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Screening and Engineering the Synthetic Potential of Carboxylating Reductases from Central Metabolism and Polyketide Biosynthesis.

Research paper by Dominik M DM Peter, Lennart L Schada von Borzyskowski, Patrick P Kiefer, Philipp P Christen, Julia A JA Vorholt, Tobias J TJ Erb

Indexed on: 19 Sep '15Published on: 19 Sep '15Published in: Angewandte Chemie International Edition



Abstract

Carboxylating enoyl-thioester reductases (ECRs) are a recently discovered class of enzymes. They catalyze the highly efficient addition of CO2 to the double bond of α,β-unsaturated CoA-thioesters and serve two biological functions. In primary metabolism of many bacteria they produce ethylmalonyl-CoA during assimilation of the central metabolite acetyl-CoA. In secondary metabolism they provide distinct α-carboxyl-acyl-thioesters to vary the backbone of numerous polyketide natural products. Different ECRs were systematically assessed with a diverse library of potential substrates. We identified three active site residues that distinguish ECRs restricted to C4 and C5-enoyl-CoAs from highly promiscuous ECRs and successfully engineered a selected ECR as proof-of-principle. This study defines the molecular basis of ECR reactivity, allowing for predicting and manipulating a key reaction in natural product diversification.