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Superenrollamiento de ADN dependiente de la transcripción en el ADN de levadura mutantes de topoisomerasa de ADN de
1Department of Biochemistry, SUNY, Stony Brook 11794.
Cell
|July 29, 1988
Resumen
Los estudios de levadura revelan que si bien la topoisomerasa I y II del ADN no son esenciales para la transcripción de la ARN polimerasa II, la topoisomerasa I es crucial para relajar las superbobinas generadas durante la expresión génica.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Genética La genética.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Las topoisomerasas de ADN son enzimas que manejan la topología del ADN.
- La transcripción por la ARN polimerasa II implica el desenrollamiento y el enrollamiento del ADN.
- La topoisomerasa I y II juegan un papel en la replicación y transcripción del ADN.
Objetivo del estudio:
- Investigar las funciones de la topoisomerasa I y II del ADN en la transcripción por la ARN polimerasa II en la levadura.
- Determinar cuándo y por qué se produce el superenrolamiento del ADN durante la transcripción.
- Comprender el mecanismo de relajación de la superbobina durante la transcripción.
Principales métodos:
- Análisis de mutantes de topoisomerasa en el ADN de la levadura (mutantes top1 y top1-top2 ts).
- Aislamiento y análisis de plásmidos portadores de genes transcripcionalmente activos.
- Observación de los niveles de superenrolamiento del ADN bajo diferentes condiciones y temperaturas mutantes.
Principales resultados:
- Ni la topoisomerasa I ni la II son esenciales para la transcripción de la ARN polimerasa II.
- Los plásmidos con genes activos acumulan superenrollamiento negativo en los mutantes de la topoisomerasa I.
- El superenrolamiento ocurre durante el alargamiento transcripcional, no la activación, y es independiente de la topoisomerasa II.
- Se requiere la topoisomerasa I para relajar las superbobinas inducidas por la transcripción.
Conclusiones:
- La topoisomerasa I es esencial para relajar las superbobinas de ADN generadas durante el alargamiento de la transcripción.
- El mecanismo preciso que causa el superenrolamiento en ausencia de topoisomerasa I requiere más investigación.
- Las topoisomerasas son críticas para administrar la topología del ADN durante el movimiento de la ARN polimerasa a lo largo de la plantilla.
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