title: Conversion of a DNA ligase into an RNA capping enzyme.
abstract: In eukaryotes, newly synthesised mRNA is 'capped' by the addition of GMP to the 5" end by RNA capping enzymes. Recent structural studies have shown that RNA capping enzymes and DNA ligases have similar protein folds, suggesting a conserved catalytic mechanism. To explore these similarities we have produced a chimeric enzyme comprising the N-terminal domain 1 of a DNA ligase fused to the C-terminal domain 2 of a mRNA capping enzyme. This report shows that this hybrid enzyme retains adenylation activity, characteristic of DNA ligases but, remarkably, the chimera has ATP-dependent mRNA capping activity. This is the first observation of ATP-dependent RNA capping. These results suggest that nucleotidyltransferases may have evolved from a common ancestral gene.
authors.affiliation: Structural Medicine Unit, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, and Department of Haematology, University of Cambridge, Hills Road, Cambridge CB2 2XY, UK. aidan@mrc-lmb.cam.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Doherty
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D011088:DNA Ligases / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism*; D012315:RNA Caps; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: C121268:ATP-dependent capping enzyme, chimeric; D012315:RNA Caps; D011993:Recombinant Fusion Proteins; D009713:Nucleotidyltransferases; D011088:DNA Ligases