title: Identification of NH4+-regulated genes of Herbaspirillum seropedicae by random insertional mutagenesis.
abstract: Random mutagenesis using transposons with promoterless reporter genes has been widely used to examine differential gene expression patterns in bacteria. Using this approach, we have identified 26 genes of the endophytic nitrogen-fixing bacterium Herbaspirillum seropedicae regulated in response to ammonium content in the growth medium. These include nine genes involved in the transport of nitrogen compounds, such as the high-affinity ammonium transporter AmtB, and uptake systems for alternative nitrogen sources; nine genes coding for proteins responsible for restoring intracellular ammonium levels through enzymatic reactions, such as nitrogenase, amidase, and arginase; and a third group includes metabolic switch genes, coding for sensor kinases or transcription regulation factors, whose role in metabolism was previously unknown. Also, four genes identified were of unknown function. This paper describes their involvement in response to ammonium limitation. The results provide a preliminary profile of the metabolic response of Herbaspirillum seropedicae to ammonium stress.
authors.affiliation: Núcleo de Fixação de Nitrogênio, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Caixa Postal 19046, CEP 81.531-990 Curitiba-PR, Brazil.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwab
authors.forename: Humberto J
authors.initials: HJ
authors.lastname: Ramos
authors.forename: Emanuel M
authors.initials: EM
authors.lastname: Souza
authors.forename: Fábio O
authors.initials: FO
authors.lastname: Pedrosa
authors.forename: Marshall G
authors.initials: MG
authors.lastname: Yates
authors.forename: Leda S
authors.initials: LS
authors.lastname: Chubatsu
authors.forename: Liu U
authors.initials: LU
authors.lastname: Rigo
mesh_terms: D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial / Q000187:drug effects* / Q000502:physiology; D042803:Herbaspirillum / Q000737:chemistry / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D016254:Mutagenesis, Insertional / Q000379:methods*; D009584:Nitrogen / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*
chemical_list: D000644:Quaternary Ammonium Compounds; D009584:Nitrogen