Lipoamide dehydrogenase mediates retention of coronin-1 on BCG vacuoles, leading to arrest in phagosome maturation
Lipoamide dehydrogenase mediates retention of coronin-1 on BCG vacuoles, leading to arrest in phagosome maturation
复制标题
DOI：
10.1242/jcs.006221
复制
发表时间：
2007-08-15
影响因子：
4
通讯作者：
Hmama, Zakaria
中科院分区：
文献类型：
--
作者：
Deghmane, Ala-Eddine;Soulhine, Hafid;Hmama, Zakaria
结核分枝杆菌通过抑制其吞噬体向杀菌吞噬酶体的成熟来逃避巨噬细胞的先天抗菌防御。尽管对分枝杆菌吞噬体进行了大量的研究，但分枝杆菌的持久性依赖于外壳蛋白冠蛋白-1的长期吞噬体滞留的机制仍不清楚。本研究表明，在牛分枝杆菌bcg感染的细胞中，有几种分枝杆菌蛋白在细胞内运输，其中一种亚基大小为M-r - 50,000的分枝杆菌蛋白在吞噬体膜上积极保留冠状蛋白-1。该蛋白最初被称为冠状蛋白相互作用蛋白（CIP） 50，并被证明在结核分枝杆菌中也表达，但在非致病性耻垢分枝杆菌中不表达。使用gst -冠状蛋白-1构建体的无细胞系统实验表明，CIP50与冠状蛋白-1的结合需要胆固醇。随后，质谱测序鉴定分枝杆菌脂酰胺脱氢酶C （LpdC）为冠状蛋白-1结合蛋白。过表达Mtb LpdC蛋白的耻垢分枝杆菌获得了维持吞噬体膜上冠状蛋白-1的能力，从而延长了其在巨噬细胞内的存活时间。重要的是，IFN γ诱导的吞噬溶酶体融合在感染BCG的细胞中导致lpdc -冠状蛋白-1复合物的解离，其机制至少部分依赖于IFN γ诱导的LRG-47表达。这些发现进一步支持了lpdc -冠状蛋白-1相互作用在吞噬体成熟阻滞中的相关性。
Mycobacterium tuberculosis evades the innate antimicrobial defenses of macrophages by inhibiting the maturation of its phagosome to a bactericidal phagolysosome. Despite intense studies of the mycobacterial phagosome, the mechanism of mycobacterial persistence dependent on prolonged phagosomal retention of the coat protein coronin-1 is still unclear. The present study demonstrated that several mycobacterial proteins traffic intracellularly in M. bovis BCG-infected cells and that one of them, with an apparent subunit size of M-r 50,000, actively retains coronin-1 on the phagosomal membrane. This protein was initially termed coronin-interacting protein ( CIP) 50 and was shown to be also expressed by M. tuberculosis but not by the non-pathogenic species M. smegmatis. Cell-free system experiments using a GST-coronin-1 construct showed that binding of CIP50 to coronin-1 required cholesterol. Thereafter, mass spectrometry sequencing identified mycobacterial lipoamide dehydrogenase C ( LpdC) as a coronin-1 binding protein. M. smegmatis over-expressing Mtb LpdC protein acquired the capacity to maintain coronin-1 on the phagosomal membrane and this prolonged its survival within the macrophage. Importantly, IFN gamma-induced phagolysosome fusion in cells infected with BCG resulted in the dissociation of the LpdC-coronin-1 complex by a mechanism dependent, at least in part, on IFN gamma-induced LRG-47 expression. These findings provide further support for the relevance of the LpdC-coronin-1 interaction in phagosome maturation arrest.