scholarly journals ADP-Ribosylation of Variants of Azotobacter vinelandiiDinitrogenase Reductase by Rhodospirillum rubrumDinitrogenase Reductase ADP-Ribosyltransferase

2000 ◽  
Vol 182 (9) ◽  
pp. 2597-2603 ◽  
Author(s):  
Sandra K. Grunwald ◽  
Matthew J. Ryle ◽  
William N. Lanzilotta ◽  
Paul W. Ludden
Keyword(s):  
Conformational Changes ◽  
Rhodospirillum Rubrum ◽  
Azotobacter Vinelandii ◽  
Critical Role ◽  
Substantial Effect ◽  
Cross Linking ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase ◽  
Mutant Forms ◽  
Adp Ribosyltransferase

ABSTRACT In a number of nitrogen-fixing bacteria, nitrogenase is posttranslationally regulated by reversible ADP-ribosylation of dinitrogenase reductase. The structure of the dinitrogenase reductase from Azotobacter vinelandii is known. In this study, mutant forms of dinitrogenase reductase from A. vinelandii that are affected in various protein activities were tested for their ability to be ADP-ribosylated or to form a complex with dinitrogenase reductase ADP-ribosyltransferase (DRAT) fromRhodospirillum rubrum. R140Q dinitrogenase reductase could not be ADP-ribosylated by DRAT, although it still formed a cross-linkable complex with DRAT. Thus, the Arg 140 residue of dinitrogenase reductase plays a critical role in the ADP-ribosylation reaction. Conformational changes in dinitrogenase reductase induced by an F135Y substitution or by removal of the Fe4S4 cluster resulted in dinitrogenase reductase not being a substrate for ADP-ribosylation. Through cross-linking studies it was also shown that these changes decreased the ability of dinitrogenase reductase to form a cross-linkable complex with DRAT. Substitution of D129E or deletion of Leu 127, which result in altered nucleotide binding regions of these dinitrogenase reductases, did not significantly change the interaction between dinitrogenase reductase and DRAT. Previous results showed that changing Lys 143 to Gln decreased the binding between dinitrogenase reductase and dinitrogenase (L. C. Seefeldt, Protein Sci. 3:2073–2081, 1994); however, this change did not have a substantial effect on the interaction between dinitrogenase reductase and DRAT.

scholarly journals ADP-ribosylation of dinitrogenase reductase from Clostridium pasteurianum prevents its inhibition of nitrogenase from Azotobacter vinelandii

1988 ◽  
Vol 251 (2) ◽  
pp. 609-612 ◽  
Author(s):  
S A Murrell ◽  
R G Lowery ◽  
P W Ludden
Keyword(s):  
Rhodospirillum Rubrum ◽  
Azotobacter Vinelandii ◽  
Clostridium Pasteurianum ◽  
Adp Ribosylation ◽  
Dinitrogenase Reductase ◽  
Adp Ribosyltransferase

The effect of ADP-ribosylation of dinitrogenase reductase on its binding to dinitrogenase was investigated. Dinitrogenase reductase from Clostridium pasteurianum (Cp2) was a substrate for the ADP-ribosyltransferase and the dinitrogenase-reductase-activating glycohydrolase from Rhodospirillum rubrum. ADP-ribosylation inactivated Cp2 and prevented its formation of a tight complex with dinitrogenase from Azotobacter vinelandii (Av1). The complex between Cp2 and Av1 could not be ADP-ribosylated once it formed.

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 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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