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2003 News Index

Pulling apart a ribozyme: Tinoco and Bustamante

Ribozyme from
Tetrahymena thermophila (Tom Cech)

from Chemical and Engineering News

RNA is made up of base-paired helices that are similar to those found in DNA. But unlike DNA, RNA's base-paired helical regions can fold to make tertiary interactions with one another. In catalytic RNA molecules called ribozymes, the stability of base-paired helices determines the ribozyme's overall thermodynamic stability.

But the ease with which ribozymes can be mechanically unfolded depends largely on Mg2+-dependent tertiary interactions between helices, according to researchers at the University of California, Berkeley. Former postdoc Bibiana Onoa, graduate student Sophie Dumont, and professor Ignacio Tinoco Jr. of the chemistry department; physics professor Carlos J. Bustamante; and coworkers used optical tweezers to determine the strength of the kinetic barriers that oppose the mechanical unfolding of single molecules of a well-characterized 390-nucleotide ribozyme from Tetrahymena thermophila [Science, 299, 1892 (2003)]. By pulling on progressively larger portions of this ribozyme, the team assigned each kinetic barrier to specific structural interactions.

"The response of complex RNA structures to locally applied mechanical forces may be analogous to the response of RNA during translation, messenger RNA export from the nucleus, and viral replication," the authors note.

Related sites:

Ignacio Tinoco Jr. website

Carlos Bustamante website

Science homepage

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