Delineation of pilin domains required for bacterial association into microcolonies and intestinal colonization by Vibrio cholerae
Delineation of pilin domains required for bacterial association into microcolonies and intestinal colonization by Vibrio cholerae
复制标题
DOI：
10.1046/j.1365-2958.2000.01764.x
复制
发表时间：
2000-02-01
影响因子：
3.6
通讯作者：
Taylor, RK
中科院分区：
文献类型：
--
作者：
Kirn, TJ;Lafferty, MJ;Taylor, RK
毒素共调节菌毛（TCP）是霍乱弧菌O 1和O 139流行株表达的4型菌毛，是人类肠道定植所必需的。TCP结构组装为TcpA菌毛蛋白的重复亚基的聚合物，其形成长纤维，其横向缔合成束。以前的被动免疫研究表明，TcpA的C-末端区域暴露在菌毛纤维的表面上，并在介导TCP的定植功能中起关键作用。在本研究中，我们已经使用定点诱变划定两个域内的C-末端区域，有助于TCP的结构和功能。第一个结构域（称为结构域）的改变导致菌毛稳定性或形态的改变。第二个结构域（称为相互作用结构域）的改变会影响CTX噬菌体的定殖和/或感染，而不影响菌毛形态。在体外和体内的tcpA突变体的分析表明，TCP的一个主要功能是介导细菌的相互作用，通过直接菌毛菌毛接触所需的小菌落形成和生产性肠道定植。这一功能的重要性得到了以下发现的支持：基因内抑制突变恢复了定植缺陷突变体的定植能力，同时恢复了菌毛介导的细菌相互作用。由抑制基因突变引起的改变也提供了深入了解菌毛纤维内和菌毛纤维之间的菌毛蛋白亚基之间的分子相互作用。
The toxin-co-regulated pilus (TCP), a type 4 pilus that is expressed by epidemic strains of Vibrio cholerae O1 and O139, is required for colonization of the human intestine. The TCP structure is assembled as a polymer of repeating subunits of TcpA pilin that form long fibres, which laterally associate into bundles. Previous passive immunization studies have suggested that the C-terminal region of TcpA is exposed on the surface of the pilus fibre and has a critical role in mediating the colonization functions of TCP. In the present study, we have used site-directed mutagenesis to delineate two domains within the C-terminal region that contribute to TCP structure and function. Alterations in the first domain, termed the structural domain, result in altered pilus stability or morphology. Alterations in the second domain, termed the interaction domain, affect colonization and/or infection by CTX-bacteriophage without affecting pilus morphology. In vitro and in vivo analyses of the tcpA mutants revealed that a major function of TCP is to mediate bacterial interaction through direct pilus-pilus contact required for microcolony formation and productive intestinal colonization. The importance of this function is supported by the finding that intragenic suppressor mutations that restore colonization ability to colonization-deficient mutants simultaneously restore pilus-mediated bacterial interactions. The alterations resulting from the suppressor mutations also provide insight into the molecular interactions between pilin subunits within and between pilus fibres.