Crystal Structure of Flagellar Export Chaperone FliS in Complex With Flagellin and HP1076 of Helicobacter pylori
Crystal Structure of Flagellar Export Chaperone FliS in Complex With Flagellin and HP1076 of Helicobacter pylori
复制标题
DOI：
10.3389/fmicb.2020.00787
复制
发表时间：
2020-05-19
影响因子：
5.2
通讯作者：
Au, Shannon Wing-Ngor
中科院分区：
文献类型：
--
作者：
Lam, Wendy Wai-Ling;Sun, Kailei;Au, Shannon Wing-Ngor
功能性鞭毛形成是一种广泛存在的毒力因子，在宿主的生存和定殖中起着关键作用。鞭毛的合成是一个复杂且高度协调的过程。轴向结构超出细胞膜的组装是由输出伴侣蛋白介导的，所述输出伴侣蛋白将其同源底物运输到输出门复合物。输出分子伴侣FliS与鞭毛蛋白相互作用，鞭毛蛋白是用于构建细丝的基本组分。与肠杆菌不同，胃病原体幽门螺杆菌产生两种不同的鞭毛蛋白，FlaA和FlaB，它们在细丝中表现出不同的空间定位模式。以前，我们证明了FliS和一个未知的蛋白质，HP 1076，在H。幽门。在这里，我们提出了FliS的晶体结构与FlaB和HP 1076的C-末端D 0结构域的复合物。虽然这种三元复合物揭示了FliS与鞭毛蛋白的相互作用，使用先前在风产液菌，枯草芽孢杆菌和沙门氏菌血清型鼠伤寒沙门氏菌中证明的保守结合模式，但FlaB在这种复合物中的螺旋构象是不同的。此外，HP 1076和鞭毛蛋白的D1结构域具有结构相似性，并与FliS上的相同结合界面相互作用。通过竞争性下拉测定和动力学结合分析进一步验证了这一观察结果。有趣的是，我们没有观察到任何有害的鞭毛虫或运动表型在hp 1076无效株。我们的定位研究表明，HP 1076是一种膜相关蛋白，其细胞定位独立于FliS。由于HP 1076在H. pylori和相关物种，我们提出，这种蛋白质可能有助于鞭毛系统的分歧，虽然它与FliS的关系仍然不完全阐明。
Functional flagella formation is a widespread virulence factor that plays a critical role in survival and host colonization. Flagellar synthesis is a complex and highly coordinated process. The assembly of the axial structure beyond the cell membrane is mediated by export chaperone proteins that transport their cognate substrates to the export gate complex. The export chaperone FliS interacts with flagellin, the basic component used to construct the filament. Unlike enterobacteria, the gastric pathogen Helicobacter pylori produces two different flagellins, FlaA and FlaB, which exhibit distinct spatial localization patterns in the filament. Previously, we demonstrated a molecular interaction between FliS and an uncharacterized protein, HP1076, in H. pylori. Here, we present the crystal structure of FliS in complex with both the C-terminal D0 domain of FlaB and HP1076. Although this ternary complex reveals that FliS interacts with flagellin using a conserved binding mode demonstrated previously in Aquifex aeolicus, Bacillus subtilis, and Salmonella enterica serovar Typhimurium, the helical conformation of FlaB in this complex was different. Moreover, HP1076 and the D1 domain of flagellin share structural similarity and interact with the same binding interface on FliS. This observation was further validated through competitive pull-down assays and kinetic binding analyses. Interestingly, we did not observe any detrimental flagellation or motility phenotypes in an hp1076-null strain. Our localization studies suggest that HP1076 is a membrane-associated protein with a cellular localization independent of FliS. As HP1076 is uniquely expressed in H. pylori and related species, we propose that this protein may contribute to the divergence of the flagellar system, although its relationship with FliS remains incompletely elucidated.