Pan Yifei, Lei Junlin, Mou Shiqi, Wu Zhili, Zhu Longchen, Zeng Liyao, Luo Feng, Ding Yaping, Liu Yu, Zhang Xin
Department of Chemistry and Research Center for Industries of the Future and Westlake University, Zhejiang Key Laboratory of Precise Synthesis of Functional Molecules, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China.
State Key Laboratory of Medical Proteomics, National Chromatographic R. & A. Center, CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
J Am Chem Soc. 2025 Jul 2;147(26):22686-22696. doi: 10.1021/jacs.5c04180. Epub 2025 Jun 15.
Biomolecular condensates exhibit distinct microenvironments that arise from interactions between proteins, RNA, and solutions. In aqueous solutions, these membraneless structures constantly encounter small molecules that could affect the structure and properties of the condensates. However, the effects of organic small molecules in water solutions on the microenvironments of condensates remain poorly understood. In this study, we used various organic solutes as an example to explore how small molecules could influence the physicochemical properties in the microenvironment of protein condensates. Particularly, we quantitatively studied micropolarity and microviscosity using a combination of techniques, including fluorescence lifetime imaging microscopy, fluorescence recovery after photobleaching, and passive rheology. Unexpectedly, our results revealed that the microenvironment was not correlated with the polarity of organic solutes; instead, the correlation was observed on the interaction strength between water and small molecules. We found that solutes with stronger interaction with water and weaker interaction with proteins increase the micropolarity and decrease the microviscosity of condensates. Furthermore, we demonstrated that the modulation of the micropolarity of condensates could impact the miscibility of multicomponent condensates. Finally, we showed that organic solutes could influence the micropolarity of condensates and the partitioning of products in condensates, thus affecting the rate and equilibrium of the chemical reactions. In summary, our work provides a quantitative analysis of how the microenvironment of biomolecular condensates is impacted by organic solutes. Since protein condensates coexist with various types of metabolites in the aqueous cellular milieu, results from this work offer insights into how organic metabolites could regulate the microenvironment and behaviors of biological condensates.
生物分子凝聚物展现出由蛋白质、RNA和溶液之间的相互作用产生的独特微环境。在水溶液中，这些无膜结构不断接触可能影响凝聚物结构和性质的小分子。然而，水溶液中的有机小分子对凝聚物微环境的影响仍知之甚少。在本研究中，我们以各种有机溶质为例，探讨小分子如何影响蛋白质凝聚物微环境中的物理化学性质。特别地，我们结合荧光寿命成像显微镜、光漂白后荧光恢复和被动流变学等技术，定量研究了微极性和微粘度。出乎意料的是，我们的结果表明微环境与有机溶质的极性无关；相反，观察到的相关性存在于水和小分子之间的相互作用强度上。我们发现与水相互作用较强且与蛋白质相互作用较弱的溶质会增加凝聚物的微极性并降低其微粘度。此外，我们证明了凝聚物微极性的调节会影响多组分凝聚物的混溶性。最后，我们表明有机溶质可以影响凝聚物的微极性以及产物在凝聚物中的分配，从而影响化学反应的速率和平衡。总之，我们的工作提供了对生物分子凝聚物微环境如何受到有机溶质影响的定量分析。由于蛋白质凝聚物在水性细胞环境中与各种类型的代谢物共存，这项工作的结果为有机代谢物如何调节生物凝聚物的微环境和行为提供了见解。
