title: Role of BacA in lipopolysaccharide synthesis, peptide transport, and nodulation by Rhizobium sp. strain NGR234.
abstract: BacA of Sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with Medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (VLCFA) to lipid A of lipopolysaccharide (LPS). We investigated the role of BacA in Rhizobium species strain NGR234 by mutating the bacA gene. In the NGR234 bacA mutant, peptide import was impaired, but no effect on VLCFA addition was observed. More importantly, the symbiotic ability of the mutant was comparable to that of the wild type for a variety of legume species. Concurrently, an acpXL mutant of NGR234 was created and assayed. In rhizobia, AcpXL is a dedicated acyl carrier protein necessary for the addition of VLCFA to lipid A. LPS extracted from the NGR234 mutant lacked VLCFA, and this mutant was severely impaired in the ability to form functional nodules with the majority of legumes tested. Our work demonstrates the importance of VLCFA in the NGR234-legume symbiosis and also shows that the necessity of BacA for bacteroid differentiation is restricted to specific legume-Rhizobium interactions.
authors.affiliation: Laboratoire de Biologie Moléculaire des Plantes Supérieures, Université de Genève, 30 Quai Ernest-Ansermet, Sciences III, 1211 Geneva 4, Switzerland.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ardissone
authors.forename: Hajime
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Kumiko
authors.initials: K
authors.lastname: Kambara
authors.forename: Coralie
authors.initials: C
authors.lastname: Rummel
authors.forename: K Dale
authors.initials: KD
authors.lastname: Noel
authors.forename: Graham C
authors.initials: GC
authors.lastname: Walker
authors.forename: William J
authors.initials: WJ
authors.lastname: Broughton
authors.forename: William J
authors.initials: WJ
authors.lastname: Deakin
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D055170:Plant Root Nodulation / Q000502:physiology*; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D012231:Rhizobium / Q000145:classification / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D026901:Membrane Transport Proteins; D011135:Polysaccharides, Bacterial; C082397:bacA protein, Rhizobium meliloti