Genetically Encoding a Lipidated Amino Acid for Extension of Protein Half-Life in vivo

Protein therapeutics are increasingly used to treat various diseases, yet they often suffer from short serum half-lives. An emerging strategy to extend lifetime in vivo is to attach fatty acids onto proteins to increase their binding to human serum albumin (HSA). Herein, the genetic encoding of ϵ-N-heptanoyl-l-lysine (HepoK) is reported, which introduces a fatty-acid-containing amino acid into proteins with exquisite site-specificity and homogeneity, overcoming issues associated with existing chemical conjugation methods. The expression in E .coli and purification of HepoK-incorporated glucagon-like peptide-1 (GLP1) is demonstrated. GLP1(HepoK) showed stronger binding to HSA than GLP1(WT), without impairing the stimulation of the GLP1 receptor in cells. Moreover, GLP1(HepoK) decreased blood glucose level to the same level as GLP1(WT) in mice, showing longer-lasting effects than GLP1(WT). HepoK incorporation will also be useful for investigating the function of protein lipidation.