scholarly journals In VitroInteractions between the PIIProteins and the Nitrogenase Regulatory Enzymes Dinitrogenase Reductase ADP-ribosyltransferase (DraT) and Dinitrogenase Reductase-activating Glycohydrolase (DraG) inAzospirillum brasilense

2009 ◽  
Vol 284 (11) ◽  
pp. 6674-6682 ◽  
Author(s):  
Luciano F. Huergo ◽  
Mike Merrick ◽  
Rose A. Monteiro ◽  
Leda S. Chubatsu ◽  
Maria B. R. Steffens ◽  
...  
Keyword(s):  
Regulatory Enzymes ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

scholarly journals Correlation of Activity Regulation and Substrate Recognition of the ADP-Ribosyltransferase That Regulates Nitrogenase Activity in Rhodospirillum rubrum

1999 ◽  
Vol 181 (5) ◽  
pp. 1698-1702 ◽  
Author(s):  
Kitai Kim ◽  
Yaoping Zhang ◽  
Gary P. Roberts
Keyword(s):  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Substrate Recognition ◽  
Posttranslational Regulation ◽  
Activity Regulation ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

ABSTRACT In Rhodospirillum rubrum, nitrogenase activity is regulated posttranslationally through the ADP-ribosylation of dinitrogenase reductase by dinitrogenase reductase ADP-ribosyltransferase (DRAT). Several DRAT variants that are altered both in the posttranslational regulation of DRAT activity and in the ability to recognize variants of dinitrogenase reductase have been found. This correlation suggests that these two properties are biochemically connected.

scholarly journals Role of the Dinitrogenase Reductase Arginine 101 Residue in Dinitrogenase Reductase ADP-Ribosyltransferase Binding, NAD Binding, and Cleavage

2001 ◽  
Vol 183 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Yan Ma ◽  
Paul W. Ludden
Keyword(s):  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

ABSTRACT Dinitrogenase reductase is posttranslationally regulated by dinitrogenase reductase ADP-ribosyltransferase (DRAT) via ADP-ribosylation of the arginine 101 residue in some bacteria.Rhodospirillum rubrum strains in which the arginine 101 of dinitrogenase reductase was replaced by tyrosine, phenylalanine, or leucine were constructed by site-directed mutagenesis of thenifH gene. The strain containing the R101F form of dinitrogenase reductase retains 91%, the strain containing the R101Y form retains 72%, and the strain containing the R101L form retains only 28% of in vivo nitrogenase activity of the strain containing the dinitrogenase reductase with arginine at position 101. In vivo acetylene reduction assays, immunoblotting with anti-dinitrogenase reductase antibody, and [adenylate-32P]NAD labeling experiments showed that no switch-off of nitrogenase activity occurred in any of the three mutants and no ADP-ribosylation of altered dinitrogenase reductases occurred either in vivo or in vitro. Altered dinitrogenase reductases from strains UR629 (R101Y) and UR630 (R101F) were purified to homogeneity. The R101F and R101Y forms of dinitrogenase reductase were able to form a complex with DRAT that could be chemically cross-linked by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. The R101F form of dinitrogenase reductase and DRAT together were not able to cleave NAD. This suggests that arginine 101 is not critical for the binding of DRAT to dinitrogenase reductase but that the availability of arginine 101 is important for NAD cleavage. Both DRAT and dinitrogenase reductase can be labeled by [carbonyl-14C]NAD individually upon UV irradiation, but most 14C label is incorporated into DRAT when both proteins are present. The ability of R101F dinitrogenase reductase to be labeled by [carbonyl-14C]NAD suggested that Arg 101 is not absolutely required for NAD binding.

scholarly journals The Nitrogenase Regulatory Enzyme Dinitrogenase Reductase ADP-Ribosyltransferase (DraT) Is Activated by Direct Interaction with the Signal Transduction Protein GlnB

2012 ◽  
Vol 195 (2) ◽  
pp. 279-286 ◽  
Author(s):  
Vivian R. Moure ◽  
Karamatullah Danyal ◽  
Zhi-Yong Yang ◽  
Shannon Wendroth ◽  
Marcelo Müller-Santos ◽  
...  
Keyword(s):  
Rhodospirillum Rubrum ◽  
Metal Cluster ◽  
Reductase Activity ◽  
Direct Interaction ◽  
Ammonium Concentration ◽  
Content Type ◽  
Fe Protein ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

