The hammerhead ribozyme

The hammerhead ribozyme is a small, self-cleaving RNA originally discovered as an element in certain plant pathogenic RNAs The availability of several different crystal structures of the hammerhead and the development of kinetic framework for the cleavage reaction permits detailed structure-function experiments with the goal of understanding the reaction mechanism Data on a series of modified pyrimidine "mutations" of the nucleotide adjacent to the cleavage site will be presented and experiments on other nucleotide modifications in the catalytic core will be summarized Since many modifications only appear to affect the transition state of the reaction, it appears that a global conformation change must occur prior to reaching the conformation required for cleavage. Terbium ton is a potent inhibitor of hammerhead cleavage. We have located the terbium binding site in the structure and will present several experiments detailing its binding properties The interesting properties of a hammerhead containing a covalent crosslink between stem 1 and stem II will be presented.