Details

Autor(en) / Beteiligte

• Trachman, 3rd, Robert J
• Autour, Alexis
• Jeng, Sunny C Y
• Abdolahzadeh, Amir
• Andreoni, Alessio
• Cojocaru, Razvan
• Garipov, Ramil
• Dolgosheina, Elena V
• Knutson, Jay R
• Ryckelynck, Michael
• Unrau, Peter J
• Ferré-D'Amaré, Adrian R

Titel

Structure and functional reselection of the Mango-III fluorogenic RNA aptamer

Ist Teil von

• Nature chemical biology, 2019-05, Vol.15 (5), p.472-479

Ort / Verlag

United States

Erscheinungsjahr

2019

Quelle

MEDLINE

Beschreibungen/Notizen

• Several turn-on RNA aptamers that activate small-molecule fluorophores have been selected in vitro. Among these, the ~30 nucleotide Mango-III is notable because it binds the thiazole orange derivative TO1-Biotin with high affinity and fluoresces brightly (quantum yield 0.55). Uniquely among related aptamers, Mango-III exhibits biphasic thermal melting, characteristic of molecules with tertiary structure. We report crystal structures of TO1-Biotin complexes of Mango-III, a structure-guided mutant Mango-III(A10U), and a functionally reselected mutant iMango-III. The structures reveal a globular architecture arising from an unprecedented pseudoknot-like connectivity between a G-quadruplex and an embedded non-canonical duplex. The fluorophore is restrained into a planar conformation by the G-quadruplex, a lone, long-range trans Watson-Crick pair (whose A10U mutation increases quantum yield to 0.66), and a pyrimidine perpendicular to the nucleobase planes of those motifs. The improved iMango-III and Mango-III(A10U) fluoresce ~50% brighter than enhanced green fluorescent protein, making them suitable tags for live cell RNA visualization.