Heilmann Christine, Thumm Günther, Chhatwal Gursharan S, Hartleib Jörg, Uekötter Andreas, Peters Georg
Institute of Medical Microbiology, University of Münster, Domagkstr. 10, D-48149 Münster, Germany.
Mikrobielle Genetik, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Microbiology (Reading). 2003 Oct;149(Pt 10):2769-2778. doi: 10.1099/mic.0.26527-0.
Staphylococcus epidermidis biofilm formation on polymer surfaces is considered a major pathogenicity factor in foreign-body-associated infections. Previously, the 148 kDa autolysin AtlE from S. epidermidis, which is involved in the initial attachment of the cells to polymer surfaces and also binds to the extracellular matrix protein vitronectin, was characterized. Here, the characterization of a novel autolysin/adhesin (Aae) in S. epidermidis is described. Aae was identified as a 35 kDa surface-associated protein that has bacteriolytic activity and binds vitronectin. Its N-terminal amino acid sequence was determined and the respective gene, aae, was cloned. DNA-sequence analysis revealed that aae encodes a deduced protein of 324 amino acids with a predicted molecular mass of 35 kDa. Aae contains three repetitive sequences in its N-terminal portion. These repeats comprise features of a putative peptidoglycan binding domain (LysM domain) found in a number of enzymes involved in cell-wall metabolism and also in some adhesins. Expression of aae by Escherichia coli and subsequent analysis revealed that Aae possesses bacteriolytic activity and adhesive properties. The interaction of Aae with fibrinogen, fibronectin and vitronectin was found to be dose-dependent and saturable and to occur with high affinity, by using the real-time Biomolecular Interaction Analysis (BIA). Aae binds to the Aalpha- and Bbeta-chains of fibrinogen and to the 29 kDa N-terminal fragment of fibronectin. In conclusion, Aae is a surface-associated protein with bacteriolytic and adhesive properties representing a new member of the staphylococcal autolysin/adhesins potentially involved in colonization.
表皮葡萄球菌在聚合物表面形成生物膜被认为是异物相关感染中的一个主要致病因素。此前，已对表皮葡萄球菌的148 kDa自溶素AtlE进行了表征，它参与细胞与聚合物表面的初始附着，还能与细胞外基质蛋白玻连蛋白结合。在此，描述了表皮葡萄球菌中一种新型自溶素/黏附素（Aae）的表征。Aae被鉴定为一种35 kDa的表面相关蛋白，具有溶菌活性并能结合玻连蛋白。测定了其N端氨基酸序列，并克隆了相应的基因aae。DNA序列分析表明，aae编码一个推导的324个氨基酸的蛋白质，预测分子量为35 kDa。Aae在其N端部分包含三个重复序列。这些重复序列具有在许多参与细胞壁代谢的酶以及一些黏附素中发现的假定肽聚糖结合结构域（LysM结构域）的特征。大肠杆菌对aae的表达及后续分析表明，Aae具有溶菌活性和黏附特性。通过实时生物分子相互作用分析（BIA）发现，Aae与纤维蛋白原、纤连蛋白和玻连蛋白的相互作用呈剂量依赖性且可饱和，并且以高亲和力发生。Aae与纤维蛋白原的Aα链和Bβ链以及纤连蛋白的29 kDa N端片段结合。总之，Aae是一种具有溶菌和黏附特性的表面相关蛋白，代表了葡萄球菌自溶素/黏附素的一个新成员，可能参与定植过程。
