University of Heidelberg Biochemistry Center, 69120 Heidelberg, Germany.
Cell. 2010 Sep 3;142(5):762-72. doi: 10.1016/j.cell.2010.08.010.
Light responses and photoadaptation of Neurospora depend on the photosensory light-oxygen-voltage (LOV) domains of the circadian transcription factor White Collar Complex (WCC) and its negative regulator VIVID (VVD). We found that light triggers LOV-mediated dimerization of the WCC. The activated WCC induces expression of VVD, which then disrupts and inactivates the WCC homodimers by the competitive formation of WCC-VVD heterodimers, leading to photoadaptation. During the day, expression levels of VVD correlate with light intensity, allowing photoadaptation over several orders of magnitude. At night, previously synthesized VVD serves as a molecular memory of the brightness of the preceding day and suppresses responses to light cues of lower intensity. We show that VVD is essential to discriminate between day and night, even in naturally ambiguous photoperiods with moonlight.
光反应和光适应依赖于Neurospora 的感光光氧电压（LOV）域的生物钟转录因子白 collar 复合物（WCC）及其负调节剂 VIVID（VVD）。我们发现光触发 LOV 介导的 WCC 二聚化。激活的 WCC 诱导 VVD 的表达，然后通过 WCC-VVD 异二聚体的竞争性形成破坏和失活 WCC 同源二聚体，导致光适应。在白天，VVD 的表达水平与光强度相关，允许在几个数量级的范围内进行光适应。在夜间，先前合成的 VVD 作为前一天亮度的分子记忆，并抑制对低强度光提示的反应。我们表明，即使在具有月光的自然模糊光周期中，VVD 对于区分白天和黑夜也是必不可少的。
