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Las deubiquitinasas agudizan la discriminación del sustrato durante la degradación de las proteínas de la membrana de

Zai-Rong Zhang¹, Juan S Bonifacino, Ramanujan S Hegde

¹Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 18 Library Drive, Bethesda, MD 20892, USA. zairong.zhang@gmail.com

|July 30, 2013

Resumen

Las ligasas de ubiquitina controlan el destino de las proteínas, pero aún no está claro cómo las interacciones sutiles dictan los resultados. Este estudio revela que la deubiquitinación continua amplifica las pequeñas diferencias en la unión proteína-ligasa, asegurando un control preciso de la calidad de las proteínas de la membrana.

Área de la Ciencia:

Biología celular Biología celular.
La bioquímica es la bioquímica.
Los mecanismos moleculares de la degradación de las proteínas.

Sus antecedentes:

Las proteínas de membrana recién sintetizadas se someten a la ubiquitinación, un proceso mediado por complejos de ubiquitina ligasa que determina su destino de degradación o no degradativo.
Los mecanismos precisos por los cuales las variaciones menores en las interacciones sustrato-ligasa conducen a distintos resultados de ubiquitinación no están completamente esclarecidos.

Objetivo del estudio:

Investigar los mecanismos que rigen la discriminación de sustratos en el control de calidad de las proteínas de membrana.
Comprender cómo los resultados de ubiquitinación diferencial surgen de las diferencias sutiles en las interacciones sustrato-ligasa.

Principales métodos:

Reconstitución del reconocimiento de proteínas de membrana y ubiquitinación en liposomas utilizando componentes purificados.
Utilizando análisis computacionales y experimentales para estudiar la ubiquitinación y la dinámica de la deubiquitinación.
Empleando células cultivadas para evaluar el destino in vivo de los clientes de proteínas degradadas y no degradadas.

Principales resultados:

Las interacciones de sustrato-ligasa dentro de la membrana impactan directamente en la procesividad de la unión de la ubiquitina, modulando así la poliubiquitinación.
La procesividad diferencial de ubiquitinación por sí sola fue insuficiente para explicar los distintos destinos celulares de los clientes de proteínas.
La deubiquitinación continua fue identificada como esencial para amplificar las pequeñas diferencias en las interacciones sustrato-ligasa, lo que lleva a una discriminación máxima del sustrato.

Conclusiones:

Se ha establecido un marco conceptual para la discriminación de sustratos en el control de calidad de las proteínas de membrana.
Las deubiquitinasas juegan un papel crítico al reducir los tiempos de permanencia de la poliubiquitina en sustratos que se disocian más fácilmente de la ligasa.
Este mecanismo amplifica las variaciones menores en la unión de sustrato-ligasa en diferencias significativas en la degradación neta de proteínas.

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