Nature Communications (Mar 2023)

Snapshots of the second-step self-splicing of Tetrahymena ribozyme revealed by cryo-EM

  • Shanshan Li,
  • Michael Z. Palo,
  • Xiaojing Zhang,
  • Grigore Pintilie,
  • Kaiming Zhang

DOI
https://doi.org/10.1038/s41467-023-36724-5
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 10

Abstract

Read online

Abstract Group I introns are catalytic RNAs that coordinate two consecutive transesterification reactions for self-splicing. To understand how the group I intron promotes catalysis and coordinates self-splicing reactions, we determine the structures of L-16 Tetrahymena ribozyme in complex with a 5′-splice site analog product and a 3′-splice site analog substrate using cryo-EM. We solve six conformations from a single specimen, corresponding to different splicing intermediates after the first ester-transfer reaction. The structures reveal dynamics during self-splicing, including large conformational changes of the internal guide sequence and the J5/4 junction as well as subtle rearrangements of active-site metals and the hydrogen bond formed between the 2′-OH group of A261 and the N2 group of guanosine substrate. These results help complete a detailed structural and mechanistic view of this paradigmatic group I intron undergoing the second step of self-splicing.