scholarly journals Integrated activities of two alternative sigma factors coordinate iron acquisition and uptake byPseudomonas aeruginosa

2017 ◽  
Vol 106 (6) ◽  
pp. 891-904 ◽  
Author(s):  
Rebecca J. Edgar ◽  
Georgina E. Hampton ◽  
G. Patricia Casas Garcia ◽  
Megan J. Maher ◽  
Matthew A. Perugini ◽  
...  
Keyword(s):  
Iron Acquisition ◽  
Sigma Factors ◽  
Alternative Sigma Factors

scholarly journals Intracellular localization of the mycobacterial stressosome complex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Malavika Ramesh ◽  
Ram Gopal Nitharwal ◽  
Phani Rama Krishna Behra ◽  
B. M. Fredrik Pettersson ◽  
Santanu Dasgupta ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Fluorescence Microscopy ◽  
Bacillus Cereus ◽  
Intracellular Localization ◽  
Sigma Factors ◽  
Alternative Sigma Factors ◽  
Expression Of Genes ◽  
Molecular Machinery ◽  
Stress Signals ◽  
Activation Pathways

AbstractMicroorganisms survive stresses by alternating the expression of genes suitable for surviving the immediate and present danger and eventually adapt to new conditions. Many bacteria have evolved a multiprotein "molecular machinery" designated the "Stressosome" that integrates different stress signals and activates alternative sigma factors for appropriate downstream responses. We and others have identified orthologs of some of the Bacillus subtilis stressosome components, RsbR, RsbS, RsbT and RsbUVW in several mycobacteria and we have previously reported mutual interactions among the stressosome components RsbR, RsbS, RsbT and RsbUVW from Mycobacterium marinum. Here we provide evidence that "STAS" domains of both RsbR and RsbS are important for establishing the interaction and thus critical for stressosome assembly. Fluorescence microscopy further suggested co-localization of RsbR and RsbS in multiprotein complexes visible as co-localized fluorescent foci distributed at scattered locations in the M. marinum cytoplasm; the number, intensity and distribution of such foci changed in cells under stressed conditions. Finally, we provide bioinformatics data that 17 (of 244) mycobacteria, which lack the RsbRST genes, carry homologs of Bacillus cereus genes rsbK and rsbM indicating the existence of alternative σF activation pathways among mycobacteria.

Alternative Sigma Factors in the Free State Are Equilibrium Mixtures of Open and Compact Conformations

Biochemistry ◽  
2010 ◽  
Vol 49 (45) ◽  
pp. 9809-9819 ◽  
Author(s):  
Paromita Raha ◽  
Suranjana Chattopadhyay ◽  
Srijata Mukherjee ◽  
Ruchira Chattopadhyay ◽  
Koushik Roy ◽  
...  
Keyword(s):  
Sigma Factors ◽  
Free State ◽  
Alternative Sigma Factors

scholarly journals Flagellar Biogenesis of Xanthomonas campestris Requires the Alternative Sigma Factors RpoN2 and FliA and Is Temporally Regulated by FlhA, FlhB, and FlgM

2009 ◽  
Vol 191 (7) ◽  
pp. 2266-2275 ◽  
Author(s):  
Tsuey-Ching Yang ◽  
Yu-Wei Leu ◽  
Hui-Chen Chang-Chien ◽  
Rouh-Mei Hu
Keyword(s):  
Transcriptional Activation ◽  
Type Iii Secretion ◽  
Xanthomonas Campestris ◽  
Sigma Factors ◽  
Structural Genes ◽  
Protein Levels ◽  
Alternative Sigma Factors ◽  
Complicated Process ◽  
System F ◽  
Flagellar Biogenesis

ABSTRACT In prokaryotes, flagellar biogenesis is a complicated process involving over 40 genes. The phytopathogen Xanthomonas campestris pv. campestris possesses a single polar flagellum, which is essential for the swimming motility. A σ54 activator, FleQ, has been shown to be required for the transcriptional activation of the flagellar type III secretion system (F-T3SS), rod, and hook proteins. One of the two rpoN genes, rpoN2, encoding σ54, is essential for flagellation. RpoN2 and FleQ direct the expression of a second alternative sigma FliA (σ28) that is essential for the expression of the flagellin FliC. FlgM interacts with FliA and represses the FliA regulons. An flgM mutant overexpressing FliC generates a deformed flagellum and displays an abnormal motility. Mutation in the two structural genes of F-T3SS, flhA and flhB, suppresses the production of FliC. Furthermore, FliA protein levels are decreased in an flhB mutant. A mutant defective in flhA, but not flhB, exhibits a decreased infection rate. In conclusion, the flagellar biogenesis of Xanthomonas campestris requires alternative sigma factors RpoN2 and FliA and is temporally regulated by FlhA, FlhB, and FlgM.

scholarly journals Transcriptional Regulation and Mechanism of SigN (ZpdN), a pBS32-Encoded Sigma Factor in Bacillus subtilis

