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Los modos alternativos de unión al cliente permiten la plasticidad funcional del Hsp70

Alireza Mashaghi¹, Sergey Bezrukavnikov¹, David P Minde¹

¹FOM institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.

|November 4, 2016

Resumen

El chaperón Hsp70 (DnaK) estabiliza las proteínas en varias etapas de plegado, no solo las cadenas desplegadas. Esta actividad de la chaperona, regulada por su tapa y ranura, afecta el plegamiento y la agregación de proteínas.

Área de la Ciencia:

Biología molecular
La bioquímica
Dinámica de las proteínas

Sus antecedentes:

La proteína de choque térmico 70 (Hsp70) es crucial para la homeostasis de las proteínas, ya que ayuda en el plegamiento, previene la agregación y regula el tráfico de proteínas.
Se cree que Hsp70 interactúa con los sustratos a través de una ranura de unión a péptidos cubierta por una tapa impulsada por ATP.
La observación directa de las interacciones del sustrato Hsp70 a través de diferentes estados de plegado y la comprensión de la dinámica de la tapa ha sido un desafío.

Objetivo del estudio:

Investigar los mecanismos de interacción de Hsp70 (DnaK) con sustratos de proteínas en varios estados conformacionales.
Para aclarar el papel de la tapa y ranura Hsp70 en la unión y estabilización del sustrato.
Explorar las implicaciones de los diversos modos de unión de Hsp70 en el plegamiento y la agregación de proteínas.

Principales métodos:

Se utilizaron pinzas ópticas para medir directamente las fuerzas e interacciones entre el homólogo bacteriano Hsp70 (DnaK) y los sustratos de proteínas.
Investigó la unión y estabilización de estructuras de proteínas desplegadas, parcialmente plegadas y casi nativas por DnaK.
Se examinaron las funciones sinérgicas de la tapa y ranura de DnaK utilizando variantes de tapa truncada y ranura mutada.

Principales resultados:

DnaK se une y estabiliza no solo las cadenas polipéptidas desplegadas, sino también las estructuras de proteínas parcialmente plegadas y casi nativas.
La tapa y la ranura Hsp70 funcionan sinérgicamente para estabilizar las estructuras plegadas; el truncamiento de la tapa o la mutación de la ranura perjudica significativamente esta función.
Hsp70 exhibe funciones duales reguladas por nucleótidos en la estabilización y desestabilización de proteínas, influyendo en el plegamiento en etapa tardía y suprimiendo la agregación al proteger varios conformadores de proteínas.

Conclusiones:

El modelo canónico de la función Hsp70 se extiende para incluir interacciones y estabilización de estados de proteínas plegadas.
La capacidad de Hsp70 para modular la estructura de proteínas a través de múltiples etapas de plegamiento tiene implicaciones significativas para el plegamiento de proteínas, la proteostasis celular y la enfermedad.
Estos hallazgos destacan la versatilidad de Hsp70 en el mantenimiento de la homeostasis de las proteínas celulares a través de diversos mecanismos de interacción con el sustrato.

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