1. The identification, purification, and characterization of CooJ. A nickel-binding protein that is co-regulated with the Ni-containing CO dehydrogenase from Rhodospirillum rubrum
- Author
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R K, Watt and P W, Ludden
- Subjects
Binding Sites ,Rhodospirillum rubrum ,Aldehyde Oxidoreductases ,Chromatography, Affinity ,Molecular Weight ,Kinetics ,Bacterial Proteins ,Species Specificity ,Multienzyme Complexes ,Nickel ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Chromatography, Gel ,Electrophoresis, Polyacrylamide Gel ,Carrier Proteins ,Gene Deletion - Abstract
CooJ, a nickel-binding protein from the CO dehydrogenase system of Rhodospirillum rubrum, was purified by immobilized metal affinity chromatography. CooJ is a CO-induced protein predicted to contain a nickel binding motif composed of 16 histidine residues in the final 34 amino acids of the 12.5-kDa protein. When cells grown in the presence of CO were fractionated on an immobilized metal affinity chromatography column and analyzed by SDS-polyacrylamide gel electrophoresis, the major protein observed in the effluent migrated at an apparent molecular mass of 19 kDa. The 19-kDa protein was absent in extracts of cells grown in the absence of CO and the mutant strain, UR294, which lacks a functional cooJ gene. N-terminal sequence analysis confirmed that the 19-kDa protein is the product of the cooJ gene. Purified CooJ was shown to bind four nickel atoms per CooJ monomer with a Kd of 4.3 microM. Other divalent metals competed with the following order of affinity and corresponding Ki: Zn2+ (5 microM)Cd2+ (19 microM)Co2+ (23 microM)Cu2+ (122 microM). CooJ chromatographed on a calibrated Superose 12 gel filtration column eluted at 39 kDa, a position consistent with a multimeric native molecular mass for CooJ.
- Published
- 1998