Characterisation of polyglutamylases in trypanosomatids
Characterisation of polyglutamylases in trypanosomatids
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DOI：
10.1016/j.ijpara.2014.09.005
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发表时间：
2015-02-01
影响因子：
4
通讯作者：
Bastien, Patrick
中科院分区：
文献类型：
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作者：
Casanova, Magali;de Monbrison, Frederique;Bastien, Patrick
微管会发生翻译后修饰，这被认为在复杂的基于微管的细胞器的功能中起着至关重要的作用。其中，多谷氨酰化是最近才发现的，它与中心体稳定性、轴丝维持和活动性以及神经突生长有关。在锥虫中，微管构成细胞骨架的重要组成部分的寄生原生动物，聚谷氨酰化微管的功能尚不清楚。在这里，为了更好地理解这种保守但高度分化的翻译后修饰的作用，我们对这些寄生虫中的谷氨酰化和推定的聚谷氨酰化酶进行了表征。我们发现微管在细胞周期的所有阶段（包括间期）都被强烈谷氨酰化。此外，沿着细胞前后轴观察到细胞周期依赖性谷氨酰化梯度，这可能与细胞周期期间微管“紧身衣”的活跃生长有关。我们还鉴定了两种推定的聚谷氨酰酶蛋白（此处分析的七种），它们在体外活性测定中似乎明显且直接参与微管聚谷氨酰化作用。矛盾的是，鉴于微管蛋白及其在这些生物体中广泛的谷氨酰化的重要性，所有这些蛋白质的基于RNA干扰的敲低对细胞生长没有影响，这表明要么是功能冗余，要么更可能是微妙的作用，例如功能调节或与蛋白质伙伴的相互作用。 (C) 2014 年澳大利亚寄生虫学协会。由 Elsevier Ltd 出版。保留所有权利。
Microtubules are subject to post-translational modifications, which are thought to have crucial roles in the function of complex microtubule-based organelles. Among these, polyglutamylation was relatively recently discovered, and was related to centrosome stability, axonemal maintenance and mobility, and neurite outgrowth. In trypanosomatids, parasitic protozoa where microtubules constitute the essential component of the cytoskeleton, the function of polyglutamylated microtubules is unknown. Here, in order to better understand the role of this conserved but highly divergent post-translational modification, we characterised glutamylation and putative polyglutamylases in these parasites. We showed that microtubules are intensely glutamylated in all stages of the cell cycle, including interphase. Moreover, a cell cycle-dependent gradient of glutamylation was observed along the cell anteroposterior axis, which might be related to active growth of the microtubule 'corset' during the cell cycle. We also identified two putative polyglutamylase proteins (among seven analysed here) which appeared to be clearly and directly involved in microtubule polyglutamylation in in vitro activity assays. Paradoxically, in view of the importance of tubulins and of their extensive glutamylation in these organisms, RNA interference-based knockdown of all these proteins had no effect on cell growth, suggesting either functional redundancy or, more likely, subtle roles such as function modulation or interaction with protein partners. (C) 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.