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Estructura de la nicasa OMEGA IsrB en complejo con ARN ω y ADN objetivo

Seiichi Hirano^1,2,3,4,5, Kalli Kappel^1,2,3,4,5, Han Altae-Tran^1,2,3,4,5

¹Broad Institute of MIT and Harvard, Cambridge, MA, USA.

|October 12, 2022

Resumen

Los investigadores revelaron la estructura de una pequeña enzima guiada por ARN, IsrB, y su guía de ARN. Este hallazgo avanza en la comprensión de la evolución de CRISPR-Cas y los sistemas guiados por ARN.

Área de la Ciencia:

Biología molecular
Biología estructural
La bioquímica

Sus antecedentes:

Los sistemas guiados por ARN como CRISPR-Cas son herramientas moleculares vitales.
Las ideas estructurales guían la ingeniería de estos sistemas.
La clase OMEGA incluye IscB y el nickase IsrB.

Objetivo del estudio:

Determinar la estructura de Desulfovirgula thermocuniculi IsrB (DtIsrB) complejo con su ARN guía y ADN diana.
Comprender la base estructural para la orientación del ADN guiado por ARN de IsrB.
Aclarar la relación evolutiva entre IsrB y Cas9.

Principales métodos:

Se utilizó la microscopía electrónica criogénica (cryo-EM) para determinar la estructura.
Análisis estructural del complejo DtIsrB-ωRNA-ADN.
Análisis estructural comparativo con otros sistemas guiados por ARN.

Principales resultados:

La estructura DtIsrB comparte un andamio con Cas9.
IsrB utiliza su ARN ω, formando una estructura ternaria análoga al lóbulo REC de Cas9, para la selección de objetivos.
El ARN ω juega un papel crucial en el reconocimiento del sustrato.

Conclusiones:

IsrB representa un sistema guiado por ARN distinto con un mecanismo único para el reconocimiento de objetivos.
Los hallazgos proporcionan información sobre la evolución de los sistemas guiados por ARN, particularmente el linaje Cas9.
Este trabajo profundiza la comprensión de la interacción entre el ARN y la proteína en el reconocimiento molecular.

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