title: Near-Atomic Resolution Structure Determination of a Cypovirus Capsid and Polymerase Complex Using Cryo-EM at 200kV.
abstract: Single-particle cryo-electron microscopy (cryo-EM) allows the high-resolution structural determination of biological assemblies in a near-native environment. However, all high-resolution (better than 3.5Å) cryo-EM structures reported to date were obtained by using 300kV transmission electron microscopes (TEMs). We report here the structures of a cypovirus capsid of 750-Å diameter at 3.3-Å resolution and of RNA-dependent RNA polymerase (RdRp) complexes within the capsid at 3.9-Å resolution using a 200-kV TEM. The newly resolved structure revealed conformational changes of two subdomains in the RdRp. These conformational changes, which were involved in RdRp's switch from non-transcribing to transcribing mode, suggest that the RdRp may facilitate the unwinding of genomic double-stranded RNA. The possibility of 3-Å resolution structural determinations for biological assemblies of relatively small sizes using cryo-EM at 200kV was discussed.
authors.affiliation: College of Physics and Information Science, Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan, 410081, China; Technology Center for Protein Sciences, Tsinghua University, Beijing, 100084, China.
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, 100084, China.
authors.forename: Niyun
authors.initials: N
authors.lastname: Zhou
authors.affiliation: College of Physics and Information Science, Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan, 410081, China.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Chen
authors.affiliation: College of Physics and Information Science, Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan, 410081, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: College of Physics and Information Science, Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan, 410081, China.
authors.forename: Xurong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Technology Center for Protein Sciences, Tsinghua University, Beijing, 100084, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, 100084, China.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Physics and Information Science, Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan, 410081, China. Electronic address: hrliu@hunnu.edu.cn.
authors.forename: Hongrong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Technology Center for Protein Sciences, Tsinghua University, Beijing, 100084, China; School of Life Sciences, Tsinghua University, Beijing, 100084, China. Electronic address: lingpengcheng@mail.tsinghua.edu.cn.
authors.forename: Lingpeng
authors.initials: L
authors.lastname: Cheng
mesh_terms: D002213:Capsid / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D046911:Macromolecular Substances / Q000648:ultrastructure*; D008958:Models, Molecular; D011487:Protein Conformation; D012367:RNA, Viral / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D012087:Reoviridae / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D046911:Macromolecular Substances; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase
keywords: RNA polymerase; accelerating voltage; cryo-EM; phase residual distribution; reovirus