Cryptochromes (CRYs) are a group of evolutionarily conserved flavoproteins found in many organisms. In plants, the well-studied CRY photoreceptor, activated by blue light, plays essential roles in plant growth and development. However, the mechanism of activation remains largely unknown. Here, we determined the oligomeric structures of the blue-light-perceiving PHR domain of Zea mays CRY1 and an Arabidopsis CRY2 constitutively active mutant. The structures form dimers and tetramers whose functional importance is examined in vitro and in vivo with Arabidopsis CRY2. Structure-based analysis suggests that blue light may be perceived by CRY to cause conformational changes, whose precise nature remains to be determined, leading to oligomerization that is essential for downstream signaling. This photoactivation mechanism may be widely used by plant CRYs. Our study reveals a molecular mechanism of plant CRY activation and also paves the way for design of CRY as a more efficient optical switch.

中文翻译：

---

植物隐花色素的寡聚结构。

隐花色素 (CRY) 是一组在许多生物体中发现的进化上保守的黄素蛋白。在植物中，经过充分研究的 CRY 光感受器被蓝光激活，在植物生长发育中起着至关重要的作用。然而，激活机制在很大程度上仍然未知。在这里，我们确定了玉米 CRY1 和拟南芥 CRY2 组成型活性突变体的蓝光感知 PHR 结构域的寡聚结构。这些结构形成二聚体和四聚体，其功能重要性通过拟南芥 CRY2 进行体外和体内检测。基于结构的分析表明，CRY 可能会感知蓝光以引起构象变化，其确切性质仍有待确定，从而导致对下游信号传导至关重要的寡聚化。这种光活化机制可能被植物 CRY 广泛使用。