Assembly and stoichiometry of <scp>FliF</scp> and <scp>FlhA</scp> in <scp><i>S</i></scp><i>almonella</i> flagellar basal body

Morimoto, Yusuke V.; Ito, Mariko; Hiraoka, Koichi D.; Che, Yong-Suk; Bai, Fan; Kami-ike, Nobunori; Namba, Keiichi; Minamino, Tetsuo

doi:10.1111/mmi.12529

Cited by 91 publications

(95 citation statements)

References 52 publications

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“…Effects of basal body proteins on the FliA flagellar regulon. One of the earliest events in flagellar biogenesis is the coordinated assembly of the MS ring and the flagellar protein export apparatus (43). The export apparatus protein FlhA is proposed to promote oligomerization of FliF monomers into the MS ring in E. coli (44).…”

Section: Discussionmentioning

confidence: 99%

Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Tsang

Hoover

2015

J Bacteriol

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Flagellar biogenesis in Helicobacter pylori is regulated by a transcriptional hierarchy governed by three sigma factors, RpoD ( 80 ), RpoN ( 54 ), and FliA ( 28 ), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaB and flgE) and FliA-dependent (flaA) genes. The MS ring (encoded by fliF) is one of the earliest flagellar structures assembled. Deletion of fliF resulted in the elimination of RpoN-dependent transcripts and an ϳ4-fold decrease in flaA transcript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions of fliH and genes encoding C ring components (fliM and fliY) decreased transcript levels of flaB and flgE but had little or no effect on transcript levels of flaA. Transcript levels of flaB and flgE were elevated in mutants where genes encoding rod proteins (fliE and flgBC) were deleted, while transcript levels of flaA was reduced ϳ2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure. T he bacterial flagellum is a complex nanomachine powered by an ion-driven rotary motor consisting of about 30 different types of proteins whose copy numbers range from a few to thousands (Fig. 1). The flagellum consists of three basic structures referred to as the basal body, hook, and filament (1). The basal body is an intricate complex that consists of the flagellar rod, rings, a motor, a switch complex, and a specialized type III secretion system (T3SS) that transports flagellar proteins across the cell membrane (1-3). The T3SS, also referred to as the flagellar protein export apparatus, consists of integral membrane proteins (FlhA, FlhB, FliO, FliP, FliQ, and FliR) which form an export pore located within the inner membrane, as well as cytoplasmic components (FliI, FliH, and FliJ) that deliver protein substrates to the export pore (4, 5). During flagellar assembly, the export apparatus initially transports rod-and hook-type substrates across the cell membrane into the lumen of the nascent flagellum (6, 7). Upon completion of the mature hook-basal body (HBB) structure, the export apparatus undergoes a conformational change that is accompanied by a switch in substrate specificity to filament-type substrates.Biogenesis of the bacterial flagellum involves a transcriptional hierarchy that is responsive to checkpoints in assembly so that expression of specific flagellar genes occurs as t...

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Section: Discussionmentioning

confidence: 99%

Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Tsang

Hoover

2015

J Bacteriol

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“…Alternatively, FlhA NT may be part of a larger complex that functions as the signal for stimulating FlgS autokinase activity. Such a complex could simply include other copies of FlhA NT , as the export apparatus is predicted to contain nine FlhA subunits (27), each of which could bind a FlgS monomer, or FlhA NT may need to work in conjunction with other proteins to stimulate FlgS autophosphorylation. Good candidates for such auxiliary proteins are the MS ring protein FliF and the C ring protein FliG, as Boll and Hendrixson showed that FlgS could be crosslinked to these proteins in vivo in the epsilonproteobacterium Campylobacter jejuni (28).…”

