湖南大学聂舟团队报道了荧光蛋白近红外核酸模拟物的研制用于开启荧光的病毒RNA活体成像。相关研究成果发表在2021年11月11日出版的国际学术期刊《美国化学会杂志》。

类GFP荧光蛋白及其分子模拟物彻底改变了生物成像研究，但它们的发射在可见光到远红色区域受到很大限制，阻碍了在完整动物体内的应用。

该文中，研究人员利用供体-受体-受体（D–A–A′）分子构型对类GFP发色团进行结构调节，发现了一组具有红外位移光谱的新型荧光衍生物。该发色团可以通过抑制发色团扭曲的分子内电荷转移，通过与独特的非规范核酸二级结构G-四链体（G4）的特异性相互作用发出荧光。该功能使研究人员能够首次在近红外（NIR）区域（Emmax=664–705 nm）创建具有可调谐发射的FP模拟，即FPs的红外G-四链体模拟（igMFP）。与FP相比，IGMFP具有更高的量子产率、更大的Stokes位移和更好的光稳定性。

在一项以病原体相关G4s为靶点的概念验证应用中，研究人员利用igMFPs通过HCV核心基因中的发色团结合病毒G4结构原位形成的天然丙型肝炎病毒（HCV）RNA基因组，直接可视化活细胞中的天然丙型肝炎病毒（HCV）RNA基因组。此外，igMFPs能够在携带HCV RNA呈递小器官的活体小鼠中进行高对比度HCV RNA成像，是FP模拟物在全动物成像中的首次应用。

附：英文原文

Title: Development of Near-Infrared Nucleic Acid Mimics of Fluorescent Proteins for In Vivo Imaging of Viral RNA with Turn-On Fluorescence

Author: Jiaheng Zhang, Huiyi Li, Bin Lin, Xingyu Luo, Peng Yin, Ting Yi, Binbin Xue, Xiao-Lian Zhang, Haizhen Zhu, Zhou Nie

Issue&Volume: November 11, 2021

Abstract: GFP-like fluorescent proteins and their molecular mimics have revolutionized bioimaging research, but their emissions are largely limited in the visible to far-red region, hampering the in vivo applications in intact animals. Herein, we structurally modulate GFP-like chromophores using a donor–acceptor–acceptor (D–A–A′) molecular configuration to discover a set of novel fluorogenic derivatives with infrared-shifted spectra. These chromophores can be fluorescently elicited by their specific interaction with G-quadruplex (G4), a unique noncanonical nucleic acid secondary structure, via inhibition of the chromophores’ twisted-intramolecular charge transfer. This feature allows us to create, for the first time, FP mimics with tunable emission in the near-infrared (NIR) region (Emmax = 664–705 nm), namely, infrared G-quadruplex mimics of FPs (igMFP). Compared with their FP counterparts, igMFPs exhibit remarkably higher quantum yields, larger Stokes shift, and better photostability. In a proof-of-concept application using pathogen-related G4s as the target, we exploited igMFPs to directly visualize native hepatitis C virus (HCV) RNA genome in living cells via their in situ formation by the chromophore-bound viral G4 structure in the HCV core gene. Furthermore, igMFPs are capable of high contrast HCV RNA imaging in living mice bearing a HCV RNA-presenting mini-organ, providing the first application of FP mimics in whole-animal imaging.

DOI: 10.1021/jacs.1c04577

Source: https://pubs.acs.org/doi/10.1021/jacs.1c04577