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Un sitio activo preorganizado en la estructura cristalina de la ribozima Tetrahymena
B L Golden1, A R Gooding, E R Podell
1Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA. bgolden@petunia.colorado.edu
Science (New York, N.Y.)
|December 5, 1998
Resumen
Los intrones del grupo I son ARN catalíticos que se autopliquen. La estructura cristalina de la Tetrahymena thermophila grupo I intron ribozima revela sitios de unión preorganizados para sustratos, similares a las enzimas de las proteínas.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Los intrones del grupo I son moléculas catalíticas de ARN conocidas por su autoesplicamiento.
- Catalizan dos reacciones secuenciales dentro de un solo sitio activo.
Objetivo del estudio:
- Para determinar la estructura cristalina de la Tetrahymena thermophila grupo I intrón núcleo catalítico.
- Para entender la base estructural para la unión al sustrato y la preorganización en esta ribozima.
Principales métodos:
- Se utilizó la cristalografía de rayos X para determinar la estructura de 5,0 angstroms.
- El estudio se centró en una ribozima de 247 nucleótidos que comprende los dos dominios activos.
Principales resultados:
- La estructura cristalina revela el empaquetado cercano de los dos dominios, formando una hendidura para la unión del sitio de empalme de 5'.
- Un bolsillo de unión distinto para el sustrato de guanosina se desvía de la geometría de la forma A.
- Estos bolsillos de unión están preformados y orientados antes de la unión del sustrato.
Conclusiones:
- La ribozima intron de Tetrahymena thermophila grupo I está en gran medida preorganizada para la catálisis.
- Esta preorganización es análoga a las características estructurales de las enzimas proteicas globulares.
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