title: Defining the Metabolic Functions and Roles in Virulence of the rpoN1 and rpoN2 Genes in Ralstonia solanacearum GMI1000.
abstract: The alternative sigma factor RpoN is a unique regulator found among bacteria. It controls numerous processes that range from basic metabolism to more complex functions such as motility and nitrogen fixation. Our current understanding of RpoN function is largely derived from studies on prototypical bacteria such as Escherichia coli. Bacillus subtilis and Pseudomonas putida. Although the extent and necessity of RpoN-dependent functions differ radically between these model organisms, each bacterium depends on a single chromosomal rpoN gene to meet the cellular demands of RpoN regulation. The bacterium Ralstonia solanacearum is often recognized for being the causative agent of wilt disease in crops, including banana, peanut and potato. However, this plant pathogen is also one of the few bacterial species whose genome possesses dual rpoN genes. To determine if the rpoN genes in this bacterium are genetically redundant and interchangeable, we constructed and characterized ΔrpoN1, ΔrpoN2 and ΔrpoN1 ΔrpoN2 mutants of R. solanacearum GMI1000. It was found that growth on a small range of metabolites, including dicarboxylates, ethanol, nitrate, ornithine, proline and xanthine, were dependent on only the rpoN1 gene. Furthermore, the rpoN1 gene was required for wilt disease on tomato whereas rpoN2 had no observable role in virulence or metabolism in R. solanacearum GMI1000. Interestingly, plasmid-based expression of rpoN2 did not fully rescue the metabolic deficiencies of the ΔrpoN1 mutants; full recovery was specific to rpoN1. In comparison, only rpoN2 was able to genetically complement a ΔrpoN E. coli mutant. These results demonstrate that the RpoN1 and RpoN2 proteins are not functionally equivalent or interchangeable in R. solanacearum GMI1000.
authors.affiliation: Department of Chemistry, State University of New York-College of Environmental Science and Forestry, Syracuse, New York, United States of America.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Lundgren
authors.affiliation: Department of Chemistry, State University of New York-College of Environmental Science and Forestry, Syracuse, New York, United States of America.
authors.forename: Morgan P
authors.initials: MP
authors.lastname: Connolly
authors.affiliation: Department of Biology, Syracuse University, Syracuse, New York, United States of America.
authors.forename: Pratibha
authors.initials: P
authors.lastname: Choudhary
authors.affiliation: Department of Chemistry, State University of New York-College of Environmental Science and Forestry, Syracuse, New York, United States of America.
authors.forename: Tiffany S
authors.initials: TS
authors.lastname: Brookins-Little
authors.affiliation: Department of Biology, Syracuse University, Syracuse, New York, United States of America.
authors.forename: Snigdha
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: Department of Biology, Syracuse University, Syracuse, New York, United States of America.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Raina
authors.affiliation: Department of Chemistry, State University of New York-College of Environmental Science and Forestry, Syracuse, New York, United States of America.|Center for Applied Microbiology, State University of New York-College of Environmental Science and Forestry, Syracuse, New York, United States of America.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Nomura
mesh_terms: D000595:Amino Acid Sequence; D003998:Dicarboxylic Acids / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D018551:Solanum lycopersicum / Q000382:microbiology; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D009952:Ornithine / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D051877:RNA Polymerase Sigma 54 / Q000235:genetics* / Q000378:metabolism; D043368:Ralstonia solanacearum / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D014774:Virulence; D019820:Xanthine / Q000378:metabolism
chemical_list: D003998:Dicarboxylic Acids; D009566:Nitrates; D019820:Xanthine; D000431:Ethanol; D011392:Proline; D009952:Ornithine; D051877:RNA Polymerase Sigma 54