Abstract：
Helicobacter pylori uses a cluster of polar, sheathed flagella for swimming motility. A search for homologs of H. pylori proteins that were conserved in Helicobacter species that possess flagellar sheaths but were underrepresented in Helicobacter species with unsheathed flagella identified several candidate proteins. Four of the identified proteins are predicted to form part of a tripartite efflux system that includes two transmembrane domains of an ABC transporter (HP1487 and HP1486), a periplasmic membrane fusion protein (HP1488), and a TolC-like outer membrane efflux protein (HP1489). Deleting hp1486/hp1487 and hp1489 homologs in H. pylori B128 resulted in reductions in motility and the number of flagella per cell. Cryo-electron tomography studies of intact motors of the Δhp1489 and Δhp1486/hp1487 mutants revealed many of the cells contained a potential flagellum disassembly product consisting of decorated L and P rings, which has been reported in other bacteria. Aberrant motors lacking specific components, including a cage-like structure that surrounds the motor, were also observed in the Δhp1489 mutant. These findings suggest a role for the H. pylori HP1486-HP1489 tripartite efflux system in flagellum stability. Three independent variants of the Δhp1486/hp1487 mutant with enhanced motility were isolated. All three motile variants had the same frameshift mutation in fliL, suggesting a role for FliL in flagellum disassembly.
摘要：
幽门螺杆菌使用一簇极性，有鞘的鞭毛用于游泳运动。在具有鞭毛鞘的螺杆菌物种中保守但在无鞘鞭毛的螺杆菌物种中代表性不足的幽门螺杆菌蛋白的同源物的搜索确定了几种候选蛋白。预测四种鉴定的蛋白质形成三方外排系统的一部分，该系统包括ABC转运蛋白的两个跨膜结构域（HP1487和HP1486）。周质膜融合蛋白（HP1488），和TolC样外膜外排蛋白(HP1489)。删除幽门螺杆菌B128中的hp1486/hp1487和hp1489同源物导致运动性和每个细胞鞭毛数量的减少。对Δhp1489和Δhp1486/hp1487突变体的完整电机的低温电子层析成像研究表明，许多细胞中含有潜在的鞭毛分解产物，由装饰的L和P环组成，这在其他细菌中也有报道。缺少特定组件的异常电机，包括围绕电机的笼状结构，在Δhp1489突变体中也观察到。这些发现表明幽门螺杆菌HP1486-HP1489三方外排系统在鞭毛稳定性中的作用。分离了运动性增强的Δhp1486/hp1487突变体的三个独立变体。所有三个能动的变种在FLIL中都有相同的移码突变，提示FliL在鞭毛拆卸中的作用。
