title: Sinorhizobium meliloti genes involved in tolerance to the antimicrobial peptide protamine.
abstract: The innate resistance of plants and animals to microbial infection is mediated in part by small cationic peptides with antimicrobial activity. We assessed the susceptibility of the alfalfa symbiont Sinorhizobium meliloti to the model antimicrobial peptide protamine. Twenty-one Tn5-induced mutants showing increased sensitivity to protamine were isolated, and nine were further characterized in detail. These nine mutants carried distinct transposon insertions that affected a total of seven different genes. Three of these genes are involved in exopolysaccharide and beta-(1,2)-glucan biosynthesis (exoT, exoU and ndvB), three other genes are implicated in nitrogen metabolism, such as a putative dyhidropyrimidinase, hutU and ureF, and the last gene exhibited similarity to the ATP binding cassette family of membrane transporters. Symbiotic defects ranging from severe to moderate were displayed by some of the protamine-hypersensitive mutants suggesting that S. meliloti possess active mechanisms to counteract hypothetical cationic peptides that may be produced by its host plant.
authors.affiliation: Dpto Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain.
authors.forename: Joaquina
authors.initials: J
authors.lastname: Nogales
authors.forename: Socorro
authors.initials: S
authors.lastname: Muñoz
authors.forename: José
authors.initials: J
authors.lastname: Olivares
authors.forename: Juan
authors.initials: J
authors.lastname: Sanjuán
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000502:physiology; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011479:Protamines / Q000378:metabolism* / Q000494:pharmacology*; D016962:Sinorhizobium meliloti / Q000187:drug effects* / Q000235:genetics / Q000502:physiology
chemical_list: D018528:ATP-Binding Cassette Transporters; D023181:Antimicrobial Cationic Peptides; D004251:DNA Transposable Elements; D011135:Polysaccharides, Bacterial; D011479:Protamines; D009584:Nitrogen