背景回顾：Light is a crucial exogenous signal sensed by cryptochrome (CRY) blue light receptors to modulate growth and the circadian clock in plants and animals. 

提出问题：However, how CRYs interpret light quantity to regulate growth in plants remains poorly understood. Furthermore, CRY2 protein levels and activity are tightly regulated in light to fine-tune hypocotyl growth; however, details of the mechanisms that explain precise control of CRY2 levels are not fully understood. 

主要发现：We show that in Arabidopsis, UBP12 and UBP13 deubiquitinases physically interact with CRY2 in light. 

结果1-UBP12/13负调控CRY2蛋白稳定性：UBP12/13 negatively regulates CRY2 by promoting its ubiquitination and turnover to modulate hypocotyl growth. Growth and development were explicitly affected in blue light when UBP12/13 were disrupted or overexpressed, indicating their role alongside CRY2. 

结果2-UBP12/13-COP1-CRY2：UBP12/13 also interacted with and stabilized COP1, which is partially required for CRY2 turnover. Our combined genetic and molecular data support a mechanistic model in which UBP12/13 interact with CRY2 and COP1, leading to the stabilization of COP1. Stabilized COP1 then promotes the ubiquitination and degradation of CRY2 under blue light. 

结论：Despite decades of studies on deubiquitinases, the knowledge of how their activity is regulated is limited. Our study provides insight into how exogenous signals and ligands, along with their receptors, regulate deubiquitinase activity by protein-protein interaction. Collectively, our results provide a framework of cryptochromes and deubiquitinases to detect and interpret light signals to control plant growth at the most appropriate time. 

 摘 要 

光对于生物来说是一种重要的外部信号，可以被隐花色素（CRY）蓝光受体感知，从而调节植物和动物的生长和生物钟。但是，CRYs是如何感知光量，从而调节植物生长的，目前仍知之甚少。此外，光照下CRY2蛋白水平和活性受到严格调控，以精细调控植物下胚轴的生长；然而，精细控制CRY2水平的分子机制还不清晰。本文中，作者发现拟南芥中的两个去泛素化酶UBP12和UBP13能够在光照下与CRY2发生物理互作。UBP12/13通过促进CRY2蛋白的泛素化和周转，负调控CRY2，从而调节下胚轴生长。在UBP12/13被扰乱或过表达时，植物在蓝光下的生长和发育明显受到影响，表明其与CRY2一起发挥作用。UBP12/13还会与COP1相互作用并稳定COP1蛋白，而COP1是CRY2周转所需的一个蛋白。进一步的遗传和分子数据支持一个机制模型，其中UBP12/13能够与CRY2和COP1相互作用，从而作用于COP1蛋白的稳定。接着，稳定的COP1蛋白在蓝光下促进CRY2蛋白的泛素化和降解。尽管对去泛素化酶的研究已经进行了数十载，但对其酶活性如何被调节这一问题的认识仍然有限。本文的研究深入地解析了外部信号和配体及其受体是如何通过蛋白-蛋白相互作用调节去泛素化酶活性的。总的来说，本文的研究结果提供了一个包含隐花色素和去泛素化酶的框架，用以感知和传递光信号，最终作用于植物最佳生长时间的控制。

 Ullas V. Pedmale