Amino Acid Replacement Studies of Human Cytochrome c by a Complementation System Using CYC1 Deficient Yeast

• Published in: Journal of biochemistry (Tokyo) 1988-09, Vol.104 (3), p.477-480
• Main Authors: Tanaka, Yoshikazu, Ashikari, Toshihiko, Shibano, Yuji, Amachi, Teruo, Yoshizumi, Hajime, Matsubara, Hiroshi
• Format: Article
• Language: English
• Subjects: amino acids; Amino Acids - analysis; Analytical, structural and metabolic biochemistry; Base Sequence; Biological and medical sciences; cytochrome c; Cytochrome c Group - genetics; DNA, Recombinant; Fundamental and applied biological sciences. Psychology; genes; Genetic Complementation Test; Hemoproteins; Humans; Metalloproteins; Molecular Sequence Data; Mutation; Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a122493

Various in vitro mutated human cytochrome c genes which encode displaced amino acid residues at the 14th, 17th, 28th, 37th, 38th, 56th, and/or 84th residues were constructed, and their degrees of complementation of yeast CYC1 deficiency were examined. Invariant Cys-17 and Arg-38 could not be replaced by alanine and tryptophan, respectively, without function impairment. Cytochromec containing Ala-14 instead of conserved Cys-14, Gly-38 or Lys-38 instead of Arg-38, and Ser-84 instead of invariant Gly-84 were partly functional. These results indicate that these invariant or conserved residues are important. Cytochromes c containing Cys-56 instead of native Gly-56 was partly functional. Cytochrome c containing Arg-37 and Gly-38 instead of Gly.-37 and Arg-38 was slightly functional. Replacement of variable Thr-28 and Gly-37 by Ile-28 and Arg-37, respectively, produced no effects. Our results are as a whole consistent with the view that conserved residues are important and variable residues are less important for cytochrome c to function.