Identifying Kinetic Barriers to Mechanical Unfolding of the T. thermophila Ribozyme

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Science  21 Mar 2003:
Vol. 299, Issue 5614, pp. 1892-1895
DOI: 10.1126/science.1081338

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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.

  • * These authors contributed equally to this work.

  • Present address: DuPont Company Experimental Station, Post Office Box 80328, Wilmington, DE 19880–0328, USA.

  • To whom correspondence should be addressed. E-mail: carlos{at}

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