In vitro characterization of five bacterial WS/DGAT acyltransferases regarding the synthesis of biotechnologically relevant short‐chain‐length esters

For the biotechnical production of biofuels, oleo-, or fine chemicals bacterial wax ester synthase/acyl-Coenzyme A:diacylglycerol acyltransferases (WS/DGAT) are discussed as interesting candidates for in vivo esterification reactions. In this study, the suitability of selected acyltransferases for the conversion of non-physiological substrates like short-chain-length alcohols and short-chain length or even branched acyl-CoAs has been investigated. In vitro analyzes of purified AtfA and AtfA(G355I) from Acinetobacter baylyi, Ma1(A360I) from Marinobacter aquaeolei, WS2 from Marinobacter hydrocarbonoclasticus, and AtfA1 from Alcanivorax borkumensis were conducted to evaluate the specific activities of these enzymes toward n-hexadecanol (C-16), n-dodecanol (C-12), ethanol (C-2), and methanol (C-1), palmitoyl-CoA (C-16), butyryl-CoA (C-4) as well as toward branched 3-hydroxybutyryl-CoA and 2-hydroxyisobutyryl-CoA. Athough long- and medium-chain-length substrates were preferred by all five enzymes, WS2 and AtfA showed the highest relative activities with ethanol or methanol when compared to n-hexadecanol, whereas residual activities toward short or branched acyl-CoAs could only be measured with AtfA and AtfA1.