Figure 6. Acceptor substrate specificity of the GatD/MurT catalyzed reaction.

(A) Radiolabeled lipid I, lipid II and lipid II-Gly₅ were incubated together with glutamine and ATP in the presence (gray bars) and absence (white bars) of GatD/MurT. The addition of a 5- and 10-fold molar excess of UDP-MurNAc-pentapeptide (black bars) only resulted in minor reduction of amidated lipid II synthesized. Amidation is not catalyzed in concert with MurA-F. (B) Purified MurA-F enzymes were incubated in the presence and absence of GatD/MurT enzymes. After incubation the reaction product was added to a MraY-catalyzed lipid I synthesis assay using C₅₅-P. No change in migration behavior of the respective lipid I reaction products was observed.