9Z6I

Cryo-EM structure of the open state of cIL RNA at 4.3 A resolution

Summary for 9Z6I

• Entry DOI: 10.2210/pdb9z6i/pdb
• Related: 9YXV
• EMDB information: 73840
• Descriptor: RNA (155-MER) (1 entity in total)
• Functional Keywords: rna, ribozyme, u1a, ribonucleoprotein (snrnp) complex
• Biological source: synthetic construct
• Total number of polymer chains: 1
• Total formula weight: 49835.68

Authors

Filippova, E.V.,Kossiakoff, A.A. (deposition date: 2025-11-14, release date: 2026-05-27, Last modification date: 2026-06-03)

Primary citation

Filippova, E.V.,Krochmal, D.,Mukherjee, S.,Piccirilli, J.A.,Kossiakoff, A.A.
A universal Fab targeting a conserved U1A-RNA epitope for RNA structure determination by cryo-EM.
Nucleic Acids Res., 54:-, 2026

PubMed Abstract: Recent advances in cryo-electron microscopy (cryo-EM) have made antigen-binding fragments (Fabs) essential tools in the field of structural biology. Fabs facilitate image alignment, thereby enhancing three-dimensional (3D) reconstruction, and increase the effective size of proteins, aiding in their structural elucidation. In this study, we sought to broaden the use of Fabs as fiducial markers to elucidate the structures of RNA molecules. Identifying an appropriate Fab for a specific RNA target can be particularly challenging due to RNA's inherent flexibility and tendency to assume multiple conformations, which complicate the process and prolong the structure determination timeline. To address this challenge, we designed a universal Fab that specifically recognizes a U1A-RNA epitope, thereby reducing the need for Fab selection tailored to each individual RNA target. We determined the cryo-EM structure of the class I ligase ribozyme complexed with a portable U1hpII loop bound to the U1A protein and the Fab. The resulting structure revealed that the Fab interacts with a conserved U1A-RNA binding region, which can be engineered into other RNA molecules. This strategy presents significant potential for streamlining the structural determination of various RNAs, which are essential for biological and biomedical research.

PubMed: 42165126
DOI: 10.1093/nar/gkag502

Experimental method

ELECTRON MICROSCOPY (4.32 Å)