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Papel del Mg2+ en la catálisis de la ribozima cabeza de martillo de simulación molecular
Tai-Sung Lee1, Carlos Silva López, George M Giambasu
1Consortium for Bioinformatics and Computational Biology, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Journal of the American Chemical Society
|February 15, 2008
Resumen
Los iones de magnesio (Mg2+) son cruciales para la catálisis de la ribozima cabeza de martillo (HHRz), estabilizando las estructuras clave y los estados de transición. Las simulaciones revelan que Mg2+ facilita la escisión del ARN mediante la coordinación de los residuos catalíticos esenciales.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología computacional Biología computacional.
- La biofísica molecular es la biofísica molecular.
Sus antecedentes:
- La ribozima cabeza de martillo (HHRz) es una pequeña molécula de ARN catalítico esencial para el procesamiento de ARN.
- Se sabe que los iones metálicos divalentes, particularmente el Mg2+, son críticos para la actividad catalítica de HHRz.
- Comprender el papel preciso de Mg2+ en el mecanismo de escisión de HHRz sigue siendo un área activa de investigación.
Objetivo del estudio:
- Para investigar las funciones estructurales y catalíticas de Mg2+ en la reacción de escisión de la ribozima de la cabeza de martillo.
- Caracterizar los modos de unión de Mg2+ y los cambios conformacionales que conducen a estados catalíticamente activos.
- Para dilucidar la estabilización del estado de transición por Mg2+ durante la catálisis del ARN.
Principales métodos:
- Realizó ocho simulaciones de dinámica molecular (DM) de 12 ns con diferentes ocupaciones de unión de Mg2+.
- Utilizó parámetros de campo de fuerza desarrollados recientemente para iones metálicos e intermedios reactivos en catálisis de ARN.
- Condujo cálculos híbridos de mecánica cuántica / mecánica molecular (QM / MM) en estados de transición temprana y tardía.
Principales resultados:
- La unión de Mg2+ estabiliza los elementos estructurales clave (tronco I y II) de las HHRz.
- El Mg2+ facilita la formación de conformaciones de ataque cercano e interacciones entre los residuos catalíticos.
- En el estado de transición, el Mg2+ hace de puente entre el grupo de salida y el catalizador ácido general (2'OH de G8).
Conclusiones:
- El Mg2+ juega un profundo papel estructural y catalítico en el mecanismo de la ribozima cabeza de martillo.
- El Mg2+ estabiliza el estado de transición coordinando el grupo saliente y facilitando la transferencia de protones.
- El modelo de simulación se alinea con los datos experimentales y proporciona una base para futuras investigaciones QM / MM.
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