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Journal articles on the topic 'Facteur sigma'

Author: Grafiati

Published: 4 June 2021

Last updated: 7 February 2022

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1

Kovarz, L., C. Coynault, V. Robbe-Saule, and F. Norel. "Rôle du facteur sigma σs (RpoS) dans la virulence de Salmonella typhimurium." Médecine et Maladies Infectieuses 25, no. 10 (October 1995): 1031–34. http://dx.doi.org/10.1016/s0399-077x(05)80327-0.

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2

De Las Peñas, A., L. Connolly, and C. A. Gross. "SigmaE is an essential sigma factor in Escherichia coli." Journal of bacteriology 179, no. 21 (1997): 6862–64. http://dx.doi.org/10.1128/jb.179.21.6862-6864.1997.

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3

Schmid, Solveig, Claudia Bevilacqua, and Anne-Marie Crutz-Le Coq. "Alternative sigma factor sigmaH activates competence gene expression in Lactobacillus sakei." BMC Microbiology 12, no. 1 (2012): 32. http://dx.doi.org/10.1186/1471-2180-12-32.

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4

Loewen, P. C., and R. Hengge-Aronis. "The Role of the Sigma Factor sigmas (KatF) in Bacterial Global Regulation." Annual Review of Microbiology 48, no. 1 (October 1994): 53–80. http://dx.doi.org/10.1146/annurev.mi.48.100194.000413.

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5

Yu, H., J. C. Boucher, N. S. Hibler, and V. Deretic. "Virulence properties of Pseudomonas aeruginosa lacking the extreme-stress sigma factor AlgU (sigmaE)." Infection and immunity 64, no. 7 (1996): 2774–81. http://dx.doi.org/10.1128/iai.64.7.2774-2781.1996.

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6

Huang, Xuejun, Ahmed Gaballa, Min Cao, and John D. Helmann. "Identification of target promoters for the Bacillus subtilis extracytoplasmic function sigma factor, sigmaW." Molecular Microbiology 31, no. 1 (January 1999): 361–71. http://dx.doi.org/10.1046/j.1365-2958.1999.01180.x.

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7

Loewen, Peter C., Bei Hu, Jeanna Strutinsky, and Richard Sparling. "Regulation in the rpoS regulon of Escherichia coli." Canadian Journal of Microbiology 44, no. 8 (August 1, 1998): 707–17. http://dx.doi.org/10.1139/w98-069.

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In Escherichia coli, the transcription factor sigmaS, encoded by rpoS, controls the expression of a large number of genes involved in cellular responses to a diverse number of stresses, including starvation, osmotic stress, acid shock, cold shock, heat shock, oxidative DNA damage, and transition to stationary phase. A list of over 50 genes under the control of rpoS has been compiled. The transcription factor sigmaS acts predominantly as a positive effector, but it does have a negative effect on some genes. The synthesis and accumulation of sigmaS are controlled by mechanisms affecting transcription, translation, proteolysis, and the formation of the holoenzyme complex. Transcriptional control of rpoS involves guanosine 3',5'-bispyrophosphate (ppGpp) and polyphosphate as positive regulators and the cAMP receptor protein - cAMP complex (CRP-cAMP) as a negative regulator. Translation of rpoS mRNA is controlled by a cascade of interacting factors, including Hfq, H-NS, dsrA RNA, LeuO, and oxyS RNA that seem to modulate the stability of a region of secondary structure in the ribosome-binding region of the gene's mRNA. The transcription factor sigmaS is sensitive to proteolysis by ClpPX in a reaction that is promoted by RssB and inhibited by the chaperone DnaK. Despite the demonstrated involvement of so many factors, arguments have been presented suggesting that sensitivity to proteolysis may be the single most important modulator of sigmaS levels. The activity of sigmaS may also be modulated by trehalose and glutamate, which activate holoenzyme formation and promote holoenzyme binding to certain promoters. Key words: transcription, translation, regulation, sigma factor, starvation.

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8

Manganelli, Riccardo, Martin I. Voskuil, Gary K. Schoolnik, Eugenie Dubnau, Manuel Gomez, and Issar Smith. "Role of the extracytoplasmic-function sigma Factor sigmaH in Mycobacterium tuberculosis global gene expression." Molecular Microbiology 45, no. 2 (July 2002): 365–74. http://dx.doi.org/10.1046/j.1365-2958.2002.03005.x.

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9

Otani, Hiroshi, Akiyoshi Higo, Hideaki Nanamiya, Sueharu Horinouchi, and Yasuo Ohnishi. "An alternative sigma factor governs the principal sigma factor inStreptomyces griseus." Molecular Microbiology 87, no. 6 (February 21, 2013): 1223–36. http://dx.doi.org/10.1111/mmi.12160.

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10

Chang, B. Y., and R. H. Doi. "Conformational properties of Bacillus subtilis RNA polymerase σA factor during transcription initiation." Biochemical Journal 294, no. 1 (August 15, 1993): 43–47. http://dx.doi.org/10.1042/bj2940043.

