Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, United States.
J Am Chem Soc. 2023 Aug 9;145(31):17143-17150. doi: 10.1021/jacs.3c03812. Epub 2023 Jul 26.
Interaction between peptides and nucleic acids is a ubiquitous process that drives many cellular functions, such as replications, transcriptions, and translations. Recently, this interaction has been found in liquid-liquid phase separation (LLPS), a process responsible for the formation of newly discovered membraneless organelles with a variety of biological functions inside cells. In this work, we studied the molecular interaction between the poly-l-lysine (PLL) peptide and nucleic acids during the early stage of an LLPS process at the single-molecule level using optical tweezers. By monitoring the mechanical tension of individual nucleic acid templates upon PLL addition, we revealed a multistage LLPS process mediated by the long-range interactions between nucleic acids and polyelectrolytes. By varying different types (ssDNA, ssRNA, and dsDNA) and sequences (A-, T-, G-, or U-rich) of nucleic acids, we pieced together transition diagrams of the PLL-nucleic acid condensates from which we concluded that the propensity to form rigid nucleic acid-PLL complexes reduces the condensate formation during the LLPS process. We anticipate that these results are instrumental in understanding the transition mechanism of LLPS condensates, which allows new strategies to interfere with the biological functions of LLPS condensates inside cells.
肽和核酸之间的相互作用是一种普遍存在的过程，驱动着许多细胞功能，如复制、转录和翻译。最近，这种相互作用在液-液相分离（LLPS）中被发现，LLPS 是一种负责形成新发现的无膜细胞器的过程，这些细胞器在细胞内具有多种生物学功能。在这项工作中，我们使用光学镊子在单分子水平上研究了聚-L-赖氨酸（PLL）肽和核酸在 LLPS 过程早期的分子相互作用。通过监测 PLL 加入后单个核酸模板的机械张力，我们揭示了一种由核酸和聚电解质之间的远程相互作用介导的多步 LLPS 过程。通过改变不同类型（ssDNA、ssRNA 和 dsDNA）和序列（富含 A、T、G 或 U）的核酸，我们拼凑出 PLL-核酸凝聚物的转变图，从中我们得出结论，形成刚性核酸-PLL 复合物的倾向降低了 LLPS 过程中凝聚物的形成。我们预计这些结果有助于理解 LLPS 凝聚物的转变机制，这为在细胞内干扰 LLPS 凝聚物的生物学功能提供了新的策略。
