– The Staphylococcus aureus transpeptidase Sortase A (SrtA) anchors virulence and colonization-associated surface proteins to the cell wall. SrtA selectively recognizes a C-terminal LPXTG motif. SrtA readily reacts with its native substrate Abz-LPETG-Dap(DNP)-NH2, cleaving it and catalyzing the formation of an amide bond between the carboxyl group of threonine and the amino group of cell-wall crossbridges.