Document Detail

Biochemical characterization of the OXI mutants of the yeast Saccharomyces cerevisiae.
MedLine Citation:
PMID:  6288115     Owner:  NLM     Status:  MEDLINE    
OXI mutants in Saccharomyces cerevisiae lack a functional cytochrome c oxidase. Wild type and OXI mutants were grown in the presence of radioactive delta-amino[14C]levulinic acid, a precursor of porphyrin and heme, and [3H]mevalonic acid, a precursor of the alkyl side-chain of heme a. SDS polyacrylamide gel electrophoresis of the delipidated mitochondria showed that delta-amino[14C]levulinic acid was distributed into three bands migrating in the regions of Mr 28 000, 13 500, and 10 000, while [3H]mevalonic acid was found in a single band with apparent Mr of 10 000. The immunoprecipitates obtained by incubating the solubilized mitochondria of any OXI mutant with antibodies against cytochrome c oxidase, showed, after delipidation, a high specific radioactivity due to delta-amino[14C]levulinic acid and [3H]mevalonic acid. This suggested that a prophyrin a was present in all these OXI mutants. HCl fractionation confirmed the presence of porphyrin a in the apooxidase of these mutants. Atomic absorption spectra of the immunoprecipitate of cytochrome c oxidase showed that copper was not detectable in the mutant OXI IIIa which lacked subunit 1, but was present in the mutant OXI IIIb, which exhibited a minor alteration in the electrophoretic mobility of subunit 1. In OXI I and II mutants there was a 50% reduction in the amount of copper in the immunoprecipitated cytochrome c oxidase. These observations may be interpretable as follows: (1) alterations in polypeptide biosynthesis due to the OXI mutations lead to an improper configuration of cytochrome c oxidase, so that ferrochelatase cannot transfer iron into porphyrin a; (2) subunit I is the binding site for copper, but the mutations in subunits II and III alter the binding site of one of the two copper atoms in subunit I.
E Keyhani; J Keyhani
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  717     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1982 Aug 
Date Detail:
Created Date:  1982-12-02     Completed Date:  1982-12-02     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  355-68     Citation Subset:  IM    
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MeSH Terms
Aminolevulinic Acid / metabolism
Copper / pharmacology
DNA, Mitochondrial / genetics
Electron Transport Complex IV / genetics*
Macromolecular Substances
Mitochondria / enzymology
Saccharomyces cerevisiae / drug effects,  enzymology,  genetics*
Spectrophotometry, Atomic
Grant Support
Reg. No./Substance:
0/DNA, Mitochondrial; 0/Macromolecular Substances; 106-60-5/Aminolevulinic Acid; 7440-50-8/Copper; EC Transport Complex IV

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