Several regions of the repeat domain of the Staphylococcus caprae autolysin, At1C, are involved in fibronectin binding

The autolysin At1C is the only known fibronectin-binding protein in Staphylococcus caprae strain 96007. The fibronectin-binding domain of At1C consists of three repeats (At1CR(1)R(2)R(3)), which are located between the two enzymatic domains. The At1CR(1)R(2)R(3) domain and the At1CR(1)R(2) and At1CR(3) subdomains were expressed separately as HiS6-tagged proteins. In Western affinity blots, only At1CR(1)R(2)R(3) and At1CR(3) but not At1CR(1)R(2) appeared to recognise fibronectin; however, in ELISA and Biacore experiments, all three bound fibronectin. The interaction between At1CR(1)R(2)R(3) and fibronectin is multivalent and involves high- and low-affinity sites that are present in a 2:1 ratio. These distinct classes of binding sites may be situated on either or on both ligands. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.