High-resolution structural studies are essential for understanding the folding and function of diverse RNAs. Herein, we present a nanoarchitectural engineering strategy for efficient structural determination of RNA-only structures using single-particle cryogenic electron microscopy (cryo-EM). This strategy–-ROCK (RNA oligomerization-enabled cryo-EM via installing kissing loops)–-involves installing kissing-loop sequences onto the functionally nonessential stems of RNAs for homomeric self-assembly into closed rings with multiplied molecular weights and mitigated structural flexibility. ROCK enables cryo-EM reconstruction of the Tetrahymena group I intron at 2.98-\AA resolution overall (2.85þinspace}\AA for the core), allowing de novo model building of the complete RNA, including the previously unknown peripheral domains. ROCK is further applied to two smaller RNAs–-the Azoarcus group I intron and the FMN riboswitch, revealing the conformational change of the former and the bound ligand in the latter. ROCK holds promise to greatly facilitate the use of cryo-EM in RNA structural studies.
JoeLoparoOur first paper investigating the mechanism of the bacterial cell wall machinery. In this collaborative work with the Kruse and Bernhardt labs, we show how conformational dynamics of RodA-PBP2 coordinate its enzymatic activities. t.co/SnwZ8p4kF0