Homma M, Iino T, Kutsukake K, Yamaguchi S
Proc Natl Acad Sci U S A. 1986 Aug;83(16):6169-73. doi: 10.1073/pnas.83.16.6169.
An in vitro system for reconstituting flagellar filaments onto hooks of filamentless mutants of Salmonella typhimurium was used to investigate the role played in filament formation by the three hook-associated proteins (HAPs, products of the flaW, flaU, and flaV genes). These proteins--FlaW, FlaU, and FlaV--are believed to be assembled in this order at the distal end of the hook. When the recipient hooks were provided by flaU mutants, whose hook tips contained FlaW only, exogenous FlaU was essential for polymerization of both exogenous and endogenous flagellin, whereas exogenous FlaV inhibited such polymerization. When the recipients were flaV-mutant hooks, whose tips contained FlaW and FlaU but not FlaV, exogenous FlaV inhibited polymerization of exogenous flagellin. FlaV also inhibited polymerization of exogenous flagellin at the tips of filament fragments. In contrast, FlaV was essential for polymerization of endogenous flagellin onto flaV-mutant hooks, and onto short filaments that had been made (in the absence of FlaV) by polymerization of exogenous flagellin on the tips of flaV-mutant hooks. These results suggest that FlaV acts not only at the tip of the hook to initiate growth of the filament, but also at the tip of the growing filament, and that FlaV is essential for polymerization of endogenous flagellin--i.e., for the normal process of filament assembly in vivo.
利用一种体外系统，将鞭毛丝重组到鼠伤寒沙门氏菌无丝突变体的钩上，以研究三种钩相关蛋白（HAPs，即flaW、flaU和flaV基因的产物）在丝形成过程中所起的作用。这些蛋白——FlaW、FlaU和FlaV——被认为按此顺序组装在钩的远端。当受体钩由flaU突变体提供时，其钩尖仅含有FlaW，外源性FlaU对于外源性和内源性鞭毛蛋白的聚合都是必需的，而外源性FlaV则抑制这种聚合。当受体是flaV突变体的钩时，其尖端含有FlaW和FlaU但不含FlaV，外源性FlaV抑制外源性鞭毛蛋白的聚合。FlaV还抑制鞭毛丝片段尖端外源性鞭毛蛋白的聚合。相比之下，FlaV对于内源性鞭毛蛋白聚合到flaV突变体的钩上以及聚合到（在没有FlaV的情况下）通过外源性鞭毛蛋白在flaV突变体钩尖端聚合而形成的短丝上是必需的。这些结果表明，FlaV不仅在钩的尖端起作用以启动丝的生长，而且在生长的丝的尖端起作用，并且FlaV对于内源性鞭毛蛋白的聚合是必需的——即对于体内丝组装的正常过程是必需的。
