Figure 13.
Two-dimensional schematic representation of proposed template model of PG assembly in E. faecium. Chain extension, occurring from right to left, and cross-linking are synchronized at lipid II, which is bound to the cell-wall membrane. The template strand (red) serves to orient nascent PG (green) so that high levels of cross-linking can be achieved. Tripeptides occur in mature PG (blue), where L,D-carboxypeptidase acts on uncross-linked stems. Seven percent of all stems terminating in D-Ala-D-Ala probably occur in nascent and template PG and are crucial for cell wall assembly. Modification of these few sites and the lipid II sites could prevent some glycopeptides from binding and inhibiting PG biosynthesis.
