%0 Journal Article
%T Capturing Hammerhead Ribozyme Structures in Action by Modulating General Base Catalysis
%A Young-In Chi
%A Monika Martick
%A Monica Lares
%A Rosalind Kim
%A William G. Scott
%A Sung-Hou Kim
%J PLOS Biology
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pbio.0060234
%X We have obtained precatalytic (enzyme¨Csubstrate complex) and postcatalytic (enzyme¨Cproduct complex) crystal structures of an active full-length hammerhead RNA that cleaves in the crystal. Using the natural satellite tobacco ringspot virus hammerhead RNA sequence, the self-cleavage reaction was modulated by substituting the general base of the ribozyme, G12, with A12, a purine variant with a much lower pKa that does not significantly perturb the ribozyme's atomic structure. The active, but slowly cleaving, ribozyme thus permitted isolation of enzyme¨Csubstrate and enzyme¨Cproduct complexes without modifying the nucleophile or leaving group of the cleavage reaction, nor any other aspect of the substrate. The predissociation enzyme-product complex structure reveals RNA and metal ion interactions potentially relevant to transition-state stabilization that are absent in precatalytic structures.
%U http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.0060234