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Updated: Apr 23, 2026

Overexpressing Long Noncoding RNAs Using Gene-activating CRISPR
Published on: March 1, 2019
Novel coding, translation, and gene expression of a replicating covalently closed circular RNA of 220 nt
Mounir Georges AbouHaidar1, Srividhya Venkataraman2, Ashkan Golshani3
1Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; and mounir.abouhaidar@utoronto.ca.
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."
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