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En cristallo, la modificación post-traduccional dentro de un complejo de MauG/pre-metilamina deshidrogenasa
Lyndal M R Jensen1, Ruslan Sanishvili, Victor L Davidson
1Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
Science (New York, N.Y.)
|March 13, 2010
Resumen
La enzima MauG crea el cofactor TTQ para la metilamina deshidrogenasa (MADH) mediante la modificación de los residuos de triptófano. La cristalografía de rayos X revela detalles estructurales y la competencia catalítica del complejo MauG-preMADH.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Enzimología Enzimología.
Sus antecedentes:
- La metilamina deshidrogenasa (MADH) requiere un triptófano triptofilquinona (TTQ) cofactor para la actividad.
- MauG es una enzima dihémica esencial para la modificación post-traduccional de los residuos de triptófano para formar el cofactor TTQ.
Objetivo del estudio:
- Para aclarar la base estructural de la síntesis de cofactores TTQ mediada por MauG.
- Para investigar el mecanismo catalítico de MauG en complejo con su sustrato preMADH.
Principales métodos:
- Se utilizó cristalografía de rayos X para determinar la estructura del complejo MauG-preMADH a una resolución de 2.1 angstroms.
- Los ensayos de actividad catalítica se realizaron mediante el monitoreo de la síntesis TTQ después de la adición de peróxido de hidrógeno.
Principales resultados:
- La estructura cristalina reveló distancias significativas entre los hierros hemo tipo c y el sitio precursor TTQ, lo que implica una transferencia de electrones de largo alcance.
- Se observó una ligadura axial His-Tyr atípica para uno de los grupos hemo.
- El complejo MauG-preMADH demostró competencia catalítica, con una síntesis TTQ dependiente de MauG que ocurre en presencia de peróxido de hidrógeno.
Conclusiones:
- Los datos estructurales y funcionales proporcionan información sobre las vías de transferencia de electrones y la ligación única en MauG.
- MauG es catalíticamente activo en su complejo cristalino, apoyando su papel en la formación de cofactores TTQ.
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