Bioinformatic analysis of WxL domain proteins

The WxL domain is found on the cell surface of many bacteria, most of which are commensal gut bacteria. Its functions are generally identified as being related to virulence and/or peptidoglycan attachment, but there is so far no clear function or structure for this domain. Here, a range of bioinformatics tools were used to clarify the structure and function. These indicate that WxL domains occur in cell surface-associated gene clusters that always contain a small WxL, large WxL and DUF916 domain; and that the small and large WxL proteins have distinct structure despite sharing two conserved WxL motifs. The two WxL motifs form a hydrophobic surface buried inside the protein. The likely function of the WxL domain is to attach to bacterial peptidoglycan, forming a platform to allow associated domains in the cluster to interact with host proteins.