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Journal articles on the topic 'Molecular chaperone DnaK'

Author: Grafiati

Published: 3 June 2025

Last updated: 31 July 2025

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1

Silberg, Jonathan J., Kevin G. Hoff, and Larry E. Vickery. "The Hsc66-Hsc20 Chaperone System inEscherichia coli: Chaperone Activity and Interactions with the DnaK-DnaJ-GrpE System." Journal of Bacteriology 180, no. 24 (1998): 6617–24. http://dx.doi.org/10.1128/jb.180.24.6617-6624.1998.

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ABSTRACT Hsc66, a stress-70 protein, and Hsc20, a J-type accessory protein, comprise a newly described Hsp70-type chaperone system in addition to DnaK-DnaJ-GrpE in Escherichia coli. Because endogenous substrates for the Hsc66-Hsc20 system have not yet been identified, we investigated chaperone-like activities of Hsc66 and Hsc20 by their ability to suppress aggregation of denatured model substrate proteins, such as rhodanese, citrate synthase, and luciferase. Hsc66 suppressed aggregation of rhodanese and citrate synthase, and ATP caused effects consistent with complex destabilization typical of

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Acebrón, Sergio P., Vanesa Fernández-Sáiz, Stefka G. Taneva, Fernando Moro, and Arturo Muga. "DnaJ Recruits DnaK to Protein Aggregates." Journal of Biological Chemistry 283, no. 3 (2007): 1381–90. http://dx.doi.org/10.1074/jbc.m706189200.

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Thermal stress might lead to protein aggregation in the cell. Reactivation of protein aggregates depends on Hsp100 and Hsp70 chaperones. We focus in this study on the ability of DnaK, the bacterial representative of the Hsp70 family, to interact with different aggregated model substrates. Our data indicate that DnaK binding to large protein aggregates is mediated by DnaJ, and therefore it depends on its affinity for the cochaperone. Mutations in the structural region of DnaK known as the “latch” decrease the affinity of the chaperone for DnaJ, resulting in a defective activity as protein aggre

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3

Susin, Michelle F., Regina L. Baldini, Frederico Gueiros-Filho, and Suely L. Gomes. "GroES/GroEL and DnaK/DnaJ Have Distinct Roles in Stress Responses and during Cell Cycle Progression in Caulobacter crescentus." Journal of Bacteriology 188, no. 23 (2006): 8044–53. http://dx.doi.org/10.1128/jb.00824-06.

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ABSTRACT Misfolding and aggregation of protein molecules are major threats to all living organisms. Therefore, cells have evolved quality control systems for proteins consisting of molecular chaperones and proteases, which prevent protein aggregation by either refolding or degrading misfolded proteins. DnaK/DnaJ and GroES/GroEL are the best-characterized molecular chaperone systems in bacteria. In Caulobacter crescentus these chaperone machines are the products of essential genes, which are both induced by heat shock and cell cycle regulated. In this work, we characterized the viabilities of c

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Macario, Alberto J. L., and Everly Conway de Macario. "The Archaeal Molecular Chaperone Machine: Peculiarities and Paradoxes." Genetics 152, no. 4 (1999): 1277–83. http://dx.doi.org/10.1093/genetics/152.4.1277.

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Abstract A major finding within the field of archaea and molecular chaperones has been the demonstration that, while some species have the stress (heat-shock) gene hsp70(dnaK), others do not. This gene encodes Hsp70(DnaK), an essential molecular chaperone in bacteria and eukaryotes. Due to the physiological importance and the high degree of conservation of this protein, its absence in archaeal organisms has raised intriguing questions pertaining to the evolution of the chaperone machine as a whole and that of its components in particular, namely, Hsp70(DnaK), Hsp40(DnaJ), and GrpE. Another arc

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Lin, Jiusheng, and Mark A. Wilson. "Escherichia coli Thioredoxin-like Protein YbbN Contains an Atypical Tetratricopeptide Repeat Motif and Is a Negative Regulator of GroEL." Journal of Biological Chemistry 286, no. 22 (2011): 19459–69. http://dx.doi.org/10.1074/jbc.m111.238741.

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Many proteins contain a thioredoxin (Trx)-like domain fused with one or more partner domains that diversify protein function by the modular construction of new molecules. The Escherichia coli protein YbbN is a Trx-like protein that contains a C-terminal domain with low homology to tetratricopeptide repeat motifs. YbbN has been proposed to act as a chaperone or co-chaperone that aids in heat stress response and DNA synthesis. We report the crystal structure of YbbN, which is an elongated molecule with a mobile Trx domain and four atypical tetratricopeptide repeat motifs. The Trx domain lacks a

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Lupoli, Tania J., Allison Fay, Carolina Adura, Michael S. Glickman, and Carl F. Nathan. "Reconstitution of aMycobacterium tuberculosisproteostasis network highlights essential cofactor interactions with chaperone DnaK." Proceedings of the National Academy of Sciences 113, no. 49 (2016): E7947—E7956. http://dx.doi.org/10.1073/pnas.1617644113.

