The FlhA linker mediates flagellar protein export switching during flagellar assembly

Inoue, Yumi; Kinoshita, Miki; Kida, Mamoru; Takekawa, Norihiro; Namba, Keiichi; Imada, Katsumi; Minamino, Tetsuo

doi:10.1038/s42003-021-02177-z

Cited by 22 publications

(27 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The specific (albeit not necessarily direct) interaction of SctG with the large export apparatus component SctV (Fig. 6), which is a key player in substrate selection [52–54], supports this hypothesis.…”

Section: Discussionmentioning

confidence: 89%

Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system

Wimmi

Fleck

Helbig

et al. 2022

Preprint

View full text Add to dashboard Cite

In animal pathogens, assembly of the type III secretion system injectisome requires the presence of so-called pilotins, small lipoproteins that assist the formation of the secretin ring in the outer membrane. Using a combination of functional assays, interaction studies, proteomics and live-cell microscopy, we determined the contribution of the pilotin to assembly, function and substrate selectivity of the T3SS and identified potential new downstream roles of pilotin proteins. In the absence of its pilotin SctG, Yersinia enterocolitica forms few, largely polar injectisome sorting platforms and needles. In line, the majority of export apparatus subcomplexes is mobile in these strains, suggesting the absence of fully assembled injectisomes. Remarkably, the export of late T3SS substrates including the virulence effectors is hardly affected in these bacteria, whereas early T3SS substrates, such as the needle subunits, are only exported to a very low degree. We found that pilotins transiently interact with the secretin and the large export apparatus component SctV, but mostly localize throughout the bacterial membrane, where they form transient mobile clusters, which do not colocalize with assembled injectisomes. In addition, pilotins interact with non-T3SS components, including sugar transporters. Pilotins therefore have additional functions downstream injectisome assembly, which include the regulation of type III secretion and a potential new link to the cellular energy metabolism.

show abstract

Section: Discussionmentioning

confidence: 89%

Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system

Wimmi

Fleck

Helbig

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…S1B in the Supplemental material) (6,15,26). FliJ also binds to FlhA C with low affinity (26). It has been shown that CdsO, a FliJ homolog, binds to CdsV C , a FlhA C homolog, at a large cleft between the D4 domains of neighboring CdsV C subunits in the CdsV C ring structure (33).…”

Section: Discussionmentioning

confidence: 99%

Conserved GYXLI motif of FlhA is involved in dynamic domain motions of FlhA required for flagellar protein export

Minamino

Kinoshita

Inoue

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Flagellar structural subunits are transported via the flagellar type III secretion system (fT3SS) and assemble at the distal end of the growing flagellar structure. The C-terminal cytoplasmic domain of FlhA (FlhAC) serves as a docking platform for export substrates and flagellar chaperones and plays an important role in hierarchical protein targeting and export. FlhAC consists of domains D1, D2, D3, and D4 and adopts open and closed conformations. Gly-368 of Salmonella FlhA is located within the highly conserved GYXLI motif and is critical for the dynamic domain motions of FlhAC. However, it remains unclear how it works. Here, we report that periodic conformational changes of the GYXLI motif induce a remodeling of hydrophobic side-chain interaction networks in FlhAC and promotes the cyclic open-close domain motions of FlhAC. The temperature-sensitive flhA(G368C) mutation stabilized a completely closed conformation at 42ºC through strong hydrophobic interactions between Gln-498 of domain D1 and Pro-667 of domain D4 and between Phe-459 of domain D2 and Pro-646 of domain D4, thereby inhibiting flagellar protein export by the fT3SS. Its intragenic suppressor mutations reorganized the hydrophobic interaction networks in the closed FlhAC structure, restoring the protein export activity of the fT3SS to a significant degree. Furthermore, the conformational flexibility of the GYXLI motif was critical for flagellar protein export. We propose that the conserved GYXLI motif acts as a structural switch to induce the dynamic domain motions of FlhAC required for efficient and rapid protein export by the fT3SS.

show abstract

“…A complete and irreversible switch would also facilitate the simultaneous assembly of multiple fT3SSs at different assembly stages and ensure that substrates are only secreted at the appropriate stage of assembly. In this respect, recent results of Inoue et al have suggested that the interaction of the flexible linker of FlhA (FlhA L ) with the cytoplasmic domain of FlhA (FlhA C ) might function as a structural switch that might contribute to the specificity switch of the fT3SS from hook-type to filament-type substrate secretion by suppressing the interaction of late substrate-chaperone complexes with FlhA C before hook completion (Inoue et al, 2021). Secondly, it also appears possible that conformational rearrangements within the export apparatus simply enlarge the substrate selectivity spectrum of the fT3SS so that it additionally recognizes and secretes a broader range of substrates: that is, after the switch, the fT3SS recognizes and secretes late substrates in addition to early substrates.…”

Section: Discussionmentioning

confidence: 99%

Hook‐basal‐body assembly state dictates substrate specificity of the flagellar type‐III secretion system

Guse

Halte

Hüsing

et al. 2021

Molecular Microbiology

View full text Add to dashboard Cite

Many bacteria move in liquid environments using a macromolecular propeller, the flagellum. A type-III secretion system (T3SS) at the base of the flagellum and the related injectisome of Gram-negative pathogens are required to build and operate these sophisticated nanomachines. The flagellar structure can be divided into three main parts:(a) a cell envelope-anchored basal body (consisting of the C-ring, the flagellar-specific T3SS, the MS-ring, the rod and the LP-ring), (b) a hook and, (c) a filament. Secretion of a variety of different T3SS substrate proteins occurs from the cytoplasm to the distal end of the growing structure in a highly regulated and sequential manner (Chevance & Hughes, 2008;Diepold & Wagner, 2014;Wagner et al., 2018). The different secretion substrates of the flagellar T3SS (fT3SS) have been

show abstract

The FlhA linker mediates flagellar protein export switching during flagellar assembly

Cited by 22 publications

References 50 publications

Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system

Pilotins are mobile T3SS components involved in assembly and substrate specificity of the bacterial type III secretion system

Conserved GYXLI motif of FlhA is involved in dynamic domain motions of FlhA required for flagellar protein export

Hook‐basal‐body assembly state dictates substrate specificity of the flagellar type‐III secretion system

Contact Info

Product

Resources

About