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Un ciclo de cuatro pasos impulsado por la hidrólisis de PI(4)P dirige el intercambio de esterol/PI(4)P por el tether

Bruno Mesmin¹, Joëlle Bigay, Joachim Moser von Filseck

¹Institut de Pharmacologie Moléculaire et Cellulaire, Université Nice Sophia Antipolis and CNRS, 06560 Valbonne, France.

|November 12, 2013

Resumen

La proteína de unión al oxicosterol (OSBP, por sus siglas en inglés) acopla la unión de los orgánulos y la transferencia de lípidos a través de un ciclo de cuatro pasos. Este proceso, impulsado por la hidrólisis de fosfoinosítidos, regula la transferencia de esteroles en los sitios de contacto de ER-Golgi.

Área de la Ciencia:

Biología celular Biología celular.
Biología de la Membrana Biología de la Membrana.
La bioquímica es la bioquímica.

Sus antecedentes:

Los sitios de contacto del retículo endoplasmático (ER) y la membrana de Golgi son cruciales para el transporte de lípidos.
Las proteínas en estos sitios a menudo poseen dominios PH, motivos FFAT y dominios de transferencia de lípidos, lo que sugiere un doble papel en el enlace y el transporte.
La proteína de unión al oxisterol (OSBP, por sus siglas en inglés) es un jugador clave en estas interfaces.

Objetivo del estudio:

Aclarar el mecanismo por el cual el OSBP acopla el enlace de la membrana y la transferencia de lípidos.
Investigar el papel del metabolismo de los fosfoinosítidos en la regulación del transporte de lípidos en los sitios de contacto de ER-Golgi.
Para determinar si este mecanismo se conserva entre otras proteínas de transferencia de lípidos.

Principales métodos:

Ensayos bioquímicos para estudiar las interacciones proteína-lípido.
Reconstitución in vitro del ciclo de transferencia de la OSBP.
Análisis de la hidrólisis del fosfoinosituro y su impacto en la transferencia de esteroles.

Principales resultados:

OSBP utiliza un ciclo de cuatro pasos que involucra el dominio PH y el enlace de motivos FFAT, la transferencia de esteroles, la transferencia de PI(4) P hacia atrás y la hidrólisis de PI(4) P por Sac1.
La energía de la hidrólisis de PI ((4) P impulsa la transferencia de esteroles y proporciona una retroalimentación negativa.
Este mecanismo de atadura es compartido por otras proteínas de transferencia de lípidos.

Conclusiones:

El OSBP acopla la unión de orgánulos y la transferencia de lípidos a través de un ciclo impulsado por hidrólisis de PI(4) P.
Este mecanismo regula el transporte de esteroles y puede coordinar otros eventos de transferencia de lípidos en la interfaz ER-Golgi.
El mecanismo de atadura conservado pone de relieve su importancia en la comunicación entre los órganos.

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