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首页> 外文期刊>Journal of Molecular Biology >Structures of the Shigella flexneri type 3 secretion system protein MxiC reveal conformational variability amongst homologues
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Structures of the Shigella flexneri type 3 secretion system protein MxiC reveal conformational variability amongst homologues

机译：志贺氏菌3型分泌系统蛋白MxiC的结构揭示了同源物之间的构象变异

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摘要

Many Gram-negative pathogenic bacteria use a complex macromolecular machine, known as the type 3 secretion system (T3SS), to transfer virulence proteins into host cells. The T3SS is composed of a cytoplasmic bulb, a basal body spanning the inner and outer bacterial membranes, and an extracellular needle. Secretion is regulated by both cytoplasmic and inner membrane proteins that must respond to specific signals in order to ensure that virulence proteins are not secreted before contact with a eukaryotic cell. This negative regulation is mediated, in part, by a family of proteins that are thought to physically block the entrance to the secretion apparatus until an appropriate signal is received following host cell contact. Despite weak sequence homology between proteins of this family, the crystal structures of Shigella flexneri MxiC we present here confirm the conservation of domain topology with the homologue from Yersinia sp. Interestingly, comparison of the Shigella and Yersinia structures reveals a significant structural change that results in substantial domain re-arrangement and opening of one face of the molecule. The conservation of a negatively charged patch on this face suggests it may have a role in binding other components of the T3SS. (C) 2008 Elsevier Ltd. All rights reserved.
机译：许多革兰氏阴性病原细菌使用复杂的大分子机器（称为3型分泌系统（T3SS））将毒力蛋白转移到宿主细胞中。 T3SS由细胞质球，横跨内细菌膜和外细菌膜的基体以及细胞外针组成。分泌受到必须响应特定信号的胞质和内膜蛋白的调节，以确保在与真核细胞接触之前不分泌毒力蛋白。这种负调节部分地由蛋白质家族介导，该蛋白质家族被认为在物理上阻止了分泌设备的进入，直到在宿主细胞接触后接收到适当的信号为止。尽管该家族蛋白之间的序列同源性较弱，但我们在此处提出的弗氏志贺氏菌MxiC的晶体结构证实了耶尔森菌属同源物的结构域拓扑结构的保守性。有趣的是，志贺氏菌和耶尔森氏菌结构的比较揭示了显着的结构变化，该结构变化导致结构域的实质性重排和分子一个表面的开放。该表面带负电荷的贴剂的保守性表明它可能在结合T3SS的其他组件中起作用。 （C）2008 Elsevier Ltd.保留所有权利。

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