小柯机器人

英国剑桥大学Philip A. Wigge小组近日取得一项新成果。他们的最新研究发现在拟南芥中EARLY FLOWERING 3 (ELF3)的朊病毒样结构域可充当温度传感器。这一研究成果于2020年8月26日在线发表在《自然》上。

研究人员发现聚谷氨酰胺（polyQ）重复序列的长度与热响应性相关。研究显示，来自热带气候植物中的ELF3蛋白并不能检测到朊病毒结构域（PrD），其在高温下具有活性并且缺乏热响应性。 ELF3的温度敏感性也受ELF4水平的调节，表明ELF4可以稳定ELF3的功能。在拟南芥和异源系统中，在较高温度时，融合绿色荧光蛋白的ELF3以PrD依赖的方式在数分钟内形成斑点。ELF3的 PrD纯化片段响应体外温度升高可逆地形成液滴，这些特性反映了由PrD直接赋予的生物物理响应。温度诱导ELF3在活性和非活性状态之间快速相转换的能力代表了以前未知的热敏机制 。

据了解，温度控制着植物的生长和发育，而气候变化已经改变了野生植物和农作物的物候。但是，植物感知温度的机制尚不清楚。Evening复合物是植物节律的主要信号枢纽和核心组件。Evening复合体对温度反应性转录起抑制作用，通过未知的机制为生长提供节律和温度反应性。Evening复合体由ELF3、小α螺旋蛋白ELF4和LUX ARRYTHMO（LUX）组成，支架蛋白ELF3是温度感受器的关键组成部分；LUX是将Evening复合体招募到转录靶点所需的DNA结合蛋白。ELF3包含一个polyQ重复序列，其嵌入预测的PrD中。

附：英文原文

Title: A prion-like domain in ELF3 functions as a thermosensor in Arabidopsis

Author: Jae-Hoon Jung, Antonio D. Barbosa, Stephanie Hutin, Janet R. Kumita, Mingjun Gao, Dorothee Derwort, Catarina S. Silva, Xuelei Lai, Elodie Pierre, Feng Geng, Sol-Bi Kim, Sujeong Baek, Chloe Zubieta, Katja E. Jaeger, Philip A. Wigge

Issue&Volume: 2020-08-26

Abstract: Temperature controls plant growth and development, and climate change has already altered the phenology of wild plants and crops1. However, the mechanisms by which plants sense temperature are not well understood. The evening complex is a major signalling hub and a core component of the plant circadian clock2,3. The evening complex acts as a temperature-responsive transcriptional repressor, providing rhythmicity and temperature responsiveness to growth through unknown mechanisms2,4,5,6. The evening complex consists of EARLY FLOWERING 3 (ELF3)4,7, a large scaffold protein and key component of temperature sensing; ELF4, a small α-helical protein; and LUX ARRYTHMO (LUX), a DNA-binding protein required to recruit the evening complex to transcriptional targets. ELF3 contains a polyglutamine (polyQ) repeat8,9,10, embedded within a predicted prion domain (PrD). Here we find that the length of the polyQ repeat correlates with thermal responsiveness. We show that ELF3 proteins in plants from hotter climates, with no detectable PrD, are active at high temperatures, and lack thermal responsiveness. The temperature sensitivity of ELF3 is also modulated by the levels of ELF4, indicating that ELF4 can stabilize the function of ELF3. In both Arabidopsis and a heterologous system, ELF3 fused with green fluorescent protein forms speckles within minutes in response to higher temperatures, in a PrD-dependent manner. A purified fragment encompassing the ELF3 PrD reversibly forms liquid droplets in response to increasing temperatures in vitro, indicating that these properties reflect a direct biophysical response conferred by the PrD. The ability of temperature to rapidly shift ELF3 between active and inactive states via phase transition represents a previously unknown thermosensory mechanism.

DOI: 10.1038/s41586-020-2644-7

Source: https://www.nature.com/articles/s41586-020-2644-7

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