title: Cleavage of dsRNAs hyper-edited by ADARs occurs at preferred editing sites.
abstract: Long double-stranded RNAs (dsRNAs) may undergo covalent modification (hyper-editing) by adenosine deaminases that act on RNA (ADARs), whereby up to 50-60% of adenosine residues are converted to inosine. Previously, we have described a ribonuclease activity in various cell extracts that specifically targets dsRNAs hyper-edited by ADARs. Such a ribonuclease may play an important role in viral defense, or may alternatively be involved in down-regulation of other RNA duplexes. Cleavage of hyper-edited dsRNA occurs within sequences containing multiple IU pairs but not in duplexes that contain either isosteric GU pairs or Watson-Crick base pairs. Here, we describe experiments aimed at further characterizing cleavage of hyper-edited dsRNA. Using various inosine-containing dsRNAs we show that cleavage occurs preferentially at a site containing both IU and UI pairs, and that inclusion of even a single GU pair inhibits cleavage. We also show that cleavage occurs on both strands within a single dsRNA molecule and requires a 2'-OH group. Strikingly, we show that ADAR1, ADAR2 or dADAR all preferentially generate the preferred cleavage site when hyper-editing a long dsRNA.
authors.affiliation: University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK. adjs@bioc.cam.ac.uk
authors.forename: A D J
authors.initials: AD
authors.lastname: Scadden
authors.forename: M A
authors.initials: MA
authors.lastname: O'Connell
mesh_terms: D000243:Adenosine Deaminase / Q000378:metabolism*; D000818:Animals; D020029:Base Pairing; D006151:Guanosine / Q000737:chemistry; D007288:Inosine / Q000737:chemistry; D009865:Oocytes / Q000378:metabolism; D017393:RNA Editing; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins; D013379:Substrate Specificity; D014529:Uridine / Q000737:chemistry; D014982:Xenopus laevis
chemical_list: D012330:RNA, Double-Stranded; D016601:RNA-Binding Proteins; D006151:Guanosine; D007288:Inosine; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase; D014529:Uridine