title: Single-molecule studies of group II intron ribozymes.
abstract: Group II intron ribozymes fold into their native structure by a unique stepwise process that involves an initial slow compaction followed by fast formation of the native state in a Mg(2+)-dependent manner. Single-molecule fluorescence reveals three distinct on-pathway conformations in dynamic equilibrium connected by relatively small activation barriers. From a most stable near-native state, the unobserved catalytically active conformer is reached. This most compact conformer occurs only transiently above 20 mM Mg(2+) and is stabilized by substrate binding, which together explain the slow cleavage of the ribozyme. Structural dynamics increase with increasing Mg(2+) concentrations, enabling the enzyme to reach its active state.
authors.affiliation: Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: Miriam
authors.initials: M
authors.lastname: Steiner
authors.forename: Krishanthi S
authors.initials: KS
authors.lastname: Karunatilaka
authors.forename: Roland K O
authors.initials: RK
authors.lastname: Sigel
authors.forename: David
authors.initials: D
authors.lastname: Rueda
mesh_terms: D002384:Catalysis; D004789:Enzyme Activation; D031541:Fluorescence Resonance Energy Transfer; D007438:Introns / Q000235:genetics*; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D044563:RNA, Ribosomal, Self-Splicing / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: C506264:D135 ribozyme, S cerevisiae; D044563:RNA, Ribosomal, Self-Splicing; D008274:Magnesium
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