title: Synthesis of phosphatidylcholine, a typical eukaryotic phospholipid, is necessary for full virulence of the intracellular bacterial parasite Brucella abortus.
abstract: Phosphatidylcholine (PC) is a typical eukaryotic phospholipid absent from most prokaryotes. Thus, its presence in some intracellular bacteria is intriguing as it may constitute host mimicry. The role of PC in Brucella abortus was examined by generating mutants in pcs (BApcs) and pmtA (BApmtA), which encode key enzymes of the two bacterial PC biosynthetic routes, the choline and methyl-transferase pathways. In rich medium, BApcs and the double mutant BApcspmtA but not BApmtA displayed reduced growth, increased phosphatidylethanolamine and no PC, showing that Pcs is essential for PC synthesis under these conditions. In minimal medium, the parental strain, BApcs and BApmtA showed reduced but significant amounts of PC suggesting that PmtA may also be functional. Probing with phage Tb, antibiotics, polycations and serum demonstrated that all mutants had altered envelopes. In macrophages, BApcs and BApcspmtA showed reduced ability to evade fusion with lysosomes and establish a replication niche. In mice, BApcs showed attenuation only at early times after infection, BApmtA at later stages and BApcspmtA throughout. The results suggest that Pcs and PmtA have complementary roles in vivo related to nutrient availability and that PC and the membrane properties that depend on this typical eukaryotic phospholipid are essential for Brucella virulence.
authors.affiliation: Departamento de Microbiología, Universidad de Navarra, Pamplona, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Conde-Alvarez
authors.forename: María J
authors.initials: MJ
authors.lastname: Grilló
authors.forename: Suzana P
authors.initials: SP
authors.lastname: Salcedo
authors.forename: María J
authors.initials: MJ
authors.lastname: de Miguel
authors.forename: Emilie
authors.initials: E
authors.lastname: Fugier
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Gorvel
authors.forename: Ignacio
authors.initials: I
authors.lastname: Moriyón
authors.forename: Maite
authors.initials: M
authors.lastname: Iriarte
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002003:Brucella abortus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D002462:Cell Membrane / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D005798:Genes, Bacterial; D066298:In Vitro Techniques; D008264:Macrophages / Q000382:microbiology; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D009154:Mutation; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D013154:Spleen / Q000382:microbiology; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010713:Phosphatidylcholines; D008780:Methyltransferases; C435200:PmtA protein, bacteria; D017855:Transferases (Other Substituted Phosphate Groups); C483298:CDP-diacylglycerol choline O-phosphatidyltransferase