The flagellar motility of Chlamydomonas pf25 mutant lacking an AKAP-binding protein is overtly sensitive to medium conditions.
The flagellar motility of Chlamydomonas pf25 mutant lacking an AKAP-binding protein is overtly sensitive to medium conditions.
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DOI：
10.1091/mbc.e05-07-0630
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发表时间：
2005-11
影响因子：
3.3
通讯作者：
Chun Yang;Pinfen Yang
中科院分区：
文献类型：
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作者：
Chun Yang;Pinfen Yang
辐射辐条是一种保守的轴丝结构复合体，被认为通过磷酸酶和调节蛋白的网络调节9 + 2纤毛和鞭毛的运动。一致性蛋白，一种衣原体辐射辐条蛋白，RSP 3，已经通过RII重叠鉴定为A-激酶锚定蛋白（AKAP），其通过结合PKA RII亚基的RIIa结构域来定位cAMP依赖性蛋白激酶（PKA）全酶。然而，PKA的高度保守的对接结构域也被发现在N末端的几个AKAP结合蛋白PKA无关，以及一个24 kDa的新的辐条蛋白，RSP 11。在这里，我们报告说，RSP 11结合RSP 3直接在体外和共定位与RSP 3对轴丝外双联体和动力蛋白电机附近的辐条基地。重要的是，RSP 11突变体pf 25显示出一系列的运动性，从瘫痪与松弛或抽搐鞭毛作为其他发言突变体野生型一样游泳。广泛的运动性取决于液体介质的条件而可逆地改变，而不替换有缺陷的蛋白质。我们假设，径向辐条使用RIIa/AKAP模块来调节纤毛和鞭毛跳动;辐条RIIa蛋白的缺失暴露了在野生型衣原体中不明显的介质敏感的调节机制。
Radial spokes are a conserved axonemal structural complex postulated to regulate the motility of 9 + 2 cilia and flagella via a network of phosphoenzymes and regulatory proteins. Consistently, a Chlamydomonas radial spoke protein, RSP3, has been identified by RII overlays as an A-kinase anchoring protein (AKAP) that localizes the cAMP-dependent protein kinase (PKA) holoenzyme by binding to the RIIa domain of PKA RII subunit. However, the highly conserved docking domain of PKA is also found in the N termini of several AKAP-binding proteins unrelated to PKA as well as a 24-kDa novel spoke protein, RSP11. Here, we report that RSP11 binds to RSP3 directly in vitro and colocalizes with RSP3 toward the spoke base near outer doublets and dynein motors in axonemes. Importantly, RSP11 mutant pf25 displays a spectrum of motility, from paralysis with flaccid or twitching flagella as other spoke mutants to wildtype-like swimming. The wide range of motility changes reversibly depending on the condition of liquid media without replacing defective proteins. We postulate that radial spokes use the RIIa/AKAP module to regulate ciliary and flagellar beating; absence of the spoke RIIa protein exposes a medium-sensitive regulatory mechanism that is not obvious in wild-type Chlamydomonas.