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Estructuras de la deformilasa del péptido de E. coli unida a formar: información sobre la preferencia por Fe2+ sobre
Rinku Jain1, Bing Hao, Ren-Peng Liu
1Departments of Biochemistry and Chemistry, and Ohio State Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA.
Journal of the American Chemical Society
|March 31, 2005
Resumen
El hierro es el metal preferido para la actividad de la peptide deformilasa (PDF) de E. coli. Los estudios estructurales revelan hierro de hierro.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Enzimología Enzimología.
Sus antecedentes:
- La peptido deformilasa de E. coli (PDF) elimina los grupos de formilo N-terminales de las proteínas recién sintetizadas.
- Inicialmente se creía que el PDF era una enzima dependiente del zinc, pero la investigación indica que el hierro es el metal activo.
- Comprender la preferencia por los metales es crucial para elucidar el mecanismo y la función catalítica del PDF.
Objetivo del estudio:
- Para investigar la base estructural de la inusual preferencia por los metales de E. coli PDF.
- Para comparar la unión del formato, un producto de deformilación, a las formas de hierro (Fe-PDF), cobalto (Co-PDF) y zinc (Zn-PDF).
- Para correlacionar las diferencias estructurales con las diferencias observadas en la actividad enzimática.
Principales métodos:
- Se empleó cristalografía de rayos X de alta resolución para determinar las estructuras de Fe-, Co- y Zn-PDF.
- Se obtuvieron estructuras para cada forma de enzima en complejo con formato, el producto de la deformilación.
- Análisis de las interacciones entre metales y ligandos y modos de unión de formatos.
Principales resultados:
- El formato se une al metal del sitio activo en las tres formas enzimáticas, interactuando con residuos específicos de aminoácidos (Leu91, Gln50, Glu133).
- Se observó una diferencia clave en la unión del formato: la unión del bidentato en Fe-PDF y Co-PDF, frente a la unión del monodentato en Zn-PDF.
- Estas variaciones estructurales ofrecen información sobre las distintas actividades catalíticas asociadas con diferentes metales.
Conclusiones:
- Los datos estructurales proporcionan la primera evidencia que explica las diferencias de actividad dependientes del metal de PDF.
- La capacidad superior del hierro para unirse y activar el estado de transición para la escisión del grupo formilo probablemente subyace a la mayor actividad de Fe-PDF.
- Este estudio avanza en la comprensión del mecanismo catalítico de PDF y la coordinación de iones metálicos.
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