Improving Sortase-A-Mediated Transpeptidation Reactions by Electrostatically Assisted Capture

Sortase A (SrtA) is a widely used transpeptidase for protein modification. However, the reversible nature of the SrtA-catalyzed transpeptidation reactions provides limited yields. In this study, we report a substrate engineering strategy that extends the LPxTG recognition motif with a positively charged polyarginine peptide module. This enables sequence-specific capture of the released peptide via electrostatically assisted aminolysis of a negatively charged thioester, thus shifting the equilibrium toward product formation. The approach is traceless and selective, operates under mild conditions, and improves SrtA efficiency with only a moderate excess of nucleophile.