Biogenesis of a Mitochondrial Outer Membrane Protein in Trypanosoma brucei: TARGETING SIGNAL AND DEPENDENCE ON A UNIQUE BIOGENESIS FACTOR
Biogenesis of a Mitochondrial Outer Membrane Protein in Trypanosoma brucei: TARGETING SIGNAL AND DEPENDENCE ON A UNIQUE BIOGENESIS FACTOR
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DOI：
10.1074/jbc.m116.755983
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发表时间：
2017-02-24
影响因子：
4.8
通讯作者：
Schneider, Andre
中科院分区：
文献类型：
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作者：
Bruggisser, Julia;Kaser, Sandro;Schneider, Andre
线粒体外膜（OM）包含单个和多个跨膜蛋白，这些蛋白需要包含确保正确靶向和插入OM的信号。到目前为止，这些蛋白质的生物发生基本上只在酵母和相关生物中进行了研究。在这里，我们表明，POMP 10，OM蛋白的早期分歧原生动物布氏锥虫，是信号锚定的。表达与GFP融合的POMP 10变体的转基因细胞表明，两侧有几个带正电荷或中性残基的N-末端跨膜结构域对于线粒体靶向是必要的和足够的。碳酸盐萃取实验表明，虽然中性而不是带正电荷的残基的存在下不干扰POMP 10的本地化，它削弱了其与OM的相互作用。GFP标记的POMP 10在可诱导RNAi细胞系中的表达表明，其线粒体定位依赖于pATOM 36，但不需要Sam 50或ATOM 40，即Tom 40输入孔的锥虫类似物。pATOM 36是一种动质体特异性OM蛋白，先前已涉及OM蛋白的组装和线粒体DNA遗传。总之，我们的研究结果表明，虽然信号锚定蛋白中的靶向信号的特征是广泛保守的，但介导其生物合成的蛋白质机制不是。
The mitochondrial outer membrane (OM) contains single and multiple membrane-spanning proteins that need to contain signals that ensure correct targeting and insertion into the OM. The biogenesis of such proteins has so far essentially only been studied in yeast and related organisms. Here we show that POMP10, an OM protein of the early diverging protozoan Trypanosoma brucei, is signal-anchored. Transgenic cells expressing variants of POMP10 fused to GFP demonstrate that the N-terminal membrane-spanning domain flanked by a few positively charged or neutral residues is both necessary and sufficient for mitochondrial targeting. Carbonate extraction experiments indicate that although the presence of neutral instead of positively charged residues did not interfere with POMP10 localization, it weakened its interaction with the OM. Expression of GFP-tagged POMP10 in inducible RNAi cell lines shows that its mitochondrial localization depends on pATOM36 but does not require Sam50 or ATOM40, the trypanosomal analogue of the Tom40 import pore. pATOM36 is a kinetoplastid-specific OM protein that has previously been implicated in the assembly of OM proteins and in mitochondrial DNA inheritance. In summary, our results show that although the features of the targeting signal in signal-anchored proteins are widely conserved, the protein machinery that mediates their biogenesis is not.