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Cristalografía bidimensional de los complejos TFIIB- e IIE-RNA polimerasa II: implicaciones para la selección del
K K Leuther1, D A Bushnell, R D Kornberg
1Department of Structural Biology, Stanford University School of Medicine, California 94305-5400, USA.
Cell
|May 31, 1996
Resumen
La cristalografía de electrones reveló los factores de transcripción IIB (TFIIB) y IIE (TFIIE) unidos a la ARN polimerasa II. Estos hallazgos sugieren que el TFIIB posiciona el ADN, mientras que el TFIIE facilita los cambios conformacionales durante la iniciación de la transcripción.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La iniciación de la transcripción es un proceso complejo regulado por varios factores proteicos.
- Comprender la base estructural de las interacciones del factor de transcripción con la ARN polimerasa II es crucial para descifrar la regulación génica.
Objetivo del estudio:
- Aclarar las funciones estructurales de los factores de transcripción IIB (TFIIB) y IIE (TFIIE) en el inicio de la transcripción.
- Para visualizar la unión de TFIIB y TFIIE a la ARN polimerasa II utilizando cristalografía electrónica de alta resolución.
Principales métodos:
- Se empleó cristalografía electrónica para determinar la estructura de la ARN polimerasa II unida al TFIIB y al TFIIE.
- El estudio logró una resolución de 15.7 Å, proporcionando imágenes de proyección del complejo.
Principales resultados:
- Visualización directa de TFIIB y TFIIE en complejo con ARN polimerasa II.
- Los datos estructurales revelaron la disposición espacial de estos factores de transcripción en relación con la polimerasa.
Conclusiones:
- TFIIB puede funcionar para posicionar el elemento de ADN de unión a TATA a una distancia específica del centro activo de la polimerasa, definiendo el sitio de inicio de la transcripción.
- Se supone que TFIIE juega un papel en un cambio conformacional crítico en el sitio activo durante la interacción entre la polimerasa y el ADN durante la iniciación de la transcripción.
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