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During host infection,Mycobacterium tuberculosis(Mtb) encounters several types of stress that impair protein integrity, including reactive oxygen and nitrogen species and chemotherapy. The resulting protein aggregates can be resolved or degraded by molecular machinery conserved from bacteria to eukaryotes. Eukaryotic Hsp104/Hsp70 and their bacterial homologs ClpB/DnaK are ATP-powered chaperones that restore toxic protein aggregates to a native folded state. DnaK is essential inMycobacterium smegmatis, and ClpB is involved in asymmetrically distributing damaged proteins during cell division as

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Zmijewski, Michał A., Joanna Skórko-Glonek, Fabio Tanfani, et al. "Structural basis of the interspecies interaction between the chaperone DnaK(Hsp70) and the co-chaperone GrpE of archaea and bacteria." Acta Biochimica Polonica 54, no. 2 (2007): 245–52. http://dx.doi.org/10.18388/abp.2007_3244.

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Hsp70s are chaperone proteins that are conserved in evolution and present in all prokaryotic and eukaryotic organisms. In the archaea, which form a distinct kingdom, the Hsp70 chaperones have been found in some species only, including Methanosarcina mazei. Both the bacterial and archaeal Hsp70(DnaK) chaperones cooperate with a GrpE co-chaperone which stimulates the ATPase activity of the DnaK protein. It is currently believed that the archaeal Hsp70 system was obtained by the lateral transfer of chaperone genes from bacteria. Our previous finding that the DnaK and GrpE proteins of M. mazei can

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8

Koch, Birgit, Mogens Kilstrup, Finn K. Vogensen, and Karin Hammer. "Induced Levels of Heat Shock Proteins in adnaK Mutant of Lactococcus lactis." Journal of Bacteriology 180, no. 15 (1998): 3873–81. http://dx.doi.org/10.1128/jb.180.15.3873-3881.1998.

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ABSTRACT The bacterial heat shock response is characterized by the elevated expression of a number of chaperone complexes and proteases, including the DnaK-GrpE-DnaJ and the GroELS chaperone complexes. In order to investigate the importance of the DnaK chaperone complex for growth and heat shock response regulation in Lactococcus lactis, we have constructed two dnaK mutants with C-terminal deletions in dnaK. The minor deletion of 65 amino acids in the dnaKΔ2 mutant resulted in a slight temperature-sensitive phenotype. BK6, containing the larger deletion of 174 amino acids (dnaKΔ1), removing th

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Lebepe, Charity Mekgwa, Pearl Rutendo Matambanadzo, Xolani Henry Makhoba, Ikechukwu Achilonu, Tawanda Zininga, and Addmore Shonhai. "Comparative Characterization of Plasmodium falciparum Hsp70-1 Relative to E. coli DnaK Reveals the Functional Specificity of the Parasite Chaperone." Biomolecules 10, no. 6 (2020): 856. http://dx.doi.org/10.3390/biom10060856.

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Hsp70 is a conserved molecular chaperone. How Hsp70 exhibits specialized functions across species remains to be understood. Plasmodium falciparum Hsp70-1 (PfHsp70-1) and Escherichia coli DnaK are cytosol localized molecular chaperones that are important for the survival of these two organisms. In the current study, we investigated comparative structure-function features of PfHsp70-1 relative to DnaK and a chimeric protein, KPf, constituted by the ATPase domain of DnaK and the substrate binding domain (SBD) of PfHsp70-1. Recombinant forms of the three Hsp70s exhibited similar secondary and tert

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Lee, Jung Ho, Dongyu Zhang, Christopher Hughes, Yusuke Okuno, Ashok Sekhar, and Silvia Cavagnero. "Heterogeneous binding of the SH3 client protein to the DnaK molecular chaperone." Proceedings of the National Academy of Sciences 112, no. 31 (2015): E4206—E4215. http://dx.doi.org/10.1073/pnas.1505173112.

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The molecular chaperone heat shock protein 70 (Hsp70) plays a vital role in cellular processes, including protein folding and assembly, and helps prevent aggregation under physiological and stress-related conditions. Although the structural changes undergone by full-length client proteins upon interaction with DnaK (i.e., Escherichia coli Hsp70) are fundamental to understand chaperone-mediated protein folding, these changes are still largely unexplored. Here, we show that multiple conformations of the SRC homology 3 domain (SH3) client protein interact with the ADP-bound form of the DnaK chape

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11

Fink, Anthony L. "Chaperone-Mediated Protein Folding." Physiological Reviews 79, no. 2 (1999): 425–49. http://dx.doi.org/10.1152/physrev.1999.79.2.425.

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The folding of most newly synthesized proteins in the cell requires the interaction of a variety of protein cofactors known as molecular chaperones. These molecules recognize and bind to nascent polypeptide chains and partially folded intermediates of proteins, preventing their aggregation and misfolding. There are several families of chaperones; those most involved in protein folding are the 40-kDa heat shock protein (HSP40; DnaJ), 60-kDa heat shock protein (HSP60; GroEL), and 70-kDa heat shock protein (HSP70; DnaK) families. The availability of high-resolution structures has facilitated a mo

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Chattopadhyay, Madhab K., Renée Kern, Michel-Yves Mistou, Abhaya M. Dandekar, Sandra L. Uratsu, and Gilbert Richarme. "The Chemical Chaperone Proline Relieves the Thermosensitivity of a dnaK Deletion Mutant at 42°C." Journal of Bacteriology 186, no. 23 (2004): 8149–52. http://dx.doi.org/10.1128/jb.186.23.8149-8152.2004.

