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Updated: Feb 3, 2026

Single-Molecule FRET Imaging for Observing the Conformational Dynamics of Dynamin-Like GTPase Atlastin
Published on: January 24, 2025
Observation of preQ1-II riboswitch dynamics using single-molecule FRET
Chandani Warnasooriya1, Clarence Ling1, Ivan A Belashov1
1a Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA.
Abstract:
PreQ1 riboswitches regulate the synthesis of the hypermodified tRNA base queuosine by sensing the pyrrolopyrimidine metabolite preQ1. Here, we use single-molecule FRET to interrogate the structural dynamics of apo and preQ1-bound states of the preQ1-II riboswitch from Lactobacillus rhamnosus. We find that the apo-form of the riboswitch spontaneously samples multiple conformations. Magnesium ions and preQ1 stabilize conformations that sequester the ribosome-binding site of the mRNA within the pseudoknotted structure, thus inhibiting translation initiation. Our results reveal that folding of the preQ1-II riboswitch is complex and provide evidence favoring a conformational selection model of effector binding by riboswitches of this class.
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