Flagellar motility contributes to cytokinesis in Trypanosoma brucei and is modulated by an evolutionarily conserved dynein regulatory system
Flagellar motility contributes to cytokinesis in Trypanosoma brucei and is modulated by an evolutionarily conserved dynein regulatory system
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DOI：
10.1128/ec.5.4.696-711.2006
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发表时间：
2006-04-01
期刊：
影响因子：
--
通讯作者：
Hill, KL
中科院分区：
文献类型：
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作者：
Ralston, KS;Lerner, AG;Hill, KL
布氏锥虫的鞭毛是一种多功能细胞器，在锥虫生命周期的运动和其他方面发挥着关键作用。锥虫蛋白是一种细胞定向运动所需的鞭毛蛋白，但其分子功能尚不清楚。最近，据报道，莱茵衣藻中的胰蛋白酶同源物是动力蛋白调节复合物（DRC）的一部分，该复合物将调节信号从中央微管对和径向辐条传递到轴丝动力蛋白。 DRC 基因被鉴定为中央对和/或径向辐条突变的外源抑制因子。我们使用 RNA 干扰来单独或与胰蛋白酶组合消除径向辐条 (RSP3) 和中央对 (PF16) 成分的表达。 rsp3 和 pf16 单敲低突变体均不能运动，鞭毛节拍严重缺陷。在rsp3的情况下，这种运动性的丧失与径向辐条的丧失相关，而在pf16的情况下，运动性的丧失与轴丝内中央对微管的异常方向相关。胰蛋白酶和 PF16 之间的遗传相互作用通过以下发现得到证实：胰蛋白酶的缺失抑制了 pf16 节拍缺陷，表明 DRC 代表了一种进化上保守的动力蛋白调节策略。令人惊讶的是，我们发现四个鞭毛节拍受损的独立突变体在胞质分裂的最后阶段均失败，这表明鞭毛运动对于布氏锥虫的正常细胞分裂是必要的。这些发现首次证明鞭毛跳动对于细胞分裂很重要，并为利用驱动鞭毛跳动的酶活性作为治疗非洲昏睡病的药物靶标提供了机会。
The flagellum of Tiypanosoma brucei is a multifunctional organelle with critical roles in motility and other aspects of the trypanosome life cycle. Trypanin is a flagellar protein required for directional cell motility, but its molecular function is unknown. Recently, a trypanin homologue in Chlamydomonas reinhardtii was reported to be part of a dynein regulatory complex (DRC) that transmits regulatory signals from central pair microtubules and radial spokes to axonemal dynein. DRC genes were identified as extragenic suppressors of central pair and/or radial spoke mutations. We used RNA interference to ablate expression of radial spoke (RSP3) and central pair (PF16) components individually or in combination with trypanin. Both rsp3 and pf16 single knockdown mutants are immotile, with severely defective flagellar beat. In the case of rsp3, this loss of motility is correlated with the loss of radial spokes, while in the case of pf16 the loss of motility correlates with an aberrant orientation of the central pair microtubules within the axoneme. Genetic interaction between trypanin and PF16 is demonstrated by the finding that loss of trypanin suppresses the pf16 beat defect, indicating that the DRC represents an evolutionarily conserved strategy for dynein regulation. Surprisingly, we discovered that four independent mutants with an impaired flagellar beat all fail in the final stage of cytokinesis, indicating that flagellar motility is necessary for normal cell division in T. brucei. These findings present the first evidence that flagellar beating is important for cell division and open the opportunity to exploit enzymatic activities that drive flagellar beat as drug targets for the treatment of African sleeping sickness.