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Dos transiciones estructurales en la formación de poros de la membrana por la neumolisina, la toxina formadora de

R J Gilbert¹, J L Jiménez, S Chen

¹Department of Biochemistry, University of Leicester, United Kingdom.

|June 15, 1999

Resumen

Streptococcus pneumoniae crea monómeros de neumolisina solubles que forman poros en forma de anillo en las membranas celulares del huésped. El análisis estructural revela un mecanismo de dos etapas que implica reorganizaciones de dominio durante el ensamblaje de poros.

Área de la Ciencia:

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

Sus antecedentes:

* Streptococcus pneumoniae es un patógeno humano que causa varias infecciones.
* La neumolisina es un factor de virulencia clave producido por S. pneumoniae.
* La neumolisina forma poros en las membranas celulares del huésped, contribuyendo a la patogénesis.

Objetivo del estudio:

* Para determinar las estructuras tridimensionales de los oligómeros de la neumolisina y los poros ligados a la membrana.
* Para dilucidar el mecanismo de la formación de poros por pneumolysin.

Principales métodos:

* Se utilizó la microscopía crioectrónica (cryo-EM) para determinar las estructuras.
* El encaje de los dominios de la estructura cristalina (perfringolisina) en las estructuras cryo-EM.

Principales resultados:

* Determinadas estructuras de oligómero helicoidal y forma de anillo unido a la membrana de la pneumolisina.
* Se identificaron las principales rotaciones de dominio durante el ensamblaje de poros.
* Se reveló un mecanismo de dos etapas que involucra el reposicionamiento del dominio 3 y la interacción de la membrana del dominio 4.

Conclusiones:

* La formación de poros de Pneumolysin implica cambios conformacionales significativos.
* Los hallazgos proporcionan información sobre el mecanismo de formación de poros de la toxina que se une al colesterol.

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