Amino acid sequence of a high redox potential ferredoxin (HiPIP) from the purple phototrophic bacterium Rhodopila globiformis, which has the highest known redox potential of its class.
Rhodopila globiformis HiPIP has a redox potential (ca. 450 mV) that is 100 mV higher than any other known iron-sulfur protein. The amino acid sequence contains 57 residues and can be aligned with that of Thiobacillus ferrooxidans without any insertions or deletions and is 51% identical. Rp. globiformis HiPIP is also similar to that of Rhodocyclus tenuis, but six- and two-residue gaps must be postulated and there is only 37% identity. Most of the amino acid residues near the iron-sulfur cluster are similar in these two species based on inspection of the three-dimensional structure of Rc. tenuis HiPIP. The reason for the higher redox potential may be a more hydrophilic environment of the Rp. globiformis HiPIP iron-sulfur cluster due to the above two deletions and to substitution of Ser 32 for Gly. Rp. globiformis is unusual in that it has a cytochrome c2 in addition to the HiPIP, and it too has a very high redox potential. These results suggest that the cytochrome c2 and HiPIP may function interchangeably and that the species normally resides in a very high potential environment, although it is not known to grow aerobically in the dark.
Ambler
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Institute of Cell and Molecular Biology, University of Edinburgh, Scotland.
Meyer
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Kamen
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D000595:Amino Acid Sequence; D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry*; D010450:Endopeptidases; D005288:Ferredoxins / Q000737:chemistry; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D045322:Photosynthetic Reaction Center Complex Proteins; D017386:Sequence Homology, Amino Acid; D013820:Thermolysin; D014357:Trypsin
D001426:Bacterial Proteins; D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D010446:Peptide Fragments; D045322:Photosynthetic Reaction Center Complex Proteins; C007943:high potential iron-sulfur protein; D010450:Endopeptidases; D014357:Trypsin; D013820:Thermolysin