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El reconocimiento específico de la secuencia de las horquillas de ARN por los antiterminadores de bacteriófagos

D Lazinski¹, E Grzadzielska, A Das

¹Department of Microbiology, University of Connecticut Health Center, Farmington 06032.

|October 6, 1989

Resumen

Los antiterminadores de bacteriófagos como la proteína N se unen específicamente a las horquillas de ARN de la caja B en los sitios de las nueces. Esta interacción modifica la ARN polimerasa, evitando la terminación de la transcripción y asegurando la especificidad del genoma.

Área de la Ciencia:

Biología Molecular Biología Molecular
Genética La genética.
Virología Virología.

Sus antecedentes:

Los antiterminadores transcripcionales son cruciales para la regulación de la expresión génica en los bacteriófagos.
Los productos del gen N de los fagos lambda, 21 y P22 son antiterminadores esenciales.
Estos antiterminadores interactúan con sitios de reconocimiento específicos (sitios de nuez) para superar la terminación transcripcional.

Objetivo del estudio:

Para identificar los elementos de proteínas y ácidos nucleicos que rigen la especificidad del antiterminador-operón.
Para dilucidar el mecanismo molecular por el cual los antiterminadores modifican la ARN polimerasa.
Comprender el papel de los motivos conservados en las interacciones proteína-ARN.

Principales métodos:

La disección de determinantes de proteínas y ácidos nucleicos.
Análisis de las interacciones entre las proteínas N y los sitios de nueces.
Análisis comparativo de los motivos proteicos conservados.

Principales resultados:

Una secuencia de horquilla única (caja B) dentro de los sitios de las nueces confiere la especificidad del genoma.
boxB interactúa con un pequeño dominio amino-terminal de la proteína N. cognata.
Un subdominio rico en arginina, conservado a través de proteínas N y otras proteínas de unión al ARN, es crítico para esta interacción.

Conclusiones:

La interacción boxB con el ARN de la horquilla es el principal determinante de la especificidad del antiterminador.
El motivo rico en arginina conservado juega un papel clave en la unión al ARN y la antiterminación.
Este motivo es funcionalmente análogo a un dominio en la proteína Tat del VIH, destacando los mecanismos conservados en la regulación génica.

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