Outside-In Assembly Pathway of the Type IV Pilus System in Myxococcus xanthus
Outside-In Assembly Pathway of the Type IV Pilus System in Myxococcus xanthus
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DOI：
10.1128/jb.01094-13
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发表时间：
2014-01-01
影响因子：
3.2
通讯作者：
Sogaard-Andersen, Lotte
中科院分区：
文献类型：
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作者：
Friedrich, Carmen;Bulyha, Iryna;Sogaard-Andersen, Lotte
IV型Pili（T4P）是无处不在的细菌细胞表面结构，经历了延伸，粘附和缩回周期的循环。 T4P功能取决于高度保守的跨膜大分子机械，该机械由10种蛋白质组成，该蛋白在牛th虫球菌中极化。使用此定位，我们通过系统地分析所有人的稳定性以及在没有其他T4P机械蛋白以及绘制直接蛋白质 - 蛋白质相互作用的情况下，通过系统地分析所有人的稳定性和八种蛋白质的定位，研究了整个T4P机械组装途径。我们的实验从外膜（OM）PILQ Secralin环开始，发现了一个顺序的外部途径。 PILQ募集了一个由内膜（IM）脂蛋白PILP和综合IM蛋白PILN和PILO组成的子复合物，通过与PILP的周质结构域直接相互作用。 PILP/PILN/PILO子复合物通过PILN和PILM之间的直接相互作用以及整体IM蛋白PILC募集了细胞质PILM蛋白。与其他T4P机械蛋白无关的伸展/回收供电/回收的PILB/PILT ATPase。因此，T4P机械的组装启动了OM Secralin环的形成，并继续向内延伸到周期和IM到细胞质。
Type IV pili (T4P) are ubiquitous bacterial cell surface structures that undergo cycles of extension, adhesion, and retraction. T4P function depends on a highly conserved envelope-spanning macromolecular machinery consisting of 10 proteins that localizes polarly in Myxococcus xanthus. Using this localization, we investigated the entire T4P machinery assembly pathway by systematically profiling the stability of all and the localization of eight of these proteins in the absence of other T4P machinery proteins as well as by mapping direct protein-protein interactions. Our experiments uncovered a sequential, outside-in pathway starting with the outer membrane (OM) PilQ secretin ring. PilQ recruits a subcomplex consisting of the inner membrane (IM) lipoprotein PilP and the integral IM proteins PilN and PilO by direct interaction with the periplasmic domain of PilP. The PilP/PilN/PilO subcomplex recruits the cytoplasmic PilM protein, by direct interaction between PilN and PilM, and the integral IM protein PilC. The PilB/PilT ATPases that power extension/retraction localize independently of other T4P machinery proteins. Thus, assembly of the T4P machinery initiates with formation of the OM secretin ring and continues inwards over the periplasm and IM to the cytoplasm.