A novel transcriptional regulation mechanism in the flagellar regulon of <i>Salmonella typhimurium</i>: an anti‐sigma factor inhibits the activity of the flagellum‐specific Sigma factor, σ<sup>F</sup>

Ohnishi, Kouhei; Kutsukake, Kazuhiro; Suzuki, Hirotoshi; lino, Tetsuo

doi:10.1111/j.1365-2958.1992.tb01771.x

Cited by 232 publications

(217 citation statements)

References 36 publications

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“…The inhibitor itself has not been identified, however, the circumstantial evidence from a number of experiments provides strong support for assuming its existence. The anti-sigma factors (Duncan and Losick, 1993;Ohnishi et al, 1992) offer another example where an inhibitor is part of a regulatory scheme. Obviously, proof of this idea awaits the genetic and functional identification of the inhibitor.…”

Section: Epiloguementioning

confidence: 99%

Transcription antitermination: the λ paradigm updated

Friedman

Court²

1995

Molecular Microbiology

128

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Section: Epiloguementioning

confidence: 99%

Transcription antitermination: the λ paradigm updated

Friedman

Court²

1995

Molecular Microbiology

128

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“…Genes transcribed from class 2 promoters encode the structural subunits of the hook-basal body (HBB) and a number of regulatory factors that include the flagellar-specific transcription factor 28 and its inhibitor, the anti-28 factor FlgM. Class 3 promoters require 28 -RNA polymerase for transcription (Ohnishi et al 1992). Flagellar class 3 operons encode genes whose products are required late in flagellar assembly, including the flagellin filament subunit and genes of the chemosensory system (Chilcott and Hughes 2000).…”

mentioning

confidence: 99%

The flagellar-specific transcription factor, σ²⁸, is the Type III secretion chaperone for the flagellar-specific anti-σ²⁸ factor FlgM

Aldridge¹,

Karlinsey²,

Aldridge³

et al. 2006

Genes Dev.

107

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The bacterial flagellum is a self-assembling macromolecular machine anchored in the bacterial membrane that allows bacteria to move through liquid environments or crawl along surfaces (Macnab 1992). Flagellar assembly and function is a complex process, which in Salmonella typhimurium involves over 60 genes (Frye et al. 2006). The construction of individual flagella requires an ordered assembly pathway (Macnab 1992). The assembly process involves the secretion of individual subunits through the hollow core of the growing flagellum where they assemble at the tip of the structure. In addition, multi-flagellated bacteria can have individual flagella in the same cell at different stages of assembly (Bardy et al. 2003). Consequently, the assembly process is tightly regulated at the levels of substrate selection by the associated secretion apparatus and coupled gene regulation. This paper reports an unexpected discovery related to the current understanding of how a cell regulates flagellar gene expression in response to intermediate stages of flagellar assembly. A flagellar-specific transcription factor, 28, plays a dual role as both a regulator of gene expression and a facilitator of flagellar-specific Type III secretion.The bacterial flagellum consists of three major substructures: (1) the basal body, which acts as motor anchoring the flagellum within the cell membranes; (2) the hook, which acts as a flexible, universal joint between the basal body; and (3) the long external filament, which acts as a propeller when rotated (Berg and Anderson 1973;Macnab 1999). Self-assembly of a flagellum begins at the inner membrane and proceeds out of the cell with construction of the basal structure. A flagellar-specific Type III secretion (T3S) apparatus is assembled within the cytoplasmic membrane at the base of the basal structure (Aldridge and Hughes 2002). Individual structural subunits are then secreted from the cytoplasm into the growing flagellum by the flagellar T3S system. Efficient flagellar assembly requires that the T3S apparatus distinguish between different secretion substrates at different stages of assembly. Recent studies have shown that there is a multi-layered regulatory network in place that couples temporal expression and delivery of flagellar

