomere-bound shelterin complexes and by euchromatic chromatin regulators internal to the subtelomeric domain. Finally, we demonstrate that telomere clustering, which is mediated via the condensed ST chromatin knob domains, does not depend on knob assembly within these domains but on Set2, which mediates H3K36 methylation.

APA, Harvard, Vancouver, ISO, and other styles

4

Moree, Ben, Corey B. Meyer, Colin J. Fuller, and Aaron F. Straight. "CENP-C recruits M18BP1 to centromeres to promote CENP-A chromatin assembly." Journal of Cell Biology 194, no. 6 (September 12, 2011): 855–71. http://dx.doi.org/10.1083/jcb.201106079.

Full text

Abstract:

Eukaryotic chromosomes segregate by attaching to microtubules of the mitotic spindle through a chromosomal microtubule binding site called the kinetochore. Kinetochores assemble on a specialized chromosomal locus termed the centromere, which is characterized by the replacement of histone H3 in centromeric nucleosomes with the essential histone H3 variant CENP-A (centromere protein A). Understanding how CENP-A chromatin is assembled and maintained is central to understanding chromosome segregation mechanisms. CENP-A nucleosome assembly requires the Mis18 complex and the CENP-A chaperone HJURP. These factors localize to centromeres in telophase/G1, when new CENP-A chromatin is assembled. The mechanisms that control their targeting are unknown. In this paper, we identify a mechanism for recruiting the Mis18 complex protein M18BP1 to centromeres. We show that depletion of CENP-C prevents M18BP1 targeting to metaphase centromeres and inhibits CENP-A chromatin assembly. We find that M18BP1 directly binds CENP-C through conserved domains in the CENP-C protein. Thus, CENP-C provides a link between existing CENP-A chromatin and the proteins required for new CENP-A nucleosome assembly.

APA, Harvard, Vancouver, ISO, and other styles

5

Lu, Lei, Mark S. Ladinsky, and Tomas Kirchhausen. "Formation of the postmitotic nuclear envelope from extended ER cisternae precedes nuclear pore assembly." Journal of Cell Biology 194, no. 3 (August 8, 2011): 425–40. http://dx.doi.org/10.1083/jcb.201012063.

Full text

Abstract:

During mitosis, the nuclear envelope merges with the endoplasmic reticulum (ER), and nuclear pore complexes are disassembled. In a current model for reassembly after mitosis, the nuclear envelope forms by a reshaping of ER tubules. For the assembly of pores, two major models have been proposed. In the insertion model, nuclear pore complexes are embedded in the nuclear envelope after their formation. In the prepore model, nucleoporins assemble on the chromatin as an intermediate nuclear pore complex before nuclear envelope formation. Using live-cell imaging and electron microscope tomography, we find that the mitotic assembly of the nuclear envelope primarily originates from ER cisternae. Moreover, the nuclear pore complexes assemble only on the already formed nuclear envelope. Indeed, all the chromatin-associated Nup107–160 complexes are in single units instead of assembled prepores. We therefore propose that the postmitotic nuclear envelope assembles directly from ER cisternae followed by membrane-dependent insertion of nuclear pore complexes.

APA, Harvard, Vancouver, ISO, and other styles

6

Isaji, Mamiko, Hisataka Iwata, Hiroshi Harayama, and Masashi Miyake. "The localization of LAP2β during pronuclear formation in bovine oocytes after fertilization or activation." Zygote 14, no. 2 (May 2006): 157–67. http://dx.doi.org/10.1017/s0967199406003613.

Full text

Abstract:

SummaryWe have shown that the assembly of lamin-associated polypeptide (LAP) 2β was detected surrounding the chromatin mass around the time of extrusion of the second polar body (PB) in some fertilized oocytes, but not in most activated oocytes, by using A23187 and cycloheximide (CaA + CH). Here, we immunohistologically analysed the correlation between LAP2β assembly and chromatin condensation in fertilized and activated oocytes during the second meiosis. In bovine cumulus cells, the onset of LAP2β assembly was observed around anaphase chromosomes with strongly phosphorylated histone H3. No LAP2β assembled around the chromosomes in the first and second polar bodies and the alternative oocyte chromatin (oCh) if histone H3 was phosphorylated. Only histone H3 of oCh was completely dephosphorylated during the telophase II/G1 transition (Tel II/G1), and then LAP2β assembled around only the oCh without phosphorylated histone H3. In the oocytes activated by CaA + CH, LAP2β did not assemble around the condensed oCh during the Tel II/G1 transition, although their histone H3 dephosphorylation occurred rather rapidly compared with that of the fertilized oocytes. The patterns of histone H3 dephosphorylation and LAP2β assembly in oocytes activated by CaA alone showed greater similarity to those in fertilized oocytes than to those in oocytes activated by CaA + CH. These results show that LAP2β assembles around only oCh after complete dephosphorylation of histone H3 after fertilization and activation using CaA alone, and that the timing of histone H3 dephosphorylation and LAP2β assembly in these oocytes is different from that of somatic cells. The results also indicate that CH treatment inhibits LAP2β assembly around oCh but not histone H3 dephosphorylation.

APA, Harvard, Vancouver, ISO, and other styles

7

Yan, Jie, Thomas J. Maresca, Dunja Skoko, Christian D. Adams, Botao Xiao, Morten O. Christensen, Rebecca Heald, and John F. Marko. "Micromanipulation Studies of Chromatin Fibers in Xenopus Egg Extracts Reveal ATP-dependent Chromatin Assembly Dynamics." Molecular Biology of the Cell 18, no. 2 (February 2007): 464–74. http://dx.doi.org/10.1091/mbc.e06-09-0800.

Full text

Abstract:

We have studied assembly of chromatin using Xenopus egg extracts and single DNA molecules held at constant tension by using magnetic tweezers. In the absence of ATP, interphase extracts were able to assemble chromatin against DNA tensions of up to 3.5 piconewtons (pN). We observed force-induced disassembly and opening–closing fluctuations, indicating our experiments were in mechanochemical equilibrium. Roughly 50-nm (150-base pair) lengthening events dominated force-driven disassembly, suggesting that the assembled fibers are chiefly composed of nucleosomes. The ATP-depleted reaction was able to do mechanical work of 27 kcal/mol per 50 nm step, which provides an estimate of the free energy difference between core histone octamers on and off DNA. Addition of ATP led to highly dynamic behavior with time courses exhibiting processive runs of assembly and disassembly not observed in the ATP-depleted case. With ATP present, application of forces of 2 pN led to nearly complete fiber disassembly. Our study suggests that ATP hydrolysis plays a major role in nucleosome rearrangement and removal and that chromatin in vivo may be subject to highly dynamic assembly and disassembly processes that are modulated by DNA tension.

APA, Harvard, Vancouver, ISO, and other styles

8

Becker, P. B., and C. Wu. "Cell-free system for assembly of transcriptionally repressed chromatin from Drosophila embryos." Molecular and Cellular Biology 12, no. 5 (May 1992): 2241–49. http://dx.doi.org/10.1128/mcb.12.5.2241-2249.1992.

