Reversible membrane association of dinitrogenase reductase activating glycohydrolase in the regulation of nitrogenase activity in Rhodospirillum rubrum; dependence on GlnJ and AmtB1.
In the photosynthetic bacterium Rhodospirillum rubrum nitrogenase activity is regulated by reversible ADP-ribosylation of dinitrogenase reductase in response to external so called "switch-off" effectors. Activation of the modified, inactive form is catalyzed by dinitrogenase reductase activating glycohydrolase (DRAG) which removes the ADP-ribose moiety. This study addresses the signal transduction between external effectors and DRAG. R. rubrum, wild-type and P(II) mutant strains, were studied with respect to DRAG localization. We conclude that GlnJ clearly has an effect on the association of DRAG to the membrane in agreement with the effect on regulation of nitrogenase activity. Furthermore, we have generated a R. rubrum mutant lacking the putative ammonium transporter AmtB1 which was shown not to respond to "switch-off" effectors; no loss of nitrogenase activity and no ADP-ribosylation. Interestingly, DRAG was mainly localized to the cytosol in this mutant. Overall the results support our model in which association to the membrane is part of the mechanism regulating DRAG activity.
Wang
He
H
Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
Franke
Claudia C
CC
Nordlund
Stefan
S
Norén
Agneta
A
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000502:physiology; D016254:Mutagenesis, Insertional; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D009591:Nitrogenase / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
D001426:Bacterial Proteins; C439048:GlnJ protein, Rhodospirillum rubrum; D008565:Membrane Proteins; D009591:Nitrogenase; D009699:N-Glycosyl Hydrolases; C036091:ADP-ribosyl-(dinitrogen reductase) hydrolase