Aligned HCA plots of the PGT domain in monofunctional glycosyltransferases (MGTs) and class A penicillin-binding proteins (PBPs). Only three sequences are shown here due to space limitations. UniProt accession numbers: Staphylococcus aureus MGT (SaMGT, Q7A0I6), S. aureus PBP2 (SaPBP2, Q9R744) and Enterococcus faecalis PBP1b (EfPBP1b, I3U3N7). A comprehensive HCA plot with more aligned sequences is shown in Supplementary Fig. 3. The standard one-letter code for amino acids is used except for glycine , proline , serine and threonine respectively. The vertical lines indicate proposed correspondence between the compared sequences. The strictly conserved residues (in the multiple sequence alignment Supplementary Fig. 1A) are indicated with a black circle. The conserved and conservatively substituted amino acids within the hydrophobic clusters (shaded in gray) suggest a structural and functional relationship. indicates motifs identified in this study.