Full text

Abstract:

We describe a cell-free system, derived from preblastoderm Drosophila embryos, for the efficient assembly of cloned DNA into chromatin. The chromatin assembly system utilizes endogenous core histones and assembly factors and yields long arrays of regularly spaced nucleosomes with a repeat length of 180 bp. The assembly system is also capable of complementary-strand DNA synthesis accompanied by rapid nucleosome formation when the starting template is single-stranded circular DNA. Chromatin assembled with the preblastoderm embryo extract is naturally deficient in histone H1, but exogenous H1 can be incorporated during nucleosome assembly in vitro. Regular spacing of nucleosomes with or without histone H1 is sufficient to maximally repress transcription from hsp70 and fushi tarazu gene promoters. The Drosophila assembly system should be particularly useful for in vitro studies of chromatin assembly during DNA synthesis and for elucidating the action of transcription factors in the context of native chromatin.

APA, Harvard, Vancouver, ISO, and other styles

9

Becker, P. B., and C. Wu. "Cell-free system for assembly of transcriptionally repressed chromatin from Drosophila embryos." Molecular and Cellular Biology 12, no. 5 (May 1992): 2241–49. http://dx.doi.org/10.1128/mcb.12.5.2241.

Full text

Abstract:

We describe a cell-free system, derived from preblastoderm Drosophila embryos, for the efficient assembly of cloned DNA into chromatin. The chromatin assembly system utilizes endogenous core histones and assembly factors and yields long arrays of regularly spaced nucleosomes with a repeat length of 180 bp. The assembly system is also capable of complementary-strand DNA synthesis accompanied by rapid nucleosome formation when the starting template is single-stranded circular DNA. Chromatin assembled with the preblastoderm embryo extract is naturally deficient in histone H1, but exogenous H1 can be incorporated during nucleosome assembly in vitro. Regular spacing of nucleosomes with or without histone H1 is sufficient to maximally repress transcription from hsp70 and fushi tarazu gene promoters. The Drosophila assembly system should be particularly useful for in vitro studies of chromatin assembly during DNA synthesis and for elucidating the action of transcription factors in the context of native chromatin.

APA, Harvard, Vancouver, ISO, and other styles

10

Kamakaka, R. T., M. Bulger, P. D. Kaufman, B. Stillman, and J. T. Kadonaga. "Postreplicative chromatin assembly by Drosophila and human chromatin assembly factor 1." Molecular and Cellular Biology 16, no. 3 (March 1996): 810–17. http://dx.doi.org/10.1128/mcb.16.3.810.

Full text

Abstract:

To study the relationship between DNA replication and chromatin assembly, we have purified a factor termed Drosophila chromatin assembly factor 1 (dCAF-1) to approximately 50% homogeneity from a nuclear extract derived from embryos. dCAF-1 appears to consist of four polypeptides with molecular masses of 180, 105, 75, and 55 kDa. dCAF-1 preferentially mediates chromatin assembly of newly replicated DNA relative to unreplicated DNA during T-antigen-dependent simian virus 40 DNA replication in vitro, as seen with human CAF-1. Analysis of the mechanism of DNA replication-coupled chromatin assembly revealed that both dCAF-1 and human CAF-1 mediate chromatin assembly preferentially with previously yet newly replicated DNA relative to unreplicated DNA. Moreover, the preferential assembly of the postreplicative DNA was observed at 30 min after inhibition of DNA replication by aphidicolin, but this effect slowly diminished until it was no longer apparent at 120 min after inhibition of replication. These findings suggest that the coupling between DNA replication and chromatin assembly may not necessarily involve a direct interaction between the replication and assembly factors at a replication fork.

APA, Harvard, Vancouver, ISO, and other styles

11

Ghaddar, Nagham, Pierre Luciano, Vincent Géli, and Yves Corda. "Chromatin assembly factor-1 preserves genome stability in ctf4∆ cells by promoting sister chromatid cohesion." Cell Stress 7, no. 9 (September 11, 2023): 69–89. http://dx.doi.org/10.15698/cst2023.09.289.

Full text

Abstract:

Chromatin assembly and the establishment of sister chromatid cohesion are intimately connected to the progression of DNA replication forks. Here we examined the genetic interaction between the heterotrimeric chromatin assembly factor-1 (CAF-1), a central component of chromatin assembly during replication, and the core replisome component Ctf4. We find that CAF-1 deficient cells as well as cells affected in newly-synthesized H3-H4 histones deposition during DNA replication exhibit a severe negative growth with ctf4∆ mutant. We dissected the role of CAF-1 in the maintenance of genome stability in ctf4∆ yeast cells. In the absence of CTF4, CAF-1 is essential for viability in cells experiencing replication problems, in cells lacking functional S-phase checkpoint or functional spindle checkpoint, and in cells lacking DNA repair pathways involving homologous recombination. We present evidence that CAF-1 affects cohesin association to chromatin in a DNA-damage-dependent manner and is essential to maintain cohesion in the absence of CTF4. We also show that Eco1-catalyzed Smc3 acetylation is reduced in absence of CAF-1. Furthermore, we describe genetic interactions between CAF-1 and essential genes involved in cohesin loading, cohesin stabilization, and cohesin component indicating that CAF-1 is crucial for viability when sister chromatid cohesion is affected. Finally, our data indicate that the CAF-1-dependent pathway required for cohesion is functionally distinct from the Rtt101-Mms1-Mms22 pathway which functions in replicated chromatin assembly. Collectively, our results suggest that the deposition by CAF-1 of newly-synthesized H3-H4 histones during DNA replication creates a chromatin environment that favors sister chromatid cohesion and maintains genome integrity.

APA, Harvard, Vancouver, ISO, and other styles

12

Gamble, Matthew J., Hediye Erdjument-Bromage, Paul Tempst, Leonard P. Freedman, and Robert P. Fisher. "The Histone Chaperone TAF-I/SET/INHAT Is Required for Transcription In Vitro of Chromatin Templates." Molecular and Cellular Biology 25, no. 2 (January 15, 2005): 797–807. http://dx.doi.org/10.1128/mcb.25.2.797-807.2005.

Full text

Abstract:

ABSTRACT To uncover factors required for transcription by RNA polymerase II on chromatin, we fractionated a mammalian cell nuclear extract. We identified the histone chaperone TAF-I (also known as INHAT [inhibitor of histone acetyltransferase]), which was previously proposed to repress transcription, as a potent activator of chromatin transcription responsive to the vitamin D3 receptor or to Gal4-VP16. TAF-I associates with chromatin in vitro and can substitute for the related protein NAP-1 in assembling chromatin onto cloned DNA templates in cooperation with the remodeling enzyme ATP-dependent chromatin assembly factor (ACF). The chromatin assembly and transcriptional activation functions are distinct, however, and can be dissociated temporally. Efficient transcription of chromatin assembled with TAF-I still requires the presence of TAF-I during the polymerization reaction. Conversely, TAF-I cannot stimulate transcript elongation when added after the other factors necessary for assembly of a preinitiation complex on naked DNA. Thus, TAF-I is required to facilitate transcription at a step after chromatin assembly but before transcript elongation.

APA, Harvard, Vancouver, ISO, and other styles

13

Kmiec, Eric B., JoAnn M. Sekiguchi, and Allyson D. Cole. "Studies on the ATP requirements of in vitro chromatin assembly." Biochemistry and Cell Biology 67, no. 8 (August 1, 1989): 443–54. http://dx.doi.org/10.1139/o89-070.

Full text

Abstract:

To gain a more complete understanding of the process of in vitro chromatin assembly, an examination of the energy requirements of nucleosome formation must be undertaken. The experiments outlined in this manuscript address this issue by making use of the Xenopus laevis S-150 cell-free extract. The S-150 catalyzes chromatin assembly on circular DNA templates dependent either on the exogenous addition of ATP or regeneration of endogenous ATP. We define two distinct, but temporally ordered, phases of the overall process. The first, nucleosome formation, occurs in the presence of endogenous levels of ATP, while the second phase, chromatin assembly, which we define as the development of properly spaced nucleosomes, requires a higher level of ATP. Both phases lead to a distribution of molecules with similar superhelical densities. Taken together, these data suggest that chromatin assembly may consist of two distinct steps differing in their strategy cofactor requirement. The experiments presented in this manuscript support the concept that nucleosomes first assemble, perhaps randomly, on the DNA and are gradually matured into a canonical chromatin structure with periodic spacing.Key words: DNA topoisomerase, chromatin assembly, energy requirements.

APA, Harvard, Vancouver, ISO, and other styles

14

Hirano, T., and T. J. Mitchison. "Cell cycle control of higher-order chromatin assembly around naked DNA in vitro." Journal of Cell Biology 115, no. 6 (December 15, 1991): 1479–89. http://dx.doi.org/10.1083/jcb.115.6.1479.

Full text

Abstract:

We have developed an in vitro system in which higher-order chromatin structures are assembled around naked DNAs in a cell cycle-dependent manner. Membrane-free soluble extracts specific to interphase and mitotic states were prepared from Xenopus eggs. When high molecular weight DNA is incubated with interphase extracts, fluffy chromatin-like structures are assembled. In contrast, mitotic extracts produce highly condensed chromosome-like structures. Immunofluorescence studies show that a monoclonal antibody MPM-2, which recognizes a class of mitosis-specific phosphoproteins, stains the "core" or "axis" of condensed mitotic chromatin but not interphase chromatin. By adding mitotic extracts, interphase chromatin structures are synchronously converted into the condensed state. The increasingly condensed state of chromatin correlates with the appearance and structural rearrangements of the MPM-2-stained structures. These results suggest that mitosis-specific phosphoproteins recognized by MPM-2 may be directly involved in the assembly of the chromosome scaffold-like structures and chromatin condensation. Although both extracts promote nucleosome assembly at the same rate, topoisomerase II (topo II) activity is four to five times higher in mitotic extracts compared with interphase extracts. The addition of a topo II inhibitor VM-26 into mitotic assembly mixtures disturbs the organization of the MPM-2-stained structures and affects the final stage of chromatin condensation. This in vitro system should be useful for identifying cis- and trans-acting elements responsible for higher-order chromatin assembly and its structural changes in the cell cycle.

APA, Harvard, Vancouver, ISO, and other styles

15

Ridgway, Patricia, and Geneviève Almouzni. "Chromatin assembly and organization." Journal of Cell Science 114, no. 15 (August 1, 2001): 2711–12. http://dx.doi.org/10.1242/jcs.114.15.2711.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Mao, Steve. "Hemimethylation drives chromatin assembly." Science 359, no. 6380 (March 8, 2018): 1114.5–1115. http://dx.doi.org/10.1126/science.359.6380.1114-e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Kumar, S., and M. Leffak. "Assembly of active chromatin." Biochemistry 25, no. 8 (April 1986): 2055–60. http://dx.doi.org/10.1021/bi00356a033.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Gant, Tracey Michele, Crafford A. Harris, and Katherine L. Wilson. "Roles of LAP2 Proteins in Nuclear Assembly and DNA Replication: Truncated LAP2β Proteins Alter Lamina Assembly, Envelope Formation, Nuclear Size, and DNA Replication Efficiency in Xenopus laevis Extracts." Journal of Cell Biology 144, no. 6 (March 22, 1999): 1083–96. http://dx.doi.org/10.1083/jcb.144.6.1083.

Full text

Abstract:

Humans express three major splicing isoforms of LAP2, a lamin- and chromatin-binding nuclear protein. LAP2β and γ are integral membrane proteins, whereas α is intranuclear. When truncated recombinant human LAP2β proteins were added to cell-free Xenopus laevis nuclear assembly reactions at high concentrations, a domain common to all LAP2 isoforms (residues 1–187) inhibited membrane binding to chromatin, whereas the chromatin- and lamin-binding region (residues 1–408) inhibited chromatin expansion. At lower concentrations of the common domain, membranes attached to chromatin with a unique scalloped morphology, but these nuclei neither accumulated lamins nor replicated. At lower concentrations of the chromatin- and lamin-binding region, nuclear envelopes and lamins assembled, but nuclei failed to enlarge and replicated on average 2.5-fold better than controls. This enhancement was not due to rereplication, as shown by density substitution experiments, suggesting the hypothesis that LAP2β is a downstream effector of lamina assembly in promoting replication competence. Overall, our findings suggest that LAP2 proteins mediate membrane–chromatin attachment and lamina assembly, and may promote replication by influencing chromatin structure.

APA, Harvard, Vancouver, ISO, and other styles

19

Banerjee, S., and C. R. Cantor. "Nucleosome assembly of simian virus 40 DNA in a mammalian cell extract." Molecular and Cellular Biology 10, no. 6 (June 1990): 2863–73. http://dx.doi.org/10.1128/mcb.10.6.2863-2873.1990.

Full text

Abstract:

We report here a mammalian cell-free system that can support chromatin assembly. Effective nucleosome assembly in HeLa cell extracts occurred at 125 to 200 mM KCl or potassium glutamate. At this physiological K+ ion concentration, two types of chromatin assembly were observed. The first was interfered with by Mg2+. Other cations such as Mn2+, Ca2+, Fe3+, and spermidine also inhibited this type of nucleosome assembly. The second type of assembly occurred in the presence of Mg2+ and at least equimolar ATP. However, even in the presence of ATP, excess Mg2+ inhibited assembly and promoted catenation of DNA; these effects could be circumvented by excess ATP, GTP, EDTA, or polyglutamic acid. The critical DNA concentration for optimum assembly in both pathways suggested a stoichiometric association of histones with DNA. The spacing of nucleosomes formed by both types of assembly on linear and circular DNA was reasonably regular, but chromatin assembled in the presence of ATP and Mg2+ was more stable.