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By the use of a partial proteolysis method and Western-blot analysis, the conformational properties of Bacillus subtilis sigma A factor in the transcription initiation stage were studied. From a comparison of the trypsin-digestion patterns of free sigma A and of sigma A associated with core enzyme, it was found that the production of 45 kDa sigma A tryptic-derived fragment was enhanced when sigma A was associated with the core enzyme. More importantly, a 40 kDa sigma A tryptic-derived fragment was found exclusively in this associated state. Based on the change of the digestion kinetics when producing the 45 kDa tryptic fragment and the generation of this new 40 kDa tryptic fragment from sigma A, it was apparent that a conformation change of sigma A occurred during the association of sigma A with the core enzyme. Also, similar patterns were found for the sigma A present in the holoenzyme-promoter DNA complex. These findings suggest that no further distinctive conformational change of sigma A occurs at the step of RNA polymerase holoenzyme and promoter DNA complex formation. Trypsin-digestion patterns of sigma A in different RNA polymerase holoenzyme and promoter DNA complexes were also studied. The presence of similar trypsin digestion-patterns of sigma A in those complexes strongly supports the idea that a similar sigma A conformation is used in the recognition of different sigma A-type promoters and the formation of different open complexes.

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11

Jaehning, J. "Sigma factor relatives in eukaryotes." Science 253, no. 5022 (August 23, 1991): 859. http://dx.doi.org/10.1126/science.1876846.

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12

van Ooij, Christiaan. "Regulation by sigma factor mimicry." Nature Reviews Microbiology 7, no. 4 (April 2009): 256–57. http://dx.doi.org/10.1038/nrmicro2120.

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13

Xie, Z. D., C. D. Hershberger, S. Shankar, R. W. Ye, and A. M. Chakrabarty. "Sigma factor-anti-sigma factor interaction in alginate synthesis: inhibition of AlgT by MucA." Journal of bacteriology 178, no. 16 (1996): 4990–96. http://dx.doi.org/10.1128/jb.178.16.4990-4996.1996.

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14

Raina, S., D. Missiakas, and C. Georgopoulos. "The rpoE gene encoding the sigma E (sigma 24) heat shock sigma factor of Escherichia coli." EMBO Journal 14, no. 5 (March 1995): 1043–55. http://dx.doi.org/10.1002/j.1460-2075.1995.tb07085.x.

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15

Sevcikova, Beatrica, and Jan Kormanec. "Activity of theStreptomyces coelicolorstress-response sigma factor ÏHis regulated by an anti-sigma factor." FEMS Microbiology Letters 209, no. 2 (April 2002): 229–35. http://dx.doi.org/10.1111/j.1574-6968.2002.tb11136.x.

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16

Britton, Robert A., Patrick Eichenberger, Jose Eduardo Gonzalez-Pastor, Paul Fawcett, Rita Monson, Richard Losick, and Alan D. Grossman. "Genome-Wide Analysis of the Stationary-Phase Sigma Factor (Sigma-H) Regulon of Bacillus subtilis." Journal of Bacteriology 184, no. 17 (September 1, 2002): 4881–90. http://dx.doi.org/10.1128/jb.184.17.4881-4890.2002.

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ABSTRACT Sigma-H is an alternative RNA polymerase sigma factor that directs the transcription of many genes that function at the transition from exponential growth to stationary phase in Bacillus subtilis. Twenty-three promoters, which drive transcription of 33 genes, are known to be recognized by sigma-H-containing RNA polymerase. To identify additional genes under the control of sigma-H on a genome-wide basis, we carried out transcriptional profiling experiments using a DNA microarray containing >99% of the annotated B. subtilis open reading frames. In addition, we used a bioinformatics-based approach aimed at the identification of promoters recognized by RNA polymerase containing sigma-H. This combination of approaches was successful in confirming most of the previously described sigma-H-controlled genes. In addition, we identified 26 putative promoters that drive expression of 54 genes not previously known to be under the direct control of sigma-H. Based on the known or inferred function of most of these genes, we conclude that, in addition to its previously known roles in sporulation and competence, sigma-H controls genes involved in many physiological processes associated with the transition to stationary phase, including cytochrome biogenesis, generation of potential nutrient sources, transport, and cell wall metabolism.

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17

Popham, D., J. Keener, and S. Kustu. "Purification of the alternative sigma factor, sigma 54, from Salmonella typhimurium and characterization of sigma 54-holoenzyme." Journal of Biological Chemistry 266, no. 29 (October 1991): 19510–18. http://dx.doi.org/10.1016/s0021-9258(18)55025-0.

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18

Silva, Wendel Alex Castro, Luciano de Oliveira Fuscaldi Neves, and Andréia de Oliveira Santos. "Six Sigma Methodology: Is It a Success Factor for Companies?" International Business Research 10, no. 5 (April 25, 2017): 179. http://dx.doi.org/10.5539/ibr.v10n5p179.

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This paper presents an analysis of the economic performance and profitability of companies using the Six Sigma methodology. Of the 425 Brazilian companies currently on the open market, 93 use Six Sigma. The companies were first categorised by their sectors, according to how they are classified on the capital market, and then, by their size according to the Brazilian Development Bank. The results in recent years (2011–2013) of companies that use Six Sigma were compared to the results of those that do not, based on a statistical inference test of the differences between the two populations, with unknown standard deviations and a confidence interval established at the 95% level. The findings show that, in nine sectors, the Six Sigma methodology contributes to the optimisation of processes and economic performance.

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19

Van Arsdell, S. W., G. L. Stetler, and J. Thorner. "The yeast repeated element sigma contains a hormone-inducible promoter." Molecular and Cellular Biology 7, no. 2 (February 1987): 749–59. http://dx.doi.org/10.1128/mcb.7.2.749.

