Torri A F, Hajduk S L
Department of Biochemistry, University of Alabama, Birmingham School of Medicine 35294.
Mol Cell Biol. 1988 Nov;8(11):4625-33. doi: 10.1128/mcb.8.11.4625-4633.1988.
We examined the expression of a nucleus-encoded mitochondrial protein, cytochrome c, during the life cycle of Trypanosoma brucei. The bloodstream forms of T. brucei, the long slender and short stumpy trypanosomes, have inactive mitochondria with no detectable cytochrome-mediated respiration. The insect form of T. brucei, the procyclic trypanosomes, has fully functional mitochondria. Cytochrome c is spectrally undetectable in the bloodstream forms of trypanosomes, but during differentiation to the procyclic form, spectrally detected holo-cytochrome c accumulates rapidly. We have purified T. brucei cytochrome c and raised antibodies that react to both holo- and apo-cytochrome c. In addition, we isolated a partial cDNA to trypanosome cytochrome c. An examination of protein expression and steady-state mRNA levels in T. brucei indicated that bloodstream trypanosomes did not express cytochrome c but maintained significant steady-state levels of cytochrome c mRNA. The results suggest that in T. brucei, cytochrome c is developmentally regulated by a posttranscriptional mechanism which prevents either translation or accumulation of cytochrome c in the bloodstream trypanosomes.
我们研究了布氏锥虫生命周期中一种细胞核编码的线粒体蛋白——细胞色素c的表达情况。布氏锥虫的血液内形式，即长形细锥虫和短粗锥虫，其线粒体不活跃，未检测到细胞色素介导的呼吸作用。布氏锥虫的昆虫形式，即前循环锥虫，具有功能完备的线粒体。在锥虫的血液内形式中无法通过光谱检测到细胞色素c，但在向前循环形式分化的过程中，可通过光谱检测到的全细胞色素c迅速积累。我们已纯化出布氏锥虫细胞色素c并制备了能与全细胞色素c和脱辅基细胞色素c发生反应的抗体。此外，我们分离出了锥虫细胞色素c的部分cDNA。对布氏锥虫中蛋白质表达和稳态mRNA水平的检测表明，血液内锥虫不表达细胞色素c，但维持着细胞色素c mRNA的显著稳态水平。结果表明，在布氏锥虫中，细胞色素c受转录后机制的发育调控，该机制可阻止细胞色素c在血液内锥虫中的翻译或积累。