Section: Discussionmentioning

confidence: 99%

Helicobacter pylori FlhA Binds the Sensor Kinase and Flagellar Gene Regulatory Protein FlgS with High Affinity

et al. 2015

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Flagellar biogenesis is a complex process that involves multiple checkpoints to coordinate transcription of flagellar genes with the assembly of the flagellum. In Helicobacter pylori, transcription of the genes needed in the middle stage of flagellar biogenesis is governed by RpoN and the two-component system consisting of the histidine kinase FlgS and response regulator FlgR. In response to an unknown signal, FlgS autophosphorylates and transfers the phosphate to FlgR, initiating transcription from RpoNdependent promoters. In the present study, export apparatus protein FlhA was examined as a potential signal protein. Helicobacter pylori is an epsilonproteobacterium that can cause significant pathologies in the stomach (1-3). Approximately 50% of the world population is infected with H. pylori, although only a small fraction of infected individuals have symptoms. H. pylori possesses 2 to 6 polar flagella that are used to burrow through the mucus layer lining the stomach epithelium. Colonization of the gastric mucosa is dependent on motility, as nonflagellated mutants are unable to colonize (4).The flagellum itself is a complex structure comprised of the basal body, hook, and filament (5). The basal body is located within the cell envelope and contains the flagellar protein export apparatus, the various flagellar rings, the rod, and motor components. The export apparatus is responsible for the secretion of axial components of the flagellum and consists of six proteins located within the inner membrane (FliO, FliP, FliQ, FliR, FlhA, and FlhB) plus three cytoplasmic proteins that bring flagellar substrates to the integral membrane component of the export apparatus (FliH, FliI, and FliJ). The C ring (or switch complex) is located at the cytoplasmic side of the inner membrane. In H. pylori it consists of four proteins, FliG, FliM, FliN, and FliY. In addition to controlling the rotational direction of the flagellum, the C ring works with the soluble components of the export apparatus to bring flagellar substrates to the export apparatus for secretion (6, 7). The rod proteins are the first proteins exported and are followed by hook proteins. The hook serves as a universal joint between the rod and the filament, transmitting torque from the motor to the filament. The filament is assembled after the completion of the hook and involves the minor flagellin FlaB and the major flagellin FlaA. Flagellar biogenesis is a complex process that involves the coordinated expression of over 50 structural and regulatory genes with assembly of the nascent flagellum. In H. pylori, temporal expression of flagellar genes is controlled by the three sigma factors found in the bacterium: RpoD ( 80 ), RpoN ( 54 ), and FliA ( 28 ). Transcription of the early flagellar genes, which encode components of the basal body, is regulated by RpoD. Genes whose products are needed for flagellar biogenesis following assembly of the basal body include components of the hook and a minor flagellin, and transcription of these genes is regulated by R...

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“…The integration of the export apparatus could not be visualized in these experiments. The presence of the large export apparatus component FlhA has been shown to induce and stabilize MS ring formation, arguing for an early role of FlhA in the assembly of the flagellum [125], although it is not absolutely required for MS ring formation [126]. For more detailed reviews on the assembly of the flagellum refer to [127][128][129].…”

Section: Transcription Hierarchy Assembly and Activation Of The T3ssmentioning

confidence: 99%

Type III secretion systems: the bacterial flagellum and the injectisome

Diepold

Armitage

2015

Phil. Trans. R. Soc. B

189

175

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One contribution of 12 to a theme issue 'The bacterial cell envelope'. The flagellum and the injectisome are two of the most complex and fascinating bacterial nanomachines. At their core, they share a type III secretion system (T3SS), a transmembrane export complex that forms the extracellular appendages, the flagellar filament and the injectisome needle. Recent advances, combining structural biology, cryo-electron tomography, molecular genetics, in vivo imaging, bioinformatics and biophysics, have greatly increased our understanding of the T3SS, especially the structure of its transmembrane and cytosolic components, the transcriptional, post-transcriptional and functional regulation and the remarkable adaptivity of the system. This review aims to integrate these new findings into our current knowledge of the evolution, function, regulation and dynamics of the T3SS, and to highlight commonalities and differences between the two systems, as well as their potential applications.

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Assembly and stoichiometry of FliF and FlhA in Salmonella flagellar basal body

Cited by 91 publications

References 52 publications

Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

Helicobacter pylori FlhA Binds the Sensor Kinase and Flagellar Gene Regulatory Protein FlgS with High Affinity

Type III secretion systems: the bacterial flagellum and the injectisome

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