title: An optimal Mg(2+) concentration for kinetic folding of the tetrahymena ribozyme.
abstract: Divalent metal ions, such as Mg(2+), are generally required for tertiary structure formation in RNA. Although the role of Mg(2+) binding in RNA-folding equilibria has been studied extensively, little is known about the role of Mg(2+) in RNA-folding kinetics. In this paper, we explore the effect of Mg(2+) on the rate-limiting step in the kinetic folding pathway of the Tetrahymena ribozyme. Analysis of these data reveals the presence of a Mg(2+)-stabilized kinetic trap that slows folding at higher Mg(2+) concentrations. Thus, the Tetrahymena ribozyme folds with an optimal rate at 2 mM Mg(2+), just above the concentration required for stable structure formation. These results suggest that thermodynamic and kinetic folding of RNA are cooptimized at a Mg(2+) concentration that is sufficient to stabilize the folded form but low enough to avoid kinetic traps and misfolding.
authors.affiliation: Department of Molecular Biology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Rook
authors.forename: D K
authors.initials: DK
authors.lastname: Treiber
authors.forename: J R
authors.initials: JR
authors.lastname: Williamson
mesh_terms: D000818:Animals; D001483:Base Sequence; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017510:Protein Folding; D016337:RNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D013768:Tetrahymena / Q000201:enzymology*
chemical_list: D016337:RNA, Catalytic; D008274:Magnesium