Delineation and characterization of the actin nucleation and effector translocation activities of Salmonella SipC
Delineation and characterization of the actin nucleation and effector translocation activities of Salmonella SipC
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DOI：
10.1111/j.1365-2958.2004.04480.x
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发表时间：
2005-03-01
影响因子：
3.6
通讯作者：
Zhou, DG
中科院分区：
文献类型：
--
作者：
Chang, JH;Chen, J;Zhou, DG
沙门氏菌分泌的III型SIPC具有双重功能：转位效应器和调节肌动蛋白。SIPC的肌动蛋白核活性在沙门氏菌诱导的肌动蛋白细胞骨架重排中的生物学意义尚未被研究。我们在这里报告了从SIPC的效应器转位活性来描绘肌动蛋白成核活性的过程。我们的数据表明，中心氨基酸区域(残基：201-220)是肌动蛋白成核活性所必需的，而C-末端氨基酸区域(321-409)是效应器移位所必需的。获得了一个SIPC核缺陷突变体，该突变体保持了其效应器易位活性。该核缺陷突变体显著降低了诱导肌动蛋白细胞骨架重排的能力，从而降低了细菌对HeLa细胞的侵袭。与以前的报道相反，我们通过尺寸排除层析和多角度激光光散射分析(SEC-LS)发现，纯化的重组野生型SIPC(199-409)蛋白在溶液中是单体。我们的数据表明，SIPC的肌动蛋白成核活性在沙门氏菌诱导的膜褶皱和随后的细菌入侵中起着至关重要的作用。
Salmonella type III secreted SipC possesses dual functions: translocation of effectors and actin modulation. The biological significance of SipC's actin nucleation activity in Salmonella-induced actin cytoskeleton rearrangements has not been studied. We report here the delineation of the actin nucleation activity from the effector translocation activity of SipC. Our data show that the central amino acid region (residues: 201-220) is essential for its actin nucleation activity and the C-terminal amino acid region (321-409) is required for translocation of effectors. A SipC nucleation-deficient mutant, which maintained its effector translocation activity, was obtained. This nucleation-deficient mutant had significantly reduced ability to induce actin cytoskeleton rearrangements, resulting in lower bacterial invasion into HeLa cells. Contrary to a previous report, we found that the purified recombinant wild-type SipC(199-409) protein is monomeric in solution by size exclusion chromatography coupled with multiangle laser light scattering assays (SEC-LS). Our data established that the actin nucleation activity of SipC plays a vital role in Salmonella-induced membrane ruffles and subsequent bacteria invasion.