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

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 (AtlCR1R2R3), which are located between the two enzymatic domains. The AtlCR1R2R3 domain and the AtlCR1R2 and AtlCR3 subdomains were expressed separately as His6-tagged proteins. In Western affinity blots, only AtlCR1R2R3 and AtlCR3 but not AtlCR1R2 appeared to recognise fibronectin; however, in ELISA and Biacore experiments, all three bound fibronectin. The interaction between AtlCR1R2R3 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.