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 (PubMed:12867450, PubMed:22487093). Hydrolyzes S2d (N-benzoyl-D-alanylmercaptoacetic acid) molecule, a synthetic thiolester analog of cell wall stem peptide (PubMed:10217767, PubMed:22487093). Active against bocillin, a fluorescent penicillin. No transpeptidase activity with non-fluorescent lysine-containing lipid II as substrate (PubMed:22487093). 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(+) Optimal transglycosylase/glycosyltransferase (GT) activity in the presence of 30-40% dimethylsulfoxide and 0.002% Triton X-100. High GT activity in the presence of CHAPS, Triton X-100 and n-dodecyl-beta-D-maltopyranoside (DDM) detergents, and to a lesser extent in the presence of Cymal-5 (PubMed:22487093). GT activity is inhibited by moenomycin (PubMed:12867450, PubMed:22487093). 50% inhibition of the GT activity with 2.8 uM moenomycin. No effect on GT activity detected with 2.8 uM vancomycin, but complete inhibition with 28 uM vancomycin (PubMed:12867450). No GT activity in the presence of n-octyl-beta-D-glucopyranoside, Cymal-3 and Cymal-4 detergents (PubMed:22487093). kcat is greater than 0.0005 sec(-1) with dansylated lipid II as substrate (PubMed:22487093). kcat/KM is 0.001 M(-1)sec(-1) with dansylated lipid II as substrate (PubMed:12867450). Cell wall biogenesis; peptidoglycan biosynthesis. Homodimer. May also form higher order oligomers. Self-association may depend on its transmembrane and/or cytoplasmic regions (PubMed:22487093). Interacts with MacP; interaction is required for the function of this protein (By similarity). Interacts with MreC in the elongasome (PubMed:28710862). 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) (PubMed:10217767, PubMed:12867450, PubMed:22487093). Transmembrane signal-anchor is required for the synthesis of longer, 20-30 disaccharide units containing, glycan chains (PubMed:22487093). Transglycosylase/glycosyltransferase (GT) domain of this protein may be an alternative target for the development of new inhibitors of S.pneumoniae as the beta-lactam antibiotics targeted against the transpeptidase domain of this protein have increasing resistance. In the N-terminal section; belongs to the glycosyltransferase 51 family. In the C-terminal section; belongs to the transpeptidase family.