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Fitocromo como máquina molecular: revelando la acción cromófora durante la fotoconversión Pfr --> Pr mediante

Thierry Rohmer¹, Christina Lang, Christian Bongards

¹Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.

Journal of the American Chemical Society

|March 9, 2010

Resumen

El fitocromo Cph1 cianobacteriano sufre un fotociclo, convirtiéndose entre los estados Pr y Pfr. El análisis estructural revela los intermediarios Lumi-F y Meta-F, detallando la vía de reacción de Pfr a Pr y la señalización de desencadenantes.

Área de la Ciencia:

La bioquímica es la bioquímica.
La espectroscopia es una técnica de espectroscopia.
La fotoquímica es la fotoquímica.

Sus antecedentes:

El fitocromo Cph1 de las cianobacterias cambia de forma reversible entre los estados Pr y Pfr.
Los fitocromos son fotorreceptores cruciales en varios organismos.

Objetivo del estudio:

Caracterizar estructuralmente los intermediarios de la reacción de retroceso de Pfr a Pr en Cph1.
Para dilucidar el mecanismo molecular y la direccionalidad del fotociclo Cph1.

Principales métodos:

Magia de giro de ángulo (MAS) espectroscopia de RMN a bajas temperaturas.
Caracterización estructural de los cromóforos de tetrapirrol etiquetados uniformemente con (13)C- y (15)N.

Principales resultados:

Dos intermediarios, Lumi-F y Meta-F, quedaron atrapados durante la conversión de Pfr a Pr.
La transición de Pfr a Lumi-F implica una fotoisomerización de doble enlace.
La transición de Lumi-F a Meta-F libera la tensión mecánica, rompiendo un enlace clave de hidrógeno e iniciando la señalización.

Conclusiones:

La vía de reacción de Pfr a Pr implica distintos intermediarios y cambios estructurales.
El orden alterado de los eventos en comparación con la reacción hacia adelante dicta la direccionalidad del fotociclo.
La dinámica de los enlaces de hidrógeno es crítica para la señalización fitocromática y la direccionalidad del fotociclo.

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