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Respiration chain and ATP-synthesis system function as tightly-bounded supercomplex Biochimica et Biophysica Acta (BBAтезисы доклада
- Авторы: Byvshev I., Murugova T.N., Ivankov O.O., Vangeli I.M., Kuklin A.I., Yaguzhinskiy L.S.
- Сборник: Biochimica et Biophysica Acta (BBA) - Bioenergetics
- Серия: Supplement 2014 EBEC abstracts
- Том: 1837
- Тезисы
- Год издания: 2014
- Издательство: ELSEVIER SCIENCE BV
- Местоположение издательства: PO BOX 211, AMSTERDAM, NETHERLANDS, 1000 AE
- Первая страница: e25
- Последняя страница: e26
- DOI: 10.1016/j.bbabio.2014.05.292
- Аннотация: In the present work, it was shown that under conditions of lowamplitude swelling (the tonicity of incubation medium is 120 mOsm) of heart mitochondria, oxidizing succinate and producing ATP, enzymes of oxidative phosphorylation system operate as a tightly-bounded supercomplex. Firstly, the double-inhibitor titration technique showed that under low tonicity (120 mOsm) partial suppression of ATP synthesis by carboxyatractyloside (CATR) leads to proportional suppression of the electron transport system activity. So during the titration by malonate (the inhibitor of succinate oxidase) there is no excess pull of electron-transfer enzymes. Under isotonic conditions (300 mOsm), when no supercomplexes are formed, partial suppression of ATP synthesis by carboxyatractyloside (CATR) leads to the formation of excess pull of active electrontransfer enzymes; as a consequence, low concentrations of malonate do not lead to the reduction of the respiration rate. Secondly, the decrease of inner membrane potential of mitochondria due to suppression of electron transport system by malonate is much greater under hypertonic (600 mOsm) and isotonic (300 mOsm) conditions than under hypotonic conditions (120 mOsm). The suppression of the electron transport system of submitochondrial particles by 85% doesn't reduce the potential on its membranes. Thirdly, at the same conditions when the changes in mitochondrial functioning are observed we investigated the ultrastructure of rat heart mitochondria by means of electron microscopy and small angle neutron scattering (SANS). Both of these methods revealed structural reorganizations of cristae at decreasing media tonicity from 300 to 90–120 mOsm. Electron microscopy revealed that in the case of isotonic media inner mitochondrial membrane forms dense packed lamellae, in the case of low tonicity most of the lamellae are reorganized into tubular structures. These tubular cristae were observed to pack in hexagon-like structures. SANS showed that under isotonic conditions scattering curves have an interference peak Abstracts e25corresponding to the distance between the lamellae which centers around 220 Å. At swelling of heart mitochondria (90 mOsm) the ordering sharply decreases and the interference peak becomes negligible. Hereby it was proved that under conditions of lowamplitude swelling of heart mitochondria the enzymes of respiration system and ATP-synthesis system function as supercomplex and these functional changes are accompanied by the changes of inner mitochondrial membrane ultrastructure.
- Добавил в систему: Ягужинский Лев Сергеевич