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A genomic clone (lambda ScG7) from Saccharomyces cerevisiae encoded a 650-nucleotide poly(A)-containing [poly(A)+] RNA that was about 50 times more abundant in MATa cells that had been exposed to the peptide pheromone alpha-factor than in untreated cells. This RNA was transcribed from a cluster of repetitive sequences: both intact and truncated delta and sigma elements adjacent to a tRNATrp gene. Strand-specific probes indicated that this RNA initiated within an intact sigma element and contained sigma sequences at its 5' end. MATa cells produced two other prominent poly(A)+ RNAs (500 and 5,300 bases) in response to alpha-factor that were homologous to the same strand of sigma but transcribed from other locations in the genome. Induction of the sigma-related transcripts was rapid, was not blocked by inhibition of protein synthesis, required a functional receptor (STE2 gene product), and hence appeared to be a primary response to pheromone. Pulse-labeling confirmed that accumulation of sigma RNA following alpha-factor administration was accounted for by an increase in its rate of transcription. The sigma RNAs also were induced in MAT alpha cells that had been treated with a-factor, but were not present at significant levels in MATa/MAT alpha diploids. In MATa cells transformed with a plasmid in which the lambda ScG7 sigma element was inserted just upstream of a gene coding for the intracellular form of invertase (SUC2) lacking its own promoter, a new poly(A)+ RNA (2.2 kilobases) appeared in response to alpha-factor that hybridized to both sigma and SUC2 probes, and intracellular invertase activity was elevated about 10-fold within 30 min. Primer extension showed that transcription from the hybrid gene initiated exclusively within the sigma sequence (117 nucleotides from the 3' end of the element).

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20

Van Arsdell, S. W., G. L. Stetler, and J. Thorner. "The yeast repeated element sigma contains a hormone-inducible promoter." Molecular and Cellular Biology 7, no. 2 (February 1987): 749–59. http://dx.doi.org/10.1128/mcb.7.2.749-759.1987.

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A genomic clone (lambda ScG7) from Saccharomyces cerevisiae encoded a 650-nucleotide poly(A)-containing [poly(A)+] RNA that was about 50 times more abundant in MATa cells that had been exposed to the peptide pheromone alpha-factor than in untreated cells. This RNA was transcribed from a cluster of repetitive sequences: both intact and truncated delta and sigma elements adjacent to a tRNATrp gene. Strand-specific probes indicated that this RNA initiated within an intact sigma element and contained sigma sequences at its 5' end. MATa cells produced two other prominent poly(A)+ RNAs (500 and 5,300 bases) in response to alpha-factor that were homologous to the same strand of sigma but transcribed from other locations in the genome. Induction of the sigma-related transcripts was rapid, was not blocked by inhibition of protein synthesis, required a functional receptor (STE2 gene product), and hence appeared to be a primary response to pheromone. Pulse-labeling confirmed that accumulation of sigma RNA following alpha-factor administration was accounted for by an increase in its rate of transcription. The sigma RNAs also were induced in MAT alpha cells that had been treated with a-factor, but were not present at significant levels in MATa/MAT alpha diploids. In MATa cells transformed with a plasmid in which the lambda ScG7 sigma element was inserted just upstream of a gene coding for the intracellular form of invertase (SUC2) lacking its own promoter, a new poly(A)+ RNA (2.2 kilobases) appeared in response to alpha-factor that hybridized to both sigma and SUC2 probes, and intracellular invertase activity was elevated about 10-fold within 30 min. Primer extension showed that transcription from the hybrid gene initiated exclusively within the sigma sequence (117 nucleotides from the 3' end of the element).

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21

Narberhaus, Franz, and Sylvia Balsiger. "Structure-Function Studies of Escherichia coli RpoH (σ32) by In Vitro Linker Insertion Mutagenesis." Journal of Bacteriology 185, no. 9 (May 1, 2003): 2731–38. http://dx.doi.org/10.1128/jb.185.9.2731-2738.2003.

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ABSTRACT The sigma factor RpoH (σ32) is the key regulator of the heat shock response in Escherichia coli. Many structural and functional properties of the sigma factor are poorly understood. To gain further insight into RpoH regions that are either important or dispensable for its cellular activity, we generated a collection of tetrapeptide insertion variants by a recently established in vitro linker insertion mutagenesis technique. Thirty-one distinct insertions were obtained, and their sigma factor activity was analyzed by using a groE-lacZ reporter fusion in an rpoH-negative background. Our study provides a map of permissive sites which tolerate linker insertions and of functionally important regions at which a linker insertion impairs sigma factor activity. Selected linker insertion mutants will be discussed in the light of known sigma factor properties and in relation to a modeled structure of an RpoH fragment containing region 2.

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22

Marrakchi, Amine. "Fullness of crossed products of factors by discrete groups." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 150, no. 5 (April 23, 2019): 2368–78. http://dx.doi.org/10.1017/prm.2019.21.

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AbstractLet M be an arbitrary factor and $\sigma : \Gamma \curvearrowright M$ an action of a discrete group. In this paper, we study the fullness of the crossed product $M \rtimes _\sigma \Gamma $. When Γ is amenable, we obtain a complete characterization: the crossed product factor $M \rtimes _\sigma \Gamma $ is full if and only if M is full and the quotient map $\overline {\sigma } : \Gamma \rightarrow {\rm out}(M)$ has finite kernel and discrete image. This answers the question of Jones from [11]. When M is full and Γ is arbitrary, we give a sufficient condition for $M \rtimes _\sigma \Gamma $ to be full which generalizes both Jones' criterion and Choda's criterion. In particular, we show that if M is any full factor (possibly of type III) and Γ is a non-inner amenable group, then the crossed product $M \rtimes _\sigma \Gamma $ is full.

