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Bio-layer Interferometry for Measuring Kinetics of Protein-protein Interactions and Allosteric Ligand Effects
Published on: February 18, 2014
Interacciones asimétricas del ATP con la AAA+ ClpX6 desfoldasa: control alostérico de una máquina de proteínas
Greg L Hersch1, Randall E Burton, Daniel N Bolon
1Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02319, USA.
Cell
|July 2, 2005
Resumen
El hexámero AAA+ ClpX utiliza sitios asimétricos de unión al ATP para desplegar y translocar proteínas para su degradación. Este mecanismo permite múltiples intentos sin liberar sustratos, lo que excluye los modelos de hidrólisis concertados.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
Sus antecedentes:
- Las proteínas AAA+, como ClpX, son máquinas moleculares dependientes del ATP y cruciales para la homeostasis de las proteínas celulares.
- Los hexámeres de ClpX utilizan la hidrólisis de ATP para impulsar el despliegue y la translocación de proteínas para su degradación por la proteasa ClpXP.
- Comprender el mecanismo de unión de nucleótidos e hidrólisis es clave para dilucidar la función de ClpX.
Objetivo del estudio:
- Para investigar las propiedades asimétricas de unión a nucleótidos del hexámero AAA+ ClpX.
- Para determinar los estados funcionales de ClpX durante el reconocimiento y procesamiento del sustrato.
- Aclarar el mecanismo de la hidrólisis del ATP y su papel en el despliegue y la translocación de proteínas.
Principales métodos:
- Ensayos bioquímicos para caracterizar la cinética de unión y hidrólisis de ATP en sitios individuales de unión de nucleótidos.
- Estudios estructurales para visualizar los estados de unión de nucleótidos del hexámero ClpX.
- Análisis del reconocimiento de sustratos y mecanismos de desarrollo en relación con la ocupación de nucleótidos.
Principales resultados:
- Identificaron tres clases distintas de sitios de unión de nucleótidos dentro del hexámero ClpX, que exhiben propiedades asimétricas.
- Se demostró que el reconocimiento del sustrato requiere la unión de ATP en sitios específicos y ATP / ADP en otros, lo que permite repetidos intentos de despliegue.
- Se descartaron modelos de hidrólisis de ATP concertada en los seis sitios, que apoyan los estados funcionales con tres o cuatro nucleótidos unidos.
Conclusiones:
- El hexámero ClpX funciona a través de un mecanismo asimétrico, utilizando distintos sitios de unión de nucleótidos para un procesamiento eficiente de proteínas.
- Los hallazgos revelan un mecanismo que permite el despliegue repetido del sustrato sin liberación, crucial para la degradación.
- Destaca los principios mecánicos conservados entre diversas proteínas AAA+, incluidas las translocasas y las helicasas.
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