Cell wall formation. Synthesis of cross-linked peptidoglycan (PG) from the lipid intermediates (By similarity). Binds dansylated lipid II and catalyzes the polymerization of glycan chains. Hydrolyzes S2d (N-benzoyl-D-alanylmercaptoacetic acid) molecule, a synthetic thiolester analog of cell wall stem peptide. Active against bocillin, a fluorescent penicillin. No transpeptidase activity with non-fluorescent lysine-containing lipid II as substrate (By similarity). Preferential cleavage: (Ac)2-L-Lys-D-Ala-|-D-Ala. Also transpeptidation of peptidyl-alanyl moieties that are N-acyl substituents of D-alanine. [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)](n)-di-trans,octa-cis-undecaprenyl diphosphate + beta-D-GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-di-trans,octa-cis-undecaprenyl diphosphate = [GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)](n+1)-di-trans-octa-cis-undecaprenyl diphosphate + di-trans,octa-cis-undecaprenyl diphosphate + H(+) Cell wall biogenesis; peptidoglycan biosynthesis. Homodimer. May also form higher order oligomers. Self-association may depend on its transmembrane and/or cytoplasmic regions (By similarity). Interacts with MacP; interaction is required for the function of this protein (PubMed:29487215). Localizes to sites of new peptidoglycan (PG) synthesis at midcell independently of MacP. Has a penicillin-insensitive transglycosylase/glycosyltransferase (GT) N-terminal domain (formation of linear glycan strands) and a penicillin-sensitive transpeptidase C-terminal domain (cross-linking of the peptide subunits). Transmembrane signal-anchor is required for the synthesis of longer, 20-30 disaccharide units containing, glycan chains. Deletion of this gene with concomitant depletion of PBP1a leads to progressive reduction in cell size before ultimate lysis. Cell wall synthesis is also dramatically reduced in these cells. In the N-terminal section; belongs to the glycosyltransferase 51 family. In the C-terminal section; belongs to the transpeptidase family.