Crystal Structures of the Mango-II RNA Aptamer Reveal Heterogeneous Fluorophore Binding and Guide Engineering of Variants with Improved Selectivity and Brightness.

ABSTRACT: Several RNA aptamers that bind small molecules and enhance their fluorescence have been successfully used to tag and track RNAs in vivo, but these genetically encodable tags have not yet achieved single-fluorophore resolution. Recently, Mango-II, an RNA that binds TO1-Biotin with ∼1 nM affinity and enhances its fluorescence by >1500-fold, was isolated by fluorescence selection from the pool that yielded the original RNA Mango. We determined the crystal structures of Mango-II in complex with two fluorophores, TO1-Biotin and TO3-Biotin, and found that despite their high affinity, the ligands adopt multiple distinct conformations, indicative of a binding pocket with modest stereoselectivity. Mutational analysis of the binding site led to Mango-II(A22U), which retains high affinity for TO1-Bio

SUBMITTER: Trachman RJ 

PROVIDER: S-EPMC6315298 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature