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Un complejo TRF1:BRF dirige la transcripción de la ARN polimerasa III de Drosophila por el ARN de Drosophila

S Takada¹, J T Lis, S Zhou

¹Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, 94720, USA.

|June 13, 2000

Resumen

En Drosophila, el factor relacionado con la proteína de unión TATA 1 (TRF1) complejado con BRF, no TBP, media la transcripción de la ARN polimerasa III. Este hallazgo desafía el papel universal de TBP en la transcripción.

Área de la Ciencia:

Biología Molecular Biología Molecular
Genética La genética.
La bioquímica es la bioquímica.

Sus antecedentes:

La proteína de unión TATA (TBP) se considera tradicionalmente un factor de transcripción universal para las polimerasas de ARN I, II y III.
Los mecanismos precisos de la iniciación de la transcripción de la ARN polimerasa III (Pol III) en Drosophila no están completamente aclarados.

Objetivo del estudio:

Para investigar el papel de los factores relacionados con TBP en la transcripción de la ARN polimerasa III en Drosophila.
Para identificar el complejo proteico específico responsable de la transcripción de Pol III en este organismo modelo.

Principales métodos:

Los ensayos de inmunoprecipitación identifican las interacciones de las proteínas.
Ensayos de transcripción in vitro utilizando extractos inmunodeprimidos y proteínas recombinantes.
Análisis de la colocalización de proteínas en los sitios del cromosoma politeno utilizando métodos in vivo.

Principales resultados:

El factor 1 relacionado con TBP (TRF1), no TBP, es esencial para la transcripción de la ARN polimerasa III en Drosophila.
Se requiere un complejo de TRF1 y BRF para reconstituir la transcripción de los genes de tRNA, 5S y U6 de ARN.
Se ha descubierto que TRF1 y BRF se complejan predominantemente in vivo y se colocalizan en los loci del gen Pol III en los cromosomas politenos.

Conclusiones:

TRF1, en complejo con BRF, juega un papel crítico en la transcripción de la ARN polimerasa III en Drosophila, reemplazando el papel generalmente aceptado de TBP.
Este estudio redefine los factores involucrados en la iniciación de la transcripción de Pol III en Drosophila, destacando la importancia de TRF1.

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