title: Crystal structure of a phage Twort group I ribozyme-product complex.
abstract: Group I introns are catalytic RNAs capable of orchestrating two sequential phosphotransesterification reactions that result in self-splicing. To understand how the group I intron active site facilitates catalysis, we have solved the structure of an active ribozyme derived from the orf142-I2 intron from phage Twort bound to a four-nucleotide product RNA at a resolution of 3.6 A. In addition to the three conserved domains characteristic of all group I introns, the Twort ribozyme has peripheral insertions characteristic of phage introns. These elements form a ring that completely envelops the active site, where a snug pocket for guanosine is formed by a series of stacked base triples. The structure of the active site reveals three potential binding sites for catalytic metals, and invokes a role for the 2' hydroxyl of the guanosine substrate in organization of the active site for catalysis.
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907, USA. barbgolden@purdue.edu
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Golden
authors.forename: Hajeong
authors.initials: H
authors.lastname: Kim
authors.forename: Elaine
authors.initials: E
authors.lastname: Chase
mesh_terms: D001435:Bacteriophages / Q000201:enzymology* / Q000235:genetics*; D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D006151:Guanosine / Q000737:chemistry / Q000378:metabolism; D007438:Introns / Q000235:genetics*; D008670:Metals / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D008670:Metals; D010710:Phosphates; D016337:RNA, Catalytic; D006151:Guanosine