Overproduction, purification and characterization of FtmPT1, a brevianamide F prenyltransferase from Aspergillus fumigatus

Abstract

A putative prenyltransferase gene,ftmPT1, was identified in the genome sequence ofAspergillus fumigatus.ftmPT1was cloned and expressed inEscherichia coli, and the protein FtmPT1 was purified to near homogeneity and characterized biochemically. This enzyme was found to catalyse the prenylation ofcyclo-l-trp-l-Pro (brevianamide F) at the C-2 position of the indole nucleus. FtmPT1 is a soluble monomeric protein, which does not contain the usual prenyl diphosphate binding site (N/D)DXXD found in most prenyltransferases, and which does not require divalent metal ions for its enzymic activity.Kmvalues for brevianamide F and dimethylallyl diphosphate were determined as 55 and 74 μM, respectively. The turnover number was 5·57 s−1. FtmPT1 showed a high substrate specificity towards dimethylallyl diphosphate, but accepted different tryptophan-containing cyclic dipeptides. Together with dimethylallyltryptophan synthase of ergot alkaloid biosynthesis, FtmPT1 belongs to a new group of prenyltransferases with aromatic substrates.