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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
Published on: September 2, 2019
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Interacciones dependientes de nucleótidos dentro de un complejo especializado Hsp70/Hsp40 involucrado en la
Jin Hae Kim1, T Reid Alderson, Ronnie O Frederick
1Mitochondrial Protein Partnership, Center for Eukaryotic Structural Genomics, and ‡Department of Biochemistry, University of Wisconsin , Madison, Wisconsin 53706, United States.
Journal of the American Chemical Society
|August 2, 2014
Resumen
El motivo HPD de HscB interactúa directamente con HscA unido al ATP, mientras que un segundo sitio de unión en HscB interactúa directamente con HscA unido al ATP.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- Las chaperonas del tipo Hsp70 y las co-chaperonas del tipo Hsp40 son cruciales para la homeostasis de las proteínas.
- El mecanismo preciso de interacción entre estos acompañantes sigue siendo incompletamente entendido.
- Escherichia coli HscA y HscB son chaperones especializados involucrados en la transferencia de clusters de hierro y azufre.
Objetivo del estudio:
- Para aclarar el mecanismo de interacción dependiente de ATP / ADP entre HscA y HscB.
- Para identificar los dominios y residuos específicos involucrados en la formación del complejo HscA-HscB.
- Para entender el papel del motivo HPD en la función de HscB.
Principales métodos:
- Se empleó espectroscopia de RMN en solución para estudiar las interacciones HscA-HscB.
- Se utilizó la mutagenesis dirigida al sitio para alterar el motivo HPD de HscB.
- Se realizaron ensayos de hidrólisis de ATP para evaluar el impacto funcional de las mutaciones.
Principales resultados:
- Las señales de RMN del dominio J de HscB, incluido el motivo HPD, se ampliaron con la adición de HscA unido a ATP, pero no de HscA unido a ADP.
- Una variante de HscB con un motivo de HPD alterado (HscB ((H32A, P33A, D34A)) no mostró cambios significativos en la señal de RMN y eliminó la estimulación de la hidrólisis de ATP de HscA.
- Los residuos 153-171 en la región C-terminal de HscB también mostraron perturbaciones de RMN al interactuar con HscA, lo que indica un segundo sitio de unión.
Conclusiones:
- El motivo HPD de HscB interactúa directamente con el HscA ligado al ATP.
- Un sitio de unión secundario, menos dependiente de nucleótidos para HscA, se encuentra en la región C-terminal de HscB.
- Estos hallazgos proporcionan una visión crítica de las bases estructurales de la cooperación de chaperones Hsp70-Hsp40.
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