title: Continuous and Discontinuous RNA Synthesis in Coronaviruses.
abstract: Replication of the coronavirus genome requires continuous RNA synthesis, whereas transcription is a discontinuous process unique among RNA viruses. Transcription includes a template switch during the synthesis of subgenomic negative-strand RNAs to add a copy of the leader sequence. Coronavirus transcription is regulated by multiple factors, including the extent of base-pairing between transcription-regulating sequences of positive and negative polarity, viral and cell protein-RNA binding, and high-order RNA-RNA interactions. Coronavirus RNA synthesis is performed by a replication-transcription complex that includes viral and cell proteins that recognize cis-acting RNA elements mainly located in the highly structured 5' and 3' untranslated regions. In addition to many viral nonstructural proteins, the presence of cell nuclear proteins and the viral nucleocapsid protein increases virus amplification efficacy. Coronavirus RNA synthesis is connected with the formation of double-membrane vesicles and convoluted membranes. Coronaviruses encode proofreading machinery, unique in the RNA virus world, to ensure the maintenance of their large genome size.
authors.affiliation: Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain; email: l.enjuanes@cnb.csic.es.
authors.forename: Isabel
authors.initials: I
authors.lastname: Sola
authors.affiliation: Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain; email: l.enjuanes@cnb.csic.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: Almazán
authors.affiliation: Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain; email: l.enjuanes@cnb.csic.es.
authors.forename: Sonia
authors.initials: S
authors.lastname: Zúñiga
authors.affiliation: Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain; email: l.enjuanes@cnb.csic.es.
authors.forename: Luis
authors.initials: L
authors.lastname: Enjuanes
mesh_terms: D000818:Animals; D017934:Coronavirus / Q000235:genetics* / Q000378:metabolism; D018352:Coronavirus Infections / Q000821:virology*; D006801:Humans; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D012367:RNA, Viral
keywords: RNA proofreading; nidovirus; positive-strand RNA viruses; replication; transcription; virus-host interaction