The protein BSU35380 from Bacillus subtilis (renamed FliW) was characterized as being a flagellar assembly factor. Experimental characterization was also carried out in Treponema pallidum (TP0658). In Campylobacter jejuni, Cj1075 has been shown to be involved in motility and flagellin biosynthesis. The two paralogues in Helicobacter pylori (HP1154 and HP1377) were found to be able to bind to flagellin. FliW proteins are involved in flagellar assembly. FliW is part of a three-part feedback loop: in Bacillus subtilis FliW inhibits CsrA (an RNA-binding protein) which inhibits FliC translation; hence FliW is required for FliC (flagellin) production.