ABSTRACTFe protein (dinitrogenase reductase) activity is reversibly inactivated by dinitrogenase reductase ADP-ribosyltransferase (DraT) in response to an increase in the ammonium concentration or a decrease in cellular energy inAzospirillum brasilense,Rhodospirillum rubrum, andRhodobacter capsulatus. The ADP-ribosyl is removed by the dinitrogenase reductase-activating glycohydrolase (DraG), promoting Fe protein reactivation. The signaling pathway leading to DraT activation by ammonium is still not completely understood, but the available evidence shows the involvement of direct interaction between the enzyme and the nitrogen-signaling PIIproteins. InA. brasilense, two PIIproteins, GlnB and GlnZ, were identified. We used Fe protein fromAzotobacter vinelandiias the substrate to assess the activity ofA. brasilenseDraTin vitrocomplexed or not with PIIproteins. Under our conditions, GlnB was necessary for DraT activity in the presence of Mg-ADP. The PIIeffector 2-oxoglutarate, in the presence of Mg-ATP, inhibited DraT-GlnB activity, possibly by inducing complex dissociation. DraT was also activated by GlnZ and by both uridylylated PIIproteins, but not by a GlnB variant carrying a partial deletion of the T loop. Kinetics studies revealed that theA. brasilenseDraT-GlnB complex was at least 18-fold more efficient than DraT purified fromR. rubrum, but with a similarKmvalue for NAD+. Our results showed that ADP-ribosylation of the Fe protein does not affect the electronic state of its metal cluster and prevents association between the Fe and MoFe proteins, thus inhibiting electron transfer.

scholarly journals The role of NAD+ as a signal during nitrogenase switch-off in Rhodospirillum rubrum

1997 ◽  
Vol 322 (3) ◽  
pp. 829-832 ◽  
Author(s):  
Agneta NORÉN ◽  
Abdelhamid SOLIMAN ◽  
Stefan NORDLUND
Keyword(s):  
Metabolic Regulation ◽  
Opposite Effect ◽  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Regulatory System ◽  
Glutamate Synthase ◽  
The Other ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

The role of NAD+ in the metabolic regulation of nitrogenase, the ‘switch-off’ effect, in Rhodospirillum rubrum has been studied. We now show that the decrease in nitrogenase activity upon addition of NAD+ to R. rubrum is due to modification of dinitrogenase reductase. There was no effect when NAD+ was added to a mutant of R. rubrumdevoid of dinitrogenase reductase ADP-ribosyltransferase, indicating that NAD+ ‘switch-off’ is an effect of the same regulatory system as ammonium ‘switch-off’. We also show that oxaloacetate and α-ketoglutarate function as ‘switch-off’ effectors. On the other hand β-hydroxybutyrate has the opposite effect by shortening the ‘switch-off’ period. Furthermore, by using an inhibitor of glutamate synthase the role of this enzyme in ‘switch-off’ was investigated. The results are discussed in relation to our proposal that changes in the concentration of NAD+ are involved in initiating ‘switch-off’.

scholarly journals Mutagenesis and Functional Characterization of theglnB, glnA, and nifA Genes from the Photosynthetic Bacterium Rhodospirillum rubrum

2000 ◽  
Vol 182 (4) ◽  
pp. 983-992 ◽  
Author(s):  
Yaoping Zhang ◽  
Edward L. Pohlmann ◽  
Paul W. Ludden ◽  
Gary P. Roberts
Keyword(s):  
Nitrogen Fixation ◽  
Rhodospirillum Rubrum ◽  
Nitrogenase Activity ◽  
Functional Characterization ◽  
Photosynthetic Bacterium ◽  
Wild Type ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

ABSTRACT Nitrogen fixation is tightly regulated in Rhodospirillum rubrum at two different levels: transcriptional regulation ofnif expression and posttranslational regulation of dinitrogenase reductase by reversible ADP-ribosylation catalyzed by the DRAT-DRAG (dinitrogenase reductase ADP-ribosyltransferase–dinitrogenase reductase-activating glycohydrolase) system. We report here the characterization ofglnB, glnA, and nifA mutants and studies of their relationship to the regulation of nitrogen fixation. Two mutants which affect glnB (structural gene for PII) were constructed. While PII-Y51F showed a lower nitrogenase activity than that of wild type, a PIIdeletion mutant showed very little nif expression. This effect of PII on nif expression is apparently the result of a requirement of PII for NifA activation, whose activity is regulated by NH4 + in R. rubrum. The modification of glutamine synthetase (GS) in theseglnB mutants appears to be similar to that seen in wild type, suggesting that a paralog of PII might exist inR. rubrum and regulate the modification of GS. PII also appears to be involved in the regulation of DRAT activity, since an altered response to NH4 + was found in a mutant expressing PII-Y51F. The adenylylation of GS plays no significant role in nif expression or the ADP-ribosylation of dinitrogenase reductase, since a mutant expressing GS-Y398F showed normal nitrogenase activity and normal modification of dinitrogenase reductase in response to NH4 + and darkness treatments.

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