Purification and partial characterization of a pyruvate oxidoreductase from the photosynthetic bacterium Rhodospirillum rubrum grown under nitrogen-fixing conditions

A pyruvate oxidoreductase with the capacity to support pyruvate-dependent nitrogenase activity in vitro has been purified from the photosynthetic bacterium Rhodospirillum rubrum. The enzyme requires CoA for activity and is irreversibly inactivated by oxygen. The molecular properties and Km values for the substrates have been studied. In supporting nitrogenase activity addition of ferredoxin is required. Overall the enzyme is similar to the nif-specific pyruvate: flavodoxin oxidoreductase purified from Klebsiella pneumoniae.

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Isolation and partial characterization of a cytochrome-o complex from chromatophores of the photosynthetic bacterium Rhodospirillum rubrum FR1

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1989.tb14778.x ◽

1989 ◽

Vol 181 (3) ◽

pp. 689-694 ◽

Cited By ~ 4

Author(s):

Andre S. SCHRATTENHOLZ ◽

Thomas NAWROTH ◽

Klaus DOSE

Keyword(s):

Rhodospirillum Rubrum ◽

Photosynthetic Bacterium ◽

Partial Characterization ◽

Cytochrome O

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Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales)

Canadian Journal of Microbiology ◽

10.1139/m80-180 ◽

1980 ◽

Vol 26 (9) ◽

pp. 1072-1089 ◽

Cited By ~ 75

Author(s):

Dwight Baker ◽

William Newcomb ◽

John G. Torrey

Keyword(s):

Host Range ◽

Nitrogenase Activity ◽

Root Nodules ◽

Host Cells ◽

Vesicle Formation ◽

Nitrogen Fixing ◽

Elaeagnus Umbellata

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

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

Journal of Bacteriology ◽

10.1128/jb.182.4.983-992.2000 ◽

2000 ◽

Vol 182 (4) ◽

pp. 983-992 ◽

Cited By ~ 49

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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