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ABSTRACT Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of γ-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the viability of a dnaK-deficient mutant at 42°C, suggesting that proline can act as a thermoprotectant for E. coli cells. Furthermore, analysis of aggregated proteins in the dnaK-deficient strain at 42°C by two-dimensional gel electrophoresis show

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Macario, Alberto J. L., Marianne Lange, Birgitte K. Ahring, and Everly Conway De Macario. "Stress Genes and Proteins in the Archaea." Microbiology and Molecular Biology Reviews 63, no. 4 (1999): 923–67. http://dx.doi.org/10.1128/mmbr.63.4.923-967.1999.

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SUMMARY The field covered in this review is new; the first sequence of a gene encoding the molecular chaperone Hsp70 and the first description of a chaperonin in the archaea were reported in 1991. These findings boosted research in other areas beyond the archaea that were directly relevant to bacteria and eukaryotes, for example, stress gene regulation, the structure-function relationship of the chaperonin complex, protein-based molecular phylogeny of organisms and eukaryotic-cell organelles, molecular biology and biochemistry of life in extreme environments, and stress tolerance at the cellul

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14

Zmijewski, Michal A., Joanna Skórko-Glonek, Fabio Tanfani, et al. "The DnaK chaperones from the archaeon Methanosarcina mazei and the bacterium Escherichia coli have different substrate specificities." Acta Biochimica Polonica 54, no. 3 (2007): 509–22. http://dx.doi.org/10.18388/abp.2007_3225.

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Hsp70 (DnaK) is a highly conserved molecular chaperone present in bacteria, eukaryotes, and some archaea. In a previous work we demonstrated that DnaK from the archaeon Methanosarcina mazei (DnaK(Mm)) and the DnaK from the bacterium Escherichia coli (DnaK(Ec)) were functionally similar when assayed in vitro but DnaK(Mm) failed to substitute for DnaK(Ec) in vivo. Searching for the molecular basis of the observed DnaK species specificity we compared substrate binding by DnaK(Mm) and DnaK(Ec). DnaK(Mm) showed a lower affinity for the model peptide (a-CALLQSRLLS) compared to DnaK(Ec). Furthermore,

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15

HAN, Wanjiang, and Philipp CHRISTEN. "Interdomain communication in the molecular chaperone DnaK." Biochemical Journal 369, no. 3 (2003): 627–34. http://dx.doi.org/10.1042/bj20020943.

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DnaK, a heat-shock protein 70 (Hsp70) homologue in Escherichia coli, possesses a single tryptophan residue in its ATPase domain. Changes in the intrinsic fluorescence of DnaK offer a simple means not only to follow the binding of ATP and of ADP plus the co-chaperone GrpE to the ATPase domain, but also to investigate the kinetics of peptide binding to the substrate-binding domain of ATP·DnaK and GrpE-liganded ADP·DnaK. Addition of ATP or of ADP plus GrpE to nucleotide-free DnaK resulted in a similar decrease in intrinsic fluorescence, indicating similar open conformations of the ATPase domain u

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Grindle, Matthew P., Ben Carter, John Paul Alao, Katherine Connors, Riina Tehver, and Andrea N. Kravats. "Structural Communication between the E. coli Chaperones DnaK and Hsp90." International Journal of Molecular Sciences 22, no. 4 (2021): 2200. http://dx.doi.org/10.3390/ijms22042200.

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The 70 kDa and 90 kDa heat shock proteins Hsp70 and Hsp90 are two abundant and highly conserved ATP-dependent molecular chaperones that participate in the maintenance of cellular homeostasis. In Escherichia coli, Hsp90 (Hsp90Ec) and Hsp70 (DnaK) directly interact and collaborate in protein remodeling. Previous work has produced a model of the direct interaction of both chaperones. The locations of the residues involved have been confirmed and the model has been validated. In this study, we investigate the allosteric communication between Hsp90Ec and DnaK and how the chaperones couple their con

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Gur, Eyal, Dvora Biran, Nelia Shechter, Pierre Genevaux, Costa Georgopoulos, and Eliora Z. Ron. "The Escherichia coli DjlA and CbpA Proteins Can Substitute for DnaJ in DnaK-Mediated Protein Disaggregation." Journal of Bacteriology 186, no. 21 (2004): 7236–42. http://dx.doi.org/10.1128/jb.186.21.7236-7242.2004.

