Biology Centre, Institute of Parasitology, Czech Academy of Sciences, and Faculty of Biology, University of South Bohemia, 37005 Ceské Budejovice (Budweis), Czech Republic.
Int J Parasitol. 2010 Jan;40(1):45-54. doi: 10.1016/j.ijpara.2009.07.005. Epub 2009 Aug 3.
Throughout eukaryotes, the gene encoding subunit 6 (ATP6) of the F(1)F(O)-ATP synthase (complex V) is maintained in mitochondrial (mt) genomes, presumably because of its high hydrophobicity due to its incorporation into the membrane-bound F(O) moiety. In Trypanosoma species, a mt transcript that undergoes extensive processing by RNA editing has a very low sequence similarity to ATP6 from other organisms. The notion that the putative ATP6 subunit is assembled into the F(O) sub-complex is ostensibly challenged by the existence of naturally occurring dyskinetoplastic (Dk) and akinetoplastid (Ak) trypanosomes, which are viable despite lacking the mtDNA required for its expression. Taking advantage of the different phenotypes between RNA interference knock-down cell lines in which the expression of proteins involved in mtRNA metabolism and editing can be silenced, we provide support for the view that ATP6 is encoded in the mt genome of Trypanosoma species and that it is incorporated into complex V. The reduction of the F(1)F(O) oligomer of complex V coincides with the accumulation of the F(1) moiety in ATP6-lacking cells, which also appear to lack the F(O) ATP9 multimeric ring. The oligomycin sensitivity of ATPase activity of complex V in ATP6-lacking cells is reduced, reflecting the insensitivity of the Dk and Ak cells to this drug. In addition, the F(1) moiety of complex V appears to exist as a dimer in steady state conditions and contains the ATP4 subunit traditionally assigned to the F(O) sub-complex.
在真核生物中，F(1)F(O)-ATP 合酶（复合物 V）的亚基 6（ATP6）的编码基因（ATP6）保存在线粒体（mt）基因组中，这可能是由于其高度疏水性，因为它整合到膜结合的 F(O) 部分中。在锥虫属物种中，经历广泛 RNA 编辑加工的 mt 转录本与其他生物体的 ATP6 具有非常低的序列相似性。假设假定的 ATP6 亚基组装到 F(O)亚复合物中，这显然受到自然发生的运动障碍（Dk）和无鞭毛原虫（Ak）锥虫的存在的挑战，尽管缺乏其表达所需的 mtDNA，但这些锥虫是可行的。利用涉及 mtRNA 代谢和编辑的蛋白质表达可以沉默的 RNA 干扰敲低细胞系之间的不同表型，我们为以下观点提供了支持：即 ATP6 编码在锥虫属物种的 mt 基因组中，并且它被整合到复合物 V 中。复合物 V 的 F(1)F(O) 寡聚体的减少与缺乏 ATP6 的细胞中 F(1)部分的积累相吻合，这些细胞似乎也缺乏 F(O)ATP9 多聚体环。缺乏 ATP6 的细胞中复合物 V 的寡霉素敏感性 ATP 酶活性降低，反映了 Dk 和 Ak 细胞对这种药物的不敏感性。此外，复合物 V 的 F(1)部分在稳态条件下似乎作为二聚体存在，并且包含传统分配给 F(O)亚复合物的 ATP4 亚基。
