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Coordinación iónico-substrato catalítico durante la extensión de primeras de ARN no enzimáticas

Ziyuan Fang¹, Lydia T Pazienza^2,3, Jian Zhang¹

¹Department of Chemistry, Howard Hughes Medical Institute, The University of Chicago, Chicago, Illinois 60637, United States.

Journal of the American Chemical Society

|April 5, 2024

Resumen

Los iones metálicos divalentes como el Mg2+ son cruciales para la copia del ARN no enzimático. Este estudio revela que el Mg2+ se coordina específicamente con un oxígeno fosfato, facilitando la extensión del primer de ARN a través de una reacción catalizada por el metal.

Área de la Ciencia:

La bioquímica
Astrobiología
El origen de los estudios biológicos

Sus antecedentes:

La copia de ARN dirigida por plantilla no enzimática es un proceso clave para comprender el origen de la vida.
Los iones metálicos divalentes son catalizadores esenciales para esta replicación del ARN.
El papel preciso de la coordinación de iones metálicos en el centro de reacción no se entiende completamente.

Objetivo del estudio:

Investigar la coordinación de iones metálicos catalíticos con sustratos de dinucleótidos con puente de imidazolio durante la extensión del primer de ARN.
Elucidar las interacciones estereospecíficas entre los iones metálicos y los sustratos de ARN modificados.

Principales métodos:

Catalización examinada utilizando iones metálicos oxófilos y tiófilos (Mg2+, Cd2+) con sustratos de dinucleótidos modificados por fosfato.
Se analizaron ambos diastereómeros de los sustratos modificados.
Determinación de las estructuras del producto mediante cristalografía de rayos X de alta resolución.

Principales resultados:

Mg2+ y Cd2+ mostraron preferencias diastereoméricas opuestas, lo que indica una interacción estereospecífica de iones metálicos.
Las estructuras de rayos X revelaron coordenadas Mg2+ con el oxígeno fosfato pro-Sp.
Los iones de cadmio interactúan preferentemente con el azufre en la misma posición.

Conclusiones:

La interacción del ion Mg2+ catalítico con el oxígeno pro-Sp es crítica para la reacción S_N2(P) en la extensión del primer de ARN no enzimático.
Este mecanismo de coordinación estereospecífico proporciona información sobre los primeros procesos de replicación del ARN.
Comprender estas interacciones es vital para la investigación del origen de la vida.

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