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El transporte de radicales facilitado por una red de transferencia de protones en la interfaz de subunidad de la
Chang Cui1, David Y Song1, Catherine L Drennan2,3,4
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Journal of the American Chemical Society
|February 22, 2023
Resumen
Las reductasas de ribonucleótidos (RNR) son cruciales para la síntesis de ADN. Este estudio revela una red de transporte de protones que incluye residuos específicos esenciales para la actividad de la enzima RNR y la formación de desoxinucleótidos.
Área de la Ciencia:
- La bioquímica
- Enzimología
- Biología molecular
Sus antecedentes:
- Las reductasas de ribonucleótidos (RNR) son enzimas vitales que catalizan la síntesis de desoxinucleótidos.
- Las RNR de clase Ia de *Escherichia coli* incluyen subunidades α y β que forman un complejo activo αα'ββ'.
- Una vía de transferencia de electrones acoplada a protones de largo alcance es esencial para la actividad RNR.
Objetivo del estudio:
- Aclarar el papel del residuo Y356[β] y la red polar asociada en la función RNR.
- Investigar el mecanismo de transferencia de protones en la interfaz α/β de *E. coli* clase Ia RNR.
Principales métodos:
- Mutagénesis dirigida al sitio utilizando aminoácidos canónicos y no naturales.
- Generación fotoquímica del radical Y356.
- Espectroscopia de absorción transitoria y ensayos de formación de desoxinucleótidos.
Principales resultados:
- El residuo Y356[β] y Y731[α] atraviesan la interfaz α/β.
- Una red de residuos (E52[β], R331[α], E326[α], E326[α']) es crucial para la oxidación de Y356.
- Esta red facilita el transporte de protones desde la interfaz hasta el disolvente a granel durante la oxidación de Y356.
Conclusiones:
- La red polar identificada (E52 [β], R331 [α], E326 [α], E326 [α']) es esencial para la actividad de RNR.
- Esta red juega un papel crítico en la transferencia de protones, apoyando el ciclo catalítico de RNR.
- Comprender este mecanismo proporciona información sobre la regulación de la biosíntesis de los desoxinucleótidos.
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