Open AccessModifications of oxidative phosphorylations in mitochondria isolated from a mutant of Saccharomyces cerevisiae
Author(s) -
MA Stephen,
GUERIN Martine
Publication year - 1988
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1988.tb13874.x
Subject(s) - mitochondrion , saccharomyces cerevisiae , mutant , oxidative phosphorylation , biochemistry , biology , mersalyl , inner membrane , phosphate , atp synthase , inner mitochondrial membrane , yeast , enzyme , gene
Mutants of Saccharomyces cerevisiae were isolated which supported two unlinked nuclear mutations conferring thermosensitivity and cold sensitivity respectively, and a mitochondrial one conferring paromomycin sensitivity. Mitochondria isolated from such a mutant exhibited modifications of several phosphate‐requiring functions: (a) kinetic parameters of the phosphate dependence of ATP synthesis were modified; (b) in the absence of phosphate the inner mitochondrial membrane exhibited a high proton leakage; (c) mutant mitochondria always exhibited a poor respiratory control and required tenfold more phosphate to reach a maximal state 3 of respiration; (d) phosphate transport, as measured by swelling experiments, was mersalyl‐insensitive and, consequently, state 3 of the respiration and ATP synthesis remained less mersalyl‐sensitive than in wild‐type mitochondria. Analysis of the mitochondrial metabolism of diploid and segregant strains indicates that these modifications are related to the cryosensitive phenotype; however, at present, a cooperative effect of the mitochondrial mutation cannot be eliminated. It is proposed that the phosphate carrier itself or a regulatory element was modified.