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ABSTRACT The DnaJ (Hsp40) protein of Escherichia coli serves as a cochaperone of DnaK (Hsp70), whose activity is involved in protein folding, protein targeting for degradation, and rescue of proteins from aggregates. Two other E. coli proteins, CbpA and DjlA, which exhibit homology with DnaJ, are known to interact with DnaK and to stimulate its chaperone activity. Although it has been shown that in dnaJ mutants both CbpA and DjlA are essential for growth at temperatures above 37°C, their in vivo role is poorly understood. Here we show that in a dnaJ mutant both CbpA and DjlA are required for e

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Lopes Ferreira, Nicolas, та Jean-Hervé Alix. "The DnaK Chaperone Is Necessary for α-Complementation of β-Galactosidase in Escherichia coli". Journal of Bacteriology 184, № 24 (2002): 7047–54. http://dx.doi.org/10.1128/jb.184.24.7047-7054.2002.

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ABSTRACT We show here the involvement of the molecular chaperone DnaK from Escherichia coli in the in vivo α-complementation of the β-galactosidase. In the dnaK756(Ts) mutant, α-complementation occurs when the organisms are grown at 30°C but not at 37 or 40°C, although these temperatures are permissive for bacterial growth. Plasmid-driven expression of wild-type dnaK restores the α-complementation in the mutant but also stimulates it in a dnaK + strain. In a mutant which contains a disrupted dnaK gene (ΔdnaK52::Cmr), α-complementation is also impaired, even at 30°C. This observation provides a

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Chan, Carissa, and Eduardo A. Groisman. "Chaperone Hsp70 helps Salmonella survive infection-relevant stress by reducing protein synthesis." PLOS Biology 22, no. 4 (2024): e3002560. http://dx.doi.org/10.1371/journal.pbio.3002560.

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In all domains of life, Hsp70 chaperones preserve protein homeostasis by promoting protein folding and degradation and preventing protein aggregation. We now report that the Hsp70 from the bacterial pathogen Salmonella enterica serovar Typhimurium—termed DnaK—independently reduces protein synthesis in vitro and in S. Typhimurium facing cytoplasmic Mg2+ starvation, a condition encountered during infection. This reduction reflects a 3-fold increase in ribosome association with DnaK and a 30-fold decrease in ribosome association with trigger factor, the chaperone normally associated with translat

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Stemp, Markus J., Suranjana Guha, F. Ulrich Hartl, and José M. Barral. "Efficient production of native actin upon translation in a bacterial lysate supplemented with the eukaryotic chaperonin TRiC." Biological Chemistry 386, no. 8 (2005): 753–57. http://dx.doi.org/10.1515/bc.2005.088.

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Abstract Recombinant expression of actin in bacteria results in non-native species that aggregate into inclusion bodies. Actin is a folding substrate of TRiC, the chaperonin of the eukaryotic cytosol. By employing bacterial in vitro translation lysates supplemented with purified chaperones, we have found that TRiC is the only eukaryotic chaperone necessary for correct folding of newly translated actin. The actin thus produced binds deoxyribonuclease I and polymerizes into filaments, hallmarks of its native state. In contrast to its rapid folding in the eukaryotic cytosol, actin translated in T

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Horikoshi, Mina, Takashi Yura, Sachie Tsuchimoto, Yoshihiro Fukumori та Masaaki Kanemori. "Conserved Region 2.1 of Escherichia coli Heat Shock Transcription Factor σ32 Is Required for Modulating both Metabolic Stability and Transcriptional Activity". Journal of Bacteriology 186, № 22 (2004): 7474–80. http://dx.doi.org/10.1128/jb.186.22.7474-7480.2004.

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ABSTRACT Escherichia coli heat shock transcription factor σ32 is rapidly degraded in vivo, with a half-life of about 1 min. A set of proteins that includes the DnaK chaperone team (DnaK, DnaJ, GrpE) and ATP-dependent proteases (FtsH, HslUV, etc.) are involved in degradation of σ32. To gain further insight into the regulation of σ32 stability, we isolated σ32 mutants that were markedly stabilized. Many of the mutants had amino acid substitutions in the N-terminal half (residues 47 to 55) of region 2.1, a region highly conserved among bacterial σ factors. The half-lives ranged from about 2-fold

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Chenoweth, Matthew R., Nancy Trun, and Sue Wickner. "In Vivo Modulation of a DnaJ Homolog, CbpA, by CbpM." Journal of Bacteriology 189, no. 9 (2007): 3635–38. http://dx.doi.org/10.1128/jb.01757-06.

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ABSTRACT CbpA, an Escherichia coli DnaJ homolog, can function as a cochaperone for the DnaK/Hsp70 chaperone system, and its in vitro activity can be modulated by CbpM. We discovered that CbpM specifically inhibits the in vivo activity of CbpA, preventing it from functioning in cell growth and division. Furthermore, we have shown that CbpM interacts with CbpA in vivo during stationary phase, suggesting that the inhibition of activity is a result of the interaction. These results reveal that the activity of the E. coli DnaK system can be regulated in vivo by a specific inhibitor.

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Arita-Morioka, Ken-ichi, Kunitoshi Yamanaka, Yoshimitsu Mizunoe, Teru Ogura, and Shinya Sugimoto. "Novel Strategy for Biofilm Inhibition by Using Small Molecules Targeting Molecular Chaperone DnaK." Antimicrobial Agents and Chemotherapy 59, no. 1 (2014): 633–41. http://dx.doi.org/10.1128/aac.04465-14.

