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Mecanismos moleculares que rigen la transcripción específica de la especie del ARN ribosomal
S P Bell1, C S Pikaard, R H Reeder
1Howard Hughes Medical Institute, Department of Biochemistry, University of California, Berkeley 94720.
Cell
|November 3, 1989
Resumen
Los factores de transcripción específicos de la especie hUBF y xUBF se unen a ADN similar, pero no se sustituyen entre sí. Las distintas interacciones proteína-proteína con SL1 determinan la activación del promotor específico de la especie.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Genética La genética.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La transcripción del ARN ribosomal (ARNr) es crucial para el crecimiento celular y está regulada por la ARN polimerasa I (Pol I).
- El reconocimiento de promotores en la transcripción de genes de ARNr exhibe especificidad de especie, un fenómeno poco comprendido.
- Los factores de transcripción como el UBF humano (hUBF) y el Xenopus UBF (xUBF) son reguladores clave de la transcripción de Pol I.
Objetivo del estudio:
- Investigar la base molecular para el reconocimiento de promotores específicos de la especie en la transcripción del ARNr.
- Para determinar si la especificidad de la especie está mediada por la unión al ADN o las interacciones proteína-proteína.
Principales métodos:
- Aislamiento y caracterización de la UBF humana (hUBF) y la UBF de Xenopus (xUBF).
- Análisis de transcripción reconstituidos utilizando factores purificados y ADN promotor.
- Análisis de la formación compleja entre los factores UBF y SL1 (un activador de Pol I específico de la especie) utilizando métodos bioquímicos.
Principales resultados:
- Tanto hUBF como xUBF se unen a los mismos elementos de la secuencia de ADN dentro de los promotores de genes de ARNr.
- hUBF y xUBF no son funcionalmente intercambiables en los sistemas de transcripción reconstituidos.
- hUBF y xUBF forman complejos distintos con el SL1 humano, independientemente de la especie de origen del promotor.
Conclusiones:
- La especificidad de la especie en la transcripción de genes de ARNr no está determinada únicamente por el reconocimiento de la secuencia de ADN por los factores UBF.
- Las interacciones específicas proteína-proteína entre UBF y SL1 son determinantes críticos de la selectividad del promotor específico de la especie.
- Esto pone de relieve la importancia de la formación de complejos de factores de transcripción en la regulación de la expresión génica específica de la especie.
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