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Aisha T. Burton ◽  
Aaron DeLoughery ◽  
Gene-Wei Li ◽  
Daniel B. Kearns
Keyword(s):  
Dna Damage ◽  
Bacillus Subtilis ◽  
Sigma Factor ◽  
Consensus Sequence ◽  
Sigma Factors ◽  
Sequencing Analysis ◽  
Dependent Manner ◽  
Content Type ◽  
Alternative Sigma Factors ◽  
Bona Fide

ABSTRACT Laboratory strains of Bacillus subtilis encode many alternative sigma factors, each dedicated to expressing a unique regulon such as those involved in stress resistance, sporulation, and motility. The ancestral strain of B. subtilis also encodes an additional sigma factor homolog, ZpdN, not found in lab strains due to being encoded on the large, low-copy-number plasmid pBS32, which was lost during domestication. DNA damage triggers pBS32 hyperreplication and cell death in a manner that depends on ZpdN, but how ZpdN mediates these effects is unknown. Here, we show that ZpdN is a bona fide sigma factor that can direct RNA polymerase to transcribe ZpdN-dependent genes, and we rename ZpdN SigN accordingly. Rend-seq (end-enriched transcriptome sequencing) analysis was used to determine the SigN regulon on pBS32, and the 5′ ends of transcripts were used to predict the SigN consensus sequence. Finally, we characterize the regulation of SigN itself and show that it is transcribed by at least three promoters: PsigN1, a strong SigA-dependent LexA-repressed promoter; PsigN2, a weak SigA-dependent constitutive promoter; and PsigN3, a SigN-dependent promoter. Thus, in response to DNA damage SigN is derepressed and then experiences positive feedback. How cells die in a pBS32-dependent manner remains unknown, but we predict that death is the product of expressing one or more genes in the SigN regulon. IMPORTANCE Sigma factors are utilized by bacteria to control and regulate gene expression. Some sigma factors are activated during times of stress to ensure the survival of the bacterium. Here, we report the presence of a sigma factor that is encoded on a plasmid that leads to cellular death after DNA damage.

scholarly journals Role of the alternative sigma factors σ E and σ S in survival of Salmonella enterica serovar Typhimurium during starvation, refrigeration and osmotic shock

Microbiology ◽  
2007 ◽  
Vol 153 (1) ◽  
pp. 263-269 ◽  
Author(s):  
Alisdair McMeechan ◽  
Mark Roberts ◽  
Tristan A. Cogan ◽  
Frieda Jørgensen ◽  
Andrew Stevenson ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Osmotic Shock ◽  
Sigma Factors ◽  
Alternative Sigma Factors ◽  
Serovar Typhimurium

scholarly journals Evaluating the Involvement of Alternative Sigma Factors SigF and SigG in Clostridium perfringens Sporulation and Enterotoxin Synthesis

2010 ◽  
Vol 78 (10) ◽  
pp. 4286-4293 ◽  
Author(s):  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
Bacillus Subtilis ◽  
Clostridium Perfringens ◽  
Food Poisoning ◽  
Sigma Factors ◽  
Wild Type ◽  
Alternative Sigma Factors ◽  
Food Borne ◽  
Food Borne Illness ◽  
Bacterial Food ◽  
Null Mutants

ABSTRACT Clostridium perfringens type A food poisoning is the second most commonly identified bacterial food-borne illness. Sporulation contributes to this disease in two ways: (i) most food-poisoning strains form exceptionally resistant spores to facilitate their survival of food-associated stresses, and (ii) the enterotoxin (CPE) responsible for the symptoms of this food poisoning is synthesized only during sporulation. In Bacillus subtilis, four alternative sigma factors mediate sporulation. The same four sigma factors are encoded by C. perfringens genomes, and two (SigE and SigK) have previously been shown to be necessary for sporulation and CPE production by SM101, a transformable derivative of a C. perfringens food-poisoning strain (K. H. Harry, R. Zhou, L. Kroos, and S. B. Melville, J. Bacteriol. 2009, 191:2728-2742). However, the importance of SigF and SigG for C. perfringens sporulation or CPE production had not yet been assessed. In the current study, after confirming that sporulating wild-type SM101 cultures produce SigF (from a tricistronic operon) and SigG, we prepared isogenic sigF- or sigG-null mutants. Whereas SM101 formed heat-resistant, phase-refractile spores, spore formation was blocked in the sigF- and sigG-null mutants. Complementation fully restored sporulation by both mutants. By use of these mutants and complementing strains, CPE production was shown to be SigF dependent but SigG independent. This finding apparently involved regulation of the production of SigE and SigK, which Harry et al. showed to be necessary for CPE synthesis, by SigF. By combining these findings with those previous results, it is now apparent that all four alternative sigma factors are necessary for C. perfringens sporulation, but only SigE, SigF, and SigK are needed for CPE synthesis.

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