title: The stereochemical course of group II intron self-splicing.
abstract: The stereochemical specificities and reaction courses for both self-splicing steps of a group II intron have been determined by phosphorothioate substitution at the 5' and 3' splice site phosphodiester bonds. Both steps of the splicing reaction proceeded with a phosphorothioate in the Sp configuration but were blocked by the Rp diastereomer. Both steps also proceeded with inversion of stereochemical configuration around phosphorus, consistent with a concerted transesterification reaction. These results are identical to those found for nuclear precursor mRNA (pre-mRNA) splicing and provide support for the hypothesis that group II introns and nuclear pre-mRNA introns share a common evolutionary history.
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas 75235.
authors.forename: R A
authors.initials: RA
authors.lastname: Padgett
authors.forename: M
authors.initials: M
authors.lastname: Podar
authors.forename: S C
authors.initials: SC
authors.lastname: Boulanger
authors.forename: P S
authors.initials: PS
authors.lastname: Perlman
mesh_terms: D001483:Base Sequence; D005091:Exons; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D012313:RNA / Q000737:chemistry* / Q000235:genetics; D012326:RNA Splicing; D013455:Sulfur / Q000737:chemistry; D013873:Thionucleotides / Q000737:chemistry
chemical_list: D009843:Oligoribonucleotides; D013873:Thionucleotides; D010758:Phosphorus; D012313:RNA; D013455:Sulfur; D010100:Oxygen