Bacterial flagella grow through an injection-diffusion mechanism

Renault, Thibaud T.; Abraham, Anthony O; Bergmiller, Tobias; Paradis, Guillaume; Rainville, Simon; Charpentier, Emmanuelle; Guet, Călin C.; Tu, Yuhai; Namba, Keiichi; Keener, James P.; Minamino, Tetsuo; Erhardt, Marc

doi:10.7554/elife.23136

Cited by 72 publications

(90 citation statements)

References 37 publications

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“…During flagellum assembly, flagellin proteins are transported through the narrow lumen of the filament and added at the growing tip. Recently, transport and assembly have been proposed to proceed via an injection-diffusion mechanism (34). Thus, the entry of flagellins into the export channel is a major step in the process.…”

Section: Discussionmentioning

confidence: 99%

Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility

et al. 2018

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Rotary flagella propel bacteria through liquid and across semisolid environments. Flagella are composed of the basal body that constitutes the motor for rotation, the curved hook that connects to the basal body, and the flagellar filament that propels the cell. Flagellar filaments can be composed of a single flagellin protein, such as in , or made up of multiple flagellins, such as in The four distinct flagellins FlaA, FlaB, FlaC, and FlaD produced by wild-type are not redundant in function but have specific properties. FlaA and FlaB are much more abundant than FlaC and FlaD and are readily observable in mature flagellar filaments, when either FlaA or FlaB is fluorescently labeled. Cells producing FlaA with any one of the other three flagellins can generate functional filaments and thus are motile, but FlaA alone cannot constitute a functional filament. In mutants that manifest swimming deficiencies, there are multiple ways by which these mutations can be phenotypically suppressed. These suppressor mutations primarily occur within or upstream of the flagellin gene or in the transcription factor regulating flagellin expression. The helical conformation of the flagellar filament appears to require a key asparagine residue present in FlaA and absent in other flagellins. However, FlaB can be spontaneously mutated to render helical flagella in the absence of FlaA, reflecting their overall similarity and perhaps the subtle differences in the specific functions they have evolved to fulfill. Flagellins are abundant bacterial proteins comprising the flagellar filaments that propel bacterial movement. Several members of the alphaproteobacterial group express multiple flagellins, in contrast to model systems, such as with , which has one type of flagellin. The plant pathogen has four flagellins, the abundant and readily detected FlaA and FlaB, and lower levels of FlaC and FlaD. Mutational analysis reveals that FlaA requires at least one of the other flagellins to function, as mutants produce nonhelical flagella and cannot swim efficiently. Suppressor mutations can rescue this swimming defect through mutations in the remaining flagellins, including structural changes imparting helical shape to the flagella, and putative regulators. Our findings shed light on how multiple flagellins contribute to motility.

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Section: Discussionmentioning

confidence: 99%

Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility

et al. 2018

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“…The bacterial flagellar hook is a tubular structure composed of the hook protein, FlgE, and acts as a universal joint to smoothly transmit torque produced by the basal body as a rotary motor to the filament as a helical propeller (Berg, 2003;Macnab, 2003;. FlgE molecules are translocated across the cytoplasmic membrane via a type III export apparatus, diffuses down the central channel of the flagellar rod and growing hook structure and assembles at its distal end with the help of the hook cap made of FlgD (Ohnishi et al, 1994;Moriya et al, 2011;Renault et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

The role of intrinsically disordered C‐terminal region of FliK in substrate specificity switching of the bacterial flagellar type III export apparatus

Kinoshita

Aizawa

Inoue

et al. 2017

Molecular Microbiology

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The bacterial flagellar export switching machinery consists of a ruler protein, FliK, and an export switch protein, FlhB and switches substrate specificity of the flagellar type III export apparatus upon completion of hook assembly. An interaction between the C-terminal domain of FliK (FliK ) and the C-terminal cytoplasmic domain of FlhB (FlhB ) is postulated to be responsible for this switch. FliK has a compactly folded domain termed FliK (residues 268-352) and an intrinsically disordered region composed of the last 53 residues, FliK (residues 353-405). Residues 301-350 of FliK and the last five residues of FliK are critical for the switching function of FliK. FliK is postulated to regulate the interaction of FliK with FlhB , but it remains unknown how. Here we report the role of FliK in the export switching mechanism. Systematic deletion analyses of FliK revealed that residues of 351-370 are responsible for efficient switching of substrate specificity of the export apparatus. Suppressor mutant analyses showed that FliK coordinates FliK action with the switching. Site-directed photo-cross-linking experiments showed that Val-302 and Ile-304 in the hydrophobic core of FliK bind to FlhB . We propose that FliK may induce conformational rearrangements of FliK to bind to FlhB .

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“…Structurally, the flagellum consists of three main parts: the basal body embedded within the inner and outer membranes of the bacterium, a flexible linking structure-the hook, and the long, external filament, which functions as the propeller of the motility device 14 . The filament is formed by more than 20,000 subunits of a single protein, flagellin 15 . Many S. enterica serovars express one of two distinct flagellins, FliC or FljB, in a process called flagellar phase variation 16 .…”

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Methylation of Salmonella Typhimurium flagella promotes bacterial adhesion and host cell invasion

et al. 2020

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The long external filament of bacterial flagella is composed of several thousand copies of a single protein, flagellin. Here, we explore the role played by lysine methylation of flagellin in Salmonella, which requires the methylase FliB. We show that both flagellins of Salmonella enterica serovar Typhimurium, FliC and FljB, are methylated at surface-exposed lysine residues by FliB. A Salmonella Typhimurium mutant deficient in flagellin methylation is outcompeted for gut colonization in a gastroenteritis mouse model, and methylation of flagellin promotes bacterial invasion of epithelial cells in vitro. Lysine methylation increases the surface hydrophobicity of flagellin, and enhances flagella-dependent adhesion of Salmonella to phosphatidylcholine vesicles and epithelial cells. Therefore, posttranslational methylation of flagellin facilitates adhesion of Salmonella Typhimurium to hydrophobic host cell surfaces, and contributes to efficient gut colonization and host infection.

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Bacterial flagella grow through an injection-diffusion mechanism

Cited by 72 publications

References 37 publications

Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility

Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility

The role of intrinsically disordered C‐terminal region of FliK in substrate specificity switching of the bacterial flagellar type III export apparatus

Methylation of Salmonella Typhimurium flagella promotes bacterial adhesion and host cell invasion

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