Crystal Structure of the Bifunctional Wax Synthase 1 from <i>Acinetobacter baylyi</i> Suggests a Conformational Change upon Substrate Binding and Formation of Additional Substrate Binding Sites

Wax esters (WE) are neutral lipids that formed by the transesterification of an activated fatty acyl moiety to a alcohol. Due their diverse physicochemical properties, WE used as industrial lubricants, in cosmetics, or for coating. There is substantial interest producing bacteria and plants genetic engineering improve sustainability reduce production costs. However, we lack detailed understanding catalytic mechanism structural determinants influence substrate specificities WE-synthesizing enzymes, which essential tailored production. One class well-studied WE-producing enzymes bifunctional bacterial wax synthases/acyl-CoA:diacylglycerol O-acyltransferases (WSD). Here, report 1.95 Å crystal structure Acinetobacter baylyi WSD1 (AbWSD1) with acid molecule bound active site. The location cocrystallized myristic confirms previously proposed acyl-CoA binding A comparison this AbWSD1 published Marinobacter aquaeolei (MaWSD1) apoenzyme revealed major difference C-terminal part AbWSD1. This leads us propose conformational change induced binding. forms then potential coenzyme (CoA) Furthermore, have identified additional cavity could show through mutational studies two amino acids lining crucial acyl-CoA:diacylglycerol O-acyltransferase (DGAT) activity enzyme. Our findings provide foundation designing WSD variants DGAT activity.