The phospholipid biosynthesis enzyme PlsB contains three distinct domains for membrane association, lysophosphatidic acid synthesis, and dimerization

Abstract

Biosynthesis of phospholipids is fundamental for membrane biogenesis in all living organisms. As a member of the glycerol‐3‐phosphate (G3P) acyltransferase family, PlsB is a crucial enzyme catalyzing the first step of phospholipid synthesis by converting G3P and fatty acyl‐coenzyme A (CoA)/acyl carrier protein (ACP) into lysophosphatidic acid and free CoA (CoASH)/ACP. In bacterial cells, PlsB participates in the formation of antibiotic‐tolerant persister cells related to multidrug tolerance, and is hence considered as a potential target for anti‐persister therapy. By using the single‐particle cryo‐electron microscopy method, we have solved the structure of full‐length PlsB from Thermomonas haemolytica ( Th PlsB) at 2.79 Å resolution. The Th PlsB protein forms a homodimer with C 2 symmetry and each monomer contains three distinct domains, namely the amino‐terminal domain (NTD), the middle catalytic domain (MCD), and the carboxy‐terminal domain. In the MCD, a fatty acyl‐CoA binds in a membrane‐facing surface groove enclosed by a lipid molecule 1,2‐dioleoyl‐sn‐glycero‐3‐phosphate (DOPA) on one side. The interactions between Th PlsB and the membrane involve four surface‐exposed amphipathic regions located in the NTD and MCD, respectively. Our structural and biochemical analysis results suggest a membrane surface association‐catalysis coupling model for the PlsB‐mediated biosynthesis of lysophosphatidic acid occurring at the membrane‐cytosol interface.