Tittawella Ivor, Yasmin Lubna, Baranov Vladimir
Department of Molecular Biology, University of Umeå, Umeå S-901 87, Sweden.
Biochem Biophys Res Commun. 2003 Aug 1;307(3):578-83. doi: 10.1016/s0006-291x(03)01218-x.
The nature, and even the existence, of trypanosome mitochondrial ribosomes has been the subject of some debate. We investigated this further in the insect trypanosome, Crithidia fasciculata. In sucrose gradients of parasite lysates, mitochondrial ribosomal RNA co-sediments at approximately 35S with nascent peptides synthesized in the presence of the cytosolic translational inhibitor, cycloheximide. Co-sedimenting peptides in this peak are much reduced when the parasites are treated with the bacterial translational inhibitor, chloramphenicol. In CsCl gradients this peak resolves at a buoyant density of 1.42 g/cm(3), a value typical for mito-ribosomes. Electron microscopy of peak material shows particles smaller than cytosolic ribosomes, but with characteristic ribosomal shapes. We propose that these particles represent the parasite's mitochondrial ribosomes.
锥虫线粒体核糖体的性质乃至其存在与否一直存在一些争议。我们在昆虫锥虫——fasiculata克氏锥虫中对此进行了进一步研究。在寄生虫裂解物的蔗糖梯度中，线粒体核糖体RNA与在胞质翻译抑制剂环己酰亚胺存在下合成的新生肽一起在约35S处共同沉降。当用细菌翻译抑制剂氯霉素处理寄生虫时，该峰中共同沉降的肽会大大减少。在CsCl梯度中，该峰在1.42 g/cm³的浮力密度下解析，这是线粒体核糖体的典型值。对峰物质的电子显微镜观察显示颗粒比胞质核糖体小，但具有特征性的核糖体形状。我们认为这些颗粒代表寄生虫的线粒体核糖体。
