title: The dioxygenase-encoding olsD gene from Burkholderia cenocepacia causes the hydroxylation of the amide-linked fatty acyl moiety of ornithine-containing membrane lipids.
abstract: Burkholderia cenocepacia is an important opportunistic pathogen, and one of the most striking features of the Burkholderia genus is the collection of polar lipids present in its membrane, including phosphatidylethanolamine (PE) and ornithine-containing lipids (OLs), as well as the 2-hydroxylated derivatives of PE and OLs (2-OH-PE and 2-OH-OLs, respectively), which differ from the standard versions by virtue of the presence of a hydroxyl group at C2 (2-OH) of an esterified fatty acyl residue. Similarly, a lipid A-esterified myristoyl group from Salmonella typhimurium can have a 2-hydroxy modification that is due to the LpxO enzyme. We thus postulated that 2-hydroxylation of 2-OH-OLs might be catalyzed by a novel dioxygenase homologue of LpxO. In B. cenocepacia, we have now identified two open reading frames (BCAM1214 and BCAM2401) homologous to LpxO from S. typhimurium. The introduction of bcam2401 (designated olsD) into Sinorhizobium meliloti leads to the formation of one new lipid and in B. cenocepacia of two new lipids. Surprisingly, the lipid modifications on OLs due to OlsD occur on the amide-linked fatty acyl chain. This is the first report of a hydroxyl modification of OLs on the amide-linked fatty acyl moiety. Formation of hydroxylated OLs occurs only when the biosynthesis pathway for nonmodified standard OLs is intact. The hydroxyl modification of OLs on the amide-linked fatty acyl moiety occurs only under acid stress conditions. An assay has been developed for the OlsD dioxygenase, and an initial characterization of the enzyme is presented.
authors.affiliation: Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos CP62251, Mexico.
authors.forename: Napoleón
authors.initials: N
authors.lastname: González-Silva
authors.forename: Isabel M
authors.initials: IM
authors.lastname: López-Lara
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Reyes-Lamothe
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Taylor
authors.forename: David
authors.initials: D
authors.lastname: Sumpton
authors.forename: Jane
authors.initials: J
authors.lastname: Thomas-Oates
authors.forename: Otto
authors.initials: O
authors.lastname: Geiger
mesh_terms: D000143:Acids / Q000494:pharmacology; D000577:Amides / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D057508:Burkholderia cenocepacia / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D002308:Cardiolipins / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D049308:Dioxygenases / Q000235:genetics* / Q000378:metabolism; D004951:Esterification / Q000187:drug effects; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics*; D006900:Hydroxylation / Q000187:drug effects; D008055:Lipids / Q000737:chemistry; D013058:Mass Spectrometry; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009952:Ornithine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000378:metabolism; D012486:Salmonella typhimurium / Q000187:drug effects / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000378:metabolism
chemical_list: D000143:Acids; D000577:Amides; D001426:Bacterial Proteins; D002308:Cardiolipins; D005227:Fatty Acids; D008055:Lipids; D008563:Membrane Lipids; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; C051524:ornithine containing aminolipid; C483858:phosphatidylethanolamine; D009952:Ornithine; D049308:Dioxygenases