title: An RNA ligase from Deinococcus radiodurans.
abstract: Although DNA repair pathways have been the focus of much attention, there is an emerging appreciation that distinct pathways exist to maintain or manipulate RNA structure in response to breakage events. Here we identify an RNA ligase (DraRnl) from the radiation-resistant bacterium Deinococcus radiodurans. DraRnl seals 3'-OH/5'-PO4 RNA nicks in either a duplex RNA or an RNA: DNA hybrid, but it cannot seal 3'-OH/5'-PO4 DNA nicks. The specificity of DraRnl arises from a requirement for RNA on the 3'-OH side of the nick. DraRnl is a 342-amino acid monomeric protein with a distinctive structure composed of a C-terminal adenylyltransferase domain linked to an N-terminal module that resembles the OB-fold of phenylalanyl-tRNA synthetases. RNA sealing activity was abolished by mutation of the predicted lysine adenylylation site (Lys-165) in the C-terminal domain and was reduced by an order of magnitude by deletion of the N-terminal OB module. Our findings highlight the existence of an RNA repair capacity in bacteria and support the hypothesis that contemporary DNA ligases, RNA ligases, and RNA capping enzymes evolved by the fusion of ancillary effector domains to an ancestral catalytic module involved in RNA repair.
authors.affiliation: The Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10021, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Martins
authors.forename: Stewart
authors.initials: S
authors.lastname: Shuman
mesh_terms: D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D002384:Catalysis; D002412:Cations; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000737:chemistry; D034301:Deinococcus / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005990:Glycerol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D011130:RNA Ligase (ATP) / Q000737:chemistry* / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
chemical_list: D002412:Cations; D011994:Recombinant Proteins; D012313:RNA; D004247:DNA; D011130:RNA Ligase (ATP); D008239:Lysine; D005990:Glycerol