Conserved Effectors Required for Protein Localization and Shigella Virulence

描述（由申请人提供）：志贺氏菌是一种革兰氏阴性菌，可引起严重的结肠上皮感染，每年导致约110万人死亡。细菌进入宿主细胞后，宿主肌动蛋白在菌极组装成肌动蛋白尾部是细菌运动和传播所必需的。IcsA是志贺氏菌特异性蛋白，是肌动蛋白尾部形成所必需的，并且定位于细菌极点。IcsA是分泌蛋白的自转运蛋白家族成员；我们已经证明，自动转运蛋白通常在极点分泌。这些蛋白定位到细菌极点的机制是高度保守的，但尚未确定。我的具体目标是：1)确定将自转运蛋白IcsA定位到细菌极点所需的基本蛋白质；2)阐明在Aim 1中鉴定的蛋白对IcsA极性定位的作用机制以及IcsA极性在志贺氏菌发病机制中的作用；3)确定Aims 1和2中鉴定的极性靶向机制在定位革兰氏阴性菌中其他自转运蛋白家族成员和其他极性蛋白中的作用。这些方法极有可能揭示IcsA定位到细菌极点所需的机制成分。这种机制可能在广泛的革兰氏阴性菌中保守，并且由于其保守性，可能代表极性蛋白质子集定位到极点的一般机制。由于许多自转运蛋白参与毒力，阐明其极点定位的机制可能导致新型广谱抗生素的开发。公共卫生相关性：志贺氏菌感染每年造成110万人死亡，并给欠发达国家造成严重的财政负担。更彻底地了解这些细菌中适当的毒力因子定位可能导致新型广谱抗生素的开发。我建议对flexneri s.f erner蛋白进行大规模分析，以确定IcsA的正确位置，并在细菌感染期间进行细胞间扩散。

DESCRIPTION (provided by applicant): Shigella is a family of gram-negative bacteria that cause severe infections of the colonic epithelium, leading to an estimated 1.1 million deaths annually. After bacterial entry into host cells, the assembly of host actin into an actin tail at the bacterial pole is required for bacterial motility and spread. IcsA is a Shigella specific protein that is required for actin tail formation and is localized to the bacterial pole. IcsA is a member of the autotransporter family of secreted proteins; we have shown that autotransporters are generally secreted at the pole. The mechanism of localization of these proteins to the bacterial pole is highly conserved, but is as yet unidentified. My specific aims are: 1) to identify essential proteins required for localization of the autotransporter IcsA to the bacterial pole; 2) to characterize the mechanism by which proteins identified in Aim 1 contribute to the localization of IcsA to the pole and the function of IcsA polarity in Shigella pathogenesis; and, 3) to define the role of the polar targeting machinery identified in Aims 1 and 2 in localizing other members of the autotransporter family and other polar proteins in Gram-negative bacteria. These approaches are highly likely to uncover components of the machinery that is required for localization of IcsA to the bacterial pole. This machinery is likely to be conserved among a broad range of Gram-negative bacteria and, because of its conservation, is likely to represent a general mechanism for the localization of a subset of polar proteins to the poles. Since many autotransporters are involved in virulence, elucidation of the mechanism of their localization to the pole may lead to the development of novel broad-spectrum antibiotics. PUBLIC HEALTH RELEVANCE: Infections by Shigella cause 1.1 million deaths annually, and create a severe monetary burden on underdeveloped nations. A more thorough understanding of proper virulence factor localization in these bacteria could lead to the development of novel broad-spectrum antibiotics. I propose a large scale analysis of S. flexneri proteins necessary for proper IcsA location, and subsequent intercellular spread during bacterial infection.