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ABSTRACTBiofilms are complex communities of microorganisms that attach to surfaces and are embedded in a self-produced extracellular matrix. Since these cells acquire increased tolerance against antimicrobial agents and host immune systems, biofilm-associated infectious diseases tend to become chronic. We show here that the molecular chaperone DnaK is important for biofilm formation and that chemical inhibition of DnaK cellular functions is effective in preventing biofilm development. Genetic, microbial, and microscopic analyses revealed that deletion of thednaKgene markedly reduced the produc

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Genevaux, Pierre, Françoise Schwager, Costa Georgopoulos, and William L. Kelley. "The djlA Gene Acts Synergistically with dnaJ in Promoting Escherichia coli Growth." Journal of Bacteriology 183, no. 19 (2001): 5747–50. http://dx.doi.org/10.1128/jb.183.19.5747-5750.2001.

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ABSTRACT The DnaK chaperone of Escherichia coli is known to interact with the J domains of DnaJ, CbpA, and DjlA. By constructing multiple mutants, we found that the djlA gene was essential for bacterial growth above 37°C in the absence ofdnaJ. This essentiality depended upon the J domain of DjlA but not upon the normal membrane location of DjlA.

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Nordquist, Erik B., Charles A. English, Eugenia M. Clerico, Woody Sherman, Lila M. Gierasch, and Jianhan Chen. "Physics-based modeling provides predictive understanding of selectively promiscuous substrate binding by Hsp70 chaperones." PLOS Computational Biology 17, no. 11 (2021): e1009567. http://dx.doi.org/10.1371/journal.pcbi.1009567.

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To help cells cope with protein misfolding and aggregation, Hsp70 molecular chaperones selectively bind a variety of sequences (“selective promiscuity”). Statistical analyses from substrate-derived peptide arrays reveal that DnaK, the E. coli Hsp70, binds to sequences containing three to five branched hydrophobic residues, although otherwise the specific amino acids can vary considerably. Several high-resolution structures of the substrate -binding domain (SBD) of DnaK bound to peptides reveal a highly conserved configuration of the bound substrate and further suggest that the substrate-bindin

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Lemos, José A. C., Yi-Ywan M. Chen, and Robert A. Burne. "Genetic and Physiologic Analysis of thegroE Operon and Role of the HrcA Repressor in Stress Gene Regulation and Acid Tolerance in Streptococcus mutans." Journal of Bacteriology 183, no. 20 (2001): 6074–84. http://dx.doi.org/10.1128/jb.183.20.6074-6084.2001.

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ABSTRACT Our working hypothesis is that the major molecular chaperones DnaK and GroE play central roles in the ability of oral bacteria to cope with the rapid and frequent stresses encountered in oral biofilms, such as acidification and nutrient limitation. Previously, our laboratory partially characterized the dnaK operon ofStreptococcus mutans(hrcA-grpE-dnaK) and demonstrated that dnaK is up-regulated in response to acid shock and sustained acidification (G. C. Jayaraman, J. E. Penders, and R. A. Burne, Mol. Microbiol. 25:329–341, 1997). Here, we show that thegroESL genes of S. mutans consti

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Swain, Joanna F., Renuka Sivendran, and Lila M. Gierasch. "Defining the structure of the substrate-free state of the DnaK molecular chaperone." Biochemical Society Symposia 68 (August 1, 2001): 69–82. http://dx.doi.org/10.1042/bss0680069.

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Members of the Hsp70 (heat-shock protein of 70 kDa) family of molecular chaperones bind to exposed hydrophobic stretches on substrate proteins in order to dissociate molecular complexes and prevent aggregation in the cell. Substrate affinity for the C-terminal domain of the Hsp70 is regulated by ATP binding to the N-terminal domain utilizing an allosteric mechanism. Our multi-dimensional NMR studies of a substrate-binding domain fragment (amino acids 387-552) from an Escherichia coli Hsp70, DnaK(387-552), have uncovered a pH-dependent conformational change, which we propose to be relevant for

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Minagawa, Shun, Yasumitsu Kondoh, Keigo Sueoka, Hiroyuki Osada, and Hitoshi Nakamoto. "Cyclic lipopeptide antibiotics bind to the N-terminal domain of the prokaryotic Hsp90 to inhibit the chaperone activity." Biochemical Journal 435, no. 1 (2011): 237–46. http://dx.doi.org/10.1042/bj20100743.

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Chemical arrays were employed to screen ligands for HtpG, the prokaryotic homologue of Hsp (heat-shock protein) 90. We found that colistins and the closely related polymyxin B interact physically with HtpG. They bind to the N-terminal domain of HtpG specifically without affecting its ATPase activity. The interaction caused inhibition of chaperone function of HtpG that suppresses thermal aggregation of substrate proteins. Further studies were performed with one of these cyclic lipopeptide antibiotics, colistin sulfate salt. It inhibited the chaperone function of the N-terminal domain of HtpG. H

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Liebscher, Markus, and Anna Roujeinikova. "Allosteric Coupling between the Lid and Interdomain Linker in DnaK Revealed by Inhibitor Binding Studies." Journal of Bacteriology 191, no. 5 (2008): 1456–62. http://dx.doi.org/10.1128/jb.01131-08.

