Catalyzes the incorporation of the first glycine of the pentaglycine interpeptide bridge, which is characteristic of the S.aureus peptidoglycan. This glycine is added to the epsilon-amino group of the L-lysine of the membrane-bound lipid II intermediate (GlcNAc-(beta-1,4)-N-acetylmuramic acid(-L-Ala-D-iGln-L-Lys-D-Ala-D-Ala)-pyrophosphoryl-undecaprenol), using glycyl-tRNA(Gly) as donor, in a ribosome-independent mechanism. Involved in methicillin resistance (By similarity). beta-D-GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-D-isoglutaminyl-L-Lys-D-Ala-D-Ala)-di-trans,octa-cis-undecaprenyl diphosphate + glycyl-tRNA(Gly) = beta-D-GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-D-isoglutaminyl-L-Lys-(N(6)-Gly)-D-Ala-D-Ala)-di-trans,octa-cis-undecaprenyl diphosphate + H(+) + tRNA(Gly) Monomer. Belongs to the FemABX family.