APA, Harvard, Vancouver, ISO, and other styles

20

Banerjee, S., and C. R. Cantor. "Nucleosome assembly of simian virus 40 DNA in a mammalian cell extract." Molecular and Cellular Biology 10, no. 6 (June 1990): 2863–73. http://dx.doi.org/10.1128/mcb.10.6.2863.

Full text

Abstract:

We report here a mammalian cell-free system that can support chromatin assembly. Effective nucleosome assembly in HeLa cell extracts occurred at 125 to 200 mM KCl or potassium glutamate. At this physiological K+ ion concentration, two types of chromatin assembly were observed. The first was interfered with by Mg2+. Other cations such as Mn2+, Ca2+, Fe3+, and spermidine also inhibited this type of nucleosome assembly. The second type of assembly occurred in the presence of Mg2+ and at least equimolar ATP. However, even in the presence of ATP, excess Mg2+ inhibited assembly and promoted catenation of DNA; these effects could be circumvented by excess ATP, GTP, EDTA, or polyglutamic acid. The critical DNA concentration for optimum assembly in both pathways suggested a stoichiometric association of histones with DNA. The spacing of nucleosomes formed by both types of assembly on linear and circular DNA was reasonably regular, but chromatin assembled in the presence of ATP and Mg2+ was more stable.

APA, Harvard, Vancouver, ISO, and other styles

21

Lynch, Patrick J., and Laura N. Rusche. "A Silencer Promotes the Assembly of Silenced Chromatin Independently of Recruitment." Molecular and Cellular Biology 29, no. 1 (October 27, 2008): 43–56. http://dx.doi.org/10.1128/mcb.00983-08.

Full text

Abstract:

ABSTRACT In Saccharomyces cerevisiae, silenced chromatin occurs at telomeres and the silent mating-type loci HMR and HML. At these sites, the Sir proteins are recruited to a silencer and then associate with adjacent chromatin. We used chromatin immunoprecipitation to compare the rates of Sir protein assembly at different genomic locations and discovered that establishment of silenced chromatin was much more rapid at HMR than at the telomere VI-R. Silenced chromatin also assembled more quickly on one side of HMR-E than on the other. Despite differences in spreading, the Sir proteins were recruited to HMR-E and telomeric silencers at equivalent rates. Additionally, insertion of HMR-E adjacent to the telomere VI-R increased the rate of Sir2p association with the telomere. These data suggest that HMR-E functions to both recruit Sir proteins and promote their assembly across several kilobases. Observations that association of Sir2p occurs simultaneously throughout HMR and that silencing at HMR is insensitive to coexpression of catalytically inactive Sir2p suggest that HMR-E acts by enabling assembly to occur in a nonlinear fashion. The ability of silencers to promote assembly of silenced chromatin over several kilobases is likely an important mechanism for maintaining what would otherwise be unstable chromatin at the correct genomic locations.

APA, Harvard, Vancouver, ISO, and other styles

22

Dabauvalle, M. C., K. Loos, H. Merkert, and U. Scheer. "Spontaneous assembly of pore complex-containing membranes ("annulate lamellae") in Xenopus egg extract in the absence of chromatin." Journal of Cell Biology 112, no. 6 (March 15, 1991): 1073–82. http://dx.doi.org/10.1083/jcb.112.6.1073.

Full text

Abstract:

Extract prepared from activated Xenopus eggs is capable of reconstituting nuclei from added DNA or chromatin. We have incubated such extract in the absence of DNA and found that numerous flattened membrane cisternae containing densely spaced pore complexes (annulate lamellae) formed de novo. By electron and immunofluorescence microscopy employing a pore complex-specific antibody we followed their appearance in the extract. Annulate lamellae were first detectable at a 30-min incubation in the form of short cisternae which already contained a high pore density. At 90-120 min they were abundantly present and formed large multilamellar stacks. The kinetics of annulate lamellae assembly were identical to that of nuclear envelope formation after addition of DNA to the extract. However, in the presence of DNA or chromatin, i.e., under conditions promoting the assembly of nuclear envelopes, annulate lamellae formation was considerably reduced and, at sufficiently high chromatin concentrations, completely inhibited. Incubation of the extract with antibodies to lamin LIII did not interfere with annulate lamellae assembly, whereas in the presence of DNA formation of nuclear envelopes around chromatin was inhibited. Our data show that nuclear membrane vesicles are able to fuse spontaneously into membrane cisternae and to assemble pore complexes independently of interactions with chromatin and a lamina. We propose that nuclear envelope precursor material will assemble into a nuclear envelope when chromatin is available for binding the membrane vesicles, and into annulate lamellae when chromatin is absent or its binding sites are saturated.

APA, Harvard, Vancouver, ISO, and other styles

23

Tyler, J. K., M. Bulger, R. T. Kamakaka, R. Kobayashi, and J. T. Kadonaga. "The p55 subunit of Drosophila chromatin assembly factor 1 is homologous to a histone deacetylase-associated protein." Molecular and Cellular Biology 16, no. 11 (November 1996): 6149–59. http://dx.doi.org/10.1128/mcb.16.11.6149.

Full text

Abstract:

To gain a better understanding of DNA replication-coupled chromatin assembly, we have isolated the cDNA encoding the smallest (apparent molecular mass, 55 kDa; termed p55) subunit of Drosophila melanogaster chromatin assembly factor 1 (dCAF-1), a multisubunit protein that is required for the assembly of nucleosomes onto newly replicated DNA in vitro. The p55 polypeptide comprises seven WD repeat motifs and is homologous to the mammalian RbAp48 protein, which is associated with the HD1 histone deacetylase. dCAF-1 was immunopurified by using affinity-purified antibodies against p55; the resulting dCAF-1 preparation possessed the four putative subunits of dCAF-1 (p180, p105, p75, and p55) and was active for DNA replication-coupled chromatin assembly. Moreover, dCAF-1 activity was specifically depleted with antibodies against p55. Thus, p55 is an integral component of dCAF-1. p55 is localized to the nucleus and is present throughout Drosophila development. Consistent with the homology between p55 and the HD1-associated RbAp48 protein, histone deacetylase activity was observed to coimmunoprecipitate specifically with p55 from a Drosophila nuclear extract. Furthermore, a fraction of the p55 protein becomes associated with the newly assembled chromatin following DNA replication. These findings collectively suggest that p55 may function as a link between DNA replication-coupled chromatin assembly and histone modification.

APA, Harvard, Vancouver, ISO, and other styles

24

Il’ina, Iu A., and A. Yu Konev. "The role of aTp-dependent chromatin remodeling factors in chromatin assembly in vivo." Vavilov Journal of Genetics and Breeding 23, no. 2 (March 30, 2019): 160–67. http://dx.doi.org/10.18699/vj19.476.

