Environmentally Regulated Glycosome Protein Composition in the African Trypanosome
Environmentally Regulated Glycosome Protein Composition in the African Trypanosome
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DOI：
10.1128/ec.00086-13
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发表时间：
2013-08-01
期刊：
影响因子：
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通讯作者：
Morris, Meredith T.
中科院分区：
文献类型：
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作者：
Bauer, Sarah;Morris, James C.;Morris, Meredith T.
锥虫将糖体中的许多代谢酶分隔开来，糖体是与过氧化物体相关的微体，对寄生虫的生存至关重要。虽然人们了解到，这些动态细胞器在整个生命周期分化过程中蛋白质组成发生了深刻的变化，但对环境条件变化的适应却不太了解。我们在原环状布氏锥虫中采用了荧光细胞器报告系统，通过表达融合到糖体靶向序列(Peroxisome-靶向序列2[pts2])的荧光蛋白(FP)。在这些细胞系中，pts2-FP定位于具有进口功能的糖体中，细胞器组成可以通过显微镜和流式细胞仪进行分析。使用这个报告系统，我们已经表征了不同糖体组成的寄生虫种群。在富含葡萄糖的培养液中，观察到两个寄生虫种群；一个种群含有携带完整的糖体蛋白的糖体，而另一个寄生虫种群包含缺乏通常的糖体驻留蛋白但确实包含糖体膜蛋白TbPEX11的糖体。有趣的是，这些细胞缺乏TbPEX13，这是一种将蛋白质输入到糖体中所必需的蛋白质。这种双峰分布在低糖介质中消失。此外，我们还证明了环境条件的变化会引起糖体蛋白组成的变化。这些发现证明了到目前为止尚未被认识到的原环糖小体多样性的水平，并提供了一个在活细胞中研究糖小体动力学的系统。这项工作增加了我们对糖体组成的调节如何与环境感知相关的理解。
Trypanosomes compartmentalize many metabolic enzymes in glycosomes, peroxisome-related microbodies that are essential to parasite survival. While it is understood that these dynamic organelles undergo profound changes in protein composition throughout life cycle differentiation, the adaptations that occur in response to changes in environmental conditions are less appreciated. We have adopted a fluorescent-organelle reporter system in procyclic Trypanosoma brucei by expressing a fluorescent protein (FP) fused to a glycosomal targeting sequence (peroxisome-targeting sequence 2 [PTS2]). In these cell lines, PTS2-FP is localized within import-competent glycosomes, and organelle composition can be analyzed by microscopy and flow cytometry. Using this reporter system, we have characterized parasite populations that differ in their glycosome composition. In glucose-rich medium, two parasite populations are observed; one population harbors glycosomes bearing the full repertoire of glycosome proteins, while the other parasite population contains glycosomes that lack the usual glycosome-resident proteins but do contain the glycosome membrane protein TbPEX11. Interestingly, these cells lack TbPEX13, a protein essential for the import of proteins into the glycosome. This bimodal distribution is lost in low-glucose medium. Furthermore, we have demonstrated that changes in environmental conditions trigger changes in glycosome protein composition. These findings demonstrate a level of procyclic glycosome diversity heretofore unappreciated and offer a system by which glycosome dynamics can be studied in live cells. This work adds to our growing understanding of how the regulation of glycosome composition relates to environmental sensing.