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Priorización de la carga sobre la geometría en los análogos de estado de transición de una proteína quinasa de doble
Liu Xiaoxia1, James P Marston, Nicola J Baxter
1Krebs Institute and Department of Molecular Biology & Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
Journal of the American Chemical Society
|February 26, 2011
Resumen
Los investigadores observaron directamente un complejo análogo de estado de transición para la fosforilación de la tirosina utilizando RMN con flúor-19. Este estudio revela cómo la quinasa MEK6 utiliza el tetrafluoroaluminato para imitar el grupo fosforilo durante la señalización.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Biología Química Biología química.
Sus antecedentes:
- Las proteínas quinasas son enzimas de señalización cruciales.
- La fosforilación de la tirosina es un mecanismo regulador clave.
- Comprender la dinámica del sitio activo de la quinasa es vital para el desarrollo de fármacos.
Objetivo del estudio:
- Para observar directamente un complejo análogo de estado de transición (TSA) para la fosforilación de tirosina.
- Para aclarar el papel de MEK6 en la formación de un complejo TSA con p38α MAP quinasa.
- Para investigar la coordinación del tetrafluoroaluminato (AlF) dentro del sitio activo de la quinasa.
Principales métodos:
- Espectroscopia de resonancia magnética nuclear (19F NMR) con fluoro-19 utilizado.
- MEK6 analizado en complejo con tetrafluoroaluminato (AlF(4)(-)), ADP y p38α MAP quinasa.
- Investigaron los desplazamientos de isótopos inducidos por disolventes y los desplazamientos químicos de la fracción AlF ((4) ((-)).
Principales resultados:
- Observación directa de un complejo TSA para la fosforilación de la tirosina por la MEK6 y la p38α MAP quinasa.
- Coordinación identificada de AlF(4)(-) por dos iones catalíticos de magnesio y residuos de proteínas.
- Se observó un complejo alternativo de AlF(4)(-) en Thr180 tras la mutación de Tyr182.
- Especie octaédrica caracterizada AlF ((4) ((-)), que difiere de los complejos bipiramidales trigonales previamente observados.
Conclusiones:
- MEK6 requiere características estructurales específicas para la formación de TSA, isoelectrónica con el grupo fosforilo.
- La coordinación de AlF(4)(-) por los iones de magnesio y los residuos de proteínas proporciona información sobre los mecanismos catalíticos de la quinasa.
- Este estudio demuestra la formación de especies octaédricas AlF(4)(-) en una quinasa con dos iones catalíticos de magnesio, ampliando el conocimiento más allá de los sistemas de iones de magnesio individuales.
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