title: A noncanonical function of sortase enables site-specific conjugation of small molecules to lysine residues in proteins.
abstract: We provide the first demonstration that isopeptide ligation, a noncanonical activity of the enzyme sortase A, can be used to modify recombinant proteins. This reaction was used in vitro to conjugate small molecules to a peptide, an engineered targeting protein, and a full-length monoclonal antibody with an exquisite level of control over the site of conjugation. Attachment to the protein substrate occurred exclusively through isopeptide bonds at a lysine ε-amino group within a specific amino acid sequence. This reaction allows more than one molecule to be site-specifically conjugated to a protein at internal sites, thereby overcoming significant limitations of the canonical native peptide ligation reaction catalyzed by sortase A. Our method provides a unique chemical ligation procedure that is orthogonal to existing methods, supplying a new method to site-specifically modify lysine residues that will be a valuable addition to the protein conjugation toolbox.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708 (USA) http://www.chilkotilab.pratt.duke.edu.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Bellucci
authors.forename: Jayanta
authors.initials: J
authors.lastname: Bhattacharyya
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Chilkoti
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D011506:Proteins; D008239:Lysine
keywords: bioconjugation; biotechnology; protein modification; sortase