9YFM

insect H/ACA snoRNP class II composite

This is a non-PDB format compatible entry.

Summary for 9YFM

• Entry DOI: 10.2210/pdb9yfm/pdb
• EMDB information: 72898
• Descriptor: H/ACA ribonucleoprotein complex subunit, H/ACA ribonucleoprotein complex subunit 2-like protein, H/ACA ribonucleoprotein complex subunit 3, ... (5 entities in total)
• Functional Keywords: pseudouridine synthase, enzyme complex, snorna, snornp, rna binding protein
• Biological source: Trichoplusia ni (cabbage looper); More
• Total number of polymer chains: 9
• Total formula weight: 242440.01

Authors

Panwar, H.S.,Worden, E.W. (deposition date: 2025-09-26, release date: 2025-12-10, Last modification date: 2025-12-31)

Primary citation

Panwar, H.S.,Vos, T.J.,Xie, X.,Jang, H.J.,Lee, H.,Sheldon, R.D.,Worden, E.J.,Kothe, U.
Interprotomer communication and functional asymmetry in H/ACA snoRNPs.
Proc.Natl.Acad.Sci.USA, 122:e2514683122-e2514683122, 2025

PubMed Abstract: H/ACA small nucleolar ribonucleoproteins (H/ACA snoRNPs) facilitate essential cellular processes such as RNA modification, folding, and stability. Here, we present multiple cryo-EM structures of endogenous insect H/ACA snoRNPs containing two protomers assembled on a two-hairpin H/ACA snoRNA. By characterizing key protein-protein and protein-RNA interactions, we reveal the coordination of pseudouridylation activity across the two protomers which explains the predominance of two-hairpin structures in eukaryotic H/ACA snoRNAs. Moreover, we found that several mutations in H/ACA proteins associated with dyskeratosis congenita (DC) directly impair pseudouridine formation suggesting how these mutations disrupt RNA modification and ribosome biogenesis in this disease. Additionally, we uncover coordinated structural changes between Nop10, Nhp2, and the N-terminal extensions of Cbf5 in the 3' protomer that resemble active and inactive conformations and may regulate H/ACA snoRNP activity. In summary, this study provides detailed insight into the structure and function of RNA modification-competent H/ACA snoRNPs, which play pivotal roles in cellular processes including ribosome biogenesis, rRNA folding, (m)RNA modification, and telomere maintenance.

PubMed: 41410763
DOI: 10.1073/pnas.2514683122

Experimental method

ELECTRON MICROSCOPY (2.95 Å)