Maslov Dmitri A, Zíková Alena, Kyselová Iveta, Lukes Julius
Department of Biology, University of California, Riverside, CA 92521, USA.
Mol Biochem Parasitol. 2002 Nov-Dec;125(1-2):113-25. doi: 10.1016/s0166-6851(02)00235-9.
A relatively large nuclear-encoded polypeptide, designated trCOIV, is found in the cytochrome c oxidase (CO) complex of trypanosomatids. In order to determine if this polypeptide represents a bona fide subunit of the complex, we have characterized the cDNA and the gene for this polypeptide in Leishmania tarentolae. Its nuclear gene has no sequence similarity to mammalian COIV. The trCOIV preprotein has a long mitochondrial targeting sequence of 31 residues. The mature polypeptide cofractionates with kinetoplast-mitochondria and its preferential mitochondrial localization was confirmed by immunofluorescence and immunoelectron microscopy. Based on the hydropathy plot analysis, the protein lacks pronounced transmembrane domains and likely occupies a peripheral position within the CO complex. The corresponding genes are also present in the sequenced portions of the Trypanosoma cruzi, Trypanosoma brucei and Leishmania major genomes, and the same polypeptide is found in cytochrome oxidase isolated from procyclic T. brucei and promastigote Leishmania mexicana amazonensis. However, the trCOIV gene, the mRNA and the polypeptide could not be detected in a respiration-deficient trypanosomatid Phytomonas serpens.
在锥虫的细胞色素c氧化酶（CO）复合物中发现了一种相对较大的核编码多肽，命名为trCOIV。为了确定该多肽是否代表该复合物的一个真正亚基，我们对大利什曼原虫中该多肽的cDNA和基因进行了表征。其核基因与哺乳动物的COIV没有序列相似性。trCOIV前体蛋白有一个由31个残基组成的长线粒体靶向序列。成熟多肽与动质体-线粒体共分离，免疫荧光和免疫电子显微镜证实了其优先的线粒体定位。基于亲水性图谱分析，该蛋白缺乏明显的跨膜结构域，可能位于CO复合物的外围位置。相应的基因也存在于克氏锥虫、布氏锥虫和硕大利什曼原虫基因组的已测序部分，并且在从布氏锥虫前循环体和亚马逊利什曼原虫前鞭毛体中分离的细胞色素氧化酶中发现了相同的多肽。然而，在呼吸缺陷型锥虫——蛇形植鞭毛虫中未检测到trCOIV基因、mRNA和多肽。
