title: A collapsed non-native RNA folding state.
abstract: At physiological Mg2+ concentrations, the catalytic core of the bI5 group I intron does not fold into its native structure. In contrast, as judged by the global size, this RNA undergoes structural collapse at Mg 2+ concentrations much lower than required to drive folding of the RNA completely to the native state. The bI5 RNA therefore exists in equilibrium between expanded and collapsed non-native states. The activation energy of RNA folding from the collapsed state to the native state is negligible and the reaction is not accelerated by the addition of urea. This collapsed state is thus distinct from the kinetic traps observed during folding of other large RNAs. The collapsed non-native state forms readily in the case of bI5 RNA and may exist generically prior to assembly of other ribonucleoprotein holoenzymes, such as the ribosome.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Buchmueller
authors.forename: A E
authors.initials: AE
authors.lastname: Webb
authors.forename: D A
authors.initials: DA
authors.lastname: Richardson
authors.forename: K M
authors.initials: KM
authors.lastname: Weeks
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D002850:Chromatography, Gel; D017124:Conserved Sequence / Q000235:genetics; D003573:Cytochrome b Group / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D007438:Introns / Q000235:genetics*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation / Q000187:drug effects; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012322:RNA Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics; D020871:RNA Stability / Q000187:drug effects; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000077278:RNA, Mitochondrial; D012997:Solvents; D013816:Thermodynamics; D014508:Urea / Q000494:pharmacology; D015003:Yeasts / Q000235:genetics
chemical_list: D003573:Cytochrome b Group; D012322:RNA Precursors; D016337:RNA, Catalytic; D012331:RNA, Fungal; D000077278:RNA, Mitochondrial; D012997:Solvents; D012313:RNA; D014508:Urea; D008274:Magnesium