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Estructura cristalográfica de la proteína de hierro nitrogenasa de Azotobacter vinelandii
M M Georgiadis1, H Komiya, P Chakrabarti
1Department of Biochemistry, Columbia University, New York, NY 10032.
Science (New York, N.Y.)
|September 18, 1992
Resumen
La estructura de la nitrogenasa Fe-proteína revela que la hidrólisis del trifosfato de adenosina (ATP) está indirectamente acoplada a la transferencia de electrones a través de cambios alostéricos. Este hallazgo ofrece información sobre la fijación del nitrógeno y otros sistemas de transducción de energía.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Fijación de nitrógeno.
Sus antecedentes:
- La nitrogenasa facilita la fijación de nitrógeno dependiente del ATP, convirtiendo el dinitrógeno en amoníaco.
- Comprende Fe-proteína y MoFe-proteína; Fe-proteína enlaza la hidrólisis de ATP con la transferencia de electrones.
Objetivo del estudio:
- Para aclarar el papel del ATP en la fijación del nitrógeno mediante la determinación de la estructura cristalina de Azotobacter vinelandii nitrogenase Fe-protein.
- Comprender el mecanismo de acoplamiento entre la hidrólisis de nucleótidos y la transferencia de electrones.
Principales métodos:
- Se utilizó la cristalografía de rayos X para determinar la estructura de la nitrogenasa Fe-proteína.
- La estructura se resolvió a una resolución de 2,9 angstroms.
Principales resultados:
- La proteína Fe es un dímero con un grupo central 4Fe:4S ligado por cisteínas de ambas subunidades.
- Una sola molécula de adenosina difosfato (ADP) se une a la interfaz de la subunidad, ~20 A desde el grupo 4Fe:4S.
- El acoplamiento directo entre la hidrólisis de ATP y la transferencia de electrones es poco probable; se propone el acoplamiento alostérico indirecto.
Conclusiones:
- La estructura sugiere un acoplamiento alostérico indirecto entre la hidrólisis de nucleótidos y la transferencia de electrones en Fe-proteína.
- Este mecanismo comparte similitudes con las proteínas H-Ras p21 y recA.
- La estructura de la proteína Fe puede informar el estudio de otros sistemas de unión de nucleótidos y transducción de energía.
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