Crystal structure of the flagellar cap protein FliD from Bdellovibrio bacteriovorus

Cho, So Yeon; Song, Wan Seok; Yoon, Sung‐il

doi:10.1016/j.bbrc.2019.09.024

Cited by 7 publications

(6 citation statements)

References 32 publications

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“…S2C). Two of the top hits for D2 of C. jejuni were the outer domain from the Pseudomonas aeruginosa A-type flagellin FliC (20) and filament cap protein, FliD, from Bdellovibrio bacteriovorus (21). Some of C. jejuni FlaA D3′s top hits were FliD from H. pylori (22) and D4 from the C. jejuni flagellar hook protein FlgE (23).…”

Section: Resultsmentioning

confidence: 99%

Atomic structure of the Campylobacter jejuni flagellar filament reveals how ε Proteobacteria escaped Toll-like receptor 5 surveillance

Kreutzberger

Ewing

Poly

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Vertebrates, from zebra fish to humans, have an innate immune recognition of many bacterial flagellins. This involves a conserved eight-amino acid epitope in flagellin recognized by the Toll-like receptor 5 (TLR5). Several important human pathogens, such as Helicobacter pylori and Campylobacter jejuni, have escaped TLR5 activation by mutations in this epitope. When such mutations were introduced into Salmonella flagellin, motility was abolished. It was previously argued, using very low-resolution cryoelectron microscopy (cryo-EM), that C. jejuni accommodated these mutations by forming filaments with 7 protofilaments, rather than the 11 found in other bacteria. We have now determined the atomic structure of the C. jejuni G508A flagellar filament from a 3.5-Å-resolution cryo-EM reconstruction, and show that it has 11 protofilaments. The residues in the C. jejuni TLR5 epitope have reduced contacts with the adjacent subunit compared to other bacterial flagellar filament structures. The weakening of the subunit−subunit interface introduced by the mutations in the TLR5 epitope is compensated for by extensive interactions between the outer domains of the flagellin subunits. In other bacteria, these outer domains can be nearly absent or removed without affecting motility. Furthermore, we provide evidence for the stabilization of these outer domain interactions through glycosylation of key residues. These results explain the essential role of glycosylation in C. jejuni motility, and show how the outer domains have evolved to play a role not previously found in other bacteria.

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Section: Resultsmentioning

confidence: 99%

Atomic structure of the Campylobacter jejuni flagellar filament reveals how ε Proteobacteria escaped Toll-like receptor 5 surveillance

Kreutzberger

Ewing

Poly

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Our results showed that D2 and D3 domains are dispensable for formation of functional filament, a surprising finding considering their apparent involvement into cap assembly [9,10,13,14]. While they may not be directly implicated in the interaction with FliC, head/plate domains may still be important in other processes, such as adhesion during infection [33][34][35][36].…”

Section: Discussionmentioning

confidence: 71%

“…FliD capping protein complexes have been shown to adopt distinct oligomeric states in different bacteria-hexamers in Pseudomonas aeruginosa and Escherichia coli [8,9], pentamers in Salmonella and Campylobacter jejuni [4,[9][10][11][12] and tetramers in Serratia marcescens and Bdellovibrio bacteriovorus [13,14]. FliD proteins from Salmonella and Pseudomonas are not interchangeable, such that the expression of the fliD gene from Salmonella in a Pseudomonas ∆fliD knockout strain does not restore bacterial motility and vice versa [15].…”

Section: Introductionmentioning

confidence: 99%

Molecular Determinants of Filament Capping Proteins Required for the Formation of Functional Flagella in Gram-Negative Bacteria

et al. 2021

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Bacterial flagella are cell surface protein appendages that are critical for motility and pathogenesis. Flagellar filaments are tubular structures constructed from thousands of copies of the protein flagellin, or FliC, arranged in helical fashion. Individual unfolded FliC subunits traverse the filament pore and are folded and sorted into place with the assistance of the flagellar capping protein complex, an oligomer of the FliD protein. The FliD filament cap is a stool-like structure, with its D2 and D3 domains forming a flat head region, and its D1 domain leg-like structures extending perpendicularly from the head towards the inner core of the filament. Here, using an approach combining bacterial genetics, motility assays, electron microscopy and molecular modeling, we define, in numerous Gram-negative bacteria, which regions of FliD are critical for interaction with FliC subunits and result in the formation of functional flagella. Our data indicate that the D1 domain of FliD is its sole functionally important domain, and that its flexible coiled coil region comprised of helices at its extreme N- and C-termini controls compatibility with the FliC filament. FliD sequences from different bacterial species in the head region are well tolerated. Additionally, head domains can be replaced by small peptides and larger head domains from different species and still produce functional flagella.

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“…This resembles the capping of the flagellar tip by FliD/HAP2, where an oligomerised platform sits atop a polymerising helical structure with peripheral domains that interact with this structure and coordinate polymerisation 58 . A further interesting parallel is that, like TssA, variable FliD symmetries have been identified (four-, five-and sixfold) which also clash with the 11-fold symmetry of the flagellar filament [58][59][60][61][62][63][64] .…”

Section: Discussionmentioning

confidence: 96%

Functionality of chimeric TssA proteins in the type VI secretion system involves sheath docking specificty

Fecht

Paracuellos

Ilangovan

et al. 2023

Preprint

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Pseudomonas aeruginosa encodes three type VI secretion systems, each comprising a dozen distinct proteins, which deliver toxins upon T6SS sheath contraction. The least conserved T6SS component, TssA, has variations in size (short: TssA1 and TssA3, long: TssA2) which influence domain organisation and structure. Here we show that the TssA Nt1 domain interacts directly with the sheath in a specific manner, while the C-terminus is essential for oligomerisation. We built chimeric TssA proteins by swapping C-termini and showed that these can be functional even when made of domains from different TssA sub-groups. Functional specificity requires the Nt1 domain, while the origin of the C-terminal domain is more permissive for T6SS function. We identify two regions, loop and hairpin, that contribute to sheath binding. We propose a docking mechanism of TssA proteins with the sheath, and a model for how sheath assembly is coordinated by TssA proteins from this position.

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Crystal structure of the flagellar cap protein FliD from Bdellovibrio bacteriovorus

Cited by 7 publications

References 32 publications

Atomic structure of the Campylobacter jejuni flagellar filament reveals how ε Proteobacteria escaped Toll-like receptor 5 surveillance

Atomic structure of the Campylobacter jejuni flagellar filament reveals how ε Proteobacteria escaped Toll-like receptor 5 surveillance

Molecular Determinants of Filament Capping Proteins Required for the Formation of Functional Flagella in Gram-Negative Bacteria

Functionality of chimeric TssA proteins in the type VI secretion system involves sheath docking specificty

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