Analysis of clock genes and proteins in Chlamydomonas: a new model system for studies on the circadian clock.

本研究以单细胞绿色藻类莱茵衣藻（Chlamydiumreinhardtii）为研究对象，分析了其生物钟基因和蛋白质的表达。我们通过ROC75基因的过表达和RNA干扰实验，揭示了ROC75和ROC40之间的遗传互作。此外，我们在衣原体中表达了带有HA、YFP和LUC标签的ROC75蛋白，并揭示了ROC75蛋白水平受昼夜节律钟的调节，并且定位于核周边。在体外和体内试验中，我们证明了ROC75结合到ROC40基因的启动子区。这些结果表明，ROC75是ROC40基因的转录调控因子，这种调控可能在衣原体的生物钟机制中起重要作用。这些发现将为绿色植物谱系的生物钟进化提供新的见解。

We analyzed clock genes and proteins in the unicellular green algae Chlamydomonas reinhardtii that is a new model system for circadian clock research. We revealed a genetic interaction between ROC75 and ROC40 through experiments of overexpression and RNA interference of ROC75 gene. Moreover, We expressed ROC75 protein tagged with HA, YFP, and LUC in Chlamydomonas, and revealed that the ROC75 protein level is regulated by the circadian clock, and is localized into the nuclear periphery. In an in vitro and in vivo assay, we demonstrated that ROC75 binds to the promoter region of the ROC40 gene. These results suggest that ROC75 is a transcriptional regulator for ROC40 gene, and the regulation may be important for the circadian clock mechanism in Chlamydomonas. These findings will provide new insights into the evolution of circadian clocks in the green plant lineage.