New Paper by the Piel Lab
An Orthogonal D2O-Based Induction System that Provides Insights into d-Amino Acid Pattern Formation by Radical S-Adenosylmethionine Peptide Epimerases
Brandon I. Morinaka, Marjan Verest, Michael F. Freeman, Muriel Gugger and Jörn Piel.
Angew Chem Int Ed Engl. 2016 Dec 13. doi: 10.1002/anie.201609469.
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Radical S-adenosyl methionine peptide epimerases (RSPEs) are an enzyme family that accomplishes regiospecific and irreversible introduction of multiple D-configured residues into ribosomally encoded peptides. Collectively, RSPEs can generate diverse epimerization patterns in a wide range of substrates. Previously, the lack of rapid methods to localize epimerized residues has impeded efforts to investigate the function and applicative potential of RSPEs. An efficient mass spectrometry-based assay is introduced that permits characterization of products generated in E. coli. Applying this to a range of non-natural peptide-epimerase combinations, it is shown that the d-amino acid pattern is largely but not exclusively dictated by the core peptide sequence, while the epimerization order is dependent on the enzyme-leader pair. RSPEs were found to be highly promiscuous, which allowed for modular introduction of peptide segments with defined patterns.