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Bases estructurales para el reconocimiento específico por base de 5' nucleótidos del ARN guía por el AGO2 humano

Filipp Frank¹, Nahum Sonenberg, Bhushan Nagar

¹Department of Biochemistry, McGill University, Montréal, Québec H3G 0B1, Canada.

|May 28, 2010

Resumen

Las proteínas argonautas humanas (AGOs) muestran una preferencia por el uracilo (U) o la adenina (A) en el extremo 5' de los microARN (miRNA). Los estudios estructurales revelan interacciones específicas dentro del dominio AGO MID que explican este sesgo de nucleótidos, crucial para la regulación génica.

Área de la Ciencia:

Biología Molecular Biología Molecular
Biología Estructural Biología estructural.
Genética La genética.

Sus antecedentes:

Los microARN (miRNA) regulan la expresión génica post-transcripcionalmente mediante la interacción con las proteínas argonautas (AGOs).
Estudios previos sobre AGOs procariotas sugirieron que la interacción del dominio MID con el extremo 5' del miRNA es independiente de los nucleótidos.
Las secuencias y experimentos de miRNA eucariotas muestran una preferencia por el uracilo (U) o la adenina (A) en la posición 5'.

Objetivo del estudio:

Determinar la base estructural para la preferencia de nucleótidos en el extremo 5' de los microARN eucariotas.
Para investigar la interacción entre el dominio MID del AGO2 humano y el extremo 5' de los imitadores de miRNA.

Principales métodos:

Cristalografía de rayos X del dominio humano AGO2 MID complejo con monofosfatos nucleósidos (AMP, CMP, GMP, UMP).
Experimentos de titulación de RMN para determinar las afinidades de unión.

Principales resultados:

La estructura cristalina revela contactos específicos entre el bucle rígido del dominio MID y el monofosfato de uracilo (UMP) o el monofosfato de adenina (AMP).
La estructura del dominio MID discrimina el monofosfato de citosina (CMP) y el monofosfato de guanina (GMP).
Las mediciones de afinidad vinculante confirman una mayor afinidad por AMP y UMP en comparación con CMP y GMP.

Conclusiones:

La evidencia estructural apoya las interacciones específicas de nucleótidos en el dominio MID de las proteínas AGO eucariotas.
Esta especificidad explica el sesgo observado para U o A en el extremo 5' de los microARN, impactando la regulación génica.

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