FIG. 2.

Schematic of MurG assay In the first step, by preincubating the membranes with UDP-MurNAc(pp), the MurG substrate, lipid I, is made by MraY present in the membranes. In the second step, the MurG reaction is initiated by providing its second substrate, UDP-[³H]GlcNAc. In a PBP1b mutant, or in the presence of moenomycin in wild-type membranes, lipid II is not converted to peptidoglycan and can be captured by WGA-SPA beads; under these conditions, the pathway of reactions stops at lipid II (solid line).