title: Covalent circularization of exogenous RNA during incubation with a wheat embryo cell extract.
abstract: Cell extracts from wheat embryos have been widely used for mRNA-directed protein production. Here, we found that a significant fraction of exogenous linear RNAs are circularized in a wheat embryo extract. The circularization was seen only in uncapped RNAs. The amount of the circular species reached around 1% of the initial RNA and increased along with an increase in the initial concentration more than proportionally. The circular RNAs were stable but unable to be translated in the extract. The circularization was competitively inhibited in the presence of a known substrate of a wheat embryo RNA ligase. Thus, we cloned the RNA ligase cDNAs. Three isoform sequences were homologous to the other plant RNA ligases. An addition of a cell-free synthesized wheat RNA ligase abolished the inhibition, which indicates a participation of its activity in the circularization. A possible role in RNA metabolism, RNA silencing in particular, is discussed.
authors.affiliation: Venture Business Laboratory, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Makino
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawasaki
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Tozawa
authors.forename: Yaeta
authors.initials: Y
authors.lastname: Endo
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Takai
mesh_terms: D002474:Cell-Free System; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis*; D034622:RNA Interference / Q000502:physiology; D011130:RNA Ligase (ATP) / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism*; D000079962:RNA, Circular; D014908:Triticum / Q000196:embryology / Q000378:metabolism*
chemical_list: D012329:RNA, Bacterial; D000079962:RNA, Circular; D012313:RNA; D011130:RNA Ligase (ATP)