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23

Schweder, T., K. H. Lee, O. Lomovskaya, and A. Matin. "Regulation of Escherichia coli starvation sigma factor (sigma s) by ClpXP protease." Journal of bacteriology 178, no. 2 (1996): 470–76. http://dx.doi.org/10.1128/jb.178.2.470-476.1996.

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24

Kim, Eun Sook, Ju Yeon Song, Dae Wi Kim, Keith F. Chater, and Kye Joon Lee. "A Possible Extended Family of Regulators of Sigma Factor Activity in Streptomyces coelicolor." Journal of Bacteriology 190, no. 22 (September 12, 2008): 7559–66. http://dx.doi.org/10.1128/jb.00470-08.

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ABSTRACT SCO4677 is one of a large number of similar genes in Streptomyces coelicolor that encode proteins with an HATPase_c domain resembling that of anti-sigma factors such as SpoIIAB of Bacillus subtilis. However, SCO4677 is not located close to genes likely to encode a cognate sigma or anti-anti-sigma factor. SCO4677 was found to regulate antibiotic production and morphological differentiation, both of which were significantly enhanced by the deletion of SCO4677. Through protein-protein interaction screening of candidate sigma factor partners using the yeast two-hybrid system, SCO4677 protein was found to interact with the developmentally specific σF, suggesting that it is an antagonistic regulator of σF. Two other proteins, encoded by SCO0781 and SCO0869, were found to interact with the SCO4677 anti-σF during a subsequent global yeast two-hybrid screen, and the SCO0869-SCO4677 protein-protein interaction was confirmed by coimmunoprecipitation. The SCO0781 and SCO0869 proteins resemble well-known anti-anti-sigma factors such as SpoIIAA of B. subtilis. It appears that streptomycetes may possess an extraordinary abundance of anti-sigma factors, some of which may influence diverse processes through interactions with multiple partners: a novel feature for such regulatory proteins.

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25

Sevcikova, Beatrica, Bronislava Rezuchova, Dagmar Homerova, and Jan Kormanec. "The Anti-Anti-Sigma Factor BldG Is Involved in Activation of the Stress Response Sigma Factor σH in Streptomyces coelicolor A3(2)." Journal of Bacteriology 192, no. 21 (September 3, 2010): 5674–81. http://dx.doi.org/10.1128/jb.00828-10.

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ABSTRACT The alternative stress response sigma factor σH has a role in regulation of the osmotic stress response and in morphological differentiation in Streptomyces coelicolor A3(2). Its gene, sigH, is located in an operon with the gene that encodes its anti-sigma factor UshX (PrsH). However, no gene with similarity to an anti-anti-sigma factor which may have a role in σH activation by a “partner-switching” mechanism is located in the operon. By using a combination of several approaches, including pull-down and bacterial two-hybrid assays and visualization of the complex by native polyacrylamide electrophoresis, we demonstrated a direct interaction between UshX and the pleiotropic sporulation-specific anti-anti-sigma factor BldG. Osmotic induction of transcription of the sigHp2 promoter that is specifically recognized by RNA polymerase containing σH was absent in an S. coelicolor bldG mutant, indicating a role of BldG in σH activation by a partner-switching-like mechanism.

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26

Sauer, Uwe, Joseph D. Santangelo, Anke Treuner, Malte Buchholz, and Peter Dürre. "Sigma factor and sporulation genes inClostridium." FEMS Microbiology Reviews 17, no. 3 (October 1995): 331–40. http://dx.doi.org/10.1111/j.1574-6976.1995.tb00216.x.

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27

Österberg, Sofia, Teresa del Peso-Santos, and Victoria Shingler. "Regulation of Alternative Sigma Factor Use." Annual Review of Microbiology 65, no. 1 (October 13, 2011): 37–55. http://dx.doi.org/10.1146/annurev.micro.112408.134219.

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28

Machado, Rosane S., Douglas C. Camelo, Darcy F. de Almeida, and Luis C. S. Ferreira. "Effect of sigma factor S (sigmaS) on the stability of penicillin-binding protein 3 (PBP3) of Escherichia colt K12." Brazilian Journal of Genetics 19, no. 4 (1996): 545–49. http://dx.doi.org/10.1590/s0100-84551996000400001.

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29

Thirunavukkarasu, Nagarajan, Mukti Nath Mishra, Stijn Spaepen, Jos Vanderleyden, Carol A. Gross, and Anil K. Tripathi. "An extra-cytoplasmic function sigma factor and anti-sigma factor control carotenoid biosynthesis in Azospirillum brasilense." Microbiology 154, no. 7 (July 1, 2008): 2096–105. http://dx.doi.org/10.1099/mic.0.2008/016428-0.

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30

Anthony, Jennifer R., Jack D. Newman, and Timothy J. Donohue. "Interactions Between the Rhodobacter sphaeroides ECF Sigma Factor, σ E , and its Anti-sigma Factor, ChrR." Journal of Molecular Biology 341, no. 2 (August 2004): 345–60. http://dx.doi.org/10.1016/j.jmb.2004.06.018.

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31

Raval, Neha, and K. Muralidharan. "A Note on 1.5 Sigma Shift in Performance Evaluation." International Journal of Reliability, Quality and Safety Engineering 23, no. 06 (December 2016): 1640007. http://dx.doi.org/10.1142/s0218539316400076.

