Lindmark H, Guss B
Department of Microbiology, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden.
Infect Immun. 1999 May;67(5):2383-8. doi: 10.1128/IAI.67.5.2383-2388.1999.
The obligate parasitic bacterium Streptococcus equi subsp. equi is the causative agent of strangles, a serious disease of the upper respiratory tract in horses. In this study we have, using shotgun phage display, cloned from S. equi subsp. equi and characterized a gene, called sfs, encoding a protein termed SFS, representing a new type of fibronectin (Fn)-binding protein. The sfs gene was found to be present in all 50 isolates of S. equi subsp. equi tested and in 41 of 48 S. equi subsp. zooepidemicus isolates tested. The sfs gene is down-regulated during growth in vitro compared to fnz, a previously characterized gene encoding an Fn-binding protein from S. equi subsp. zooepidemicus. Sequence comparisons revealed no similarities to previously characterized Fn-binding proteins, but high scores were obtained against collagen. Besides similarity due to the high content of glycine, serine, and proline residues present in both proteins, there was a nine-residue motif present both in collagen and in the Fn-binding domain of SFS. By searching the Oklahoma S. pyogenes database, we found that this motif is also present in a potential cell surface protein from S. pyogenes. Protein SFS was found to inhibit the binding between Fn and collagen in a concentration-dependent way.
专性寄生细菌马链球菌马亚种是马属动物上呼吸道严重疾病马腺疫的病原体。在本研究中，我们利用鸟枪法噬菌体展示技术，从马链球菌马亚种中克隆并鉴定了一个名为sfs的基因，该基因编码一种名为SFS的蛋白质，它代表一种新型的纤连蛋白（Fn）结合蛋白。研究发现，在所检测的50株马链球菌马亚种菌株以及48株兽疫链球菌马亚种菌株中的41株中均存在sfs基因。与fnz相比，sfs基因在体外生长过程中表达下调，fnz是先前鉴定的一个来自兽疫链球菌马亚种的编码Fn结合蛋白的基因。序列比较显示，该基因与先前鉴定的Fn结合蛋白没有相似性，但与胶原蛋白的比对得分较高。除了由于两种蛋白质中甘氨酸、丝氨酸和脯氨酸残基含量较高而具有相似性外，胶原蛋白和SFS的Fn结合域中都存在一个九肽基序。通过搜索俄克拉荷马酿脓链球菌数据库，我们发现该基序也存在于酿脓链球菌一种潜在的细胞表面蛋白中。研究发现，蛋白质SFS能够以浓度依赖的方式抑制Fn与胶原蛋白之间的结合。
