Bacillus subtilis CwlQ (previous YjbJ) is a bifunctional enzyme exhibiting muramidase and soluble-lytic transglycosylase activities.

CwlQ (previous YjbJ) is one of the putative cell wall hydrolases in Bacillus subtilis. Its domain has an amino acid sequence similar to the soluble-lytic transglycosylase (SLT) of Escherichia coli Slt70 and also goose lysozyme (muramidase). To characterize the enzyme, the domain of CwlQ was cloned and expressed in E. coli. The purified CwlQ protein exhibited cell wall hydrolytic activity. Surprisingly, RP-HPLC, mass spectrometry (MS), and MS/MS analyses showed that CwlQ produces two products, 1,6-anhydro-N-acetylmuramic acid and N-acetylmuramic acid, thus indicating that CwlQ is a bifunctional enzyme. The site-directed mutagenesis revealed that glutamic acid 85 (Glu-85) is an amino acid residue essential to both activities.