Sequence analysis of LysB4. (a) Domain structures of LysB4 compared with four other peptidoglycan hydrolases. CwlK, the cell wall hydrolase in B. subtilis (ZP 08507241); Ply500, an endolysin in a L. monocytogenes phage (CAA59365); Ply21, an endolysin in a B. cereus phage (CAA72267); and LysBG1, an endolysin from a Bacillus phage (ABX56141). The grey shadows indicate conserved regions between proteins. (b) Alignment of amino acid sequences of LysB4, Ply500 and CwlK in their VanY domains. Three small triangles indicate Zn2+ binding residues, and the zinc binding motif was boxed.