Catalyzes the formation of the pentaglycine interpeptide bridge, which is characteristic of the S.aureus peptidoglycan. Adds glycines 4 and 5 of the pentaglycine bridge, using glycyl-tRNA(Gly) as donor. Involved in resistance to methicillin (By similarity). 2 glycyl-tRNA(Gly) + MurNAc-L-Ala-D-isoglutaminyl-L-Lys-(N(6)-tri-Gly)-D-Ala-D-Ala-diphospho-di-trans,octa-cis-undecaprenyl-GlcNAc = 2 H(+) + MurNAc-L-Ala-D-isoglutaminyl-L-Lys-(N(6)-penta-Gly)-D-Ala-D-Ala-diphospho-di-trans,octa-cis-undecaprenyl-GlcNAc + 2 tRNA(Gly) Homodimer. Interacts with FemA (By similarity). Belongs to the FemABX family.