title: Effect of an ntrBC mutation on the posttranslational regulation of nitrogenase activity in Rhodospirillum rubrum.
abstract: Homologs of ntrB and ntrC genes from Rhodospirillum rubrum were cloned and sequenced. A mutant lacking ntrBC was constructed, and this mutant has normal nitrogenase activity under nif-derepressing conditions, indicating that ntrBC are not necessary for the expression of the nif genes in R. rubrum. However, the post-translational regulation of nitrogenase activity by ADP-ribosylation in response to NH4+ was partially abolished in this mutant. More surprisingly, the regulation of nitrogenase activity in response to darkness was also affected, suggesting a physiological link between the ntr system and energy signal transduction in R. rubrum. The expression of glutamine synthetase, as well as its posttranslational regulation, was also altered in this ntrBC mutant.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison 53706, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: A D
authors.initials: AD
authors.lastname: Cummings
authors.forename: R H
authors.initials: RH
authors.lastname: Burris
authors.forename: P W
authors.initials: PW
authors.lastname: Ludden
authors.forename: G P
authors.initials: GP
authors.lastname: Roberts
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D003624:Darkness; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics*; D009591:Nitrogenase / Q000378:metabolism*; D051922:PII Nitrogen Regulatory Proteins; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D016601:RNA-Binding Proteins; D012247:Rhodospirillum rubrum / Q000201:enzymology / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds; D016601:RNA-Binding Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C087372:nfrA protein, Azorhizobium caulinodans; D009591:Nitrogenase; D036002:ADP Ribose Transferases; C057637:dinitrogenase reductase ADP-ribosyltransferase; D011494:Protein Kinases; C055699:protein kinase-phosphatase NTRB; D010749:Phosphoprotein Phosphatases; D005974:Glutamate-Ammonia Ligase