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Tratamiento de la redox basada en ligandos en la reductasa de sulfoxido de metionina dependiente del molibdeno
Laura J Ingersol1, Jing Yang1, Khadanand Kc1
1Department of Chemistry and Chemical Biology , The University of New Mexico , MSC03 2060, 1 University of New Mexico , Albuquerque , New Mexico 87131-0001 , United States.
Journal of the American Chemical Society
|January 29, 2020
Resumen
Los investigadores estudiaron la metionina sulfóxido reductasa (MsrP) de E. coli utilizando una espectroscopia avanzada. Descubrieron una estructura única de sitio activo "bloqueado por tiol", diferente de las enzimas relacionadas.
Área de la Ciencia:
- La bioquímica
- Biofísica y Química
- Enzimología
Sus antecedentes:
- Las metionina sulfóxido reductasas (MsrP) son enzimas cruciales involucradas en la homeostasis redox celular.
- Comprender la estructura del sitio activo de MsrP es clave para dilucidar su mecanismo de transferencia de átomos de oxígeno.
Objetivo del estudio:
- Investigar la estructura geométrica y electrónica de la reductasa de sulfoxido de metionina dependiente del molibdeno en el periplasma de E. coli (MsrP).
- Caracterizar la coordinación del sitio activo y las propiedades redox del MsrP en su estado aislado.
Principales métodos:
- Espectroscopia de resonancia paramagnética de electrones pulsados (EPR) (incluido el etiquetado 17O y 1H).
- Espectroscopía de ondas continuas (CW) EPR.
- Espectroscopia de absorción de rayos X (XAS), específicamente Estructura fina de absorción de rayos X extendida (EXAFS).
Principales resultados:
- El Mo(V) MsrP aislado no contiene un ligando intercambiable H2O/OH en el centro de molibdeno, a diferencia de las enzimas oxidantes de sulfito relacionadas.
- La reevaluación de los espectros de CW EPR, respaldada por datos de una variante MsrP-N45R y análogos de moléculas pequeñas, indica una nueva estructura de sitio activo "bloqueado por tiol": [(PDT) MoVO (((SCys)) ]-.
- Los datos de EXAFS corroboran el ambiente de coordinación bloqueado por tiol propuesto.
Conclusiones:
- Los hallazgos revelan una arquitectura de sitio activo única en MsrP, caracterizada por un centro de molibdeno "bloqueado por tiol".
- Esta característica estructural tiene implicaciones para la comprensión del mecanismo catalítico de la enzima, particularmente sus capacidades de transferencia de átomos de oxígeno.
- El estudio contribuye a una comprensión más amplia de las enzimas dependientes de molibdeno y su química redox.
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