title: Oxygen-regulated in vitro transcription of Rhizobium meliloti nifA and fixK genes.
abstract: Oxygen concentration regulates the expression of nitrogen fixation genes in the symbiotic bacterium Rhizobium meliloti. We demonstrate that two proteins, FixL and FixJ, that belong to the two-component family of regulatory proteins are necessary and sufficient for oxygen-regulated in vitro transcription of the two key regulatory genes, nifA and fixK. We show directly that FixJ is a transcriptional activator, working in conjunction with the RNA polymerase sigma 70 holoenzyme. Addition of FixL122, a soluble form of the sensor FixL protein, to the transcription assay enhanced FixJ transcriptional activity in response to low oxygen concentration. This enhancement of FixJ activity was correlated with FixJ phosphorylation.
authors.affiliation: Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, CNRS-INRA, France.
authors.forename: J M
authors.initials: JM
authors.lastname: Reyrat
authors.forename: M
authors.initials: M
authors.lastname: David
authors.forename: C
authors.initials: C
authors.lastname: Blonski
authors.forename: P
authors.initials: P
authors.lastname: Boistard
authors.forename: J
authors.initials: J
authors.lastname: Batut
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial / Q000187:drug effects*; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000187:drug effects* / Q000235:genetics*; D010100:Oxygen / Q000494:pharmacology*; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; C061338:NifA protein, Bacteria; D011994:Recombinant Proteins; D014157:Transcription Factors; C066628:FixK protein, Bacteria; C069289:FixJ protein, Bacteria; D010100:Oxygen