Engineering the Specificity of Acetyl-CoA Synthetase for Diverse Acyl-CoA Thioester Generation

CoA thioesters are valuable intermediates in numerous biosynthetic routes and metabolic processes. However, diversifying these compounds and their corresponding downstream products hinges on broadening the promiscuity of CoA ligases that produce them or using additional enzymes to functionalize them. Here, the inherent promiscuity of an acyl-CoA ligase from Pseudomonas chlororaphis was probed with carboxylic acids of varying sizes and functionality. The enzyme was engineered to improve its activity with a diverse panel of acyl-CoA thioesters, including halogenated and oxidized acids, that can be used in downstream biosynthetic production strategies. To demonstrate the utility of the engineered enzyme, a subset of the substrates was leveraged for the complete in situ biosynthesis of a small panel of pyrones via a portion of the archetypal polyketide synthase (PKS), 6-deoxyerythronolide B synthase (DEBS). This approach supports probing the promiscuity of polyketide biosynthesis and the diversification of natural product scaffolds.