Roucou X, Manon S, Guérin M
Institut de Biochimie et de Génétique Cellulaires du Centre National de la Recherche Scientifique, Université de Bordeaux II, France.
Biochim Biophys Acta. 1997 Feb 21;1324(1):120-32. doi: 10.1016/s0005-2736(96)00215-5.
The effect of ATP and other nucleotides on the respiration of Saccharomyces cerevisiae mitochondria was investigated. It was observed that ATP induced a stimulation of the respiration rate only in the presence of a salt in mitochondria from the baker's yeast Yeast Foam, whereas an ATP-induced stimulation occurred even in the absence of salt in mitochondria from three different laboratory strains. In both cases, the stimulation was related to a collapse of the transmembrane potential, suggesting the opening of ion- and/or proton-conducting pathways. Not only ATP, but also GTP and CTP, induced these pathways. Moreover, a similar stimulation was obtained with GDP and its analog GDP-beta-S. The fact that, as opposed to NTPs, GDP did not induce any non-specific anion channel, allowed us to use it to demonstrate unambiguously that a proton-conducting pathway was opened through the inner mitochondrial membrane of laboratory strains but not of Yeast Foam. Three additional aspects of this nucleotide-induced permeability were investigated. (i) The proton-conducting pathway was insensitive to Mg2+, whereas the anion-conducting pathway was fully inhibited by 4 mM Mg2-. (ii) The proton-conducting pathway of mitochondria isolated from laboratory strains was opened by the action of nucleotides outside the mitochondrion, since it was fully insensitive to (carboxy)atractyloside, and fully active in mitochondria isolated from op1 and delta anc strains. On the other hand, the cation-conducting pathway of Yeast Foam mitochondria was partly sensitive to (carboxy)atractyloside and insensitive to bongkrekic acid, suggesting a role of the conformational state of ANC in this activity. (iii) Both the proton and cation-conducting pathways were inhibited by very low concentrations of vanadate, under conditions where this oxyanion was polymerized to decavanadate: a competitor to nucleotide-binding sites on some enzymes.
研究了ATP和其他核苷酸对酿酒酵母线粒体呼吸作用的影响。观察到，只有在来自面包酵母酵母泡沫的线粒体中存在盐的情况下，ATP才会诱导呼吸速率的刺激，而在来自三种不同实验室菌株的线粒体中，即使不存在盐，ATP诱导的刺激也会发生。在这两种情况下，刺激都与跨膜电位的崩溃有关，表明离子和/或质子传导途径的开放。不仅ATP，而且GTP和CTP也能诱导这些途径。此外，GDP及其类似物GDP-β-S也能产生类似的刺激。与NTPs不同，GDP不会诱导任何非特异性阴离子通道，这一事实使我们能够明确证明，质子传导途径是通过实验室菌株的线粒体内膜打开的，而不是酵母泡沫的线粒体内膜。研究了这种核苷酸诱导的通透性的另外三个方面。(i)质子传导途径对Mg2+不敏感，而阴离子传导途径被4 mM Mg2-完全抑制。(ii)从实验室菌株分离的线粒体的质子传导途径是由线粒体外的核苷酸作用打开的，因为它对(羧基)苍术苷完全不敏感，并且在从op1和δ anc菌株分离的线粒体中完全活跃。另一方面，酵母泡沫线粒体的阳离子传导途径对(羧基)苍术苷部分敏感，对 Bongkrekic 酸不敏感，这表明ANC的构象状态在这种活性中起作用。(iii)在钒酸盐聚合成十钒酸盐的条件下，极低浓度的钒酸盐就能抑制质子和阳离子传导途径：十钒酸盐是某些酶上核苷酸结合位点的竞争者。
