Large Is Fast, Small Is Tight: Determinants of Speed and Affinity in Subunit Capture by a Periplasmic Chaperone
Large Is Fast, Small Is Tight: Determinants of Speed and Affinity in Subunit Capture by a Periplasmic Chaperone
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DOI：
10.1016/j.jmb.2012.01.020
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发表时间：
2012-04-06
影响因子：
5.6
通讯作者：
Zavialov, Anton V.
中科院分区：
文献类型：
--
作者：
Di Yu, Xiao;Fooks, Laura J.;Zavialov, Anton V.
伴侣/引导途径组装革兰氏阴性菌的表面毒力细胞器，由线性聚合的蛋白质亚基的纤维组成。纤维亚基通过“供体链互补”连接：每个亚基通过提供第七条反式β链来完成相邻亚基的免疫球蛋白（IG）样折叠。而IG结构域的折叠是快速的一级过程，IG模块折叠成纤维构象是缓慢的二级过程。周质伴侣通过与亚基形成瞬时复合物将这一过程分为两部分。分子伴侣和亚基之间的相互作用也基于供体链互补的原理。在这项研究中，我们进行了突变的结合基序的Caf 1 M伴侣和Caf 1荚膜亚基鼠疫耶尔森氏菌和分析的结构，稳定性和动力学的Caf 1 M-Caf 1和Caf 1-Caf 1相互作用的突变的影响。结果表明，一个大的疏水效应结合广泛的主链氢键使Caf 1 M迅速绑定早期折叠中间体的Caf 1和指导其部分折叠。从Caf 1 M-Caf 1接触到疏水性较低但相当紧密且动态性较低的Caf 1-Caf 1接触的转换通过拉链-外拉链-内供体链交换途径发生，其中口袋5充当起始位点。基于这些发现，Caf 1 M被设计成更快、更紧或更快、更紧地结合Caf 1。据我们所知，这是第一次成功的尝试，合理设计一个组装分子伴侣与改进分子伴侣功能。(C)2012爱思唯尔有限公司保留所有权利。
The chaperone/usher pathway assembles surface virulence organelles of Gram-negative bacteria, consisting of fibers of linearly polymerized protein subunits. Fiber subunits are connected through 'donor strand complementation': each subunit completes the immunoglobulin (Ig)-like fold of the neighboring subunit by donating the seventh beta-strand in trans. Whereas the folding of Ig domains is a fast first-order process, folding of Ig modules into the fiber conformation is a slow second-order process. Periplasmic chaperones separate this process in two parts by forming transient complexes with subunits. Interactions between chaperones and subunits are also based on the principle of donor strand complementation. In this study, we have performed mutagenesis of the binding motifs of the Caf1M chaperone and Caf1 capsular subunit from Yersinia pestis and analyzed the effect of the mutations on the structure, stability, and kinetics of Caf1M-Caf1 and Caf1-Caf1 interactions. The results suggest that a large hydrophobic effect combined with extensive main-chain hydrogen bonding enables Caf1M to rapidly bind an early folding intermediate of Caf1 and direct its partial folding. The switch from the Caf1M-Caf1 contact to the less hydrophobic, but considerably tighter and less dynamic Caf1-Caf1 contact occurs via the zip-out-zip-in donor strand exchange pathway with pocket 5 acting as the initiation site. Based on these findings, Caf1M was engineered to bind Caf1 faster, tighter, or both faster and tighter. To our knowledge, this is the first successful attempt to rationally design an assembly chaperone with improved chaperone function. (C) 2012 Elsevier Ltd. All rights reserved.