title: Cytoplasmic polyhedrosis virus structure at 8 A by electron cryomicroscopy: structural basis of capsid stability and mRNA processing regulation.
abstract: The single-shelled cytoplasmic polyhedrosis virus (CPV) is a unique member of the Reoviridae. Despite lacking protective outer shells, it exhibits striking capsid stability and is capable of endogenous RNA transcription and processing. The 8 A three-dimensional structure of CPV by electron cryomicroscopy reveals secondary structure elements present in the capsid proteins CSP, LPP, and TP, which have alpha+beta folds. The extensive nonequivalent interactions between CSP and LPP, the unique CSP protrusion domain, and the perfect inter-CSP surface complementarities may account for the enhanced capsid stability. The slanted disposition of TP functional domains and the stacking of channel constrictions suggest an iris diaphragm-like mechanism for opening/closing capsid pores and turret channels in regulating the highly coordinated steps of mRNA transcription, processing, and release.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Texas Medical School, Houston, TX 77030, USA. z.h.zhou@uth.tmc.edu
authors.forename: Z Hong
authors.initials: ZH
authors.lastname: Zhou
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Joanita
authors.initials: J
authors.lastname: Jakana
authors.forename: Xing-Ying
authors.initials: XY
authors.lastname: Lu
authors.forename: Jing-Qiang
authors.initials: JQ
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002213:Capsid / Q000737:chemistry* / Q000378:metabolism; D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D011487:Protein Conformation; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism*; D012087:Reoviridae / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D012333:RNA, Messenger