Transcription from two promoters and autoregulation contribute to the control of expression of the Salmonella typhimurium flagellar regulatory gene flgM

Gillen, K L; Hughes, Kelly T.

doi:10.1128/jb.175.21.7006-7015.1993

Cited by 59 publications

(60 citation statements)

References 30 publications

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“…More recently it was demonstrated that 28 will transcribe from the promoter regions of the early and middle genes, but the transcriptional start sites differ for FlhDC-dependent class 2 and 28 -dependent class 3 promoters within the middle gene promoter regions (43,63,67,77). A negative regulator of 28 , the FlgM protein (31), is transcribed from a class 2 and a class 3 promoter (32). Among the late genes are those transcribed only from class 3 promoters.…”

Section: Class 2 and Class 3 Promotersmentioning

confidence: 99%

“…The flgN gene is transcribed in the middle class flgAMN operon in addition to the 28 -dependent class 3 flgMN transcript (32,50,72,111). Mutations in flgN result in a poorly motile phenotype with only one or two flagella per cell instead of the normal complement of six to ten (72).…”

Section: Flgn Proteinmentioning

confidence: 99%

“…However, this relatively simple transcriptional hierarchy was complicated by the fact that many of the genes are expressed from more than one promoter class. For example, the flgK, flgL, flgM, flgN, fliD, fliS, and fliT genes are transcribed from both FlhDC-dependent class 2 promoters and 28 -dependent class 3 promoters (32,66,72). The coupling of gene expression to flagellar assembly is accomplished by the regu-lation of 28 activity by the anti- 28 factor FlgM (Fig.…”

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confidence: 99%

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Coupling of Flagellar Gene Expression to Flagellar Assembly in Salmonella enterica Serovar Typhimurium and Escherichia coli

Chilcott

Hughes

2000

Microbiol Mol Biol Rev

591

554

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SUMMARY How do organisms assess the degree of completion of a large structure, especially an extracellular structure such as a flagellum? Bacteria can do this. Mutants that lack key components needed early in assembly fail to express proteins that would normally be added at later assembly stages. In some cases, the regulatory circuitry is able to sense completion of structures beyond the cell surface, such as completion of the external hook structure. In Salmonella and Escherichia coli, regulation occurs at both transcriptional and posttranscriptional levels. One transcriptional regulatory mechanism involves a regulatory protein, FlgM, that escapes from the cell (and thus can no longer act) through a complete flagellum and is held inside when the structure has not reached a later stage of completion. FlgM prevents late flagellar gene transcription by binding the flagellum-specific transcription factor ς28. FlgM is itself regulated in response to the assembly of an incomplete flagellum known as the hook-basal body intermediate structure. Upon completion of the hook-basal body structure, FlgM is exported through this structure out of the cell. Inhibition of ς28-dependent transcription is relieved, and genes required for the later assembly stages are expressed, allowing completion of the flagellar organelle. Distinct posttranscriptional regulatory mechanisms occur in response to assembly of the flagellar type III secretion apparatus and of ring structures in the peptidoglycan and lipopolysaccharide layers. The entire flagellar regulatory pathway is regulated in response to environmental cues. Cell cycle control and flagellar development are codependent. We discuss how all these levels of regulation ensure efficient assembly of the flagellum in response to environmental stimuli.

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Section: Class 2 and Class 3 Promotersmentioning

confidence: 99%

Section: Flgn Proteinmentioning

confidence: 99%

mentioning

confidence: 99%

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Coupling of Flagellar Gene Expression to Flagellar Assembly in Salmonella enterica Serovar Typhimurium and Escherichia coli

Chilcott

Hughes

2000

Microbiol Mol Biol Rev

591

554

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“…One operon, flhDC, is categorized into class I. The flhDC operon encodes activators required for transcription of the class II operons, including fliA, which encodes the 28 subfamily sigma factor responsible for expression of the class III genes (84,161), and flgM, which encodes the FlgM antisigma factor that regulates activity of FliA (63,162). The remaining class II genes encode proteins responsible for formation of the flagellar basal body and hook apparatus.…”

Section: Fliamentioning

confidence: 99%

Alternative Sigma Factors and Their Roles in Bacterial Virulence

Kazmierczak

Wiedmann

Boor

2005

Microbiol Mol Biol Rev

317

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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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“…EGTA (10 mM) was added to the plating medium to limit lysogeny of transductants. Methods for the creation of MudJ transcriptional fusions and Tn10dTc transposon technology were as reported previously (Gillen & Hughes, 1993;Kleckner et al, 1977). For the isolation of loss-of-function mutants following transposition mutagenesis (e.g.…”

Section: Methodsmentioning

confidence: 99%

Mutations in yhiT enable utilization of exogenous pyrimidine intermediates in Salmonella enterica serovar Typhimurium

et al. 2007

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Transcription from two promoters and autoregulation contribute to the control of expression of the Salmonella typhimurium flagellar regulatory gene flgM

Cited by 59 publications

References 30 publications

Coupling of Flagellar Gene Expression to Flagellar Assembly in Salmonella enterica Serovar Typhimurium and Escherichia coli

Coupling of Flagellar Gene Expression to Flagellar Assembly in Salmonella enterica Serovar Typhimurium and Escherichia coli

Alternative Sigma Factors and Their Roles in Bacterial Virulence

Mutations in yhiT enable utilization of exogenous pyrimidine intermediates in Salmonella enterica serovar Typhimurium

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