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El plegamiento mediado por la chaperonina en el citosol eucariota procede a través de rondas de liberación de formas

G W Farr¹, E C Scharl, R J Schumacher

¹Department of Genetics and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510, USA.

|June 13, 1997

Resumen

La chaperonina citosólica eucariota (CCT) facilita el plegamiento de las proteínas. Una nueva investigación muestra que la CCT libera proteínas en ciclos, con solo una fracción que alcanza la forma nativa, similar al GroEL bacteriano.

Área de la Ciencia:

Biología Molecular Biología Molecular
Biología celular Biología celular.
El plegamiento de las proteínas.

Sus antecedentes:

La chaperonina citosólica eucariota, CCT, es crucial para el plegamiento dependiente de ATP de proteínas esenciales como la actina y la tubulina.
Existe un debate en curso con respecto al mecanismo de plegado de la CCT: una asociación / liberación de una sola ronda frente a la unión cíclica con liberación parcial y plegado.

Objetivo del estudio:

Para investigar la trayectoria de plegado de sustratos recién sintetizados unidos a CCT.
Para determinar si la CCT libera proteínas totalmente nativas o productos intermedios parcialmente plegados.

Principales métodos:

Los experimentos se llevaron a cabo utilizando lisado de reticulocitos y óvulos de Xenopus intactos.
Se introdujo una "trampa" de chaperonina de no liberación para estudiar el destino de las proteínas del sustrato.
El recién identificado sustrato G ((alfa) -transducina fue analizado junto con la actina y la tubulina.

Principales resultados:

La introducción de la trampa de chaperonina inhibió significativamente la producción de proteínas nativas, con sustratos que se transfieren a la trampa.
Las formas predominantemente no nativas de actina, tubulina y G ((alfa) -transducina fueron liberadas de la TCC.
Una pequeña fracción inaccesible a la trampa de las proteínas liberadas alcanzó la forma nativa en cada ciclo.

Conclusiones:

La CCT media el plegamiento de proteínas a través de la unión y liberación cíclica, donde solo un subconjunto de proteínas liberadas alcanza el estado nativo.
Este mecanismo es análogo al observado para la chaperonina bacteriana GroEL.
Los hallazgos aclaran el complejo proceso iterativo de maduración de proteínas mediada por CCT.

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