Institut de Biochimie et de Génétique Cellulaires, UMR5095, CNRS et Université de Bordeaux, CS61390, 1 Rue Camille Saint-Saëns, 33000 Bordeaux, France.
Institut des Biomolécules Max Mousseron, UMR 5247, CNRS, Université de Montpellier, ENSCM, et Université d'Avignon et des Pays de Vaucluse, BP 21239, 301 rue Baruch de Spinoza, 84916 Avignon cedex 9, France.
Biochim Biophys Acta Biomembr. 2017 Jun;1859(6):1144-1155. doi: 10.1016/j.bbamem.2017.03.010. Epub 2017 Mar 16.
Bax is a major player in the apoptotic process, being at the core of the mitochondria permeabilization events. In spite of the major recent advances in the knowledge of Bax organization within the membrane, the precise behavior of the C-terminal helix α9 remains elusive, since it was absent from the resolved structure of active Bax. The Proline 168 (P168) residue, located in the short loop between α8 and α9, has been the target of site-directed mutagenesis experiments, with conflicting results. We have produced and purified a recombinant mutant Bax-P168A, and we have compared its behavior with that of wild-type Bax in a series of tests on Large Unilamellar Vesicles (LUVs) and isolated mitochondria. We conclude that Bax-P168A had a greater ability to oligomerize and bind to membranes. Bax-P168A was not more efficient than wild-type Bax to permeabilize liposomes to small molecules but was more prone to release cytochrome c from mitochondria.
Bax 是细胞凋亡过程中的主要参与者，是线粒体通透化事件的核心。尽管最近在 Bax 在膜内的组织方面取得了重大进展，但 C 端螺旋α9 的精确行为仍然难以捉摸，因为它在活性 Bax 的解析结构中不存在。脯氨酸 168（P168）残基位于α8 和α9 之间的短环中，一直是定点诱变实验的目标，但结果存在冲突。我们已经产生并纯化了重组突变体 Bax-P168A，并在一系列针对大单层囊泡（LUV）和分离线粒体的测试中比较了其与野生型 Bax 的行为。我们得出的结论是，Bax-P168A 具有更强的寡聚化和与膜结合的能力。Bax-P168A 渗透小分子量脂质体的效率并不高于野生型 Bax，但更倾向于从线粒体中释放细胞色素 c。
