title: Three phosphatidylglycerol-phosphate phosphatases in the inner membrane of Escherichia coli.
abstract: The phospholipids of Escherichia coli consist mainly of phosphatidylethanolamine, phosphatidylglycerol (PG), and cardiolipin. PG makes up ∼25% of the cellular phospholipid and is essential for growth in wild-type cells. PG is synthesized on the inner surface of the inner membrane from cytidine diphosphate-diacylglycerol and glycerol 3-phosphate, generating the precursor phosphatidylglycerol-phosphate (PGP). This compound is present at low levels (∼0.1% of the total lipid). Dephosphorylation of PGP to PG is catalyzed by several PGP-phosphatases. The pgpA and pgpB genes, which encode structurally distinct PGP-phosphatases, were identified previously. Double deletion mutants lacking pgpA and pgpB are viable and still make PG, suggesting the presence of additional phosphatase(s). We have identified a third PGP-phosphatase gene (previously annotated as yfhB but renamed pgpC) using an expression cloning strategy. A mutant with deletions in all three phosphatase genes is not viable unless covered by a plasmid expressing either pgpA, pgpB, or pgpC. When the triple mutant is covered with the temperature-sensitive plasmid pMAK705 expressing any one of the three pgp genes, the cells grow at 30 but not 42 °C. As growth slows at 42 °C, PGP accumulates to high levels, and the PG content declines. PgpC orthologs are present in many other bacteria.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Yi-Hsueh
authors.initials: YH
authors.lastname: Lu
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Guan
authors.forename: Jinshi
authors.initials: J
authors.lastname: Zhao
authors.forename: Christian R H
authors.initials: CR
authors.lastname: Raetz
mesh_terms: D002308:Cardiolipins / Q000096:biosynthesis* / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics; D048168:Escherichia coli K12 / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*
chemical_list: D002308:Cardiolipins; D029968:Escherichia coli Proteins; D010744:Phosphoric Monoester Hydrolases