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ABSTRACT The molecular chaperone DnaK assists protein folding and refolding, translocation across membranes, and regulation of the heat shock response. In Escherichia coli, the protein is a target for insect-derived antimicrobial peptides, pyrrhocoricins. We present here the X-ray crystallographic analysis of the E. coli DnaK substrate-binding domain in complex with pyrrhocoricin-derived peptide inhibitors. The structures show that pyrrhocoricins act as site-specific, dual-mode (competitive and allosteric) inhibitors, occupying the substrate-binding tunnel and disrupting the latch between the

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Eaton, Daniel S., Sean Crosson, and Aretha Fiebig. "Proper Control of Caulobacter crescentus Cell Surface Adhesion Requires the General Protein Chaperone DnaK." Journal of Bacteriology 198, no. 19 (2016): 2631–42. http://dx.doi.org/10.1128/jb.00027-16.

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ABSTRACTGrowth in a surface-attached bacterial community, or biofilm, confers a number of advantages. However, as a biofilm matures, high-density growth imposes stresses on individual cells, and it can become less advantageous for progeny to remain in the community. Thus, bacteria employ a variety of mechanisms to control attachment to and dispersal from surfaces in response to the state of the environment. The freshwater oligotrophCaulobacter crescentuscan elaborate a polysaccharide-rich polar organelle, known as the holdfast, which enables permanent surface attachment. Holdfast development i

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Gustavsson, Kristina, Tomas Bergman, Andres Veide, and Sven‐Olof Enfors. "Invitro complex‐formation between the molecular chaperone DnaK and staphylococcal ProteinA derivatives produced in Escherichia coli and its use inthe purification of DnaK." Biotechnology and Applied Biochemistry 25, no. 2 (1997): 173–80. http://dx.doi.org/10.1111/j.1470-8744.1997.tb00430.x.

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Complex‐formation between a truncated staphylococcal Protein A produced in Escherichia coli and a native E. coli molecular chaperone, DnaK, can be used for the purification of DnaK by IgG‐affinity chromatography. The half‐time constant for in vitro formation of the Protein AŐDnaK complex is about 14 min. Complex‐formation in the presence of ATP is faster, but pre‐incubation of DnaK with ATP decreases the final amount of the complex. A second complex with a slower migration on native PAGE is formed when the ratio of DnaK to Protein A is increased. A derivative of Protein A, ZZ, which essentiall

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Wickner, S., S. Gottesman, D. Skowyra, J. Hoskins, K. McKenney, and M. R. Maurizi. "A molecular chaperone, ClpA, functions like DnaK and DnaJ." Proceedings of the National Academy of Sciences 91, no. 25 (1994): 12218–22. http://dx.doi.org/10.1073/pnas.91.25.12218.

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Miyata, Yoshinari, Lyra Chang, Anthony Bainor, et al. "High-Throughput Screen for Escherichia coli Heat Shock Protein 70 (Hsp70/DnaK)." Journal of Biomolecular Screening 15, no. 10 (2010): 1211–19. http://dx.doi.org/10.1177/1087057110380571.

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Members of the heat shock protein 70 (Hsp70) family of molecular chaperones are emerging as potential therapeutic targets. Their ATPase activity has classically been measured using colorimetric phosphate detection reagents, such as quinaldine red (QR). Although such assays are suitable for 96-well plate formats, they typically lose sensitivity when attempted in lower volume due to path length and meniscus effects. These limitations and Hsp70’s weak enzymatic activity have combined to create significant challenges in high-throughput screening. To overcome these difficulties, the authors have ad

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Maisonneuve, Etienne, Laetitia Fraysse, Danielle Moinier, and Sam Dukan. "Existence of Abnormal Protein Aggregates in Healthy Escherichia coli Cells." Journal of Bacteriology 190, no. 3 (2007): 887–93. http://dx.doi.org/10.1128/jb.01603-07.

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ABSTRACT Protein aggregation is a phenomenon observed in all organisms and has often been linked with cell disorders. In addition, several groups have reported a virtual absence of protein aggregates in healthy cells. In contrast to previous studies and the expected outcome, we observed aggregated proteins in aerobic exponentially growing and “healthy” Escherichia coli cells. We observed overrepresentation of “aberrant proteins,” as well as substrates of the major conserved chaperone DnaK (Hsp70) and the protease ClpXP (a serine protease), in the aggregates. In addition, the protein aggregates

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Suppini, Jean-Philippe, Mouna Amor, Jean-Hervé Alix, and Moncef M. Ladjimi. "Complementation of an Escherichia coli DnaK Defect by Hsc70-DnaK Chimeric Proteins." Journal of Bacteriology 186, no. 18 (2004): 6248–53. http://dx.doi.org/10.1128/jb.186.18.6248-6253.2004.

