Shigella Spa33 is an essential C-ring component of type III secretion machinery
Shigella Spa33 is an essential C-ring component of type III secretion machinery
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DOI：
10.1074/jbc.m509644200
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发表时间：
2006-01-06
影响因子：
4.8
通讯作者：
Sasakawa, C
中科院分区：
文献类型：
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作者：
Morita-Ishihara, T;Ogawa, M;Sasakawa, C
III 型分泌机器 (TTSM) 由针、基体和 C 环室组成，可将效应器子集递送到宿主细胞中。在这里，我们证明志贺氏菌 Spa33 是 C 环区室的重要组成部分，参与介导各种 TTSM 相关易位蛋白的转运。电子显微镜分析和下拉分析显示 Spa33 通过与 MxiG 和 MxiJ（基础身体成分）相互作用定位在 TTSM 下方。 Spa33 还能够与 Spa47（TTSM ATP 酶）、MxiK、MxiN（针组件 MxiH 转运所需）、Spa32（确定针长度所需）和多个效应器相互作用。 Spa33 C 末端区域在 SpaO-YscQ-HrcQB-FliN 家族中高度保守，其遗传和功能分析表明，一些保守残基对于通过与 MxiN 相互作用形成针状结构至关重要。因此，Spa33 作为 C 环成分在招募/输出 TTSM 相关蛋白中发挥着核心作用。
Type III secretion machinery (TTSM), composed of a needle, a basal body, and a C-ring compartment, delivers a subset of effectors into host cells. Here, we show that Shigella Spa33 is an essential component of the C-ring compartment involved in mediating the transit of various TTSM-associated translocated proteins. Electron microscopic analysis and pull-down assay revealed Spa33 to be localized beneath the TTSM via interaction with MxiG and MxiJ (basal body components). Spa33 is also capable of interacting with Spa47 (TTSM ATPase), MxiK, MxiN (required for the transit of MxiH, the needle component), Spa32 (required for determining needle length), and several effectors. Genetic and functional analyses of the Spa33 C-terminal region, which is highly conserved in the SpaO-YscQ-HrcQB-FliN family, indicate that some of the conserved residues are crucial for needle formation via interactions with MxiN. Thus, Spa33 plays a central role as the C-ring component in recruiting/ exporting TTSM-associated proteins.