22TR

Cryo-EM structure of Crimean-Congo hemorrhagic fever virus RNA polymerase in complex with 5' vRNA promotor

Summary for 22TR

• Entry DOI: 10.2210/pdb22tr/pdb
• Related: 22TE 22TH
• EMDB information: 68663
• Descriptor: RNA-directed RNA polymerase L, RNA (5'-R(P*UP*CP*UP*CP*AP*AP*AP*GP*AP*UP*AP*UP*CP*GP*U)-3'), ZINC ION, ... (4 entities in total)
• Functional Keywords: polymerase, rna binding protein/rna, rna binding protein-rna complex
• Biological source: Crimean-Congo hemorrhagic fever virus strain IbAr10200; More
• Total number of polymer chains: 2
• Total formula weight: 456471.24

Authors

Ma, J.,Yang, K.,Wu, H.,Liang, Z. (deposition date: 2026-01-22, release date: 2026-08-19, Last modification date: 2026-09-16)

Primary citation

Yang, K.,Wu, H.,Liu, X.,Liang, Z.,Zou, J.,Wang, Y.,Ma, J.
Cryo-EM structures of CCHFV polymerase reveal a stepwise initiation stabilization pathway and a dual-site inhibition mechanism.
Cell Rep, 45:117945-117945, 2026

PubMed Abstract: Crimean-Congo hemorrhagic fever virus (CCHFV) is a high-priority pathogen with high case-fatality rates, yet approved therapeutics remain unavailable. The CCHFV L segment encodes a ∼450-kDa RNA-dependent RNA polymerase (L protein) orchestrating viral replication, but its structural mechanisms remain elusive. Here, we present high-resolution cryo-EM structures of the CCHFV L protein in apo, 5' vRNA-bound, 5'/3' promoter-bound, and inhibitor-bound states. The catalytic core exhibits the canonical architecture of the Bunyavirales order, featuring conserved motifs and coordinated promoter recognition via a 5' vRNA "hook" and a secondary 3' vRNA-binding site. Using suramin as a probe, we identified a dual-site mechanism of polymerase inhibition. Suramin competitively occludes the 5' vRNA-binding pocket through electrostatic mimicry of the RNA backbone and concurrently traps a distal linker-fingers interface, restricting the conformational dynamics required for catalysis. Collectively, these findings provide structural insights into CCHFV polymerase regulation and inhibition.

PubMed: 42696455
DOI: 10.1016/j.celrep.2026.117945

Experimental method

ELECTRON MICROSCOPY (2.75 Å)