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Torceduras en la catálisis: conformaciones alternas de la Escherichia coli tioredoxina reductasa
B W Lennon1, C H Williams, M L Ludwig
1Biophysics Research Division, Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
Science (New York, N.Y.)
|August 19, 2000
Resumen
La tioredoxina reductasa de Escherichia coli (TrxR) se somete a reorganizaciones de dominio para la reducción y reoxidación del dinucleótido de adenina flavina (FAD). Una estructura de 3.0 angstrom revela una conformación reductora de flavinas que permite la reducción de FAD por NADPH.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Enzimología Enzimología.
Sus antecedentes:
- La tioredoxina reductasa (TrxR) de Escherichia coli utiliza un cofactor de dinucleótido de adenina flavina (FAD, por sus siglas en inglés).
- La actividad enzimática implica la reducción cíclica y la reoxidación de FAD, dependiendo de las reorganizaciones de dominio.
Objetivo del estudio:
- Para aclarar la base estructural de la reducción de la flavina en E. coli TrxR.
- Para caracterizar la conformación reductora de flavinas de E. coli TrxR.
Principales métodos:
- Cristalografía de rayos X con una resolución de 3.0 angstroms.
- Comparación estructural de las diferentes conformaciones enzimáticas.
Principales resultados:
- Se determinó la estructura de la conformación reductora de flavinas de E. coli TrxR.
- Esta conformación permite la reducción de la FAD por NADPH y la oxidación del ditiol por tioredoxina.
- La comparación con una conformación alternativa revela una rotación de 67 grados del dominio de unión de nucleótidos de piridina, descrito como un movimiento de "bola y toma".
Conclusiones:
- Las reorganizaciones de dominio son críticas para el ciclo catalítico de E. coli TrxR.
- La conformación reductora de flavinas identificada proporciona información sobre el mecanismo de la reducción de FAD y las reacciones enzimáticas posteriores.
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