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Understanding variation is critical to quality (CTQ) of product or service delivery, which is the key to success. Six Sigma is the business process improvement strategy that extensively focuses on variation reduction thereby reducing number of defects. One of the major constituents of Six Sigma definitions is 1.5 sigma shift, which is attributable to random error. It is not possible to understand Six Sigma thoroughly by overlooking the concept of 1.5 sigma shift. A conventional 3.4 defect per million opportunity (DPMO) capability of Six Sigma process is based on 1.5 sigma shift. This paper aimed at explaining ancestry of 1.5 sigma shift in connection with quality engineering methods. Origin of 1.5 sigma shift factor with reference to producibility analysis, worst-case sampling error and other quality engineering methods has been discussed in this paper.

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32

Costanzo, Alessandra, and Sarah E. Ades. "Growth Phase-Dependent Regulation of the Extracytoplasmic Stress Factor, σE, by Guanosine 3′,5′-Bispyrophosphate (ppGpp)." Journal of Bacteriology 188, no. 13 (July 1, 2006): 4627–34. http://dx.doi.org/10.1128/jb.01981-05.

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ABSTRACT The sigma subunit of procaryotic RNA polymerases is responsible for specific promoter recognition and transcription initiation. In addition to the major sigma factor, σ70, in Escherichia coli, which directs most of the transcription in the cell, bacteria possess multiple, alternative sigma factors that direct RNA polymerase to distinct sets of promoters in response to environmental signals. By activating an alternative sigma factor, gene expression can be rapidly reprogrammed to meet the needs of the cell as the environment changes. Sigma factors are subject to multiple levels of regulation that control their levels and activities. The alternative sigma factor σE in Escherichia coli is induced in response to extracytoplasmic stress. Here we demonstrate that σE can also respond to signals other than extracytoplasmic stress. σE activity increases in a growth phase-dependent manner as a culture enters stationary phase. The signaling pathway that activates σE during entry into stationary phase is dependent upon the alarmone guanosine 3′,5′-bispyrophosphate (ppGpp) and is distinct from the pathway that signals extracytoplasmic stress. ppGpp is the first cytoplasmic factor shown to control σE activity, demonstrating that σE can respond to internal signals as well as signals originating in the cell envelope. ppGpp is a general signal of starvation stress and is also required for activation of the σS and σ54 alternative sigma factors upon entry into stationary phase, suggesting that this is a key mechanism by which alternative sigma factors can be activated in concert to provide a coordinated response to nutritional stress.

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33

Macadlo, Lauren A., Iskander M. Ibrahim, and Sujith Puthiyaveetil. "Sigma factor 1 in chloroplast gene transcription and photosynthetic light acclimation." Journal of Experimental Botany 71, no. 3 (October 23, 2019): 1029–38. http://dx.doi.org/10.1093/jxb/erz464.

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Abstract Sigma factors are dissociable subunits of bacterial RNA polymerase that ensure efficient transcription initiation from gene promoters. Owing to their prokaryotic origin, chloroplasts possess a typical bacterial RNA polymerase together with its sigma factor subunit. The higher plant Arabidopsis thaliana contain as many as six sigma factors for the hundred or so of its chloroplast genes. The role of this relatively large number of transcription initiation factors for the miniature chloroplast genome, however, is not fully understood. Using two Arabidopsis T-DNA insertion mutants, we show that sigma factor 1 (SIG1) initiates transcription of a specific subset of chloroplast genes. We further show that the photosynthetic control of PSI reaction center gene transcription requires complementary regulation of the nuclear SIG1 gene at the transcriptional level. This SIG1 gene regulation is dependent on both a plastid redox signal and a light signal transduced by the phytochrome photoreceptor.

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34

Evans, Louise, Joanna Clarkson, Michael D. Yudkin, Jeff Errington, and Andrea Feucht. "Analysis of the Interaction between the Transcription Factor σG and the Anti-Sigma Factor SpoIIAB of Bacillus subtilis." Journal of Bacteriology 185, no. 15 (August 1, 2003): 4615–19. http://dx.doi.org/10.1128/jb.185.15.4615-4619.2003.

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ABSTRACT The activation of σG, a transcription factor, in Bacillus subtilis is coupled to the completion of engulfment during sporulation. SpoIIAB, an anti-sigma factor involved in regulation of σF, is also shown to form a complex with σG in vitro. SpoIIAA, the corresponding anti-anti-sigma factor, can disrupt the SpoIIAB:σG complex, releasing free σG. The data suggest the existence of an as-yet-unknown mechanism to keep σG inactive prior to engulfment.

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35

Kazmierczak, Mark J., Martin Wiedmann, and Kathryn J. Boor. "Alternative Sigma Factors and Their Roles in Bacterial Virulence." Microbiology and Molecular Biology Reviews 69, no. 4 (December 2005): 527–43. http://dx.doi.org/10.1128/mmbr.69.4.527-543.2005.

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SUMMARY Sigma factors provide promoter recognition specificity to RNA polymerase holoenzyme, contribute to DNA strand separation, and then dissociate from the core enzyme following transcription initiation. As the regulon of a single sigma factor can be composed of hundreds of genes, sigma factors can provide effective mechanisms for simultaneously regulating expression of large numbers of prokaryotic genes. One newly emerging field is identification of the specific roles of alternative sigma factors in regulating expression of virulence genes and virulence-associated genes in bacterial pathogens. Virulence genes encode proteins whose functions are essential for the bacterium to effectively establish an infection in a host organism. In contrast, virulence-associated genes can contribute to bacterial survival in the environment and therefore may enhance the capacity of the bacterium to spread to new individuals or to survive passage through a host organism. As alternative sigma factors have been shown to regulate expression of both virulence and virulence-associated genes, these proteins can contribute both directly and indirectly to bacterial virulence. Sigma factors are classified into two structurally unrelated families, the σ70 and the σ54 families. The σ70 family includes primary sigma factors (e.g., Bacillus subtilis σA) as well as related alternative sigma factors; σ54 forms a distinct subfamily of sigma factors referred to as σN in almost all species for which these proteins have been characterized to date. We present several examples of alternative sigma factors that have been shown to contribute to virulence in at least one organism. For each sigma factor, when applicable, examples are drawn from multiple species.

