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The cytoplasmically‐made subunit IV is necessary for assembly of cytochrome c oxidase in yeast.
Author(s) -
Dowhan W.,
Bibus C.R.,
Schatz G.
Publication year - 1985
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1985.tb02334.x
Subject(s) - cytochrome c oxidase , biology , protein subunit , biochemistry , mutant , cytochrome b , oxidase test , electron transport complex iv , cytochrome , heme , saccharomyces cerevisiae , mitochondrion , yeast , microbiology and biotechnology , gene , enzyme , mitochondrial dna
Yeast cytochrome c oxidase contains three large subunits made in mitochondria and at least six smaller subunits made in the cytoplasm. There is evidence that the catalytic centers (heme a and copper) are associated with the mitochondrially‐made subunits, but the role of the cytoplasmically‐made subunits has remained open. Using a gene interruption technique, we have now constructed a Saccharomyces cerevisiae mutant which lacks the largest of the cytoplasmically‐made subunits (subunit IV). This mutant is devoid of cyanide‐sensitive respiration, the absorption spectrum of cytochrome aa3 and cytochrome c oxidase activity. It still contains the other cytochrome c oxidase subunits but these are not assembled into a stable complex. Active cytochrome c oxidase was restored to the mutant by introducing a plasmid‐borne wild‐type subunit IV gene; no restoration was seen with a gene carrying an internal deletion corresponding to amino acid residues 28‐66 of the mature subunit. Subunit IV is thus necessary for proper assembly of cytochrome c oxidase.