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“…It also contains five other genes: flgN,flgM,flgA,flgD, and flgJ. Except for flgM, which codes for an inhibitor of the flagellum-specific sigma factor, u F (2,23), and flgN, which has an unknown function (3), these genes are thought to be related to hook-basal body formation (26,27). Assembly is blocked at the stage of hook protein polymerization inflgD mutants and at the stage of outer-ring formation in flgA mutants (15).…”

mentioning

confidence: 99%

FlgD is a scaffolding protein needed for flagellar hook assembly in Salmonella typhimurium

et al. 1994

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FlgD is known to be absolutely required for hook assembly, yet it has not been detected in the mature flagellum. We have overproduced and purified FlgD and raised an antibody against it. By using this antibody, we have detected FlgD in substantial amounts in isolated basal bodies fromflgA,flgE,flgH,flgI,flgK, andfliK mutants, in much smaller amounts in those from the wild type andflgL,fli4,fliC,fliD, andfliE mutants, and not at all in those fromflgB,flgD,flgG, andflgj mutants. In terms of the morphological assembly pathway, these results indicate that FlgD is first added to the structure when the rod is completed and is discarded when the hook, having reached its mature length, has the first of the hook-filament junction proteins, FlgK, added to its tip. Immunoelectron microscopy established that FlgD initially is located at the distal end of the rod and eventually is located at the distal end of the hook. Thus, it appears to act as a hook-capping protein to enable assembly of hook protein subunits, much as another flagellar protein, FliD, does for the flagellin subunits of the filament. However, whereas FliD is associated with the filament tip indefinitely, FlgD is only transiently associated with the hook tip; i.e., it acts as a scaffolding protein. When FlgD was added to the culture medium of aflgD mutant, cells gained motility; thus, although the hook cap is normally added endogenously, it can be added exogenously. When culture media were analyzed for the presence of hook protein, it was found only with the flgD mutant and, in smaller amounts, the fliK (polyhook) mutant. Thus, although FlgD is needed for assembly of hook protein, it is not needed for its export.The bacterial flagellum is a complicated structure composed of the basal body, the hook, and the filament (see, e.g., reference 19), as well as more labile structures, such as the motor, switch, and export apparatus. Flagella, under the control of the associated sensory apparatus, provide the cell with the ability to move to favorable environments. The flagellar basal body consists of subunits of at least eight different proteins, which form two outer rings (the L and P rings), an inner ring (the MS ring), and the rod (Fig. 1). The hook and the filament are homopolymers of hook protein and flagellin, respectively. The morphological pathway of flagellar formation is well characterized in both Escherichia coli and Salmonella typhimurium (13,15,26,27) and is coordinated with flagellar gene expression (17). The flagellum is sequentially constructed from simpler to more complex structures. At the earliest stage, the MS ring complex is formed from subunits of the FliF protein. It is thought that the flagellar switch and the flagellar export apparatus are then added (13, 15). Basal body assembly continues with formation of the rod and addition of the outer (P and L) rings. After the basal body is completed, the hook is assembled and finally polymerization of the filament, the major external structure and the propeller for the cell, commences and continues in...

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A novel transcriptional regulation mechanism in the flagellar regulon of Salmonella typhimurium: an anti‐sigma factor inhibits the activity of the flagellum‐specific Sigma factor, σ^F

Cited by 232 publications

References 36 publications

Transcription antitermination: the λ paradigm updated

Transcription antitermination: the λ paradigm updated

The flagellar-specific transcription factor, σ²⁸, is the Type III secretion chaperone for the flagellar-specific anti-σ²⁸ factor FlgM

FlgD is a scaffolding protein needed for flagellar hook assembly in Salmonella typhimurium

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A novel transcriptional regulation mechanism in the flagellar regulon of Salmonella typhimurium: an anti‐sigma factor inhibits the activity of the flagellum‐specific Sigma factor, σF

Cited by 232 publications

References 36 publications

Transcription antitermination: the λ paradigm updated

Transcription antitermination: the λ paradigm updated

The flagellar-specific transcription factor, σ28, is the Type III secretion chaperone for the flagellar-specific anti-σ28 factor FlgM

FlgD is a scaffolding protein needed for flagellar hook assembly in Salmonella typhimurium

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A novel transcriptional regulation mechanism in the flagellar regulon of Salmonella typhimurium: an anti‐sigma factor inhibits the activity of the flagellum‐specific Sigma factor, σ^F

The flagellar-specific transcription factor, σ²⁸, is the Type III secretion chaperone for the flagellar-specific anti-σ²⁸ factor FlgM