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36

Song, Taeksun, Simon L. Dove, Kon Ho Lee, and Robert N. Husson. "RshA, an anti‐sigma factor that regulates the activity of the mycobacterial stress response sigma factor SigH." Molecular Microbiology 50, no. 3 (October 6, 2003): 949–59. http://dx.doi.org/10.1046/j.1365-2958.2003.03739.x.

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37

Sevcikova, B. "Activity of the Streptomyces coelicolor stress-response sigma factor σH is regulated by an anti-sigma factor." FEMS Microbiology Letters 209, no. 2 (April 9, 2002): 229–35. http://dx.doi.org/10.1016/s0378-1097(02)00513-x.

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38

Bastiat, Bénédicte, Laurent Sauviac, and Claude Bruand. "Dual Control of Sinorhizobium meliloti RpoE2 Sigma Factor Activity by Two PhyR-Type Two-Component Response Regulators." Journal of Bacteriology 192, no. 8 (February 12, 2010): 2255–65. http://dx.doi.org/10.1128/jb.01666-09.

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ABSTRACT RpoE2 is an extracytoplasmic function (ECF) sigma factor involved in the general stress response of Sinorhizobium meliloti, the nitrogen-fixing symbiont of the legume plant alfalfa. RpoE2 orthologues are widely found among alphaproteobacteria, where they play various roles in stress resistance and/or host colonization. In this paper, we report a genetic and biochemical investigation of the mechanisms of signal transduction leading to S. meliloti RpoE2 activation in response to stress. We showed that RpoE2 activity is negatively controlled by two paralogous anti-sigma factors, RsiA1 (SMc01505) and RsiA2 (SMc04884), and that RpoE2 activation by stress requires two redundant paralogous PhyR-type response regulators, RsiB1 (SMc01504) and RsiB2 (SMc00794). RsiB1 and RsiB2 do not act at the level of rpoE2 transcription but instead interact with the anti-sigma factors, and we therefore propose that they act as anti-anti-sigma factors to relieve RpoE2 inhibition in response to stress. This model closely resembles a recently proposed model of activation of RpoE2-like sigma factors in Methylobacterium extorquens and Bradyrhizobium japonicum, but the existence of two pairs of anti- and anti-anti-sigma factors in S. meliloti adds an unexpected level of complexity, which may allow the regulatory system to integrate multiple stimuli.

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da Silva Neto, José F., Tie Koide, Suely L. Gomes, and Marilis V. Marques. "The Single Extracytoplasmic-Function Sigma Factor of Xylella fastidiosa Is Involved in the Heat Shock Response and Presents an Unusual Regulatory Mechanism." Journal of Bacteriology 189, no. 2 (November 10, 2006): 551–60. http://dx.doi.org/10.1128/jb.00986-06.

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ABSTRACT Genome sequence analysis of the bacterium Xylella fastidiosa revealed the presence of two genes, named rpoE and rseA, predicted to encode an extracytoplasmic function (ECF) sigma factor and an anti-sigma factor, respectively. In this work, an rpoE null mutant was constructed in the citrus strain J1a12 and shown to be sensitive to exposure to heat shock and ethanol. To identify the X. fastidiosa σE regulon, global gene expression profiles were obtained by DNA microarray analysis of bacterial cells under heat shock, identifying 21 σE-dependent genes. These genes encode proteins belonging to different functional categories, such as enzymes involved in protein folding and degradation, signal transduction, and DNA restriction modification and hypothetical proteins. Several putative σE-dependent promoters were mapped by primer extension, and alignment of the mapped promoters revealed a consensus sequence similar to those of ECF sigma factor promoters of other bacteria. Like other ECF sigma factors, rpoE and rseA were shown to comprise an operon in X. fastidiosa, together with a third open reading frame (XF2241). However, upon heat shock, rpoE expression was not induced, while rseA and XF2241 were highly induced at a newly identified σE-dependent promoter internal to the operon. Therefore, unlike many other ECF sigma factors, rpoE is not autoregulated but instead positively regulates the gene encoding its putative anti-sigma factor.

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40

Gehring, Amy M., Narie J. Yoo, and Richard Losick. "RNA Polymerase Sigma Factor That Blocks Morphological Differentiation by Streptomyces coelicolor." Journal of Bacteriology 183, no. 20 (October 15, 2001): 5991–96. http://dx.doi.org/10.1128/jb.183.20.5991-5996.2001.

