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Tit-for-tat: contraataque del sistema de secreción tipo VI durante las interacciones célula-célula bacteriana

Marek Basler¹, Brian T Ho, John J Mekalanos

¹Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.

|February 19, 2013

Resumen

Los sistemas de secreción bacteriana tipo VI (T6SS) participan en un "duelo" que mejora la matanza de sus presas. Los ataques de Pseudomonas aeruginosa T6SS son impulsados por la actividad de la presa T6SS, lo que sugiere un mecanismo de señalización de contraataque.

Área de la Ciencia:

Microbiología Microbiología.
Interacciones bacterianas célula-célula.
Sistemas de secreción de proteínas.

Sus antecedentes:

El sistema de secreción bacteriana de tipo VI (T6SS) es una máquina compleja para entregar proteínas efectoras en las células diana.
Se han observado interacciones dinámicas entre los orgánulos T6SS en las células adyacentes de Pseudomonas aeruginosa, denominadas "duelos T6SS".
Se supone que el duelo T6SS es un mecanismo para el ataque y la defensa bacteriana.

Objetivo del estudio:

Investigar la influencia del duelo T6SS en la depredación de especies bacterianas heterólogas por P. aeruginosa.
Para determinar si la actividad de T6SS de la presa afecta la eficacia de la matanza mediada por T6SS de P. aeruginosa.
Para aclarar las señales reguladoras que rigen el ensamblaje de orgánulos T6SS y contraataque.

Principales métodos:

Microscopía de fluorescencia en lapso de tiempo para observar la dinámica T6SS en P. aeruginosa.
Experimentos de co-cultivo con P. aeruginosa y especies de presas (Vibrio cholerae, Acinetobacter baylyi).
Pruebas para cuantificar la muerte bacteriana y la actividad T6SS en poblaciones que interactúan.

Principales resultados:

El duelo T6SS mejora significativamente la capacidad de P. aeruginosa para aprovecharse de otras especies bacterianas.
La matanza de V. cholerae y A. baylyi por P. aeruginosa T6SS es fuertemente estimulada por la presencia de actividad de T6SS en la presa.
Un mecanismo de señalización parece regular el montaje de P. aeruginosa T6SS y el contraataque letal en respuesta al ataque directo de T6SS.

Conclusiones:

El duelo T6SS es un factor crítico en la competencia y la depredación bacteriana entre especies.
La eficacia de los ataques bacterianos T6SS está modulada por las capacidades defensivas de la presa.
Una nueva vía de señalización vincula la detección de ataques T6SS con la activación de contraofensivas mediadas por T6SS.

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