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Tensión de ángulo de torsión del centro activo revelada en la estructura de resolución de 1,6 A de la proteína
Z Jia1, M Vandonselaar, J W Quail
1Department of Chemistry, University of Saskatchewan, Saskatoon, Canada.
Nature
|January 7, 1993
Resumen
La estructura de la proteína fosfotransportadora (HPr) que contiene histidina revela una tensión de ángulo de torsión única en su sitio activo. Esta cepa probablemente reduce la barrera de energía de activación, facilitando el transporte de carbohidratos bacterianos a través del sistema de la fosfotransferasa.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Microbiología Microbiología.
Sus antecedentes:
- El phosphoenolpyruvate: el sistema de azúcar phosphotransferase (PTS) es crucial para el transporte de carbohidratos bacterianos a través de las membranas celulares.
- La proteína fosfotransportadora que contiene histidina (HPr) es un intermediario clave en la cascada de fosfotransferencia del PTS.
- El PTS facilita el transporte de azúcares termodinámicamente favorable utilizando fosfoenolpiruvato de alta energía.
Objetivo del estudio:
- Para determinar la estructura de rayos X de alta resolución de HPr de Streptococcus faecalis. para determinar la estructura de rayos X de alta resolución de HPr de Streptococcus faecalis. para determinar la estructura de rayos X de alta resolución de HPr de Streptococcus faecalis.
- Investigar el papel de la tensión del ángulo de torsión del sitio activo en la función HPr y el mecanismo de fosfotransferencia.
- Proponer un mecanismo detallado para el ciclo de HPr fosfotransfer.
Principales métodos:
- Se utilizó la cristalografía de rayos X para determinar la estructura 3D de HPr de Streptococcus faecalis a una resolución de 1,6 Å.
- Análisis de los ángulos de torsión de Ramachandran en el centro activo para identificar y cuantificar la tensión.
- Análisis estructural comparado con HPr de Bacillus subtilis.
Principales resultados:
- La estructura de rayos X de Streptococcus faecalis HPr reveló ángulos de torsión Ramachandran significativos y no permitidos en el centro activo, lo que indica una tensión sustancial de ángulo de torsión.
- Se supone que esta tensión de ángulo de torsión reduce la barrera de energía de activación para el fosfotransfer durante la fosforilación.
- La comparación con la estructura HPr de Bacillus subtilis (estado fosforilado, sin tensión) apoya el papel funcional de la tensión de ángulo de torsión en la actividad HPr.
Conclusiones:
- La deformación del ángulo de torsión en el centro activo de HPr es una característica crítica directamente involucrada en facilitar la reacción de fosfotransferencia.
- Un mecanismo propuesto para el ciclo del HPr fosfotransfer es apoyado por datos estructurales de HPr y otras proteínas PTS.
- Comprender las relaciones estructura-función de la HPr proporciona información sobre el metabolismo bacteriano de los carbohidratos y la regulación del transporte.
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