title: Regulation of nitrogenase in the photosynthetic bacterium Rhodobacter sphaeroides containing draTG and nifHDK genes from Rhodobacter capsulatus.
abstract: The photosynthetic bacteria Rhodobacter capsulatus and Rhodospirillum rubrum regulate their nitrogenase activity by the reversible ADP-ribosylation of nitrogenase Fe-protein in response to ammonium addition or darkness. This regulation is mediated by two enzymes, dinitrogenase reductase ADP-ribosyl transferase (DRAT) and dinitrogenase reductase activating glycohydrolase (DRAG). Recently, we demonstrated that another photosynthetic bacterium, Rhodobacter sphaeroides, appears to have no draTG genes, and no evidence of Fe-protein ADP-ribosylation was found in this bacterium under a variety of growth and incubation conditions. Here we show that four different strains of Rba. sphaeroides are incapable of modifying Fe-protein, whereas four out of five Rba. capsulatus strains possess this ability. Introduction of Rba. capsulatus draTG and nifHDK (structural genes for nitrogenase proteins) into Rba. sphaeroides had no effect on in vivo nitrogenase activity and on nitrogenase switch-off by ammonium. However, transfer of draTG from Rba. capsulatus was sufficient to confer on Rba. sphaeroides the ability to reversibly modify the nitrogenase Fe-protein in response to either ammonium addition or darkness. These data suggest that Rba. sphaeroides, which lacks DRAT and DRAG, possesses all the elements necessary for the transduction of signals generated by ammonium or darkness to these proteins.
authors: Département de microbiologie et immunologie, Université de Montréal, QC, Canada.
authors: A F
authors: AF
authors: Yakunin
authors: A S
authors: AS
authors: Fedorov
authors: T V
authors: TV
authors: Laurinavichene
authors: V M
authors: VM
authors: Glaser
authors: N S
authors: NS
authors: Egorov
authors: A A
authors: AA
authors: Tsygankov
authors: V V
authors: VV
authors: Zinchenko
authors: P C
authors: PC
authors: Hallenbeck
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006026:Glycoside Hydrolases / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D009699:N-Glycosyl Hydrolases; D009586:Nitrogen Fixation / Q000235:genetics*; D009591:Nitrogenase / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics; D010788:Photosynthesis; D011499:Protein Processing, Post-Translational; D016992:Rhodobacter / Q000201:enzymology / Q000235:genetics*; D016354:Rhodobacter capsulatus / Q000201:enzymology / Q000235:genetics; D012242:Rhodobacter sphaeroides / Q000201:enzymology / Q000235:genetics; D013045:Species Specificity
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C492406:NIFK protein, human; D009687:Nuclear Proteins; D010088:Oxidoreductases; D009591:Nitrogenase; C029130:nitrogenase reductase; D036002:ADP Ribose Transferases; C057637:dinitrogenase reductase ADP-ribosyltransferase; D006026:Glycoside Hydrolases; D009699:N-Glycosyl Hydrolases; C036091:ADP-ribosyl-(dinitrogen reductase) hydrolase