Vibrio vulnificus toxin-receptor interactions

摘要 创伤弧菌是一种革兰氏阴性细菌病原体，可导致严重的危及生命的感染， 吃贝类或在温暖的海水中游泳后的人类。在美国，每年大约有200例 死亡率和发病率都很高虽然与其他食源性疾病相比， 由于病原体的广泛传播，患者的高死亡率给人类生活和经济带来了沉重的负担。 由于气候危机，创伤弧菌感染的发病率预计将增加。最 创伤弧菌的主要毒力因子是5208个氨基酸的MARTX家族毒素，其递送细胞毒性效应物， 细胞和这些效应物对于小鼠模型中的毒力是必需的。虽然我们已经掌握了大量信息， 关于效应子的作用机制，对蛋白质剩余的2800多个氨基酸知之甚少 毒素已知这些区域对于细菌分泌毒素是必需的和足够的， 毒素与真核细胞表面的相互作用，以及效应物穿过血浆的易位 膜的该项目建议使用以下方法确定中毒所必需的宿主细胞受体和宿主因子： 遗传筛选和选择在毒素的细胞溶解作用下存活的突变细胞。我们还将使用 基于结构-功能的方法来鉴定MARTX毒素的I型分泌所必需的区域， 细菌，毒素与假定的表面受体的结合，质膜中孔的形成， 以及效应子移位到真核细胞胞质溶胶。这项研究将促进我们对 MARTX毒素重复区的详细功能，预计将影响我们对 创伤弧菌感染的病理生理学

ABSTRACT Vibrio vulnificus is a Gram-negative bacterial pathogen that causes severe life-threatening infections in humans after eating shellfish or swimming in warm seawater. In the US, there are about 200 cases annually with high rates of mortality and morbidity. While the number of cases is low compared to other food-borne pathogens, the high rates of death among patients exerts a significant burden on human life and the economy. This is expected to increase as incidence of V. vulnificus infections is rising due to the climate crisis. The most prominent virulence factor of V. vulnificus is a 5208 aa MARTX family toxin that delivers cytotoxic effectors to cells and these effectors are essential for virulence in a mouse model. While extensive information is known about the mechanisms of the effectors, very little is known about the remaining over 2800 aa of the protein toxin. These regions are known to be both necessary and sufficient for secretion of the toxin from the bacteria, interaction of the toxin with the eukaryotic cell surface, and translocation of the effectors across the plasma membrane. The project proposes to identify host cell receptors and host factors essential for intoxication using a genetic screen and selection for mutant cells that survive the cytolytic action of the toxin. We will also use a structure-function based approach to identify regions of the MARTX toxin essential for Type I secretion from the bacterium, binding of the toxin to a putative surface receptor, formation of a pore in the plasma membrane, and translocation of effectors to the eukaryotic cell cytosol. This study will advance our understanding of the function of the MARTX toxin repeat regions in detail and is expected to impact our understanding of pathophysiology during V. vulnificus infection.