Rosato E, Codd V, Mazzotta G, Piccin A, Zordan M, Costa R, Kyriacou C P
Department of Biology, University of Leicester, University Road, LE1 7RH, Leicester, United Kingdom.
Curr Biol. 2001 Jun 26;11(12):909-17. doi: 10.1016/s0960-9822(01)00259-7.
The biological clock synchronizes the organism with the environment, responding to changes in light and temperature. Drosophila CRYPTOCHROME (CRY), a putative circadian photoreceptor, has previously been reported to interact with the clock protein TIMELESS (TIM) in a light-dependent manner. Although TIM dimerizes with PERIOD (PER), no association between CRY and PER has previously been revealed, and aspects of the light dependence of the TIM/CRY interaction are still unclear.
Behavioral analysis of double mutants of per and cry suggested a genetic interaction between the two loci. To investigate whether this was reflected in a physical interaction, we employed a yeast-two-hybrid system that revealed a dimerization between PER and CRY. This was further supported by a coimmunoprecipitation assay in tissue culture cells. We also show that the light-dependent nuclear interactions of PER and TIM with CRY require the C terminus of CRY and may involve a trans-acting repressor.
This study shows that, as in mammals, Drosophila CRY interacts with PER, and, as in plants, the C terminus of CRY is involved in mediating light responses. A model for the light dependence of CRY is discussed.
生物钟使生物体与环境同步，对光和温度的变化做出反应。果蝇隐花色素（CRY）是一种假定的昼夜节律光感受器，此前有报道称它以光依赖的方式与生物钟蛋白无时间性（TIM）相互作用。尽管TIM与周期蛋白（PER）形成二聚体，但此前尚未发现CRY与PER之间存在关联，并且TIM/CRY相互作用的光依赖性方面仍不清楚。
对per和cry双突变体的行为分析表明这两个基因座之间存在遗传相互作用。为了研究这是否反映在物理相互作用中，我们采用了酵母双杂交系统，该系统揭示了PER与CRY之间的二聚化。组织培养细胞中的免疫共沉淀试验进一步支持了这一点。我们还表明，PER和TIM与CRY的光依赖性核相互作用需要CRY的C末端，并且可能涉及一种反式作用阻遏物。
这项研究表明，与哺乳动物一样，果蝇CRY与PER相互作用，并且与植物一样，CRY的C末端参与介导光反应。讨论了CRY光依赖性的模型。
