PgsA

PgsA, or phosphatidylglycerophosphate synthase, is a membrane-bound enzyme that plays a key role in bacterial phospholipid biosynthesis. It is typically encoded by the pgsA gene and is found in many bacteria, where it contributes to the production of major membrane lipids.

The catalytic reaction catalyzed by PgsA uses CDP-diacylglycerol and glycerol-3-phosphate as substrates to generate phosphatidylglycerophosphate and CMP. The phosphatidylglycerophosphate (PGP) produced by PgsA is subsequently dephosphorylated to phosphatidylglycerol (PG), which is a principal anionic phospholipid and a precursor for cardiolipin synthesis in bacteria. Through these steps, PgsA links the formation of three major phospholipid classes in bacterial membranes.

PgsA belongs to the CDP-alcohol phosphotransferase superfamily and is typically a multi-pass membrane protein with several transmembrane helices. The active site is formed by conserved motifs characteristic of this enzyme family, and catalysis occurs within the membrane environment, with substrates accessible from the cytoplasmic side.

Biological significance and regulation: PgsA is essential for the production of phosphatidylglycerol, a dominant membrane lipid in many bacteria, and it feeds into cardiolipin biosynthesis. The enzyme is integral to maintaining membrane integrity and proper function, and disruption of PgsA can lead to severe growth defects or lethality in some species. The gene is often studied as a potential target for antimicrobial strategies due to its central role in membrane lipid biosynthesis.

Overall, PgsA is a conserved, membrane-associated enzyme that initiates the major bacterial pathway for phosphatidylglycerol formation, linking glycerophospholipid synthesis to broader membrane lipid homeostasis.