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Pruebas filogenéticas y genéticas de bases triples en el dominio catalítico de los intrones del grupo I

F Michel¹, A D Ellington, S Couture

¹Department of Molecular Biology, Massachusetts General Hospital, Boston 02114.

|October 11, 1990

Resumen

Los intrones del grupo I, un tipo de ribozima, utilizan nuevas interacciones base-triple para su estructura. Estas covariaciones filogenéticas, más allá de los emparejamientos de bases estándar, son cruciales para la función de la ribozima.

Área de la Ciencia:

Biología Molecular Biología Molecular
La bioquímica es la bioquímica.
La estructura del ARN es la estructura del ARN.

Sus antecedentes:

Las ribozimas catalizan las reacciones químicas, lo que requiere una comprensión profunda de su estructura.
La estructura secundaria de los intrones del grupo I está bien establecida a través de comparaciones de secuencias, protección química y estudios genéticos.
Los datos filogenéticos han demostrado ser efectivos para predecir las interacciones de ARN terciario, como se demuestra con el ARN de transferencia y el ARN ribosomal.

Objetivo del estudio:

Identificar nuevas interacciones terciarias en intrones del grupo I más allá de las parejas de bases canónicas.
Investigar las covariaciones evolutivas en secuencias de ARN que sugieren interacciones de bases no canónicas.
Para confirmar la importancia funcional de estas interacciones previstas a través de experimentos genéticos.

Principales métodos:

Análisis comparativo de secuencias de regiones del núcleo alineadas de intrones del grupo I.
La búsqueda de covariaciones filogenéticas no explicadas por Watson-Crick o emparejamientos de bases wobble.
Utilizando experimentos genéticos (mutaciones compensatorias) en los intrones Tetrahymena y sunY.

Principales resultados:

Se identificaron dos casos de covariación filogenética en intrones del grupo I.
Estas covariaciones se explican mejor por la presencia de bases triples enlazadas con hidrógeno, análogas a las del ARN de transferencia.
Los experimentos genéticos confirmaron la importancia de estas interacciones base-triple para la estructura de la ribozima.

Conclusiones:

Los intrones del grupo I emplean interacciones base-triple, además de los pares Watson-Crick y de oscilación, para la estabilidad estructural.
Estas interacciones no canónicas se conservan evolutivamente y son funcionalmente importantes para la actividad de la ribozima.
Los hallazgos amplían nuestra comprensión de los motivos estructurales del ARN y su papel en la catálisis.

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