ADP-ribosylation of dinitrogenase reductase in Rhodobacter capsulatus
- Centre d'Etudes Nucleaires de Grenoble (France)
In the photosynthetic bacterium Rhodobacter capsulatus, nitrogenase is regulated by a reversible covalent modification of Fe protein or dinitrogenase reductase (Rc2). The linkage of the modifying group to inactive Rc2 was found to be sensitive to alkali and to neutral hydroxylamine. Complete release of the modifying group was achieved by incubation of inactive Rc2 in 0.4 or 1 M hydroxylamine. After hydroxylamine treatment of the Rc2 preparation, the modifying group could be isolated and purified by affinity chromatography and ion-exchange HPLC. The modifying group comigrated with ADP-ribose on both ion-exchange HPLC and thin-layer chromatography. Analyses by {sup 31}P NMR spectroscopy and mass spectrometry provided further evidence that the modifying group was ADP-ribose. The NMR spectrum of inactive Rc2 exhibited signals characteristic of ADP-ribose; integration of these signals allowed calculation of a molar ration ADP-ribose/Rc2 of 0.63. A hexapeptide carrying the ADP-ribose moiety was purified from a subtilisin digest of inactive Rc2. The structure of this peptide, determined by amino acid analysis and sequencing, is Gly-Arg(ADP-ribose)-Gly-Val-Ile-Thr. This structure allows identification of the binding site for ADP-ribose as Arg 101 of the polypeptide chain of Rc2. It is concluded that nitrogenase activity in R. capsulatus is regulated by reversible ADP-ribosylation of a specific arginyl residue of dinitrogenase reductase.
- OSTI ID:
- 5434462
- Journal Information:
- Biochemistry; (USA), Vol. 28:15; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NITROREDUCTASES
NUCLEAR MAGNETIC RESONANCE
PHOTOSYNTHETIC BACTERIA
ENZYME ACTIVITY
ADP
CHEMICAL REACTIONS
ION EXCHANGE CHROMATOGRAPHY
LIQUID COLUMN CHROMATOGRAPHY
PHOSPHORUS 31
PURIFICATION
RIBOSE
THIN-LAYER CHROMATOGRAPHY
ALDEHYDES
CARBOHYDRATES
CHROMATOGRAPHY
ENZYMES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MONOSACCHARIDES
NITRO-GROUP DEHYDROGENASES
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PENTOSES
PHOSPHORUS ISOTOPES
RESONANCE
SACCHARIDES
SEPARATION PROCESSES
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques