Département de sciences biologiques, Université de Montréal, Montréal, QC, Canada.
Department of Biology, Acadia University, Wolfville, NS, Canada.
Biol Lett. 2022 Jun;18(6):20220122. doi: 10.1098/rsbl.2022.0122. Epub 2022 Jun 8.
Cytochrome c oxidase subunit II (COX2) is one of the three mitochondrially encoded proteins of the complex IV of the respiratory chain that catalyses the reduction of oxygen to water. The gene spans about 690 base pairs in most animal species and produces a protein composed of approximately 230 amino acids. We discovered an extreme departure from this pattern in the male-transmitted mitogenome of the bivalve with doubly uniparental inheritance (DUI) of mitochondrial DNA (mtDNA), which possesses an important in-frame insertion of approximately 4.8 kb in its gene. This feature-an enlarged male gene-is found in many species with DUI; the COX2 protein can be up to 420 amino acids long. Through RT-PCRs, immunoassays and comparative genetics, the evolution and functionality of this insertion in were characterized. The in-frame insertion is conserved among individuals from different populations and bears the signature of purifying selection seemingly indicating maintenance of functionality. Its transcription and translation were confirmed: this gene produces a polypeptide of 1892 amino acids, making it the largest metazoan COX2 protein known to date. We hypothesize that these extreme modifications in the COX2 protein affect the metabolism of mitochondria containing the male-transmitted mtDNA in .
细胞色素 c 氧化酶亚基 II（COX2）是呼吸链复合物 IV 中线粒体编码的三种蛋白质之一，它催化氧气还原为水。该基因在大多数动物物种中跨越约 690 个碱基对，产生由大约 230 个氨基酸组成的蛋白质。我们在具有线粒体 DNA（mtDNA）双重单亲遗传（DUI）的双壳类雄性传递的线粒体基因组中发现了这种模式的极端偏离，其基因中存在约 4.8kb 的重要框内插入。这个特征——一个扩大的雄性基因——存在于许多具有 DUI 的物种中；COX2 蛋白可以长达 420 个氨基酸。通过 RT-PCR、免疫测定和比较遗传学，我们对 COX2 基因中的这种插入的进化和功能进行了表征。该框内插入在来自不同种群的个体中是保守的，并且带有纯化选择的特征，似乎表明其功能的维持。其转录和翻译得到了证实：该基因产生一个由 1892 个氨基酸组成的多肽，使其成为迄今为止已知的最大的后生动物 COX2 蛋白。我们假设 COX2 蛋白的这些极端修饰会影响含有雄性传递的 mtDNA 的线粒体的代谢。
