title: Mitochondria from Dipodascus (Endomyces) magnusii and Yarrowia lipolytica yeasts did not undergo a Ca²⁺-dependent permeability transition even under anaerobic conditions.
abstract: In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus (Endomyces) magnusii yeasts. The two yeast strains are good alternatives to Saccharomyces cerevisiae, being aerobes containing well structured mitochondria (thus ensuring less structural limitation to observe their appreciable swelling) and fully competent respiratory chain with three invariantly functioning energy conservation points, including Complex I, that can be involved in induction of the canonical Ca²⁺/P(i)-dependent mitochondrial permeability transition (mPTP pore) with an increased open probability when electron flux increases(Fontaine et al. J Biol Chem 273: 25734–25740, 1998; Bernardi et al. FEBS J 273:2077–2099, 2006). High amplitude swelling and collapse of the membrane potential were used as parameters for demonstrating pore opening. Previously (Kovaleva et al. J Bioenerg Biomembr 41:239–249, 2009; Kovaleva et al. Biochemistry (Moscow) 75: 297–303, 2010) we have shown that mitochondria from Y.lipolytica and D. magnusii were very resistant to the Ca²⁺overload combined with varying concentrations of P(i),palmitic acid, SH-reagents, carboxyatractyloside (an inhibitor of ADP/ATP translocator), as well as depletion of intramitochondrial adenine nucleotide pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high [P(i)]. Here we subjected yeast mitochondria to other conditions known to induce an mPTP in animal and plant mitochondria, namely to Ca²⁺ overload under hypoxic conditions (anaerobiosis). We were unable to observe Ca²⁺-induced high permeability of the inner membrane of D. magnusii and Y. lipolytica yeast mitochondria under anaerobic conditions, thus suggesting that an mPTP-like pore, if it ever occurs in yeast mitochondria, is not coupled with the Ca²⁺ uptake. The results provide the first demonstration of ATP-dependent energization of yeast mitochondria under conditions of anaerobiosis.
authors.affiliation: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, 119071 Moscow, Russia.
authors.forename: Tat'yana
authors.initials: T
authors.lastname: Trendeleva
authors.forename: Evgeniya
authors.initials: E
authors.lastname: Sukhanova
authors.forename: Ludmila
authors.initials: L
authors.lastname: Ural'skaya
authors.forename: Nils-Erik
authors.initials: NE
authors.lastname: Saris
authors.forename: Renata
authors.initials: R
authors.lastname: Zvyagilskaya
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000693:Anaerobiosis; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000502:physiology*; D055157:Dipodascus / Q000502:physiology*; D008564:Membrane Potentials; D008928:Mitochondria / Q000502:physiology*; D008933:Mitochondrial Swelling; D025062:Yarrowia / Q000502:physiology*
chemical_list: D000255:Adenosine Triphosphate; D002118:Calcium