Peptidoglycan glycosyltransferase

Peptidoglycan glycosyltransferase is an enzyme used in the biosynthesis of peptidoglycan. It transfers a disaccharide-peptide from a donor substrate to synthesize a glycan chain.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-(1->4)-(N-acetyl-D-mu ramoylpentapeptide):undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-( 1->4)-N-acetyl-D-muramoylpentapeptide) disaccharidetransferase. Other names in common use include PG-II, bactoprenyldiphospho-N-acetylmuramoyl-(N-acetyl-D-glucosaminyl)-, pentapeptide:peptidoglycan, N-acetylmuramoyl-N-acetyl-D-glucosaminyltransferase, penicillin binding protein (3 or 1B), and peptidoglycan transglycosylase.

Function
Peptidoglycan glycosyltransferase couples Lipid II subunits to synthesize the peptidoglycan chains. Transpeptidases crosslink the carbohydrate chains to provide the framework for the cell wall.

It catalyzes the chemical reaction
 * [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)]n-diphosphoundecaprenol + GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol
 * [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)]n+1- diphosphoundecaprenol + undecaprenyl diphosphate
 * [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)]n+1- diphosphoundecaprenol + undecaprenyl diphosphate

The 2 substrates of this enzyme are
 * [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)]n-diphosphoundecaprenol,
 * GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol,

whereas its 2 products are
 * [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)]n+1-diphosphoundecaprenol, and
 * undecaprenyl diphosphate.

Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes, , and.