Full text

Abstract:

Chromatin assembly is a fundamental process essential for chromosome duplication subsequent to DNA replication. In addition, histone removal and incorporation take place constantly throughout the cell cycle in the course of DNA-utilizing processes, such as transcription, damage repair or recombination. In vitro studies have revealed that nucleosome assembly relies on the combined action of core histone chaperones and ATP-utilizing molecular motor proteins such as ACF or CHD1. Despite extensive biochemical characterization of ATP-dependent chromatin assembly and remodeling factors, it has remained unclear to what extent nucleosome assembly is an ATP-dependent process in vivo. Our original and published data about the functions of ATP-dependent chromatin assembly and remodeling factors clearly demonstrated that these proteins are important for nucleosome assembly and histone exchange in vivo. During male pronucleus reorganization after fertilization CHD1 has a critical role in the genomescale, replication-independent nucleosome assembly involving the histone variant H3.3. Thus, the molecular motor proteins, such as CHD1, function not only in the remodeling of existing nucleosomes but also in de novo nucleosome assembly from DNA and histones in vivo. ATP-dependent chromatin assembly and remodeling factors have been implicated in the process of histone exchange during transcription and DNA repair, in the maintenance of centromeric chromatin and in the loading and remodeling of nucleosomes behind a replication fork. Thus, chromatin remodeling factors are involved in the processes of both replication-dependent and replication-independent chromatin assembly. The role of these proteins is especially prominent in the processes of large-scale chromatin reorganization; for example, during male pronucleus formation or in DNA repair. Together, ATP-dependent chromatin assembly factors, histone chaperones and chromatin modifying enzymes form a “chromatin integrity network” to ensure proper maintenance and propagation of chromatin landscape.

APA, Harvard, Vancouver, ISO, and other styles

25

Lu, Z. H., D. B. Sittman, D. T. Brown, R. Munshi, and G. H. Leno. "Histone H1 modulates DNA replication through multiple pathways in Xenopus egg extract." Journal of Cell Science 110, no. 21 (November 1, 1997): 2745–58. http://dx.doi.org/10.1242/jcs.110.21.2745.

Full text

Abstract:

We investigated the effects of histone H1s on DNA replication using Xenopus egg extract. Mouse variants H1c and H10 were assembled onto Xenopus sperm chromatin by the extract during the remodeling that accompanies nuclear decondensation. The association of H1 with chromatin was rapid and concentration dependent. H1-associated chromatin displayed a typical nucleosomal repeat pattern indicating that linker histones are properly positioned along the DNA. The presence of H1 on sperm chromatin reduced both the rate and extent of DNA replication in egg extract. This reduction in rate is due, in part, to a delay in initiation of replication within individual nuclei. Initiation in extract is dependent upon nuclear assembly. Analysis of the assembly process revealed that H1 does not inhibit nuclear membrane formation or the import of nuclear protein, however, it does slow the rate of nuclear lamina formation. This H1-induced delay in lamina assembly is responsible for the delay in initiation as pre-assembled H1-containing nuclei initiate replication at the same time as control nuclei. However, H1 inhibits replication even when lamina assembly is complete suggesting that H1 also affects replication directly. These data indicate that H1 modulates DNA replication through multiple pathways in egg extract.

APA, Harvard, Vancouver, ISO, and other styles

26

Xiao, Botao, Benjamin S. Freedman, Kelly E. Miller, Rebecca Heald, and John F. Marko. "Histone H1 compacts DNA under force and during chromatin assembly." Molecular Biology of the Cell 23, no. 24 (December 15, 2012): 4864–71. http://dx.doi.org/10.1091/mbc.e12-07-0518.

Full text

Abstract:

Histone H1 binds to linker DNA between nucleosomes, but the dynamics and biological ramifications of this interaction remain poorly understood. We performed single-molecule experiments using magnetic tweezers to determine the effects of H1 on naked DNA in buffer or during chromatin assembly in Xenopus egg extracts. In buffer, nanomolar concentrations of H1 induce bending and looping of naked DNA at stretching forces below 0.6 pN, effects that can be reversed with 2.7-pN force or in 200 mM monovalent salt concentrations. Consecutive tens-of-nanometer bending events suggest that H1 binds to naked DNA in buffer at high stoichiometries. In egg extracts, single DNA molecules assemble into nucleosomes and undergo rapid compaction. Histone H1 at endogenous physiological concentrations increases the DNA compaction rate during chromatin assembly under 2-pN force and decreases it during disassembly under 5-pN force. In egg cytoplasm, histone H1 protects sperm nuclei undergoing genome-wide decondensation and chromatin assembly from becoming abnormally stretched or fragmented due to astral microtubule pulling forces. These results reveal functional ramifications of H1 binding to DNA at the single-molecule level and suggest an important physiological role for H1 in compacting DNA under force and during chromatin assembly.

APA, Harvard, Vancouver, ISO, and other styles

27

Krude, Torsten. "Chromatin Assembly: The Kinetochore Connection." Current Biology 12, no. 7 (April 2002): R256—R258. http://dx.doi.org/10.1016/s0960-9822(02)00786-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Kaufman, Paul. "Histone chaperones and chromatin assembly." Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms 1819, no. 3-4 (March 2012): 195. http://dx.doi.org/10.1016/j.bbagrm.2012.02.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Okuwaki, Mitsuru, Kohsuke Kato, Hideto Shimahara, Shin-ichi Tate, and Kyosuke Nagata. "Assembly and Disassembly of Nucleosome Core Particles Containing Histone Variants by Human Nucleosome Assembly Protein I." Molecular and Cellular Biology 25, no. 23 (December 1, 2005): 10639–51. http://dx.doi.org/10.1128/mcb.25.23.10639-10651.2005.

Full text

Abstract:

ABSTRACT Histone variants play important roles in the maintenance and regulation of the chromatin structure. In order to characterize the biochemical properties of the chromatin structure containing histone variants, we investigated the dynamic status of nucleosome core particles (NCPs) that were assembled with recombinant histones. We found that in the presence of nucleosome assembly protein I (NAP-I), a histone chaperone, H2A-Barr body deficient (H2A.Bbd) confers the most flexible nucleosome structure among the mammalian histone H2A variants known thus far. NAP-I mediated the efficient assembly and disassembly of the H2A.Bbd-H2B dimers from NCPs. This reaction was accomplished more efficiently when the NCPs contained H3.3, a histone H3 variant known to be localized in the active chromatin, than when the NCPs contained the canonical H3. These observations indicate that the histone variants H2A.Bbd and H3.3 are involved in the formation and maintenance of the active chromatin structure. We also observed that acidic histone binding proteins, TAF-I/SET and B23.1, demonstrated dimer assembly and disassembly activity, but the efficiency of their activity was considerably lower than that of NAP-I. Thus, both the acidic nature of NAP-I and its other functional structure(s) may be essential to mediate the assembly and disassembly of the dimers in NCPs.

