title: A DNA enzyme that mimics the first step of RNA splicing.
abstract: We have discovered an artificial DNA enzyme that mimics the first step of RNA splicing. In vitro selection was used to identify DNA enzymes that ligate RNA. One of the new DNA enzymes carries out splicing-related catalysis by specifically recognizing an unpaired internal adenosine and facilitating attack of its 2'-hydroxyl onto a 5'-triphosphate. This reaction forms 2',5'-branched RNA and is analogous to the first step of in vivo RNA splicing, in which a ribozyme cleaves itself with formation of a branched intermediate. Unlike a natural ribozyme, the new DNA enzyme has no 2'-hydroxyl groups to aid in the catalytic mechanism. Our finding has two important implications. First, branch-site adenosine reactivity seems to be mechanistically favored by nucleic acid enzymes. Second, hydroxyl groups are not obligatory components of nucleic acid enzymes that carry out biologically related catalysis.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Coppins
authors.forename: Scott K
authors.initials: SK
authors.lastname: Silverman
mesh_terms: D000241:Adenosine / Q000378:metabolism; D001483:Base Sequence; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D018716:Molecular Mimicry; D009690:Nucleic Acid Conformation; D012313:RNA / Q000378:metabolism; D012326:RNA Splicing
chemical_list: D021881:DNA, Catalytic; D012313:RNA; D000241:Adenosine