Isolated peptidoglycan glycosyltransferases from different organisms produce different glycan chain lengths

Peptidoglycan is an essential component of bacterial cell wall. The glycan strands of peptidoglycan are synthesized by enzymes called peptidoglycan glycosyltransferases (PGTs). Using a high-resolution SDS-PAGE assay, we compared the glycan strand lengths of four different PGTs from three different organisms (Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus). We report that each enzyme makes a polymer having an intrinsic characteristic length that is independent of the enzyme:substrate ratio. The glycan strand lengths vary considerably, depending on the enzyme. These results indicate that each enzyme must have some mechanism, as yet unknown, for controlling product length. The observation that different PGTs produce different length glycan chains may have implications for their cellular roles and for the three-dimensional structure of bacterial peptidoglycan.