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La estructura cristalina de la biotina sintasa, una enzima radical dependiente de la S-adenosilmetionina, también es
Frederick Berkovitch1, Yvain Nicolet, Jason T Wan
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (New York, N.Y.)
|January 6, 2004
Resumen
La estructura cristalina de la biotina sintetasa revela cómo las enzimas SAM radicales generan radicales orgánicos utilizando racimos de hierro-azufre y S-adenosil-L-metionina para sintetizar la biotina.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Enzimología Enzimología.
Sus antecedentes:
- Las enzimas SAM radicales utilizan grupos de hierro-azufre y S-adenosil-L-metionina (AdoMet) para generar radicales orgánicos.
- La biotina sintasa es una enzima clave en la biosíntesis de la biotina, catalizando una reacción de inserción de azufre mediada por radicales.
Objetivo del estudio:
- Para dilucidar el mecanismo de generación de radicales y procesamiento de sustratos en la biotina sintasa.
- Determinar la estructura cristalina de alta resolución de la biotina sintasa en complejo con sus sustratos.
Principales métodos:
- Se empleó cristalografía de rayos X para determinar la estructura.
- La estructura fue resuelta a una resolución de 3.4 angstroms.
Principales resultados:
- La estructura cristalina de la biotina sintetasa de Escherichia coli fue determinada en complejo con S-adenosil-L-metionina y deshiobiotina.
- Se observaron sustratos posicionados entre los grupos Fe4S4 y Fe2S2, cruciales para la generación de radicales y la transferencia de azufre.
- Se identificaron entornos de coordinación sin precedentes para ambos grupos de hierro-azufre.
Conclusiones:
- La estructura determinada proporciona información a nivel atómico sobre el mecanismo SAM radical empleado por la biotina sintasa.
- Este trabajo aclara las funciones de los distintos grupos de hierro-azufre en el ciclo catalítico de la enzima.
- Los hallazgos avanzan en nuestra comprensión de las reacciones enzimáticas mediadas por radicales y la biosíntesis de biotina.
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