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Publication Abstract from PubMed

Cryo-EM structure determination of protein-free RNAs has remained difficult with most attempts yielding low to moderate resolution and lacking nucleotide-level detail. These difficulties are compounded for small RNAs as cryo-EM is inherently more difficult for lower molecular weight macromolecules. Here we present a strategy for fusing small RNAs to a group II intron that yields high resolution structures of the appended RNA, which we demonstrate with the 86-nucleotide thiamine pyrophosphate (TPP) riboswitch, and visualizing the riboswitch ligand binding pocket at 2.5 A resolution. We also determined the structure of the ligand-free apo state and observe that the aptamer domain of the riboswitch undergoes a large-scale conformational change upon ligand binding, illustrating how small molecule binding to an RNA can induce large effects on gene expression. This study both sets a new standard for cryo-EM riboswitch visualization and offers a versatile strategy applicable to a broad range of small to moderate-sized RNAs, which were previously intractable for high-resolution cryo-EM studies.

Scaffold-enabled high-resolution cryo-EM structure determination of RNA.,Haack DB, Rudolfs B, Jin S, Weeks KM, Toor N bioRxiv [Preprint]. 2024 Jun 10:2024.06.10.598011. doi: , 10.1101/2024.06.10.598011. PMID:38915706^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.