Oligomeric C‐terminal truncated Bax preferentially releases cytochrome c but not adenylate kinase from mitochondria, outer membrane vesicles and proteoliposomes

FEBS Letters

Dymkowska, Dorota³  Vyssokikh, Mikhail¹  Brdiczka, Dieter¹  Antonsson, Bruno²  Wieęckowski, Mariusz R.³  Wojtczak, Lech³ 

[1] Department of Biology, University of Konstanz, D-78434 Konstanz, Germany;Serono Pharmaceutical Research Institute, 14 chemin des Aulx, CH-1228 Geneva, Switzerland;Nencki Institute of Experimental Biology, Pasteura 3, PL-02-093 Warsaw, Poland

关键词: Cytochrome c;    Adenylate kinase;    Bax;    Bcl-2;    Contact site;    Outer membrane;    Mitochondrion;    Apoptosis;    ANT;    adenine nucleotide translocase;    CCCP;    carbonyl cyanide m-chlorophenylhydrazone;   

DOI  :  10.1016/S0014-5793(01)02858-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The mechanism by which the proapoptotic protein Bax releases cytochrome c from mitochondria is not fully understood. The present work approaches this problem using C-terminal truncated oligomeric Bax (BaxΔC). Micromolar concentrations of BaxΔC released cytochrome c from isolated rat heart and liver mitochondria, while the release of adenylate kinase was not significantly affected. BaxΔC also released cytochrome c but not adenylate kinase from outer membrane vesicles filled with these proteins. However, BaxΔC was ineffective in releasing cytochrome c when outer membrane vesicles were obtained in the presence of glycerol, conditions under which the number of contact sites was drastically reduced. BaxΔC did not liberate encapsulated cytochrome c and adenylate kinase from pure phospholipid vesicles or vesicles reconstituted with porin. However, when the hexokinase–porin–adenine nucleotide translocase complex from brain mitochondria was reconstituted in vesicles, BaxΔC released internal cytochrome c but not adenylate kinase. In all these systems, only a small portion of total cytochrome c present in either mitochondria or vesicles could be liberated by BaxΔC. BaxΔC also increased the accessibility of external cytochrome c to either oxidation by complex IV or reduction by complex III in intact liver and heart mitochondria. Conclusions: (1) BaxΔC selectively releases cytochrome c and enables a bidirectional movement of cytochrome c across the outer mitochondrial membrane. (2) A multiprotein complex that resembles the mitochondrial contact sites is a prerequisite for BaxΔC action. (3) A limited pool of cytochrome c becomes the first target for BaxΔC.

【 授权许可】

Unknown