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

Biosynthesis of phospholipids is fundamental for membrane biogenesis in all living organisms. As a member of the Glycerol-3-phosphate (G3P) Acyltransferase (GPAT) 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 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 (cryo-EM) method, we have solved the structure of full-length PlsB from Themomonas haemolytica (ThPlsB) at 2.79 [A] resolution. The ThPlsB protein forms a homodimer with C2 symmetry and each monomer contains three distinct domains, namely the amino-terminal domain (NTD), the middle catalytic domain (MCD) and the carboxy-terminal domain (CTD). For the first time, we have unraveled the binding sites of a fatty acyl-CoA and a 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) molecule in the MCD of PlsB. The interactions between ThPlsB and the membrane involve two surface-exposed amphipathic regions located in the NTD and MCD respectively. The results of structural and biochemical analyses suggest a membrane surface association-catalysis coupling model for the PlsB-mediated biosynthesis of lysophosphatidic acid occurring at the membrane-cytosol interface.