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ABSTRACT Escherichia coli DnaK and rat Hsc70 are members of the highly conserved 70-kDa heat shock protein (Hsp70) family that show strong sequence and structure similarities and comparable functional properties in terms of interactions with peptides and unfolded proteins and cooperation with cochaperones. We show here that, while the DnaK protein is, as expected, able to complement an E. coli dnaK mutant strain for growth at high temperatures and λ phage propagation, Hsc70 protein is not. However, an Hsc70 in which the peptide-binding domain has been replaced by that of DnaK is able to comple

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Nakahigashi, Kenji, Hideki Yanagi та Takashi Yura. "DnaK Chaperone-Mediated Control of Activity of a ς32 Homolog (RpoH) Plays a Major Role in the Heat Shock Response of Agrobacterium tumefaciens". Journal of Bacteriology 183, № 18 (2001): 5302–10. http://dx.doi.org/10.1128/jb.183.18.5302-5310.2001.

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ABSTRACT RpoH (Escherichia coli ς32 and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. Here we studied salient regulatory features of RpoH in Agrobacterium tumefaciens by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37°C. Heat induction of RpoH synthesis occurred at the level of transcription from an RpoH-dependent promoter, coordinately with that of DnaK, and followed by an increase in the RpoH level. Essentially normal induction of heat shock proteins was observed even with a strain that was u

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Rajaram, Hema, Akhilesh Kumar Chaurasia, and Shree Kumar Apte. "Cyanobacterial heat-shock response: role and regulation of molecular chaperones." Microbiology 160, no. 4 (2014): 647–58. http://dx.doi.org/10.1099/mic.0.073478-0.

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Cyanobacteria constitute a morphologically diverse group of oxygenic photoautotrophic microbes which range from unicellular to multicellular, and non-nitrogen-fixing to nitrogen-fixing types. Sustained long-term exposure to changing environmental conditions, during their three billion years of evolution, has presumably led to their adaptation to diverse ecological niches. The ability to maintain protein conformational homeostasis (folding–misfolding–refolding or aggregation–degradation) by molecular chaperones holds the key to the stress adaptability of cyanobacteria. Although cyanobacteria po

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Sugimoto, Shinya, Hiroyuki Yoshida, Yoshimitsu Mizunoe, Keigo Tsuruno, Jiro Nakayama, and Kenji Sonomoto. "Structural and Functional Conversion of Molecular Chaperone ClpB from the Gram-Positive Halophilic Lactic Acid Bacterium Tetragenococcus halophilus Mediated by ATP and Stress." Journal of Bacteriology 188, no. 23 (2006): 8070–78. http://dx.doi.org/10.1128/jb.00404-06.

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ABSTRACT In this study, we report the purification, initial structural characterization, and functional analysis of the molecular chaperone ClpB from the gram-positive, halophilic lactic acid bacterium Tetragenococcus halophilus. A recombinant T. halophilus ClpB (ClpB Tha ) was overexpressed in Escherichia coli and purified by affinity chromatography, hydroxyapatite chromatography, and gel filtration chromatography. As demonstrated by gel filtration chromatography, chemical cross-linking with glutaraldehyde, and electron microscopy, ClpB Tha forms a homohexameric single-ring structure in the p

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Zhuravleva, Anastasia, and Lila M. Gierasch. "Substrate-binding domain conformational dynamics mediate Hsp70 allostery." Proceedings of the National Academy of Sciences 112, no. 22 (2015): E2865—E2873. http://dx.doi.org/10.1073/pnas.1506692112.

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Binding of ATP to the N-terminal nucleotide-binding domain (NBD) of heat shock protein 70 (Hsp70) molecular chaperones reduces the affinity of their C-terminal substrate-binding domain (SBD) for unfolded protein substrates. ATP binding to the NBD leads to docking between NBD and βSBD and releasing of the α-helical lid that covers the substrate-binding cleft in the SBD. However, these structural changes alone do not fully account for the allosteric mechanism of modulation of substrate affinity and binding kinetics. Through a multipronged study of the Escherichia coli Hsp70 DnaK, we found that c

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Witt, Stephan N., Floyd J. Galiano, and Sergey V. Slepenkov. "Reactions of protamine with the molecular chaperone DnaK." Cell Stress & Chaperones 2, no. 2 (1997): 110. http://dx.doi.org/10.1379/1466-1268(1997)002<0110:ropwtm>2.3.co;2.

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Pepe, Simona, Vincenzo Scarlato, and Davide Roncarati. "The Helicobacter pylori HspR-Modulator CbpA Is a Multifunctional Heat-Shock Protein." Microorganisms 8, no. 2 (2020): 251. http://dx.doi.org/10.3390/microorganisms8020251.

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The medically important human pathogen Helicobacter pylori relies on a collection of highly conserved heat-shock and chaperone proteins to preserve the integrity of cellular polypeptides and to control their homeostasis in response to external stress and changing environmental conditions. Among this set of chaperones, the CbpA protein has been shown to play a regulatory role in heat-shock gene regulation by directly interacting with the master stress-responsive repressor HspR. Apart from this regulatory role, little is known so far about CbpA functional activities. Using biochemistry and molec

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Makumire, Stanley, Tendamudzimu Harmfree Dongola, Graham Chakafana, et al. "Mutation of GGMP Repeat Segments of Plasmodium falciparum Hsp70-1 Compromises Chaperone Function and Hop Co-Chaperone Binding." International Journal of Molecular Sciences 22, no. 4 (2021): 2226. http://dx.doi.org/10.3390/ijms22042226.