APA, Harvard, Vancouver, ISO, and other styles

30

Gaillard, Pierre-Henri L., Emmanuelle M. D. Martini, Paul D. Kaufman, Bruce Stillman, Ethel Moustacchi, and Geneviève Almouzni. "Chromatin Assembly Coupled to DNA Repair: A New Role for Chromatin Assembly Factor I." Cell 86, no. 6 (September 1996): 887–96. http://dx.doi.org/10.1016/s0092-8674(00)80164-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Ahmad, Kami, and Steven Henikoff. "Centromeres Are Specialized Replication Domains in Heterochromatin." Journal of Cell Biology 153, no. 1 (April 2, 2001): 101–10. http://dx.doi.org/10.1083/jcb.153.1.101.

Full text

Abstract:

The properties that define centromeres in complex eukaryotes are poorly understood because the underlying DNA is normally repetitive and indistinguishable from surrounding noncentromeric sequences. However, centromeric chromatin contains variant H3-like histones that may specify centromeric regions. Nucleosomes are normally assembled during DNA replication; therefore, we examined replication and chromatin assembly at centromeres in Drosophila cells. DNA in pericentric heterochromatin replicates late in S phase, and so centromeres are also thought to replicate late. In contrast to expectation, we show that centromeres replicate as isolated domains early in S phase. These domains do not appear to assemble conventional H3-containing nucleosomes, and deposition of the Cid centromeric H3-like variant proceeds by a replication-independent pathway. We suggest that late-replicating pericentric heterochromatin helps to maintain embedded centromeres by blocking conventional nucleosome assembly early in S phase, thereby allowing the deposition of centromeric histones.

APA, Harvard, Vancouver, ISO, and other styles

32

Groen, Aaron C., Thomas J. Maresca, Jesse C. Gatlin, Edward D. Salmon, and Timothy J. Mitchison. "Functional Overlap of Microtubule Assembly Factors in Chromatin-Promoted Spindle Assembly." Molecular Biology of the Cell 20, no. 11 (June 2009): 2766–73. http://dx.doi.org/10.1091/mbc.e09-01-0043.

Full text

Abstract:

Distinct pathways from centrosomes and chromatin are thought to contribute in parallel to microtubule nucleation and stabilization during animal cell mitotic spindle assembly, but their full mechanisms are not known. We investigated the function of three proposed nucleation/stabilization factors, TPX2, γ-tubulin and XMAP215, in chromatin-promoted assembly of anastral spindles in Xenopus laevis egg extract. In addition to conventional depletion-add back experiments, we tested whether factors could substitute for each other, indicative of functional redundancy. All three factors were required for microtubule polymerization and bipolar spindle assembly around chromatin beads. Depletion of TPX2 was partially rescued by the addition of excess XMAP215 or EB1, or inhibiting MCAK (a Kinesin-13). Depletion of either γ-tubulin or XMAP215 was partially rescued by adding back XMAP215, but not by adding any of the other factors. These data reveal functional redundancy between specific assembly factors in the chromatin pathway, suggesting individual proteins or pathways commonly viewed to be essential may not have entirely unique functions.

APA, Harvard, Vancouver, ISO, and other styles

33

Gallego-Paez, Lina Marcela, Hiroshi Tanaka, Masashige Bando, Motoko Takahashi, Naohito Nozaki, Ryuichiro Nakato, Katsuhiko Shirahige, and Toru Hirota. "Smc5/6-mediated regulation of replication progression contributes to chromosome assembly during mitosis in human cells." Molecular Biology of the Cell 25, no. 2 (January 15, 2014): 302–17. http://dx.doi.org/10.1091/mbc.e13-01-0020.

Full text

Abstract:

The structural maintenance of chromosomes (SMC) proteins constitute the core of critical complexes involved in structural organization of chromosomes. In yeast, the Smc5/6 complex is known to mediate repair of DNA breaks and replication of repetitive genomic regions, including ribosomal DNA loci and telomeres. In mammalian cells, which have diverse genome structure and scale from yeast, the Smc5/6 complex has also been implicated in DNA damage response, but its further function in unchallenged conditions remains elusive. In this study, we addressed the behavior and function of Smc5/6 during the cell cycle. Chromatin fractionation, immunofluorescence, and live-cell imaging analyses indicated that Smc5/6 associates with chromatin during interphase but largely dissociates from chromosomes when they condense in mitosis. Depletion of Smc5 and Smc6 resulted in aberrant mitotic chromosome phenotypes that were accompanied by the abnormal distribution of topoisomerase IIα (topo IIα) and condensins and by chromosome segregation errors. Importantly, interphase chromatin structure indicated by the premature chromosome condensation assay suggested that Smc5/6 is required for the on-time progression of DNA replication and subsequent binding of topo IIα on replicated chromatids. These results indicate an essential role of the Smc5/6 complex in processing DNA replication, which becomes indispensable for proper sister chromatid assembly in mitosis.

APA, Harvard, Vancouver, ISO, and other styles

34

Li, Cong-jun, Alex Vassilev, and Melvin L. DePamphilis. "Role for Cdk1 (Cdc2)/Cyclin A in Preventing the Mammalian Origin Recognition Complex's Largest Subunit (Orc1) from Binding to Chromatin during Mitosis." Molecular and Cellular Biology 24, no. 13 (July 1, 2004): 5875–86. http://dx.doi.org/10.1128/mcb.24.13.5875-5886.2004.

Full text

Abstract:

ABSTRACT The eukaryotic origin recognition complex (ORC) selects the genomic sites where prereplication complexes are assembled and DNA replication begins. In proliferating mammalian cells, ORC activity appears to be regulated by reducing the affinity of the Orc1 subunit for chromatin during S phase and then preventing reformation of a stable ORC-chromatin complex until mitosis is completed and a nuclear membrane is assembled. Here we show that part of the mechanism by which this is accomplished is the selective association of Orc1 with Cdk1 (Cdc2)/cyclin A during the G2/M phase of cell division. This association accounted for the appearance in M-phase cells of hyperphosphorylated Orc1 that was subsequently dephosphorylated during the M-to-G1 transition. Moreover, inhibition of Cdk activity in metaphase cells resulted in rapid binding of Orc1 to chromatin. However, chromatin binding was not mediated through increased affinity of Orc1 for Orc2, suggesting that additional events are involved in the assembly of functional ORC-chromatin sites. These results reveal that the same cyclin-dependent protein kinase that initiates mitosis in mammalian cells also concomitantly inhibits assembly of functional ORC-chromatin sites.

APA, Harvard, Vancouver, ISO, and other styles

35

Barnhart, Meghan C., P. Henning J. L. Kuich, Madison E. Stellfox, Jared A. Ward, Emily A. Bassett, Ben E. Black, and Daniel R. Foltz. "HJURP is a CENP-A chromatin assembly factor sufficient to form a functional de novo kinetochore." Journal of Cell Biology 194, no. 2 (July 18, 2011): 229–43. http://dx.doi.org/10.1083/jcb.201012017.

