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Las interacciones electrostáticas del sitio activo de la ATPasa controlan la conformación global de la 100 kDa SecA
Dorothy M Kim1, Haiyan Zheng, Yuanpeng J Huang
1Department of Biological Sciences and Northeast Structural Genomics Consortium, 702A Fairchild Center, MC2434, Columbia University, New York, New York 10027, USA.
Journal of the American Chemical Society
|November 22, 2012
Resumen
Una sola carga en la enzima SecA.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- El transporte de proteínas en transporte.
Sus antecedentes:
- SecA es una mecanoenzima crucial para la secreción de proteínas en las bacterias.
- Su motor ATPasa comparte homología con las helicasas de ARN DEAD-box.
- Comprender cómo la hidrólisis local de ATP afecta la conformación global de SecA es clave.
Objetivo del estudio:
- Para investigar el papel de la carga electrostática en el sitio activo de la ATPasa de SecA.
- Aclarar el mecanismo que vincula los eventos químicos locales con los cambios conformacionales globales.
- Para caracterizar la mecanoquímica alostérica de SecA.
Principales métodos:
- Métodos biofísicos, incluida la calorimetría.
- La mutación isostérica (del glutamato a la glutamina) en la base catalítica.
- Espectrometría de masas de intercambio de hidrógeno y deuterio.
Principales resultados:
- Una sola carga electrostática en el sitio activo de la ATPasa controla la conformación global de SecA.
- Una mutación de glutamato a glutamina facilita o desencadena la transición conformacional de la enzima.
- Esta mutación aumenta la dinámica de la columna vertebral de la proteína en sitios remotos, lo que indica una regulación alostérica.
Conclusiones:
- Los cambios electrostáticos locales durante la hidrólisis de ATP están acoplados a cambios conformacionales y dinámicos globales en SecA.
- Este acoplamiento está mediado por una intrincada red de interacciones estructurales.
- La mecanoquímica alostérica de SecA convierte eficientemente la energía química en trabajo mecánico para el transporte de proteínas.
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