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A Multicolor Large Stokes Shift Fluorogen-Activating RNA Aptamer with Cationic Chromophores |
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| Authors: | Christian Steinmetzger Navaneethan Palanisamy Dr Kiran R Gore Prof?Dr Claudia Höbartner |
| Institution: | 1. Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany;2. International Max Planck Research School Molecular Biology, University of Göttingen, Germany
Present address: BIOSS Center for Biological Signaling Studies, University of Freiburg, Germany;3. Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany Present address: Department of Chemistry, University of Mumbai, India |
| Abstract: | Large Stokes shift (LSS) fluorescent proteins (FPs) exploit excited state proton transfer pathways to enable fluorescence emission from the phenolate intermediate of their internal 4-hydroxybenzylidene imidazolone (HBI) chromophore. An RNA aptamer named Chili mimics LSS FPs by inducing highly Stokes-shifted emission from several new green and red HBI analogues that are non-fluorescent when free in solution. The ligands are bound by the RNA in their protonated phenol form and feature a cationic aromatic side chain for increased RNA affinity and reduced magnesium dependence. In combination with oxidative functionalization at the C2 position of the imidazolone, this strategy yielded DMHBO+, which binds to the Chili aptamer with a low-nanomolar KD. Because of its highly red-shifted fluorescence emission at 592 nm, the Chili–DMHBO+ complex is an ideal fluorescence donor for Förster resonance energy transfer (FRET) to the rhodamine dye Atto 590 and will therefore find applications in FRET-based analytical RNA systems. |
| Keywords: | fluorescence Förster resonance energy transfer fluorescent proteins large Stokes shift RNA aptamers |