title: The Azospirillum brasilense Sp7 noeJ and noeL genes are involved in extracellular polysaccharide biosynthesis.
abstract: Azospirillum brasilense is a plant root-colonizing bacterium that exerts beneficial effects on the growth of many agricultural crops. Extracellular polysaccharides of the bacterium play an important role in its interactions with plant roots. The pRhico plasmid of A. brasilense Sp7, also named p90, carries several genes involved in synthesis and export of cell surface polysaccharides. We generated two Sp7 mutants impaired in two pRhico-located genes, noeJ and noeL, encoding mannose-6-phosphate isomerase and GDP-mannose 4,6-dehydratase, respectively. Our results demonstrate that in A. brasilense Sp7, noeJ and noeL are involved in lipopolysaccharide and exopolysaccharide synthesis. noeJ and noeL mutant strains were significantly altered in their outer membrane and cytoplasmic/periplasmic protein profiles relative to the wild-type strain. Moreover, both noeJ and noeL mutations significantly affected the bacterial responses to several stresses and antimicrobial compounds. Disruption of noeL, but not noeJ, affected the ability of the A. brasilense Sp7 to form biofilms. The pleiotropic alterations observed in the mutants could be due, at least partially, to their altered lipopolysaccharides and exopolysaccharides relative to the wild-type.
authors.affiliation: Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Anat
authors.initials: A
authors.lastname: Lerner
authors.affiliation: Sección Bioquímica, Facultad de Ciencias, Universidad de la República y Laboratorio de Microbiologia Molecular, Instituto Clemente Estable, Igua 4225, Montevideo, Uruguay.|Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Susana
authors.initials: S
authors.lastname: Castro-Sowinski
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Salamanca, Consejo Superior de Investigaciones Científicas (IRNASA-CSIC), Salamanca, Spain.|Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Angel
authors.initials: A
authors.lastname: Valverde
authors.affiliation: Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Hadas
authors.initials: H
authors.lastname: Lerner
authors.affiliation: Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Rachel
authors.initials: R
authors.lastname: Dror
authors.affiliation: Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Yaacov
authors.initials: Y
authors.lastname: Okon
authors.affiliation: Department of Plant Pathology and Microbiology and The Otto Warburg Minerva Center for Agricultural Biotechnology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
authors.forename: Saul
authors.initials: S
authors.lastname: Burdman
mesh_terms: D015806:Azospirillum brasilense / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000096:biosynthesis; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D013312:Stress, Physiological
chemical_list: D004269:DNA, Bacterial; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; C422948:GDP-D-mannose dehydratase, bacteria; D006836:Hydro-Lyases; D008359:Mannose-6-Phosphate Isomerase