title: Identifying kinetic barriers to mechanical unfolding of the T. thermophila ribozyme.
abstract: Mechanical unfolding trajectories for single molecules of the Tetrahymena thermophila ribozyme display eight intermediates corresponding to discrete kinetic barriers that oppose mechanical unfolding with lifetimes of seconds and rupture forces between 10 and 30 piconewtons. Barriers are magnesium dependent and correspond to known intra- and interdomain interactions. Several barrier structures are "brittle," breakage requiring high forces but small (1 to 3 nanometers) deformations. Barrier crossing is stochastic, leading to variable unfolding paths. The response of complex RNA structures to locally applied mechanical forces may be analogous to the responses of RNA during translation, messenger RNA export from the nucleus, and viral replication.
authors.affiliation: Department of Physics and Department of Molecular and Cell Biology and Howard Hughes Medical Institute.
authors.forename: Bibiana
authors.initials: B
authors.lastname: Onoa
authors.forename: Sophie
authors.initials: S
authors.lastname: Dumont
authors.forename: Jan
authors.initials: J
authors.lastname: Liphardt
authors.forename: Steven B
authors.initials: SB
authors.lastname: Smith
authors.forename: Ignacio
authors.initials: I
authors.lastname: Tinoco
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D007700:Kinetics; D008274:Magnesium; D009154:Mutation; D009690:Nucleic Acid Conformation; D016376:Oligonucleotides, Antisense; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics; D016808:Tetrahymena thermophila / Q000201:enzymology*; D013816:Thermodynamics
chemical_list: D016376:Oligonucleotides, Antisense; D016337:RNA, Catalytic; D008274:Magnesium