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ABSTRACT The filamentous bacterium Streptomyces coelicolorundergoes a complicated process of morphological differentiation that begins with the formation of an aerial mycelium and culminates in sporulation. Genes required for the initiation of aerial mycelium formation have been termed bld (bald), describing the smooth, undifferentiated colonies of mutant strains. By using an insertional mutagenesis protocol that relies on in vitro transposition, we have isolated a bld mutant harboring an insertion in a previously uncharacterized gene, SCE59.12c, renamed here rsuA. The insertion mutant exhibited no measurable growth defect but failed to produce an aerial mycelium and showed a significant delay in the production of the polyketide antibiotic actinorhodin. The rsuA gene encodes an apparent anti-sigma factor and is located immediately downstream ofSCE59.13c, renamed here sigU, whose product is inferred to be a member of the extracytoplasmic function subfamily of RNA polymerase sigma factors. The absence ofrsuA in a strain that contained sigUcaused a block in development, and the overexpression ofsigU in an otherwise wild-type strain caused a delay in aerial mycelium formation. However, a strain in which bothrsuA and sigU had been deleted was able to undergo morphological differentiation normally. We conclude that thersuA-encoded anti-sigma factor is responsible for antagonizing the function of the sigma factor encoded bysigU. We also conclude that thesigU-encoded sigma factor is not normally required for development but that its uncontrolled activity obstructs morphological differentiation at an early stage.

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Gentry, D. R., V. J. Hernandez, L. H. Nguyen, D. B. Jensen, and M. Cashel. "Synthesis of the stationary-phase sigma factor sigma s is positively regulated by ppGpp." Journal of Bacteriology 175, no. 24 (1993): 7982–89. http://dx.doi.org/10.1128/jb.175.24.7982-7989.1993.

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Binnie, C., M. Lampe, and R. Losick. "Gene encoding the sigma 37 species of RNA polymerase sigma factor from Bacillus subtilis." Proceedings of the National Academy of Sciences 83, no. 16 (August 1, 1986): 5943–47. http://dx.doi.org/10.1073/pnas.83.16.5943.

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Lewis, Peter J., Ling Juan Wu, and Jeffery Errington. "Establishment of Prespore-Specific Gene Expression inBacillus subtilis: Localization of SpoIIE Phosphatase and Initiation of Compartment-Specific Proteolysis." Journal of Bacteriology 180, no. 13 (July 1, 1998): 3276–84. http://dx.doi.org/10.1128/jb.180.13.3276-3284.1998.

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ABSTRACT Immunofluorescence microscopy was used to study the establishment of compartment-specific transcription during sporulation inBacillus subtilis. Analysis of the distribution of the anti-anti-sigma factor, SpoIIAA, in a variety of mutant backgrounds supports a model in which the SpoIIE phosphatase, which activates SpoIIAA by dephosphorylation, is sequestered onto the prespore face of the asymmetric septum. Thus, prespore-specific gene expression apparently arises as a result of the compartmentalization of SpoIIE protein. The results also suggest the existence of at least two compartment-specific programs of proteolysis, one dependent on the mother cell-specific sigma factor ςE and the other dependent on the prespore-specific sigma factor ςF.

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McQuade, Ryan S., Natalia Comella, and Alan D. Grossman. "Control of a Family of Phosphatase Regulatory Genes (phr) by the Alternate Sigma Factor Sigma-H ofBacillus subtilis." Journal of Bacteriology 183, no. 16 (August 15, 2001): 4905–9. http://dx.doi.org/10.1128/jb.183.16.4905-4909.2001.

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ABSTRACT A family of 11 phosphatases can help to modulate the activity of response regulator proteins in Bacillus subtilis. Downstream of seven of the rap (phosphatase) genes arephr genes, encoding secreted peptides that function as phosphatase regulators. By using fusions to lacZ and primer extension analysis, we found that six of the sevenphr genes are controlled by the alternate sigma factor sigma-H. These results expand the potential of sigma-H to contribute to the output of several response regulators by controlling expression of inhibitors of phosphatases.

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Donà, Valentina, Sébastien Rodrigue, Elisa Dainese, Giorgio Palù, Luc Gaudreau, Riccardo Manganelli, and Roberta Provvedi. "Evidence of Complex Transcriptional, Translational, and Posttranslational Regulation of the Extracytoplasmic Function Sigma Factor σE in Mycobacterium tuberculosis." Journal of Bacteriology 190, no. 17 (July 7, 2008): 5963–71. http://dx.doi.org/10.1128/jb.00622-08.

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ABSTRACT The extracytoplasmic factor (ECF) sigma factor σE is one of the most studied sigma factors of Mycobacterium tuberculosis. It has been shown to be involved in virulence as well as in survival under conditions of high temperature, alkaline pH, and exposure to detergents and oxidative stress. Unlike many ECF sigma factors, σE does not directly regulate the transcription of its own gene. Two promoters have been identified upstream of the sigE gene; one is regulated by the two-component system MprAB, while the other has been shown to be σH dependent. In this paper, we further characterize the regulation of σE by identifying its anti-sigma factor and a previously unknown promoter. Finally, we show that sigE can be translated from three different translational start codons, depending on the promoter used. Taken together, our data demonstrate that σE not only is subjected to complex transcriptional regulation but is also controlled at the translational and posttranslational levels.

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Wilson, Megan J., and Iain L. Lamont. "Mutational Analysis of an Extracytoplasmic-Function Sigma Factor To Investigate Its Interactions with RNA Polymerase and DNA." Journal of Bacteriology 188, no. 5 (March 1, 2006): 1935–42. http://dx.doi.org/10.1128/jb.188.5.1935-1942.2006.

