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Una bobina enrollada de la subunidad beta' de la polimerasa de ARN induce alostericamente la unión selectiva de la
B A Young1, L C Anthony, T M Gruber
1Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA.
Cell
|July 6, 2001
Resumen
Un pequeño péptido de la subunidad beta' de la ARN polimerasa permite a sigma ((70) reconocer el ADN promotor. Esta interacción es clave para el inicio de la transcripción, imitando la eficiencia de las enzimas centrales.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- La iniciación de la transcripción requiere de la ARN polimerasa para reconocer y desenrollar el ADN promotor.
- La vinculación selectiva a la cadena no modelo de la región -10 del promotor es crucial para este proceso.
- La subunidad sigma ((70) juega un papel en el reconocimiento del promotor.
Objetivo del estudio:
- Para investigar el papel de una región específica de la subunidad beta' de la ARN polimerasa en el reconocimiento de promotores.
- Para determinar si un fragmento de péptido puede inducir a sigma ((70) a realizar una unión selectiva de hebras no modelo.
- Para dilucidar el mecanismo de la transición alostérica en sigma ((70) mediada por la subunidad beta '.
Principales métodos:
- Investigó la función de un péptido en espiral de 48 aminoácidos de la subunidad beta' (aa 262-309).
- Se evaluó la capacidad de este péptido para inducir sigma ((70) para unirse a la hebra no modelo del promotor.
- Utilizó la información estructural de sigma para comprender el mecanismo de interacción.
Principales resultados:
- El péptido beta' coiled-coil (aa 262-309) indujo sigma ((70) para unir la hebra no modelo con la eficiencia de la polimerasa de ARN cercano al núcleo.
- La evidencia sugiere una interacción entre la región beta' coiled-coil y la región sigma ((70) 2.2.
- Esta interacción promueve una transición alostérica en sigma (70), lo que permite el reconocimiento selectivo de hebras no modelo.
- El reconocimiento no modelo se reconstituyó utilizando solo el péptido beta' y una porción cristalizada de sigma (70), que representa una pequeña fracción de la holoenzima.
Conclusiones:
- Un péptido mínimo de la subunidad beta' de la ARN polimerasa puede conferir un reconocimiento eficiente de cadenas de promotores no modelo a sigma (70).
- La interacción entre la región beta' coiled-coil y la región sigma ((70) 2.2 es crítica para esta función.
- Este hallazgo simplifica la comprensión de la iniciación de la transcripción al identificar los componentes clave para la unión del promotor.
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