Saturation mutagenesis on Arg244 of the tryptophan C4-prenyltransferase FgaPT2 leads to enhanced catalytic ability and different preferences for tryptophan-containing cyclic dipeptides
- 437 Downloads
FgaPT2 from Aspergillus fumigatus catalyzes a Friedel–Crafts alkylation at C-4 of l-tryptophan and is involved in the biosynthesis of the ergot alkaloids fumigaclavines. Several tryptophan-containing cyclic dipeptides had also been prenylated by FgaPT2, but the turnover rate (k cat) was low. Here, we report the generation of FgaPT2 mutants by saturation mutagenesis at the amino acid residue Arg244 to improve its catalytic efficiency toward cyclic dipeptides. Thirteen mutated enzymes demonstrated up to 76-fold higher turnover number toward seven cyclic dipeptides than the non-mutated FgaPT2. More importantly, the mutated enzymes exhibited different preferences toward these substrates. This study provides a convenient approach for creation of new biocatalysts for production of C4-prenylated cyclic dipeptides.
KeywordsCyclic dipeptide Dimethylallyltryptophan synthase Enzyme catalysis Friedel–Crafts alkylation Prenyltransferase Saturation mutagenesis
We thank Lena Ludwig for synthesis of DMAPP, and Nina Zitzer and Stefan Newel for taking MS and NMR spectra, respectively.
Compliance with ethical standards
This study was funded by Li844/4-1 from the Deutsche Forschungsgemeinschaft. Aili Fan is a recipient of a scholarship from China Scholarship Council (2011601056).
Conflict of interest
The authors declare that they have no conflict of interest.
Human and animal rights
This article does not contain any studies with human participants or animals performed by any of the authors.