Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function

Moriya, Nao; Minamino, Tetsuo; Ferris, Hedda U.; Morimoto, Yusuke V.; Ashihara, Masamichi; Kato, Takayuki; Namba, Keiichi

doi:10.2142/biophysics.9.63

Cited by 16 publications

(12 citation statements)

References 41 publications

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“…4A, lower panel). These results are in agreement with the findings of Kornacker and Newton (1994) and Moriya et al . (2013) who showed in a deletion analysis of FlgE that a region comprising residues 30–58 is important for export of FlgE.…”

Section: Resultssupporting

confidence: 94%

Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates

Singer

Erhardt

Hughes

2014

Molecular Microbiology

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Summary A remarkable feature of the flagellar-specific type III secretion system (T3SS) is the selective recognition of a few substrate proteins among the many thousand cytoplasmic proteins. Secretion substrates are divided into two specificity classes: early substrates secreted for hook-basal body (HBB) construction and late substrates secreted after HBB completion. Secretion was reported to require a disordered N-terminal secretion signal, mRNA secretion signals within the 5′-untranslated region (5′-UTR) and for late substrates, piloting proteins known as the T3S chaperones. Here, we utilized translational β-lactamase fusions to probe the secretion efficacy of the N-terminal secretion signal of fourteen secreted flagellar substrates in Salmonella enterica. We observed a surprising variety in secretion capability between flagellar proteins of the same secretory class. The peptide secretion signals of the early-type substrates FlgD, FlgF, FlgE and the late-type substrate FlgL were analysed in detail. Analysing the role of the 5′-UTR in secretion of flgB and flgE revealed that the native 5′-UTR substantially enhanced protein translation and secretion. Based on our data, we propose a multicomponent signal that drives secretion via the flagellar T3SS. Both mRNA and peptide signals are recognized by the export apparatus and together with substrate-specific chaperones allowing for targeted secretion of flagellar substrates.

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Section: Resultssupporting

confidence: 94%

Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates

Singer

Erhardt

Hughes

2014

Molecular Microbiology

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“…Residues Gly 329 -Asp 330 of subunit 0 at the tip of a short β-hairpin of domain D1 interact with residues Ala 39 -Asp 40 of subunit 5 in the distal part of the long β-hairpin of domain Dc, and this interaction does not change by protofilament compression and extension (Fig. 3d), indicating the importance of the long β-hairpin of domain Dc for the structural stability of the hook as found by deletion mutation experiments 13 .…”

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confidence: 62%

Structure of the native supercoiled flagellar hook as a universal joint

Kato

Makino

Miyata

et al. 2019

Preprint

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Bacteria swim in viscous liquid environments by using the flagellum1–3. The flagellum is composed of about 30 different proteins and can be roughly divided into three parts: the basal body, the hook and the filament. The basal body acts as a rotary motor powered by ion motive force across the cytoplasmic membrane as well as a protein export apparatus to construct the axial structure of the flagellum. The filament is as a helical propeller, and it is a supercoiled form of a helical tubular assembly consisting of a few tens of thousands of flagellin molecules4. The hook is a relatively short axial segment working as a universal joint connecting the basal body and the filament for smooth transmission of motor torque to the filament5,6. The structure of hook has been studied by combining X-ray crystal structure of a core fragment of hook protein FlgE and electron cryomicroscopy (cryoEM) helical image analysis of the polyhook in the straight form and has given a deep insight into the universal joint mechanism7. However, the supercoiled structure of the hook was an approximate model based on the atomic model of the straight hook without its inner core domain7 and EM observations of supercoiled polyhook by freeze-dry and Pt/Pd shadow cast8. Here we report the native supercoiled hook structure at 3.1 Å resolution by cryoEM single particle image analysis of the polyhook. The atomic model built on the three-dimensional (3D) density map show the actual changes in subunit conformation and intersubunit interactions upon compression and extension of the 11 protofilaments that occur during their smoke ring-like rotation and allow the hook to function as a dynamic molecular universal joint with high bending flexibility and twisting rigidity.

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“…It has been shown that the Dc domain of FlgE affects the hook supercoiling27. To investigate how the GSS insertion affects the morphology of the hook and its mechanical property, we isolated the flagellar hook-basal bodies from the wild-type and flgE + GSS mutant cells (Fig.…”

Section: Resultsmentioning

confidence: 99%

Straight and rigid flagellar hook made by insertion of the FlgG specific sequence into FlgE

Hiraoka

Morimoto

Inoue

et al. 2017

Sci Rep

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The bacterial flagellar hook connects the helical flagellar filament to the rotary motor at its base. Bending flexibility of the hook allows the helical filaments to form a bundle behind the cell body to produce thrust for bacterial motility. The hook protein FlgE shows considerable sequence and structural similarities to the distal rod protein FlgG; however, the hook is supercoiled and flexible as a universal joint whereas the rod is straight and rigid as a drive shaft. A short FlgG specific sequence (GSS) has been postulated to confer the rigidity on the FlgG rod, and insertion of GSS at the position between Phe-42 and Ala-43 of FlgE actually made the hook straight. However, it remains unclear whether inserted GSS confers the rigidity as well. Here, we provide evidence that insertion of GSS makes the hook much more rigid. The GSS insertion inhibited flagellar bundle formation behind the cell body, thereby reducing motility. This indicates that the GSS insertion markedly reduced the bending flexibility of the hook. Therefore, we propose that the inserted GSS makes axial packing interactions of FlgE subunits much tighter in the hook to suppress axial compression and extension of the protofilaments required for bending flexibility.

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Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function

Cited by 16 publications

References 41 publications

Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates

Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates

Structure of the native supercoiled flagellar hook as a universal joint

Straight and rigid flagellar hook made by insertion of the FlgG specific sequence into FlgE

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