Full text

Abstract:

Centromeres of higher eukaryotes are epigenetically marked by the centromere-specific CENP-A nucleosome. New CENP-A recruitment requires the CENP-A histone chaperone HJURP. In this paper, we show that a LacI (Lac repressor) fusion of HJURP drove the stable recruitment of CENP-A to a LacO (Lac operon) array at a noncentromeric locus. Ectopically targeted CENP-A chromatin at the LacO array was sufficient to direct the assembly of a functional centromere as indicated by the recruitment of the constitutive centromere-associated network proteins, the microtubule-binding protein NDC80, and the formation of stable kinetochore–microtubule attachments. An amino-terminal fragment of HJURP was able to assemble CENP-A nucleosomes in vitro, demonstrating that HJURP is a chromatin assembly factor. Furthermore, HJURP recruitment to endogenous centromeres required the Mis18 complex. Together, these data suggest that the role of the Mis18 complex in CENP-A deposition is to recruit HJURP and that the CENP-A nucleosome assembly activity of HJURP is responsible for centromeric chromatin assembly to maintain the epigenetic mark.

APA, Harvard, Vancouver, ISO, and other styles

36

Van Hooser, Aaron A., Ilia I. Ouspenski, Heather C. Gregson, Daniel A. Starr, Tim J. Yen, Michael L. Goldberg, Kyoko Yokomori, William C. Earnshaw, Kevin F. Sullivan, and B. R. Brinkley. "Specification of kinetochore-forming chromatin by the histone H3 variant CENP-A." Journal of Cell Science 114, no. 19 (October 1, 2001): 3529–42. http://dx.doi.org/10.1242/jcs.114.19.3529.

Full text

Abstract:

The mechanisms that specify precisely where mammalian kinetochores form within arrays of centromeric heterochromatin remain largely unknown. Localization of CENP-A exclusively beneath kinetochore plates suggests that this distinctive histone might direct kinetochore formation by altering the structure of heterochromatin within a sub-region of the centromere. To test this hypothesis, we experimentally mistargeted CENP-A to non-centromeric regions of chromatin and determined whether other centromere-kinetochore components were recruited. CENP-A-containing non-centromeric chromatin assembles a subset of centromere-kinetochore components, including CENP-C, hSMC1, and HZwint-1 by a mechanism that requires the unique CENP-A N-terminal tail. The sequence-specific DNA-binding protein CENP-B and the microtubule-associated proteins CENP-E and HZW10 were not recruited, and neocentromeric activity was not detected. Experimental mistargeting of CENP-A to inactive centromeres or to acentric double-minute chromosomes was also not sufficient to assemble complete kinetochore activity. The recruitment of centromere-kinetochore proteins to chromatin appears to be a unique function of CENP-A, as the mistargeting of other components was not sufficient for assembly of the same complex. Our results indicate at least two distinct steps in kinetochore assembly: (1) precise targeting of CENP-A, which is sufficient to assemble components of a centromere-prekinetochore scaffold; and (2) targeting of kinetochore microtubule-associated proteins by an additional mechanism present only at active centromeres.

APA, Harvard, Vancouver, ISO, and other styles

37

Ito, T., M. Bulger, R. Kobayashi, and J. T. Kadonaga. "Drosophila NAP-1 is a core histone chaperone that functions in ATP-facilitated assembly of regularly spaced nucleosomal arrays." Molecular and Cellular Biology 16, no. 6 (June 1996): 3112–24. http://dx.doi.org/10.1128/mcb.16.6.3112.

Full text

Abstract:

We describe the cloning and analysis of Drosophila nucleosome assembly protein 1 (dNAP-1), a core histone-binding protein that functions with other chromatin assembly activities in a Drosophila chromatin assembly factor 1-containing fraction (dCAF-1 fraction) in the ATP-facilitated assembly of regularly spaced nucleosomal arrays from purified core histones and DNA. Purified, recombinant dNAP-1 acts cooperatively with a factor(s) in the dCAF-1 fraction in the efficient and DNA replication-independent assembly of chromatin. In the presence of histone H1, the repeat length of the chromatin is similar to that of native chromatin from Drosophila embryos. By coimmunoprecipitation analysis, dNAP-1 was found to be associated with histones H2A and H2B in a crude whole-embryo extract, which suggests that dNAP-1 is bound to the histones in vivo. Studies of the localization of dNAP-1 in the Drosophila embryo revealed that the factor is present in the nucleus during S phase and is predominantly cytoplasmic during G2 phase. These data suggest that NAP-1 acts as a core histone shuttle which delivers the histones from the cytoplasm to the chromatin assembly machinery in the nucleus. Thus, NAP-1 appears to be one component of a multifactor chromatin assembly machinery that mediates the ATP-facilitated assembly of regularly spaced nucleosomal arrays.

APA, Harvard, Vancouver, ISO, and other styles

38

Hoek, M., and B. Stillman. "Chromatin assembly factor 1 is essential and couples chromatin assembly to DNA replication in vivo." Proceedings of the National Academy of Sciences 100, no. 21 (September 30, 2003): 12183–88. http://dx.doi.org/10.1073/pnas.1635158100.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Ulitzur, N., A. Harel, N. Feinstein, and Y. Gruenbaum. "Lamin activity is essential for nuclear envelope assembly in a Drosophila embryo cell-free extract." Journal of Cell Biology 119, no. 1 (October 1, 1992): 17–25. http://dx.doi.org/10.1083/jcb.119.1.17.

Full text

Abstract:

The role of the Drosophila lamin protein in nuclear envelope assembly was studied using a Drosophila in vitro assembly system that reconstitutes nuclei from added sperm chromatin or naked DNA. Upon incubation of the embryonic assembly extract with anti-Drosophila lamin antibodies, the attachment of nuclear membrane vesicles to chromatin surface and nuclear envelope formation did not occur. Lamina assembly and nuclear membrane vesicles attachment to the chromatin were inhibited only when the activity of the 75-kD lamin isoform was inhibited in both soluble and membrane-vesicles fractions. Incubation of decondensed sperm chromatin with an extract that was depleted of nuclear membranes revealed the presence of lamin molecules on the chromatin periphery. In addition, high concentrations of bacterially expressed lamin molecules added to the extract, were able to associate with the chromatin periphery, and did not inhibit nuclear envelope assembly. After nuclear reconstitution, a fraction of the lamin pool was converted into the typical 74- and 76-kD isoforms. Together, these data strongly support an essential role of the lamina in nuclear envelope assembly.

APA, Harvard, Vancouver, ISO, and other styles

40

Sinclair, Paul, Qian Bian, Matt Plutz, Edith Heard, and Andrew S. Belmont. "Dynamic plasticity of large-scale chromatin structure revealed by self-assembly of engineered chromosome regions." Journal of Cell Biology 190, no. 5 (September 6, 2010): 761–76. http://dx.doi.org/10.1083/jcb.200912167.

