National Institute of Pharmaceutical Education and Research (NIPER), Phase X, Sector 67, SAS Nagar, Punjab 160062, India.
Institute of Microbial Technology (IMTECH), Sector 39A, Chandigarh 160036, India.
Nat Commun. 2014 Aug 28;5:4730. doi: 10.1038/ncomms5730.
Mycobacterium tuberculosis (M.tb), which requires iron for survival, acquires this element by synthesizing iron-binding molecules known as siderophores and by recruiting a host iron-transport protein, transferrin, to the phagosome. The siderophores extract iron from transferrin and transport it into the bacterium. Here we describe an additional mechanism for iron acquisition, consisting of an M.tb protein that drives transport of human holo-transferrin into M.tb cells. The pathogenic strain M.tb H37Rv expresses several proteins that can bind human holo-transferrin. One of these proteins is the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH, Rv1436), which is present on the surface of M.tb and its relative Mycobacterium smegmatis. Overexpression of GAPDH results in increased transferrin binding to M.tb cells and iron uptake. Human transferrin is internalized across the mycobacterial cell wall in a GAPDH-dependent manner within infected macrophages.
结核分枝杆菌(M.tb)在生存过程中需要铁,它通过合成铁结合分子(称为铁载体)并招募宿主铁转运蛋白转铁蛋白到吞噬体来获取这种元素。铁载体从转铁蛋白中提取铁并将其运输到细菌中。在这里,我们描述了一种额外的铁获取机制,该机制由一种 M.tb 蛋白组成,该蛋白驱动人血转铁蛋白进入 M.tb 细胞的运输。致病性菌株 M.tb H37Rv 表达几种可以结合人血转铁蛋白的蛋白质。其中一种蛋白质是糖酵解酶甘油醛-3-磷酸脱氢酶(GAPDH,Rv1436),它存在于 M.tb 及其相关分枝杆菌属中的表面。GAPDH 的过表达导致转铁蛋白与 M.tb 细胞的结合增加和铁摄取增加。人转铁蛋白在感染的巨噬细胞中以 GAPDH 依赖的方式穿过分枝杆菌细胞壁内化。