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El objetivo del ARN desencadena la actividad indiscriminada de la nucleasa de CRISPR-Cas12a2

Jack P K Bravo¹, Thomson Hallmark², Bronson Naegle²

¹Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA.

|January 4, 2023

Resumen

La enzima Cas12a2 asociada a CRISPR degrada el ARN y el ADN después de unirse a un ARN objetivo. Los estudios estructurales revelan su vía de activación y el mecanismo para conferir inmunidad a nivel de población.

Área de la Ciencia:

Biología molecular
Biología estructural
La genética

Sus antecedentes:

Las nucleasas asociadas a CRISPR (Cas) son componentes clave de la inmunidad adaptativa en las procariotas.
Cas12a2 es una nucleasa CRISPR conocida por degradar varios ácidos nucleicos después del reconocimiento del objetivo.
La comprensión del mecanismo de activación de Cas12a2 es crucial para sus aplicaciones biotecnológicas.

Objetivo del estudio:

Aclarar la base estructural de la activación de Cas12a2 y su mecanismo de acción.
Para revelar la vía de activación completa de Cas12a2 a través del análisis estructural.
Proporcionar información sobre cómo Cas12a2 contribuye a la infección abortiva y la inmunidad a nivel de la población.

Principales métodos:

Se utilizó la cristalografía de rayos X para determinar las estructuras de Cas12a2 en diferentes estados complejos (binario, ternario, cuaternario).
Es probable que se hayan empleado ensayos bioquímicos para estudiar la degradación del sustrato y la actividad enzimática.
Se utilizaron experimentos in vivo para evaluar el papel de Cas12a2 en la función inmune.

Principales resultados:

Las estructuras revelaron que Cas12a2 es autoinhibido y requiere la unión al ARN objetivo para su activación.
La unión al ARN expone el sitio activo de RuvC, permitiendo la degradación no específica de ssRNA, ssDNA y dsDNA.
Las características estructurales específicas, incluida una hendidura cargada positivamente y los residuos de "clamps aromáticos", facilitan la captura y degradación del ADN.

Conclusiones:

El estudio proporciona una comprensión estructural completa de la vía de activación de Cas12a2.
El mecanismo de acción de Cas12a2, incluida la degradación de dsDNA, está estructuralmente definido, lo que explica su papel en la infección abortiva.
Estos hallazgos pueden orientar la ingeniería de variantes de Cas12a2 con especificidades de sustrato adaptadas a diversas aplicaciones.

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