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La unión de un ligando específico inhibe la importación de una proteína precursora purificada en las mitocondrias

M Eilers, G Schatz

|July 17, 1986

Resumen

El metotrexato bloquea la importación mitocondrial de dihidrofolato reductasa estabilizándola, no enmascarando su señal. Esto indica que la dihidrofolato reductasa debe desarrollarse para el transporte mitocondrial.

Área de la Ciencia:

Biología mitocondrial Biología mitocondrial
Biología molecular La biología molecular.
La bioquímica es la bioquímica.

Sus antecedentes:

Las proteínas mitocondriales se sintetizan en el citosol y se importan a las mitocondrias.
La pre-secuencia mitocondrial apunta las proteínas a las mitocondrias.
La dihidrofolato reductasa (DHFR) es una enzima involucrada en el metabolismo del folato.

Objetivo del estudio:

Para investigar el mecanismo por el cual el metotrexato afecta la importación mitocondrial de dihidrofolato reductasa.
Para determinar si el metotrexato inhibe el paso de orientación o translocación de la importación mitocondrial.

Principales métodos:

Fusión de la dihidrofolato reductasa del ratón con una preseguencia mitocondrial.
Ensayos de importación in vitro en mitocondrias aisladas.
Análisis de la estabilidad y conformación de las proteínas.

Principales resultados:

El metotrexato bloqueó la importación mitocondrial de la proteína de fusión de la pre-secuencia DHFR.
El metotrexato estabilizó la fracción de dihidrofolato reductasa, pero no enmascaró la pre-secuencia.
La importación de la proteína precursora auténtica no fue inhibida por el metotrexato.

Conclusiones:

El metotrexato inhibe la importación mitocondrial de DHFR estabilizando la proteína, no bloqueando la pre-secuencia.
Los resultados sugieren que la dihidrofolato reductasa debe al menos desplegarse parcialmente para ser transportada a través de las membranas mitocondriales.

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