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ABSTRACT The extracytoplasmic-function (ECF) family of sigma factors comprises a large group of proteins required for synthesis of a wide variety of extracytoplasmic products by bacteria. Residues important for core RNA polymerase (RNAP) binding, DNA melting, and promoter recognition have been identified in conserved regions 2 and 4.2 of primary sigma factors. Seventeen residues in region 2 and eight residues in region 4.2 of an ECF sigma factor, PvdS from Pseudomonas aeruginosa, were selected for alanine-scanning mutagenesis on the basis of sequence alignments with other sigma factors. Fourteen of the mutations in region 2 had a significant effect on protein function in an in vivo assay. Four proteins with alterations in regions 2.1 and 2.2 were purified as His-tagged fusions, and all showed a reduced affinity for core RNAP in vitro, consistent with a role in core binding. Region 2.3 and 2.4 mutant proteins retained the ability to bind core RNAP, but four mutants had reduced or no ability to cause core RNA polymerase to bind promoter DNA in a band-shift assay, identifying residues important for DNA binding. All mutations in region 4.2 reduced the activity of PvdS in vivo. Two of the region 4.2 mutant proteins were purified, and each showed a reduced ability to cause core RNA polymerase to bind to promoter DNA. The results show that some residues in PvdS have functions equivalent to those of corresponding residues in primary sigma factors; however, they also show that several residues not shared with primary sigma factors contribute to protein function.

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Fernandes, Norvin D., Qi-long Wu, Dequan Kong, Xiaoling Puyang, Sumeet Garg, and Robert N. Husson. "A Mycobacterial Extracytoplasmic Sigma Factor Involved in Survival following Heat Shock and Oxidative Stress." Journal of Bacteriology 181, no. 14 (July 15, 1999): 4266–74. http://dx.doi.org/10.1128/jb.181.14.4266-4274.1999.

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ABSTRACT Extracytoplasmic function (ECF) sigma factors are a heterogeneous group of alternative sigma factors that regulate gene expression in response to a variety of conditions, including stress. We previously characterized a mycobacterial ECF sigma factor, SigE, that contributes to survival following several distinct stresses. A gene encoding a closely related sigma factor, sigH, was cloned fromMycobacterium tuberculosis and Mycobacterium smegmatis. A single copy of this gene is present in these and other fast- and slow-growing mycobacteria, including M. fortuitum and M. avium. While the M. tuberculosis and M. smegmatis sigH genes encode highly similar proteins, there are multiple differences in adjacent genes. The single in vivo transcriptional start site identified inM. smegmatis and one of two identified in M. bovis BCG were found to have −35 promoter sequences that match the ECF-dependent −35 promoter consensus. Expression from these promoters was strongly induced by 50°C heat shock. In comparison to the wild type, an M. smegmatis sigH mutant was found to be more susceptible to cumene hydroperoxide stress but to be similar in logarithmic growth, stationary-phase survival, and survival following several other stresses. Survival of an M. smegmatis sigH sigE double mutant was found to be markedly decreased following 53°C heat shock and following exposure to cumene hydroperoxide. Expression of the second gene in the sigH operon is required for complementation of the sigH stress phenotypes. SigH is an alternative sigma factor that plays a role in the mycobacterial stress response.

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Hatt, Janet K., and Philip Youngman. "Spo0A Mutants of Bacillus subtilis with Sigma Factor-Specific Defects in Transcription Activation." Journal of Bacteriology 180, no. 14 (July 15, 1998): 3584–91. http://dx.doi.org/10.1128/jb.180.14.3584-3591.1998.

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ABSTRACT The transcription factor Spo0A of Bacillus subtilis has the unique ability to activate transcription from promoters that require different forms of RNA polymerase holoenzyme. One class of Spo0A-activated promoter, which includes spoIIEp, is recognized by RNA polymerase associated with the primary sigma factor, sigma A (ςA); the second, which includesspoIIAp, is recognized by RNA polymerase associated with an early-sporulation sigma factor, sigma H (ςH). Evidence suggests that Spo0A probably interacts directly with RNA polymerase to activate transcription from these promoters. To identify residues of Spo0A that may be involved in transcriptional activation, we used PCR mutagenesis of the entire spo0A gene and designed a screen using two distinguishable reporter fusions, spoIIE-gus andspoIIA-lacZ. Here we report the identification and characterization of five mutants of Spo0A that are specifically defective in activation of ςA-dependent promoters while maintaining activation of ςH-dependent promoters. These five mutants identify a 14-amino-acid segment of Spo0A, from residue 227 to residue 240, that is required for transcriptional activation of ςA-dependent promoters. This region may define a surface or domain of Spo0A that makes direct contacts with ςA-associated holoenzyme.

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Homerova, Dagmar, Beatrica Sevcikova, Bronislava Rezuchova, and Jan Kormanec. "Regulation of an alternative sigma factor σI by a partner switching mechanism with an anti-sigma factor PrsI and an anti-anti-sigma factor ArsI in Streptomyces coelicolor A3(2)." Gene 492, no. 1 (January 2012): 71–80. http://dx.doi.org/10.1016/j.gene.2011.11.011.

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Goh, Thong-Ngee. "Some Practical Issues in the Application of Lean Six Sigma to Service Systems." Nang Yan Business Journal 1, no. 1 (November 20, 2014): 21–26. http://dx.doi.org/10.2478/nybj-2014-0004.

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Abstract Six Sigma as a quality improvement framework has gained considerable popularity in the past two decades. Its extension Lean Six Sigma has also been embraced by many organizations for improvement of quality and business competitiveness. One important factor for the popularity of Six Sigma and Lean Six Sigma is their potential for improving service systems, in contrast to the conventional perceptions that only manufacturing systems can benefit from statistics-based methodologies. There are however a number of issues related to the nature of service systems that must be resolved before the full benefits of Lean Six Sigma can be realized. In this paper, these issues are discussed from a practical point of view from three angles: analytical, organizational, and personal. Awareness of the existence of such issues, if not the answers to all of them, is a pre-requisite to effective adoption of Lean Six Sigma tools.

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