Characterization of TtALV2, an Essential Charged Repeat Motif Protein of the Tetrahymena thermophila Membrane Skeleton
Characterization of TtALV2, an Essential Charged Repeat Motif Protein of the Tetrahymena thermophila Membrane Skeleton
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DOI：
10.1128/ec.00050-13
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发表时间：
2013-06-01
期刊：
影响因子：
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通讯作者：
Gould, Sven B.
中科院分区：
文献类型：
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作者：
El-Haddad, Houda;Przyborski, Jude M.;Gould, Sven B.
肺泡蛋白是最近被描述的一类蛋白，它具有保守的带电重复序列(CRM)，但其确切功能尚不清楚。我们分析了嗜热四膜虫两种肺泡蛋白中较小的一种，TtALV2。蛋白质定位于排列在纵向微管排之间的分散的、破碎的斑块。Ttalv2的大核敲除导致没有明显细胞极性的多核细胞和随机发生的细胞突起，无论是通过中断细胞膜的完整性，还是通过干扰细胞质分裂。TtALV2与肺泡或膜的正确结合是复杂的，取决于蛋白质的末端和带电重复基序。含有类似CRM的蛋白质是纤毛膜细胞骨架的主要部分，这表明这些基序可能在介导膜附着和/或细胞骨架结合中发挥更一般的作用。为了更好地了解它们与细胞骨架的整合，我们定位了一系列基于CRM的融合蛋白，这表明具有CRM的蛋白质存在一种固有的趋势，即定位于外围细胞骨架，一些以丝状形式在基底上成核。即使是模仿这些蛋白质的电荷和重复模式的合成蛋白质，也会将报告蛋白质导向四膜虫的各种外围细胞骨架结构。这些基序可能为肺泡目的复合膜和细胞骨架的结合提供了一个蓝图。
Alveolins are a recently described class of proteins common to all members of the superphylum Alveolata that are characterized by conserved charged repeat motifs (CRMs) but whose exact function remains unknown. We have analyzed the smaller of the two alveolins of Tetrahymena thermophila, TtALV2. The protein localizes to dispersed, broken patches arranged between the rows of the longitudinal microtubules. Macronuclear knockdown of Ttalv2 leads to multinuclear cells with no apparent cell polarity and randomly occurring cell protrusions, either by interrupting pellicle integrity or by disturbing cytokinesis. Correct association of TtALV2 with the alveoli or the pellicle is complex and depends on both the termini as well as the charged repeat motifs of the protein. Proteins containing similar CRMs are a dominant part of the ciliate membrane cytoskeleton, suggesting that these motifs may play a more general role in mediating membrane attachment and/or cytoskeletal association. To better understand their integration into the cytoskeleton, we localized a range of CRM-based fusion proteins, which suggested there is an inherent tendency for proteins with CRMs to be located in the peripheral cytoskeleton, some nucleating as filaments at the basal bodies. Even a synthetic protein, mimicking the charge and repeat pattern of these proteins, directed a reporter protein to a variety of peripheral cytoskeletal structures in Tetrahymena. These motifs might provide a blueprint for membrane and cytoskeleton affiliation in the complex pellicles of Alveolata.