Site-Specific N- and C-Terminal Labeling of a Single Polypeptide Using Sortases of Different Specificity

摘要

Methods for site-specific modification of proteins remain in high demand. The transpeptidation reaction catalyzed by sortase A from Staphylococcus aureus (SrtA_(staph)) allows site-specific derivatization of proteins with virtually any type of functional material. Target proteins are engineered to contain the SrtA_(staph) recognition site (LPXTG) near their C terminus, thus allowing a transacylation reaction in which the residues C-terminal to threonine are exchanged for a synthetic oligoglycine peptide (Scheme 1). While the range of applications for this technology has expanded considerably, the ligation chemistry itself has seen relatively few modifications or improvements. Since nearly all Gram-positive bacteria possess sortases, many with reactivity distinct from SrtA_(staph), there is an exciting opportunity to develop complementary strategies for protein engineering using other members of this enzyme family.