beta-D-GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-O-P-Glu-L-Lys-D-Ala-D-Ala)-di-trans,octa-cis-undecaprenyl diphosphate + NH4(+) = beta-D-GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-D-isoglutaminyl-L-Lys-D-Ala-D-Ala)-di-trans,octa-cis-undecaprenyl diphosphate + phosphate + H(+) — reaction