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Los sustratos controlan la multimerización y la activación del motor de ATPasa de múltiples dominios de la secreción

Oren S Rosenberg¹, Dustin Dovala², Xueming Li³

¹Division of Infectious Diseases, Department of Medicine, UCSF Medical Center, University of California, San Francisco, San Francisco, CA 94143-0654, USA.

|April 14, 2015

Resumen

El sistema de secreción de proteínas tipo VII (T7S) requiere todos los sustratos para funcionar. La unión al sustrato EsxB activa la translocasa EccC estimulando la multimerización, no de manera alosterica.

Área de la Ciencia:

Microbiología Microbiología.
Biología Estructural Biología estructural.
La bioquímica es la bioquímica.

Sus antecedentes:

La secreción de proteína tipo VII (T7S) es esencial para la virulencia en bacterias como Mycobacterium tuberculosis y Staphylococcus aureus.
Los sistemas T7S requieren exclusivamente que todos los sustratos de secreción estén activos, lo que sugiere mecanismos reguladores complejos.

Objetivo del estudio:

Para dilucidar la función de la translocación T7S EccC y su sustrato EsxB utilizando la biología estructural.
Comprender el mecanismo de la interdependencia de sustratos en el T7S.

Principales métodos:

Se utilizó la cristalografía de rayos X para determinar la estructura de la translocasa EccC.
Se realizaron ensayos bioquímicos para estudiar la interacción entre EccC y EsxB.

Principales resultados:

La estructura cristalina de EccC reveló interacciones entre sus tres dominios ATPasa que modulan la actividad enzimática.
EsxB se une al dominio C-terminal de la ATPasa de EccC, aumentando su actividad.
La unión al sustrato activa EccC a través de la multimerización, no de la regulación alostérica.

Conclusiones:

El sustrato EsxB es un componente integral de la maquinaria T7S, lo que explica la interdependencia de sustratos.
Se propone un modelo en el que la unión al sustrato regula su liberación coordinada de la bacteria.

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