Secretion of the housekeeping protein glyceraldehyde-3-phosphate dehydrogenase by the LEE-encoded type III secretion system in enteropathogenic Escherichia coli
Secretion of the housekeeping protein glyceraldehyde-3-phosphate dehydrogenase by the LEE-encoded type III secretion system in enteropathogenic Escherichia coli
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DOI：
10.1016/j.biocel.2012.03.002
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发表时间：
2012-06-01
影响因子：
4
通讯作者：
Baldoma, Laura
中科院分区：
文献类型：
--
作者：
Aguilera, Laura;Ferreira, Elaine;Baldoma, Laura
甘油醛-3-磷酸脱氢酶（GAPDH）是由病原体分泌的多功能管家蛋白，并参与粘附和/或毒力。以前我们报道了肠出血性（EHEC）和肠致病性（EPEC）大肠杆菌分泌GAPDH到培养基中。这种细菌蛋白结合人纤溶酶原和纤维蛋白原，并在感染后保持与Caco-2细胞结合。在这些病原体中，GAPDH的分泌与外膜囊泡无关，取决于生长条件，尽管其分泌机制仍不清楚。EPEC是一种附着和消失的病原体，能够通过III型分泌系统（T3 SS）分泌和转运多种效应蛋白进入感染细胞。分泌过程通常依赖于细菌伴侣。分子伴侣CesT显示广泛的底物特异性，并在招募多个III型效应子到T3 SS装置中发挥核心作用。在这里，我们提供了遗传证据GAPDH分泌通过T3 SS的EPEC在DMEM中生长。Delta sepD突变体中GADH的分泌增加，而III型ATP酶EscN缺陷突变体中GADH的分泌消失。与escN基因互补恢复GAPDH分泌。此外，我们通过下拉实验，重叠免疫印迹和生物层干涉技术证明了GAPDH和伴侣CesT之间的一种新的相互作用。这种强烈且缓慢解离的相互作用可以使GAPDH分子群体稳定在分泌能力状态，并将它们靶向III型分泌器。这是第一次描述CesT与管家蛋白的相互作用及其通过T3 SS的出口。(C)2012爱思唯尔有限公司保留所有权利。
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional housekeeping protein secreted by pathogens and involved in adhesion and/or virulence. Previously we reported that enterohemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli secrete GAPDH into the culture medium. This bacterial protein binds human plasminogen and fibrinogen and remains associated with Caco-2 cells upon infection. In these pathogens, GAPDH secretion is not linked to outer membrane vesicles and depends on growth conditions, although the secretion mechanism is still unknown. EPEC is an attaching and effacing pathogen able to secrete and translocate multiple effector proteins into infected cells through a type III secretion system (T3SS). The secretion process is often dependent on a bacterial chaperone. The chaperone CesT displays broad substrate specificity and plays a central role in the recruitment of multiple type III effectors to the T3SS apparatus. Here we provide genetic evidences on GAPDH secretion through T3SS by EPEC grown in DMEM. Secretion of GAPDH is increased in Delta sepD mutants and abolished in mutants defective in the type III ATPase EscN. Complementation with escN gene restores GAPDH secretion. In addition, we prove by means of pull down experiments, overlay immunoblotting and biolayer interferometry a novel interaction between GAPDH and the chaperone CesT. This interaction, which is strong and slow dissociating, may stabilize a population of GAPDH molecules in a secretion competent-state and target them to the type III secretion apparatus. This is the first description of CesT interaction with a housekeeping protein and its export through T3SS. (C) 2012 Elsevier Ltd. All rights reserved.