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La fosforilación de Sld2 y Sld3 por las cinasas dependientes de ciclina promueve la replicación del ADN en las
Philip Zegerman1, John F X Diffley
1Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.
Nature
|December 15, 2006
Resumen
Las cinasas dependientes de ciclina (CDK) inician la replicación del ADN. La fosforilación de las proteínas Sld2 y Sld3 por las S-CDK es esencial para este proceso, revelando los objetivos mínimos de CDK requeridos para la replicación del ADN.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología celular Biología celular.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Las cinasas dependientes de ciclina (CDK) regulan eventos críticos del ciclo celular, incluida la iniciación de la replicación del ADN.
- La proteína Sld3 es un objetivo clave para las CDK de fase S (S-CDK) en la levadura en ciernes.
- La proteína Dpb11, que contiene repeticiones BRCT, interactúa con Sld3.3.
Objetivo del estudio:
- Investigar la importancia funcional de los sitios de fosforilación de S-CDK en Sld3.
- Para dilucidar la interacción entre Sld3 fosforilado y Dpb11.
- Determinar el conjunto mínimo de objetivos S-CDK esenciales para la replicación del ADN.
Principales métodos:
- Mutagénesis dirigida al sitio para identificar sitios de fosforilación de S-CDK en Sld3.
- La genética de la levadura para crear construcciones de fusión Sld3-Dpb11.
- Análisis de la iniciación de la replicación del ADN en varias cepas de levadura mutantes.
Principales resultados:
- Dos sitios de fosforilación de S-CDK en Sld3 son esenciales para la replicación del ADN.
- El Sld3 fosforilado se une a las repeticiones BRCT de Dpb11.
- Una fusión Sld3-Dpb11 evita la necesidad de fosforilación de Sld3 y las repeticiones BRCT de Dpb11.
- La coexpresión de la fusión con un mutante Sld2 que imita el fosfo promueve la replicación sin S-CDK.
- La expresión de la subunidad de la quinasa Cdc7 Dbf4 es necesaria para la replicación en las células deficientes en G1-CDK, junto con el bypass de Sld2 y Sld3.
Conclusiones:
- Sld2 y Sld3 son los mínimos sustratos S-CDK requeridos para el inicio de la replicación del ADN.
- La interacción entre Sld3 fosforilado y Dpb11 es crucial para la replicación.
- Este estudio aclara los roles de G1- y S-CDKs en la promoción de la replicación del ADN de la levadura.
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