美国国家癌症研究所John S. Schneekloth Jr团队实现了一种超亮RNA激活荧光团的结构设计。相关论文于2025年5月28日发表于《自然-化学》杂志上。

基于RNA的荧光适配体，如Mango，是成像RNA的独特强大工具，在结合时激活弱荧光或非荧光小分子的荧光。一个核心挑战是开发更明亮、更特异和高亲和力的适配体系统用于细胞成像。

研究组报告了一种使用结构知情、基于片段的小分子微阵列方法发现的Mango II系统的超亮荧光团。这种染料被称为SALAD1（结构知情、阵列激活的LigAnD1），与广泛使用的荧光系统Mango II-TO1-生物素对相比，具有亚纳米适配体亲和力和3.5倍的荧光。 

通过调节RNA染料分子识别而不改变荧光团的π系统来提高性能。高分辨率X射线结构揭示了SALAD1的结合模式，该模式表现出改进的口袋占有率、更明确的结合姿势和与钾的独特结合相互作用。SALAD1具有细胞渗透性，有助于改善细胞内共聚焦RNA成像。这项工作引入了一种额外的RNA激活荧光团，展示了如何使用基于片段的配体发现为RNA靶标创建高性能配体。

附：英文原文

Title: Structure-informed design of an ultrabright RNA-activated fluorophore

Author: Yang, Mo, Prestwood, Peri R., Passalacqua, Luiz F. M., Balaratnam, Sumirtha, Fullenkamp, Christopher R., Arney, J. Winston, Weeks, Kevin M., Ferre-DAmare, Adrian, Schneekloth, John S.

Issue&Volume: 2025-05-28

Abstract: RNA-based fluorogenic aptamers, such as Mango, are uniquely powerful tools for imaging RNA that activate the fluorescence of a weakly or non-fluorescent small molecule when bound. A central challenge has been to develop brighter, more specific and high-affinity aptamer–ligand systems for cellular imaging. Here we report an ultrabright fluorophore for the Mango II system discovered using a structure-informed, fragment-based small-molecule microarray approach. This dye—termed SALAD1 (structure-informed, array-enabled LigAnD 1)—exhibits subnanomolar aptamer affinity and 3.5-fold brighter fluorescence than Mango II-TO1–biotin pair, a widely used fluorogenic system. Performance was improved by modulating RNA-dye molecular recognition without altering the fluorophore’s π-system. High-resolution X-ray structures reveal the binding mode for SALAD1, which exhibits improved pocket occupancy, a more defined binding pose and a unique bonding interaction with potassium. SALAD1 is cell-permeable and facilitates improved in-cell confocal RNA imaging. This work introduces an additional RNA-activated fluorophore demonstrating how fragment-based ligand discovery can be used to create high-performance ligands for RNA targets.

DOI: 10.1038/s41557-025-01832-w

Source: https://www.nature.com/articles/s41557-025-01832-w