Phototropin Influence on Eyespot Development and Regulation of Phototactic Behavior in Chlamydomonas reinhardtii[W]
Phototropin Influence on Eyespot Development and Regulation of Phototactic Behavior in Chlamydomonas reinhardtii[W]
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DOI：
10.1105/tpc.112.103523
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发表时间：
2012-11
期刊：
影响因子：
11.6
通讯作者：
Jessica Trippens;André Greiner;Jana Schellwat;M. Neukam;Theresa Rottmann;Yinghong Lu;S. Kateriya;P. Hegemann;G. Kreimer
中科院分区：
文献类型：
--
作者：
Jessica Trippens;André Greiner;Jana Schellwat;M. Neukam;Theresa Rottmann;Yinghong Lu;S. Kateriya;P. Hegemann;G. Kreimer
这项研究表明，眼斑是一个动态的细胞器，蓝光感光细胞的phototropin参与调节眼斑的大小和通道视紫红质1，这是光运动反应的初级感光细胞的水平。这项工作还描述了，除了C-末端激酶结构域，N-末端光感受器结构域具有独立的信号传导功能。莱茵衣藻的眼点是一种对光敏感的细胞器，对衣藻的趋光定向具有重要作用。在这里，我们发现眼点大小是菌株特异性的，并且在光照下下调。通过同源重组删除蓝光感受器趋光蛋白的菌株，其眼点大小的光调节受到影响。我们恢复了这种功能障碍，在不同的phototropin互补实验。互补与phototropin激酶片段减少了眼斑的大小，独立于光。有趣的是，N-末端光、氧或电压传感结构域（LOV 1 + LOV 2）单独过表达也影响眼点大小和趋光性，这表明除了激酶结构域的激活之外，它们在细胞中实现独立的信号传导功能。此外，趋光蛋白参与调节视紫红质通道蛋白-1的水平，视紫红质通道蛋白-1是眼斑内趋光性的主要受体。光照开始时的通道视紫红质-1水平及其在光照期间的稳态水平均被趋光素下调，而通道视紫红质-2的水平没有显着改变。此外，光强度依赖的C-末端截短的光致蛋白形式的形成进行了观察。我们认为，向光素是一种趋光性的光调节剂，当蓝光强度增加时，它会使眼点脱敏。
This study shows that an eyespot is a dynamic organelle and that the blue light photoreceptor phototropin is involved in the regulation of eyespot size and level of channelrhodopsin 1, which is the primary photoreceptor for photo-movement responses. This work also describes that, in addition to the C-terminal kinase domain, the N-terminal photoreceptor domains have independent signaling functions. The eyespot of Chlamydomonas reinhardtii is a light-sensitive organelle important for phototactic orientation of the alga. Here, we found that eyespot size is strain specific and downregulated in light. In a strain in which the blue light photoreceptor phototropin was deleted by homologous recombination, the light regulation of the eyespot size was affected. We restored this dysfunction in different phototropin complementation experiments. Complementation with the phototropin kinase fragment reduced the eyespot size, independent of light. Interestingly, overexpression of the N-terminal light, oxygen or voltage sensing domains (LOV1+LOV2) alone also affected eyespot size and phototaxis, suggesting that aside from activation of the kinase domain, they fulfill an independent signaling function in the cell. Moreover, phototropin is involved in adjusting the level of channelrhodopsin-1, the dominant primary receptor for phototaxis within the eyespot. Both the level of channelrhodopsin-1 at the onset of illumination and its steady state level during the light period are downregulated by phototropin, whereas the level of channelrhodopsin-2 is not significantly altered. Furthermore, a light intensity–dependent formation of a C-terminal truncated phototropin form was observed. We propose that phototropin is a light regulator of phototaxis that desensitizes the eyespot when blue light intensities increase.