title: Cryo-EM shows the polymerase structures and a nonspooled genome within a dsRNA virus.
abstract: Double-stranded RNA (dsRNA) viruses possess a segmented dsRNA genome and a number of RNA-dependent RNA polymerases (RdRps) enclosed in a capsid. Until now, the precise structures of genomes and RdRps within the capsids have been unknown. Here we report the structures of RdRps and associated RNAs within nontranscribing and transcribing cypoviruses (NCPV and TCPV, respectively), using a combination of cryo-electron microscopy (cryo-EM) and a symmetry-mismatch reconstruction method. The RdRps and associated RNAs appear to exhibit a pseudo-D3 symmetric organization in both NCPV and TCPV. However, the molecular interactions between RdRps and the genomic RNA were found to differ in these states. Our work provides insight into the mechanisms of the replication and transcription in dsRNA viruses and paves a way for structural determination of lower-symmetry complexes enclosed in higher-symmetry structures.
authors.affiliation: College of Physics and Information Science, Hunan Normal University, Changsha, Hunan 410081, China. hrliu@hunnu.edu.cn lingpengcheng@mail.tsinghua.edu.cn.
authors.forename: Hongrong
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing 100084, China. hrliu@hunnu.edu.cn lingpengcheng@mail.tsinghua.edu.cn.
authors.forename: Lingpeng
authors.initials: L
authors.lastname: Cheng
mesh_terms: D000818:Animals; D002213:Capsid / Q000201:enzymology / Q000648:ultrastructure; D036022:Capsid Proteins / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D016679:Genome, Viral; D006801:Humans; D011487:Protein Conformation; D012330:RNA, Double-Stranded / Q000235:genetics / Q000648:ultrastructure*; D012367:RNA, Viral / Q000235:genetics / Q000648:ultrastructure*; D012324:RNA-Dependent RNA Polymerase / Q000648:ultrastructure*; D012087:Reoviridae / Q000201:enzymology / Q000235:genetics / Q000648:ultrastructure; D014158:Transcription, Genetic; D019065:Virus Assembly
chemical_list: D036022:Capsid Proteins; D012330:RNA, Double-Stranded; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase