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

Abstract : The autolysin AtlC is the only known fibronectin-binding protein in Staphylococcus caprae strain 96007. The fibronectin-binding domain of AtlC consists of three repeats (AtlCR 1 R 2 R 3), which are located between the two enzymatic domains. The AtlCR 1 R 2 R 3 domain and the AtlCR 1 R 2 and AtlCR 3 subdomains were expressed separately as His 6-tagged proteins. In Western affinity blots, only AtlCR 1 R 2 R 3 and AtlCR 3 but not AtlCR 1 R 2 appeared to recognise fibronectin; however, in ELISA and Biacore experiments, all three bound fibronectin. The interaction between AtlCR 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.