Full text

Abstract:

Interphase chromatin compaction well above the 30-nm fiber is well documented, but the structural motifs underlying this level of chromatin folding remain unknown. Taking a reductionist approach, we analyzed in mouse embryonic stem (ES) cells and ES-derived fibroblasts and erythroblasts the folding of 10–160-megabase pair engineered chromosome regions consisting of tandem repeats of bacterial artificial chromosomes (BACs) containing ∼200 kilobases of mammalian genomic DNA tagged with lac operator (LacO) arrays. Unexpectedly, linear mitotic and interphase chromatid regions formed from noncontiguously folded DNA topologies. Particularly, in ES cells, these model chromosome regions self-organized with distant sequences segregating into functionally distinct, compact domains. Transcriptionally active and histone H3K27me3-modified regions positioned toward the engineered chromosome subterritory exterior, with LacO repeats and the BAC vector backbone localizing within an H3K9me3, HP1-enriched core. Differential compaction of Dhfr and α- and β-globin transgenes was superimposed on dramatic, lineage-specific reorganization of large-scale chromatin folding, demonstrating a surprising plasticity of large-scale chromatin organization.

APA, Harvard, Vancouver, ISO, and other styles

41

Young, Tiffany J., Yi Cui, Claire Pfeffer, Emilie Hobbs, Wenjie Liu, Joseph Irudayaraj, and Ann L. Kirchmaier. "CAF-1 and Rtt101p function within the replication-coupled chromatin assembly network to promote H4 K16ac, preventing ectopic silencing." PLOS Genetics 16, no. 12 (December 7, 2020): e1009226. http://dx.doi.org/10.1371/journal.pgen.1009226.

Full text

Abstract:

Replication-coupled chromatin assembly is achieved by a network of alternate pathways containing different chromatin assembly factors and histone-modifying enzymes that coordinate deposition of nucleosomes at the replication fork. Here we describe the organization of a CAF-1-dependent pathway in Saccharomyces cerevisiae that regulates acetylation of histone H4 K16. We demonstrate factors that function in this CAF-1-dependent pathway are important for preventing establishment of silenced states at inappropriate genomic sites using a crippled HMR locus as a model, while factors specific to other assembly pathways do not. This CAF-1-dependent pathway required the cullin Rtt101p, but was functionally distinct from an alternate pathway involving Rtt101p-dependent ubiquitination of histone H3 and the chromatin assembly factor Rtt106p. A major implication from this work is that cells have the inherent ability to create different chromatin modification patterns during DNA replication via differential processing and deposition of histones by distinct chromatin assembly pathways within the network.

APA, Harvard, Vancouver, ISO, and other styles

42

Conconi, Antonio, Michel Paquette, Deirdre Fahy, Vyacheslav A. Bespalov, and Michael J. Smerdon. "Repair-Independent Chromatin Assembly onto Active Ribosomal Genes in Yeast after UV Irradiation." Molecular and Cellular Biology 25, no. 22 (November 15, 2005): 9773–83. http://dx.doi.org/10.1128/mcb.25.22.9773-9783.2005.

Full text

Abstract:

ABSTRACT Chromatin rearrangements occur during repair of cyclobutane pyrimidine dimers (CPDs) by nucleotide excision repair (NER). Thereafter, the original structure must be restored to retain normal genomic functions. How NER proceeds through nonnucleosomal chromatin and how open chromatin is reestablished after repair are unknown. We analyzed NER in ribosomal genes (rDNA), which are present in multiple copies but only a fraction are actively transcribed and nonnucleosomal. We show that removal of CPDs is fast in the active rDNA and that chromatin reorganization occurs during NER. Furthermore, chromatin assembles on nonnucleosomal rDNA during the early events of NER but in the absence of DNA repair. The resumption of transcription after removal of CPDs correlates with the reappearance of nonnucleosomal chromatin. To date, only the passage of replication machinery was thought to package ribosomal genes in nucleosomes. In this report, we show that early events after formation of UV photoproducts in DNA also promote chromatin assembly.

APA, Harvard, Vancouver, ISO, and other styles

43

Rudner, Adam D., Brian E. Hall, Tom Ellenberger, and Danesh Moazed. "A Nonhistone Protein-Protein Interaction Required for Assembly of the SIR Complex and Silent Chromatin." Molecular and Cellular Biology 25, no. 11 (June 1, 2005): 4514–28. http://dx.doi.org/10.1128/mcb.25.11.4514-4528.2005.

Full text

Abstract:

ABSTRACT Budding yeast silent chromatin, or heterochromatin, is composed of histones and the Sir2, Sir3, and Sir4 proteins. Their assembly into silent chromatin is believed to require the deacetylation of histones by the NAD-dependent deacetylase Sir2 and the subsequent interaction of Sir3 and Sir4 with these hypoacetylated regions of chromatin. Here we explore the role of interactions among the Sir proteins in the assembly of the SIR complex and the formation of silent chromatin. We show that significant fractions of Sir2, Sir3, and Sir4 are associated together in a stable complex. When the assembly of Sir3 into this complex is disrupted by a specific mutation on the surface of the C-terminal coiled-coil domain of Sir4, Sir3 is no longer recruited to chromatin and silencing is disrupted. Because in sir4 mutant cells the association of Sir3 with chromatin is greatly reduced despite the partial Sir2-dependent deacetylation of histones near silencers, we conclude that histone deacetylation is not sufficient for the full recruitment of silencing proteins to chromatin and that Sir-Sir interactions are essential for the assembly of heterochromatin.

APA, Harvard, Vancouver, ISO, and other styles

44

Henikoff, Steven, and Kami Ahmad. "ASSEMBLY OF VARIANT HISTONES INTO CHROMATIN." Annual Review of Cell and Developmental Biology 21, no. 1 (November 2005): 133–53. http://dx.doi.org/10.1146/annurev.cellbio.21.012704.133518.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Almouzni, Geneviéve, David J. Clark, Marcel Méchali, and Alan P. Wolffe. "Chromatin assembly on replicating DNAin vitro." Nucleic Acids Research 18, no. 19 (1990): 5767–74. http://dx.doi.org/10.1093/nar/18.19.5767.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Clemente‐Ruiz, Marta, and Félix Prado. "Chromatin assembly controls replication fork stability." EMBO reports 10, no. 7 (May 22, 2009): 790–96. http://dx.doi.org/10.1038/embor.2009.67.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

duband-Goulet, Isabelle, Khalid Ouararhni, and Ali Hamiche. "Methods for chromatin assembly and remodeling." Methods 33, no. 1 (May 2004): 12–17. http://dx.doi.org/10.1016/j.ymeth.2003.10.015.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Spector, David J. "Default assembly of early adenovirus chromatin." Virology 359, no. 1 (March 2007): 116–25. http://dx.doi.org/10.1016/j.virol.2006.09.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Kadam, Shilpa, and Beverly M. Emerson. "Mechanisms of chromatin assembly and transcription." Current Opinion in Cell Biology 14, no. 3 (June 2002): 262–68. http://dx.doi.org/10.1016/s0955-0674(02)00330-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Krude, Torsten. "Chromatin: Nucleosome assembly during DNA replication." Current Biology 5, no. 11 (November 1995): 1232–34. http://dx.doi.org/10.1016/s0960-9822(95)00245-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Chromatin Assembly'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles