Trypanosoma brucei is an important human pathogen. In this study, we have focused on the characterization of FtsH protease, ATP-dependent membrane-bound mitochondrial enzyme important for regulation of protein abundance. We have determined localization and orientation of all six putative T.brucei FtsH homologs in the inner mitochondrial membrane by in silico analyses, by immunofluorescence, and with protease assay. The evolutionary origin of these homologs has been tested by comparative phylogenetic analysis. Surprisingly, some kinetoplastid FtsH proteins display inverted orientation in the mitochondrial membrane compared to related proteins of other examined eukaryotes. Moreover, our data strongly suggest that during evolution the orientation of FtsH protease in T. brucei varied due to both loss and acquisition of the transmembrane domain.

布氏锥虫是一种重要的人类病原体。在这项研究中，我们集中于FtsH蛋白酶的表征，FtsH蛋白酶是ATP依赖的膜结合线粒体酶，对调节蛋白质丰度很重要。我们通过计算机分析，免疫荧光和蛋白酶测定，确定了线粒体内膜上所有六个推定的布鲁氏杆菌FtsH同源物的定位和方向。这些同源物的进化起源已通过比较系统发生分析进行了测试。出人意料的是，与其他检查的真核生物的相关蛋白相比，某些动素体FtsH蛋白在线粒体膜中显示了反向取向。此外，我们的数据强烈表明，在进化过程中，FtsH蛋白酶的方向布氏锥虫因跨膜结构域的丢失和获得而变化。