Flagellin-Containing Membrane Vesicles Excreted from Vibrio alginolyticus Mutants Lacking a Polar-Flagellar Filament

Abstract

Polar flagellum-defective mutants (Pof- Laf-) have been isolated from a lateral flagella-defective mutant (Pof+ Laf-). Among these Pof- Laf- mutants, polar-filamentless mutants, which have the hook structure but not the filament, were identified by electron microscopy. Their hooks were covered with a sheath structure which is contiguous to the outer membrane. The filament proteins, flagellins, were shed into the culture medium of these mutants. These flagellins could be sedimented by high-speed centrifugation even after heat or low pH treatment whereas the depolymerized flagellin of the Pof+ strain was degraded by these treatments. After Triton X-100 treatment, most flagellin of the filamentless mutants could no longer be sedimented, and was degraded. We observed vesicle-like structures on the tips of the hooks and in the flagellin fraction sedimented by high speed centrifugation. These results suggest that flagellin of the filamentless mutants is not assembled into the tip of the hook, but is excreted together with a membrane structure which is probably the sheath of polar flagella.

A Pseudomonas T6SS effector recruits PQS-containing outer membrane vesicles for iron acquisition

“…9), indicating that the association of TseF with OMVs occurs in a PQS-dependent manner. Consistent with earlier findings50, flagellin FliC-VSVG is associated with OMVs prepared from both the Δ tseF and the Δ tseF Δ pqsH strains. In contrast, the VgrG1b protein involved in substrate translocation was not detectably associated with purified vesicles (Fig.…”

Morphological analysis of the sheathed flagellum of Brucella melitensis

“…One hypothetical function of this club-like structure could be the formation of a confined space facilitating the self-assembly of flagellin monomers into a filament, despite the lack of a FliD homologue. Similarly in Vibrio alginolyticus , it was assumed that the sheath could trap excreted flagellin to allow polymerization independently of FliD [33]. Secondly, the sheath of the flagellum of B. melitensis is likely an extension of the outer membrane and contains LPS, which is also observed in H. pylori , B. bacteriovorus and some Vibrio spp., [1,32,34-38].…”

Collaboration of FlhF and FlhG to regulate polar-flagella number and localization in Vibrio alginolyticus

“…Proteins in the samples were separated by SDS-PAGE and then electrophoretically transferred to a PVDF membrane (Millipore) using a semi-dry blotting apparatus (Bio-craft) according to the manufacturer's instructions. Immunoblotting was performed with anti-FlhF, anti-FlhG, anti-FlgI, anti-MotX, anti-MotY, anti-PomA, anti-PomB and anti-flagellin antibodies, as described previously (Nambu & Kutsukake, 2000;Yagasaki et al, 2006;Fukuoka et al, 2005;Nishioka et al, 1998).…”