The C-terminal domain of Escherichia coli trigger factor represents the central module of its chaperone activity
The C-terminal domain of Escherichia coli trigger factor represents the central module of its chaperone activity
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DOI：
10.1074/jbc.m605164200
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发表时间：
2006-10-20
影响因子：
4.8
通讯作者：
Deuerling, Elke
中科院分区：
文献类型：
--
作者：
Merz, Frieder;Hoffmann, Anja;Deuerling, Elke
在细菌中，核糖体结合的触发因子有助于新合成蛋白质的折叠。触发因子的 N 末端结构域 (N) 介导核糖体结合，而中间结构域 (P) 具有肽基脯氨酰异构酶活性。由于孤立的结构不稳定，C 端结构域 (C) 的功能仍然是个谜。在这里，我们描述了 C 域 (C-S) 的稳定版本，该版本是基于最近解决的触发因子原子结构而设计的。引人注目的是，只有分离的 C-S 结构域或其结构域组合（NCS、PCS）在体外和体内显示出显着的伴侣活性。此外，为了破坏 C 结构域而不影响整体触发因子结构，我们通过删除 C 端 53 个氨基酸残基生成了突变体 (Delta 53)。这种截短导致触发因子的体外伴侣活性完全丧失，并严重损害其体内功能。因此，我们得出结论，触发因子的伴侣活性关键取决于其作为中心结构伴侣模块的C端结构域。有趣的是，在周质伴侣 SurA 和 MPN555（一种功能未知的蛋白质）中发现了结构相似的模块。我们推测这个保守模块可以单独存在或与其他结构域组合存在，以实现细胞中的多种伴侣功能。
In bacteria, ribosome-bound Trigger Factor assists the folding of newly synthesized proteins. The N-terminal domain (N) of Trigger Factor mediates ribosome binding, whereas the middle domain (P) harbors peptidyl-prolyl isomerase activity. The function of the C-terminal domain (C) has remained enigmatic due to structural instability in isolation. Here, we have characterized a stabilized version of the C domain (C-S), designed on the basis of the recently solved atomic structure of Trigger Factor. Strikingly, only the isolated C-S domain or domain combinations thereof (NCS, PCS) revealed substantial chaperone activity in vitro and in vivo. Furthermore, to disrupt the C domain without affecting the overall Trigger Factor structure, we generated a mutant (Delta 53) by deletion of the C-terminal 53 amino acid residues. This truncation caused the complete loss of the chaperone activity of Trigger Factor in vitro and severely impaired its function in vivo. Therefore, we conclude that the chaperone activity of Trigger Factor critically depends on its C-terminal domain as the central structural chaperone module. Intriguingly, a structurally similar module is found in the periplasmic chaperone SurA and in MPN555, a protein of unknown function. We speculate that this conserved module can exist solely or in combination with additional domains to fulfill diverse chaperone functions in the cell.