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Inhibición de las ligasas de ubiquitina bacteriana por glutamilación catalizada por SidJ-calmodulina
Sagar Bhogaraju1,2,3, Florian Bonn4, Rukmini Mukherjee4,5
1Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt am Main, Germany. bhogaraju@embl.fr.
Nature
|July 23, 2019
Resumen
La virulencia de Legionella pneumophila se basa en las enzimas SidE. SidJ actúa como una glutamilasa, inactivando SidE mediante la modificación de su glutamato catalítico, un proceso que requiere calmodulina e iones de calcio.
Área de la Ciencia:
- Microbiología
- Biología molecular
- La bioquímica
Sus antecedentes:
- Legionella pneumophila utiliza las enzimas SidE para la ubiquitinación y la infectividad.
- SidJ se opone a la toxicidad de SidE, pero su mecanismo era desconocido.
- SidJ es crucial para el crecimiento de Legionella en las células huésped.
Objetivo del estudio:
- Para aclarar el mecanismo de SidJ en la actividad de oposición de SidE.
- Para caracterizar a SidJ como una glutamilasa.
- Para explorar el papel de la calmodulina y el calcio en la función SidJ.
Principales métodos:
- Pruebas bioquímicas para identificar la actividad enzimática de SidJ.
- Microscopía criolectrónica para determinar la estructura del complejo SidJ-calmodulina.
- Proteómica cuantitativa para identificar los objetivos del SidJ.
Principales resultados:
- SidJ es una glutamilasa que modifica el glutamato catalítico de SdeA, inhibiendo su actividad ligasa.
- La actividad de SidJ depende de la calmodulina y el calcio intracelular.
- El análisis estructural reveló la arquitectura heterodimérica de la glutamilasa.
- SidJ glutamiliza las enzimas SidE en las vacuolas que contienen Legionella.
- Proteomics identificó las proteínas del huésped como objetivos potenciales de SidJ.
Conclusiones:
- SidJ inhibe las ligasas de SidE a través de la glutamilación dependiente de la calmodulina.
- Este estudio revela un nuevo mecanismo de regulación del efector bacteriano.
- Destaca la glutamilación como una modificación eucariota poco estudiada.
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