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Evolución en el tiempo de la activación alostérica en milisegundos de la imidazol glicerol fosfato sintasa

Carla Calvó-Tusell¹, Miguel A Maria-Solano^1,2, Sílvia Osuna^1,3

¹Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, c/Maria Aurèlia Capmany 69, 17003 Girona, Catalonia, Spain.

Journal of the American Chemical Society

|April 12, 2022

Resumen

Este estudio revela el mecanismo molecular a escala de milisegundos de la activación alosterica de la imidazol glicerol fosfato sintasa (IGPS). Los métodos computacionales muestran cómo el efector y la unión al sustrato desencadenan cambios conformacionales para una hidrólisis eficiente de la glutamina.

Área de la Ciencia:

Bioquímica y Biología Molecular
Biofísica computacional

Sus antecedentes:

La regulación alostérica enzimática es crucial para los procesos celulares.
La caracterización de los estados funcionales transitorios y la dinámica de milisegundos de enzimas como la imidazol glicerol fosfato sintasa (IGPS) sigue siendo un desafío.
La comprensión de la activación alostérica de IGPS es clave para descifrar su mecanismo catalítico.

Objetivo del estudio:

Para aclarar los mecanismos moleculares y la evolución en el tiempo de la activación alostérica de IGPS.
Caracterizar la transición de la forma libre de sustrato al complejo ternario activo.
Para descubrir los detalles moleculares ocultos de la regulación alosterica de milisegundos de largo alcance.

Principales métodos:

Simulaciones extensas de dinámica molecular.
Técnicas de muestreo mejoradas.
Análisis dinámico de la red.

Principales resultados:

Las simulaciones revelaron la captura espontánea de glutamina y la formación del complejo ternario activo sin conocimiento previo del estado activo.
El estudio identificó cambios conformacionales clave: la interfaz HisF:HisH cerrada y la formación de agujeros de oxyanión en HisH.
La unión combinada de efector y sustrato redujo significativamente la barrera conformacional para la formación de agujeros de oxyanión, lo que explica un aumento de actividad de 4500 veces.

Conclusiones:

La activación alostérica de IGPS es impulsada por redes dinámicas correlacionadas que conectan los sitios de unión del efector y el sustrato.
La estrategia computacional describió con éxito eventos en escala de tiempo de milisegundos en la regulación alosterica de la enzima.
Este enfoque puede guiar la ingeniería IGPS y racionalizar los efectos de la mutación en la regulación alostérica.

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