Site‐Specific Protein Labeling via Sortase‐Mediated Transpeptidation

Abstract Strategies for site‐specific protein modification are highly desirable for the construction of conjugates containing non‐genetically‐encoded functional groups. Ideally, these strategies should proceed under mild conditions, and be compatible with a wide range of protein targets and non‐natural moieties. The transpeptidation reaction catalyzed by bacterial sortases is a prominent strategy for protein derivatization that possesses these features. Naturally occurring or engineered variants of sortase A from Staphylococcus aureus catalyze a ligation reaction between a five‐amino‐acid substrate motif (LPXTG) and oligoglycine nucleophiles. By pairing proteins and synthetic peptides that possess these ligation handles, it is possible to install modifications onto the protein N‐ or C‐terminus in site‐specific fashion. As described in this unit, the successful implementation of sortase‐mediated labeling involves straightforward solid‐phase synthesis and molecular biology techniques, and this method is compatible with proteins in solution or on the surface of live cells. © 2017 by John Wiley & Sons, Inc.