Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510, México, D.F, Mexico.
J Bioenerg Biomembr. 2017 Dec;49(6):453-461. doi: 10.1007/s10863-017-9728-6. Epub 2017 Oct 17.
Subunit II of cytochrome c oxidase (Cox2) is usually encoded in the mitochondrial genome, synthesized in the organelle, inserted co-translationally into the inner mitochondrial membrane, and assembled into the respiratory complex. In chlorophycean algae however, the cox2 gene was split into the cox2a and cox2b genes, and in some algal species like Chlamydomonas reinhardtii and Polytomella sp. both fragmented genes migrated to the nucleus. The corresponding Cox2A and Cox2B subunits are imported into mitochondria forming a heterodimeric Cox2 subunit. When comparing the sequences of chlorophycean Cox2A and Cox2B proteins with orthodox Cox2 subunits, a C-terminal extension in Cox2A and an N-terminal extension in Cox2B were identified. It was proposed that these extensions favor the Cox2A/Cox2B interaction. In vitro studies carried out in this work suggest that the removal of the Cox2B extension only partially affects binding of Cox2B to Cox2A. We conclude that this extension is dispensable, but when present it weakly reinforces the Cox2A/Cox2B interaction.
细胞色素 c 氧化酶亚基 II（Cox2）通常由线粒体基因组编码，在细胞器中合成，共翻译插入到线粒体内膜中，并组装到呼吸复合物中。然而，在绿藻中，cox2 基因被分裂成 cox2a 和 cox2b 基因，并且在一些藻类物种中，如莱茵衣藻和聚球藻属，这两个断裂的基因都迁移到了细胞核中。相应的 Cox2A 和 Cox2B 亚基被导入线粒体形成异二聚体 Cox2 亚基。当比较绿藻 Cox2A 和 Cox2B 蛋白与传统 Cox2 亚基的序列时，发现 Cox2A 中有 C 末端延伸，Cox2B 中有 N 末端延伸。有人提出，这些延伸有利于 Cox2A/Cox2B 相互作用。本工作进行的体外研究表明，去除 Cox2B 延伸部分仅部分影响 Cox2B 与 Cox2A 的结合。我们得出结论，这个延伸是可有可无的，但当存在时，它会微弱地加强 Cox2A/Cox2B 相互作用。
