The Streptomyces aureofaciens homologue of the whiG gene encoding a putative sigma factor essential for sporulation

ABSTRACT Listeria monocytogenes is well known for its robust physiology, which permits growth at low temperatures under conditions of high osmolarity and low pH. Although studies have provided insight into the mechanisms used by L. monocytogenes to allay the physiological consequences of these adverse environments, little is known about how these responses are coordinated. In the studies presented here, we have cloned the sigB gene and severalrsb genes from L. monocytogenes, encoding homologs of the alternative sigma factor ςB and the RsbUVWX proteins, which govern transcription of a general stress regulon in the related bacterium Bacillus subtilis. TheL. monocytogenes and B. subtilis sigB andrsb genes are similar in sequence and physical organization; however, we observed that the activity of ςB in L. monocytogenes was uniquely responsive to osmotic upshifting, temperature downshifting, and the presence of EDTA in the growth medium. The magnitude of the response was greatest after an osmotic upshift, suggesting a role for ςB in coordinating osmotic responses in L. monocytogenes. A null mutation in the sigB gene led to substantial defects in the ability of L. monocytogenesto use betaine and carnitine as osmoprotectants. Subsequent measurements of betaine transport confirmed that the absence of ςB reduced the ability of the cells to accumulate betaine. Thus, ςB coordinates responses to a variety of physical and chemical signals, and its function facilitates the growth of L. monocytogenes under conditions of high osmotic strength.

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Regulation of indoleacetic acid production inPseudomonas putidaGR12-2 by tryptophan and the stationary-phase sigma factor RpoS

Canadian Journal of Microbiology ◽

10.1139/w02-053 ◽

2002 ◽

Vol 48 (7) ◽

pp. 635-642 ◽

Cited By ~ 72

Author(s):

Cheryl L Patten ◽

Bernard R Glick

Keyword(s):

Stationary Phase ◽

Sigma Factor ◽

Indoleacetic Acid ◽

Recognition Sequence ◽

Gene Encoding ◽

Light Production ◽

Key Enzyme ◽

Plant Growth Promoting ◽

Polymerase Chain ◽

Sigma Factor Rpos

The phytohormone indole-3-acetic acid (IAA) accumulates in the culture medium of the plant growth-promoting bacterium Pseudomonas putida GR12-2 only when grown in the presence of exogenous tryptophan, suggesting that expression of indolepyruvate decarboxylase, a key enzyme in the IAA biosynthesis pathway in this bacterium, may be regulated by tryptophan. To test this hypothesis, we isolated the promoter region for the ipdc gene encoding indolepyruvate decarboxylase by inverse polymerase chain reaction (PCR) and inserted it upstream of the bioluminescent reporter gene luxAB on a plasmid in P. putida GR12-2. Activity of the ipdc promoter, measured by quantifying light production, increased fivefold in the presence of L-tryptophan, confirming that ipdc expression is induced by tryptophan. In addition, transcription of ipdc is regulated by the stationary phase sigma factor RpoS: the ipdc promoter contains a sequence similar to the RpoS recognition sequence, and transformation of P. putida GR12-2 with a plasmid carrying rpoS under the control of a constitutive promoter induced promoter activity before the onset of stationary phase when RpoS is not normally produced and prolonged a higher level of transcription at the later stages of the cell cycle.Key words: indoleacetic acid, indolepyruvate decarboxylase, regulation, tryptophan, RpoS.

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A Membrane-Embedded Amino Acid Couples the SpoIIQ Channel Protein to Anti-Sigma Factor Transcriptional Repression during Bacillus subtilis Sporulation

Journal of Bacteriology ◽

10.1128/jb.00958-15 ◽

2016 ◽

Vol 198 (9) ◽

pp. 1451-1463 ◽

Cited By ~ 7

Author(s):

Kelly A. Flanagan ◽

Joseph D. Comber ◽

Elizabeth Mearls ◽

Colleen Fenton ◽

Anna F. Wang Erickson ◽

...

Keyword(s):

Gene Expression ◽

Bacillus Subtilis ◽

Amino Acid ◽

Sigma Factor ◽

Late Gene ◽

Late Gene Expression ◽

Gene Encoding ◽

Content Type ◽

Regulatory Circuit ◽

Gene Regulatory

ABSTRACTSpoIIQ is an essential component of a channel connecting the developing forespore to the adjacent mother cell duringBacillus subtilissporulation. This channel is generally required for late gene expression in the forespore, including that directed by the late-acting sigma factor σG. Here, we present evidence that SpoIIQ also participates in a previously unknown gene regulatory circuit that specifically represses expression of the gene encoding the anti-sigma factor CsfB, a potent inhibitor of σG. ThecsfBgene is ordinarily transcribed in the forespore only by the early-acting sigma factor σF. However, in a mutant lacking the highly conserved SpoIIQ transmembrane amino acid Tyr-28,csfBwas also aberrantly transcribed later by σG, the very target of CsfB inhibition. This regulation ofcsfBby SpoIIQ Tyr-28 is specific, given that the expression of other σF-dependent genes was unaffected. Moreover, we identified a conserved element within thecsfBpromoter region that is both necessary and sufficient for SpoIIQ Tyr-28-mediated inhibition. These results indicate that SpoIIQ is a bifunctional protein that not only generally promotes σGactivity in the forespore as a channel component but also specifically maximizes σGactivity as part of a gene regulatory circuit that represses σG-dependent expression of its own inhibitor, CsfB. Finally, we demonstrate that SpoIIQ Tyr-28 is required for the proper localization and stability of the SpoIIE phosphatase, raising the possibility that these two multifunctional proteins cooperate to fine-tune developmental gene expression in the forespore at late times.IMPORTANCECellular development is orchestrated by gene regulatory networks that activate or repress developmental genes at the right time and place. Late gene expression in the developingBacillus subtilisspore is directed by the alternative sigma factor σG. The activity of σGrequires a channel apparatus through which the adjacent mother cell provides substrates that generally support gene expression. Here we report that the channel protein SpoIIQ also specifically maximizes σGactivity as part of a previously unknown regulatory circuit that prevents σGfrom activating transcription of the gene encoding its own inhibitor, the anti-sigma factor CsfB. The discovery of this regulatory circuit significantly expands our understanding of the gene regulatory network controlling late gene expression in the developingB. subtilisspore.

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