Discovery,\nCharacterization and Engineering of the\nFree l‑Histidine <i>C4</i>-Prenyltransferase

Prenylation\nof amino acids is a critical step for synthesizing\nbuilding blocks of prenylated alkaloid family natural products, where\nthe corresponding prenyltransferase that catalyzes prenylation on\nfree l-histidine (l-His) has not yet been identified.\nHere, we first discovered and characterized a prenyltransferase FunA\nfrom the antifungal agent fungerin pathway that efficiently performs <i>C4</i>-dimethylallylation on l-His. Crystal structure-guided\nengineering of the prenyl-binding pocket of FunA, a single M181A mutation,\nsuccessfully converted it into a <i>C4</i>-geranyltransferase.\nFurthermore, FunA and its variant FunA-M181A show broad substrate\npromiscuity toward substrates that vary in substituents of the imidazole\nring. Our work furthers our knowledge of free amino acid prenyltransferase\nand expands the arsenal of alkylation biocatalysts for imidazole-containing\nsmall molecules.