Open AccessActivation by ATP of a proton‐conducting pathway in yeast mitochondria
Author(s) -
PRIETO Susana,
BOUILLAUD Frédéric,
RICQUIER Daniel,
RIAL Eduardo
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb17212.x
Subject(s) - chemiosmosis , mitochondrion , cytosol , saccharomyces cerevisiae , nad+ kinase , biochemistry , atp synthase , biophysics , uncoupling agents , chemistry , yeast , redox , cellular respiration , adenine nucleotide , microbiology and biotechnology , nucleotide , oxygen , biology , enzyme , organic chemistry , gene
The growth of Saccharomyces cerevisiae cells under aerobic conditions, in the presence of an energy‐rich source, leads to production of an excess of NAD(P)H. Since the redox balance must be maintained, it has been postulated that NAD(P)H reoxidation is accelerated by the activation of energy‐dissipating reactions, which would, in turn, explain the low growth efficiencies observed. It has been demonstrated already in S. cerevisiae cultures that these putative energy‐dissipating reactions are stimulated both by oxygen and high cytosolic ATP levels. In this paper, we show that ATP induces a proton‐permeability pathway in mitochondria at concentrations which are within the physiological range, as revealed both from the ATP stimulation of respiration and from the induction of H + ‐dependent swelling. We also demonstrate that phosphate acts as a competitive inhibitor of the nucleotide, and since activation is observed even in the presence of atractylate, we postulate that the ATP‐binding site is located in the outer face of the mitochondrial inner membrane.