The structure of a LysM domain from E-coli membrane-bound lytic murein transglycosylase D (MltD)

The LysM domain is a widespread protein module. It was originally identifie d in enzymes that degrade bacterial cell walls but is also present in many other bacterial proteins. Several proteins that contain the domain, such as Staphylococcal IgG binding proteins and Escherichia coli intimin, are invo lved in bacterial pathogenesis. LysM domains are also found in some eukaryo tic proteins, apparently as a result of horizontal gene transfer from bacte ria. The available evidence suggests that the LysM domain is a general pept idoglycan-binding module. We have determined the structure of this domain f rom E. coli membrane-bound lyric murein transglycosylase D. The LysM domain has a beta alpha alpha beta secondary structure with the two helices packi ng onto the same side of an antiparallel beta sheet. The structure shows no similarity to other bacterial cell surface domains. A potential binding si te in a shallow groove on surface of the protein has been identified. (C) 2 000 Academic Press.