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A preorganized active site in the crystal structure of the Tetrahymena ribozyme
A preorganized active site in the crystal structure of the Tetrahymena ribozyme.
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Group I introns possess a single active site that catalyzes the two sequential reactions of self-splicing. An RNA comprising the two domains of the Tetrahymena thermophila group I intron catalytic core retains activity, and the 5.0 angstrom crystal structure of this 247-nucleotide ribozyme is now described. Close packing of the two domains forms a shallow cleft capable of binding the short helix that contains the 5' splice site. The helix that provides the binding site for the guanosine substrate deviates significantly from A-form geometry, providing a tight binding pocket. The binding pockets for both the 5' splice site helix and guanosine are formed and oriented in the absence of these substrates. Thus, this large ribozyme is largely preorganized for catalysis, much like a globular protein enzyme.
Golden BL, Gooding AR, Podell ER, Cech TR
Science (New York, N.Y.)
1998-10-09 00:00
282
5387
259-64
Animals,Base Pairing,Base Sequence,Binding Sites,Catalysis,Crystallography, X-Ray,Guanosine,Introns,Magnesium,Manganese,Models, Molecular,Molecular Sequence Data,Nucleic Acid Conformation,Phosphates,RNA Splicing,RNA, Catalytic,Tetrahymena thermophila,Phosphates,RNA, Catalytic,Guanosine,Magnesium,Manganese
Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA bgoldenpetuniacoloradoedu
Science
0036-8075
132
True
9841391
