清华大学方晓峰团队通过生物分子凝聚的细胞水势传感。2026年5月27日，国际知名学术期刊《自然》发表了这一成果。

在这里，小组鉴定了一种含有无菌α基序（SAM）的蛋白SAM8，它在体内和体外都经历水势依赖的冷凝，对高渗胁迫耐受性和种子萌发至关重要。课题组采用生物物理技术、体外重构和生物成像来证明SAM8在正常水条件下具有强水合性，从而防止其宏观凝结。带负电荷的贴片通过产生电场和微极性环境来决定SAM8的水合作用。缺水条件削弱了这种水合作用，从而通过重新编程氢键、静电和疏水相互作用激活SAM8缩合。

此外，该课题组研究人员证明了SAM8凝聚物选择性地隔离RNA输出因子，导致mRNA的核保留和高渗胁迫下的翻译重编程。他们的发现揭示了植物细胞直接感知和响应水分状态的机制，揭示了它们如何适应缺水条件。

研究人员表示，水分子作为生物分子的溶剂，对细胞是必不可少的。在缺水条件下，细胞的水势降低，但细胞如何感知水势的变化仍然未知。

附：英文原文

Title: Cellular water-potential sensing through biomolecular condensation

Author: Wang, Yunhe, Zhu, Longchen, Yang, Yun, Li, Xiaoshuang, Zhang, Xin, Fang, Xiaofeng

Issue&Volume: 2026-05-27

Abstract: Water molecules, as solvents for biomolecules, are essential to cells. The water potential of the cell decreases under water-deficient conditions1,2, yet how cells sense changes in water potential remains unknown. Here we identify a sterile alpha motif (SAM)-containing protein, SAM8, that undergoes water-potential-dependent condensation both in vivo and in vitro and is crucial for hyperosmotic stress tolerance and seed germination. We use biophysical techniques, in vitro reconstitution and bioimaging to demonstrate that SAM8 is strongly hydrated under normal water conditions, preventing its macroscopic condensation. A negatively charged patch determines SAM8 hydration by creating an electric field and micropolar environment. Water-deficient conditions weaken this hydration, thereby activating SAM8 condensation by reprogramming hydrogen bond, electrostatic and hydrophobic interactions. Furthermore, we demonstrate that SAM8 condensates selectively sequester RNA export factors, leading to nuclear retention of mRNAs and translational reprogramming under hyperosmotic stress. Our findings show a mechanism by which plant cells directly sense and respond to water status, shedding light on how they adapt to water deficit conditions.

DOI: 10.1038/s41586-026-10591-8

Source: https://www.nature.com/articles/s41586-026-10591-8