Fig. 9.

Hypothetical model illustrating the processive mechanism of lipid II polymerization by PGT. Structure of lipid II is shown in the inset. Cartoon representation of PGT ($\alpha$-helices shown as cylinders) showing the head subdomain (colored orange) and the jaw subdomain (colored yellow). The key active site residues are shown as sticks and coloured by atom type. The flap and motif III helices are labelled. The putative allosteric site is shown as a star (colored pink). The movement of the flap to show open and closed orientation is indicated by arrows (colored yellow). PGT conformer representing the respective functional state approximate the select experimentally determined PGT structures and are annotated as follows: Resting and Translocation (PDB ID code 3DWK chains B and C), Allosteric Intermediate (PDB ID codes 3VMQ chain A, 2OQO), Activation, Catalysis and New Lipid II (PDB ID codes 3HZS, 3VMT chain A). (For interpretation of the references to colour in this figure caption, the reader is referred to the web version of this article.)