Daigneault Michelle C, Lo Reggie Y C
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
FEMS Microbiol Lett. 2009 Nov;300(2):242-8. doi: 10.1111/j.1574-6968.2009.01786.x. Epub 2009 Sep 9.
A locus that codes for a high-molecular-weight adhesin was previously isolated from Mannheimia haemolytica A1. In this study, we showed that this locus, named ahs, codes for two proteins (AhsA and AhsB) that exhibit characteristics of a trimeric autotransporter adhesin. Sequence analysis of AhsA showed the presence of 21 collagen-binding motifs in the protein. Collagen-binding assays showed that M. haemolytica A1 binds to collagen in a dose-dependent manner. This binding activity is trypsin sensitive and can be inhibited by anti-AhsA antibody. AhsB is the cognate transporter for AhsA. The C-terminal of AhsB showed highly conserved amino acids typical of trimeric autotransporters. Experimental data showed that the C-terminal 120 amino acids of AhsB could indeed form trimeric molecules. Western immunoblots showed the presence of anti-AhsA antibodies in the sera of calves that had been challenged with M. haemolytica A1, suggesting that AhsA is expressed and immunogenic in cattle.
一个编码高分子量粘附素的基因座先前已从溶血曼氏杆菌A1中分离出来。在本研究中，我们表明这个名为ahs的基因座编码两种蛋白质（AhsA和AhsB），它们具有三聚体自转运粘附素的特征。AhsA的序列分析表明该蛋白中存在21个胶原结合基序。胶原结合试验表明，溶血曼氏杆菌A1以剂量依赖的方式与胶原结合。这种结合活性对胰蛋白酶敏感，并且可以被抗AhsA抗体抑制。AhsB是AhsA的同源转运蛋白。AhsB的C末端显示出三聚体自转运蛋白典型的高度保守氨基酸。实验数据表明，AhsB的C末端120个氨基酸确实可以形成三聚体分子。Western免疫印迹显示，用溶血曼氏杆菌A1攻击的犊牛血清中存在抗AhsA抗体，这表明AhsA在牛中表达且具有免疫原性。
