Off-pathway assembly of fimbria subunits is prevented by chaperone CfaA of CFA/I fimbriae from enterotoxigenic E. coli.
Off-pathway assembly of fimbria subunits is prevented by chaperone CfaA of CFA/I fimbriae from enterotoxigenic E. coli.
复制标题
产肠毒素大肠杆菌的 CFA/I 菌毛的伴侣 CfaA 可以防止菌毛亚基的离路组装。
DOI：
10.1111/mmi.13530
复制
发表时间：
2016-12
影响因子：
3.6
通讯作者：
Xia D
中科院分区：
文献类型：
--
作者：
Bao R;Liu Y;Savarino SJ;Xia D
重组大肠杆菌5类CFA/I菌毛的组装大肠杆菌中，提出通过交替伴侣-引导途径进行。在这里，我们表明，在没有伴侣CfaA，CfaB，CFA/I菌毛的主要菌毛蛋白亚基，是能够自发重折叠和折叠成环状三聚体。CfaA在动力学上捕获CfaB以形成可通过突变稳定的亚稳态复合物。稳定的复合物的晶体结构揭示了独特的相互作用，通过供体链互补和裂缝介导的锚定，由CfaA捕获CfaB在组装能力状态。突变表明，供体链互补控制的伴侣蛋白亚基复合物的稳定性和裂缝介导的锚定的亚基C-末端另外协助亚基重折叠。令人惊讶的是，过度稳定的伴侣蛋白亚基复合物导致延迟的菌毛组装，而不稳定的复合物导致没有菌毛。因此，CfaA主要充当动力学陷阱，通过稳定亚基以避免其产生能量上有利的三聚体的非途径自聚合，并且可以充当CFA/I菌毛组装的驱动力，代表5类菌毛组装所特有的能量景观。定植因子抗原I（CFA/I）皮利是一组人类特异性肠致病性大肠杆菌的原型。大肠杆菌（ETEC）中，并通过交替伴侣引导途径组装。在这里，我们提出的伴侣蛋白CfaA的结构与亚基CfaB的复合物，并证明CfaA在CFA/I菌毛组装的作用是避免关闭途径自聚合的亚基CfaB（虚线箭头）。
The assembly of the class 5 CFA/I fimbriae of enterotoxigenic E. coli was proposed to proceed via the alternate chaperone-usher pathway. Here, we show that in the absence of the chaperone CfaA, CfaB, the major pilin subunit of CFA/I fimbriae, is able to spontaneously refold and polymerize into cyclic trimers. CfaA kinetically traps CfaB to form a metastable complex that can be stabilized by mutations. Crystal structure of the stabilized complex reveals distinctive interactions provided by CfaA to trap CfaB in an assembly competent state through donor-strand complementation and cleft-mediated anchorage. Mutagenesis indicated that donor-strand complementation controls the stability of the chaperone-subunit complex and the cleft-mediated anchorage of the subunit C-terminus additionally assist in subunit refolding. Surprisingly, over-stabilization of the chaperone-subunit complex led to delayed fimbria assembly, whereas destabilizing the complex resulted in no fimbriation. Thus, CfaA acts predominantly as a kinetic trap by stabilizing subunit to avoid its off-pathway self-polymerization that results in energetically favorable trimers and could serve as a driving force for CFA/I pilus assembly, representing an energetic landscape unique to class 5 fimbria assembly. The colonization factor antigen I (CFA/I) pili are archetypal of a group of human-specific enterotoxigenic E. coli (ETEC) and are assembled via the alternate chaperoneusher pathway. Here, we present the structure of the chaperone CfaA in complex with subunit CfaB and demonstrate that the role of CfaA in CFA/I pilus assembly is to avoid off pathway self-polymerization of the subunit CfaB (dotted arrows).
登录
查看更多内容
影响因子：
6.7
作者：
Bao R;Fordyce A;Chen YX;McVeigh A;Savarino SJ;Xia D
通讯作者：
Xia D
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
DOI：
10.1107/s1744309109001584
发表时间：
2009-03-01
影响因子：
0.9
作者：
Li, Yong-Fu;Poole, Steven;Xia, Di
通讯作者：
Xia, Di
影响因子：
4.8
作者：
Li, Yong-Fu;Poole, Steven;Xia, Di
通讯作者：
Xia, Di
DOI：
10.1073/pnas.0812843106
发表时间：
2009-06-30
影响因子：
11.1
作者：
Li, Yong-Fu;Poole, Steven;Bullitt, Esther
通讯作者：
Bullitt, Esther