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Dinámica conformacional de la ligasa E3 bacteriana SspH1

Cassandra R Kennedy¹, Diego Esposito¹, Jessica Huber¹

¹Molecular Structure of Cell Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, United Kingdom.

The Journal of biological chemistry

|September 3, 2025

Resumen

Las nuevas ligasas E3 como Salmonella SspH1 son cruciales para la patogénesis bacteriana. La unión al sustrato modula, pero no libera completamente, la autoinhibición de SspH1, lo que sugiere que se necesitan otros mecanismos para la transferencia de ubiquitina.

Área de la Ciencia:

Microbiología
Biología molecular
Biología estructural

Sus antecedentes:

La familia SspH/IpaH de nuevas ligasas E3 (NEL) son factores esenciales de virulencia en las bacterias Gram negativas.
Estas enzimas se dirigen a las proteínas del huésped para su degradación, ayudando a la patogénesis bacteriana.
La naturaleza autoinhibida de estas ligasas E3 y los mecanismos de transferencia de ubiquitina no se comprenden completamente.

Objetivo del estudio:

Para aclarar los mecanismos moleculares de la autoinhibición de Salmonella SspH1 y la interacción con el sustrato.
Determinar la base estructural para la reacción de transferencia de ubiquitina mediada por SspH1.

Principales métodos:

Se utilizó la cristalografía de rayos X para determinar la estructura de Salmonella SspH1.
Se realizaron análisis de las propiedades de la solución en SspH1 solo y en complejo con sustrato y ubiquitina.

Principales resultados:

Salmonella SspH1 existe en un equilibrio conformacional entre los estados abierto y cerrado.
La unión al sustrato influye en este equilibrio, pero no induce cambios conformacionales significativos.
Los hallazgos sugieren que se requieren factores adicionales para facilitar la proximidad del sustrato al sitio activo para la transferencia de ubiquitina.

Conclusiones:

La autoinhibición de SspH1 está regulada por un equilibrio conformacional en lugar de únicamente por la unión al sustrato.
El mecanismo de transferencia de ubiquitina por SspH1 probablemente involucra factores más allá de los cambios conformacionales inducidos directamente por el sustrato.
Se necesita más investigación para identificar los mecanismos adicionales que facilitan la ubiquitinación mediada por SspH1.

Palabras clave:

E3 ubiquitina ligasa Mecanismo enzimático Dinámica de las proteínas estructura-función ubiquitinación Factor de virulencia

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