Identification of the bile salt binding site on IpaD from Shigella flexneri and the influence of ligand binding on IpaD structure.
Identification of the bile salt binding site on IpaD from Shigella flexneri and the influence of ligand binding on IpaD structure.
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DOI：
10.1002/prot.23251
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发表时间：
2012-03
影响因子：
2.9
通讯作者：
Picking, William D.
中科院分区：
文献类型：
--
作者：
Barta, Michael L.;Guragain, Manita;Adam, Philip;Dickenson, Nicholas E.;Patil, Mrinalini;Geisbrecht, Brian V.;Picking, Wendy L.;Picking, William D.
Ⅲ型分泌物（TTS）是福氏志贺菌（Shigellaflexneri）的一个重要毒力因子，是志贺菌病的致病因子。志贺氏菌TTS装置（TTSA）是一种优雅的纳米机器，由基体、将效应物递送到人体细胞中的外部针和控制分泌激活的针尖复合物组成。iPad位于新生TTSA针的尖端，在那里它控制TTS激活的第一步。胆盐脱氧胆酸盐（DOC）结合iPad，诱导募集转运蛋白IpaB进入成熟的尖端复合物。我们最近使用光谱分析表明，iPad经历了结构重排，伴随着结合DOC。在这里，我们报告的晶体结构的iPad与DOC绑定和测试的重要性，使iPad功能的DOC结合口袋的残基。iPad在螺旋α3和α7之间的界面处结合DOC，伴随着螺旋α7相对于其在未结合iPad中的位置的方向移动。当参与DOC结合的iPad残基发生突变时，发现一些iPad残基导致改变的侵袭和分泌表型。这些发现表明，采用DOC结合的结构状态iPad启动志贺氏菌TTSA与宿主细胞接触。这里和导致这项工作的研究中提供的数据为开发志贺氏菌TTS激活第一步的模型提供了基础。
Type III secretion (TTS) is an essential virulence factor for Shigella flexneri, the causative agent of shigellosis. The Shigella TTS apparatus (TTSA) is an elegant nano-machine that is composed of a basal body, an external needle to deliver effectors into human cells, and a needle tip complex that controls secretion activation. IpaD is at the tip of the nascent TTSA needle where it controls the first step of TTS activation. The bile salt deoxycholate (DOC) binds to IpaD to induce recruitment of the translocator protein IpaB into the maturing tip complex. We recently used spectroscopic analyses to show that IpaD undergoes a structural rearrangement that accompanies binding to DOC. Here we report a crystal structure of IpaD with DOC bound and test the importance of the residues that make up the DOC binding pocket on IpaD function. IpaD binds DOC at the interface between helices α3 and α7, with concomitant movement in the orientation of helix α7 relative to its position in unbound IpaD. When the IpaD residues involved in DOC binding are mutated, some are found to lead to altered invasion and secretion phenotypes. These findings suggest that adoption of a DOC-bound structural state for IpaD primes the Shigella TTSA for contact with host cells. The data presented here and in the studies leading up to this work provide the foundation for developing a model of the first step in Shigella TTS activation.
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DOI：
10.1016/j.str.2009.06.008
发表时间：
2009-08-12
期刊：
Structure (London, England : 1993)
影响因子：
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作者：
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通讯作者：
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DOI：
10.1107/s0907444904019158
发表时间：
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影响因子：
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影响因子：
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作者：
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影响因子：
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作者：
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