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Parasitic organisms especially those of the Apicomplexan phylum, harbour a cytosol localised canonical Hsp70 chaperone. One of the defining features of this protein is the presence of GGMP repeat residues sandwiched between α-helical lid and C-terminal EEVD motif. The role of the GGMP repeats of Hsp70s remains unknown. In the current study, we introduced GGMP mutations in the cytosol localised Hsp70-1 of Plasmodium falciparum (PfHsp70-1) and a chimeric protein (KPf), constituted by the ATPase domain of E. coli DnaK fused to the C-terminal substrate binding domain of PfHsp70-1. A complementatio

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Suh, W. C., W. F. Burkholder, C. Z. Lu, X. Zhao, M. E. Gottesman, and C. A. Gross. "Interaction of the Hsp70 molecular chaperone, DnaK, with its cochaperone DnaJ." Proceedings of the National Academy of Sciences 95, no. 26 (1998): 15223–28. http://dx.doi.org/10.1073/pnas.95.26.15223.

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Liebscher, Markus, Günther Jahreis, Christian Lücke, Susanne Grabley, Satish Raina, and Cordelia Schiene-Fischer. "Fatty Acyl Benzamido Antibacterials Based on Inhibition of DnaK-catalyzed Protein Folding." Journal of Biological Chemistry 282, no. 7 (2006): 4437–46. http://dx.doi.org/10.1074/jbc.m607667200.

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We have reported that the hsp70 chaperone DnaK from Escherichia coli might assist protein folding by catalyzing the cis/trans isomerization of secondary amide peptide bonds in unfolded or partially folded proteins. In this study a series of fatty acylated benzamido inhibitors of the cis/trans isomerase activity of DnaK was developed and tested for antibacterial effects in E. coli MC4100 cells. Nα-[Tetradecanoyl-(4-aminomethylbenzoyl)]-l-asparagine is the most effective antibacterial with a minimal inhibitory concentration of 100 ± 20 μg/ml. The compounds were shown to compete with fluorophore-

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Benedetti, Francesca, Fiorenza Cocchi, Olga S. Latinovic, et al. "Role of Mycoplasma Chaperone DnaK in Cellular Transformation." International Journal of Molecular Sciences 21, no. 4 (2020): 1311. http://dx.doi.org/10.3390/ijms21041311.

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Studies of the human microbiome have elucidated an array of complex interactions between prokaryotes and their hosts. However, precise bacterial pathogen–cancer relationships remain largely elusive, although several bacteria, particularly those establishing persistent intra-cellular infections, like mycoplasmas, can alter host cell cycles, affect apoptotic pathways, and stimulate the production of inflammatory substances linked to DNA damage, thus potentially promoting abnormal cell growth and transformation. Consistent with this idea, in vivo experiments in several chemically induced or genet

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Slepenkov, Sergey V., and Stephan N. Witt. "Peptide-Induced Conformational Changes in the Molecular Chaperone DnaK†." Biochemistry 37, no. 47 (1998): 16749–56. http://dx.doi.org/10.1021/bi981738k.

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Liu, W., D. Bratko, J. M. Prausnitz, and H. W. Blanch. "Electrostatic Interactions between Peptides and the Molecular Chaperone DnaK." Journal of Physical Chemistry B 107, no. 41 (2003): 11563–69. http://dx.doi.org/10.1021/jp035872c.

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Feifel, Bastian, Erika Sandmeier, Hans-Joachim Schonfeld, and Philipp Christen. "Potassium Ions and the Molecular-Chaperone Activity of DnaK." European Journal of Biochemistry 237, no. 1 (1996): 318–21. http://dx.doi.org/10.1111/j.1432-1033.1996.0318n.x.

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Arsène, Florence, Toshifumi Tomoyasu, Axel Mogk, Christiane Schirra, Agnes Schulze-Specking та Bernd Bukau. "Role of Region C in Regulation of the Heat Shock Gene-Specific Sigma Factor of Escherichia coli, ς32". Journal of Bacteriology 181, № 11 (1999): 3552–61. http://dx.doi.org/10.1128/jb.181.11.3552-3561.1999.

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ABSTRACT Expression of heat shock genes is controlled in Escherichia coli by the antagonistic action of the ς32 subunit of RNA polymerase and the DnaK chaperone system, which inactivates ς32 by stress-dependent association and mediates ς32 degradation by the FtsH protease. A stretch of 23 residues (R122 to Q144) conserved among ς32 homologs, termed region C, was proposed to play a role in ς32degradation, and peptide analysis identified two potential DnaK binding sites central and peripheral to region C. Region C is thus a prime candidate for mediating stress control of ς32, a hypothesis that w

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Banecki, Bogdan, and Maciej Zylicz. "Real Time Kinetics of the DnaK/DnaJ/GrpE Molecular Chaperone Machine Action." Journal of Biological Chemistry 271, no. 11 (1996): 6137–43. http://dx.doi.org/10.1074/jbc.271.11.6137.

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