title: Novel coding, translation, and gene expression of a replicating covalently closed circular RNA of 220 nt.
abstract: The highly structured (64% GC) covalently closed circular (CCC) RNA (220 nt) of the virusoid associated with rice yellow mottle virus codes for a 16-kDa highly basic protein using novel modalities for coding, translation, and gene expression. This CCC RNA is the smallest among all known viroids and virusoids and the only one that codes proteins. Its sequence possesses an internal ribosome entry site and is directly translated through two (or three) completely overlapping ORFs (shifting to a new reading frame at the end of each round). The initiation and termination codons overlap UGAUGA (underline highlights the initiation codon AUG within the combined initiation-termination sequence). Termination codons can be ignored to obtain larger read-through proteins. This circular RNA with no noncoding sequences is a unique natural supercompact "nanogenome."
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; and mounir.abouhaidar@utoronto.ca.
authors.forename: Mounir Georges
authors.initials: MG
authors.lastname: AbouHaidar
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; and.
authors.forename: Srividhya
authors.initials: S
authors.lastname: Venkataraman
authors.affiliation: Biology Department, Carleton University, Ottawa, ON, Canada K1S 5B6.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Golshani
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; and.
authors.forename: Bolin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; and.
authors.forename: Tauqeer
authors.initials: T
authors.lastname: Ahmad
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002853:Chromatography, Liquid; D018387:Codon, Initiator / Q000235:genetics; D018388:Codon, Terminator / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics*; D012313:RNA / Q000235:genetics*; D000079962:RNA, Circular; D012367:RNA, Viral / Q000235:genetics*; D053719:Tandem Mass Spectrometry; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D014772:Viroids / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D018387:Codon, Initiator; D018388:Codon, Terminator; D010455:Peptides; D000079962:RNA, Circular; D012367:RNA, Viral; D014764:Viral Proteins; D012313:RNA
keywords: circular RNA translation; hammerhead ribozyme; leaky termination codons; sobemovirus