Replacement of putative axial ligands of heme iron in yeast cytochrome c sub(1) by site-directed mutagenesis

The His-44 and Met-164 residues of yeast cytochrome c sub(1) are evolutionally conserved and regarded as heme axial ligands bonding to the fifth and sixth coordination sites of the heme iron, which is directly involved in the electron transfer mechanism. Oligonucleotide-directed mutagenesis was used...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 1990-01, Vol.108 (5), p.798-803
Main Authors: Nakai, M, Ishiwatari, H, Asada, A, Bogaki, M, Kawai, K, Tanaka, Y, Matsubara, H
Format: Article
Language:English
Subjects:
Saccharomyces cerevisiae
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Summary:The His-44 and Met-164 residues of yeast cytochrome c sub(1) are evolutionally conserved and regarded as heme axial ligands bonding to the fifth and sixth coordination sites of the heme iron, which is directly involved in the electron transfer mechanism. Oligonucleotide-directed mutagenesis was used to generate mutant forms of cytochrome c sub(1) of yeast having amino acid replacements of the putative axial ligands of the heme iron. When a cytochrome c sub(1)-deficiency yeast strain was transformed with a gene encoding the Phe-44, Tyr-44, Leu-164, or Lys-164 protein, none of these transformants could grow on the nonfermentable carbon source. These results suggest that the His-44 and Met-164 residues have a critical role in the function of cytochrome c sub(1) in vivo, most probably as axial ligands of the heme iron.
ISSN:0021-924X