School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane Queensland 4072, Australia.
Environ Microbiol. 2009 Jul;11(7):1803-14. doi: 10.1111/j.1462-2920.2009.01905.x. Epub 2009 Mar 31.
Enterohaemorrhagic Escherichia coli (EHEC) are a subgroup of Shiga toxin-producing E. coli that cause gastrointestinal disease with the potential for life-threatening sequelae. Cattle serve as the natural reservoir for EHEC and outbreaks occur sporadically as a result of contaminated beef and other farming products. While certain EHEC virulence mechanisms have been extensively studied, the factors that mediate host colonization are poorly defined. Previously, we identified four proteins (EhaA,B,C,D) from the prototypic EHEC strain EDL933 that belong to the autotransporter (AT) family. Here we characterize the EhaB AT protein. EhaB was shown to be located at the cell surface and overexpression in E. coli K-12 resulted in significant biofilm formation under continuous flow conditions. Overexpression of EhaB in E. coli K12 and EDL933 backgrounds also promoted adhesion to the extracellular matrix proteins collagen I and laminin. An EhaB-specific antibody revealed that EhaB is expressed in E. coli EDL933 following in vitro growth. EhaB also cross-reacted with serum IgA from cattle challenged with E. coli O157:H7, indicating that EhaB is expressed in vivo and elicits a host IgA immune response.
产志贺毒素大肠埃希氏菌（EHEC）是产志贺毒素大肠埃希氏菌的一个亚群，可引起胃肠道疾病，并有可能产生危及生命的后遗症。牛是 EHEC 的天然宿主，由于受污染的牛肉和其他农产品，零星爆发此类疾病。虽然某些 EHEC 毒力机制已得到广泛研究，但介导宿主定植的因素尚未明确。先前，我们从原型 EHEC 菌株 EDL933 中鉴定出属于自转运体（AT）家族的四种蛋白（EhaA、B、C、D）。在此，我们对 EhaB AT 蛋白进行了特征描述。EhaB 被证明位于细胞表面，在大肠杆菌 K-12 中过表达会导致在连续流动条件下形成明显的生物膜。在大肠杆菌 K12 和 EDL933 背景中过表达 EhaB 也促进了对细胞外基质蛋白胶原蛋白 I 和层粘连蛋白的黏附。EhaB 特异性抗体显示，EhaB 在体外生长的 E. coli EDL933 中表达。EhaB 还与感染大肠杆菌 O157:H7 的牛的血清 IgA 发生交叉反应，表明 EhaB 在体内表达并引发宿主 IgA 免疫反应。
