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La fosforilación y activación de la condensina 13S por Cdc2 in vitro
K Kimura1, M Hirano, R Kobayashi
1Cold Spring Harbor Laboratory, Post Office Box 100, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Science (New York, N.Y.)
|October 17, 1998
Resumen
La condensación del cromosoma mitótico en extractos de huevo de Xenopus se basa en la condensación 13S. La fosforilación por Cdc2 quinasa activa este complejo, lo que sugiere un papel clave en el desencadenamiento de la condensación cromosómica.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología celular Biología celular.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La 13S condensina es un complejo proteico crucial para la condensación del cromosoma mitótico en extractos de huevo de Xenopus.
- Se sabe que este complejo interactúa con el ADN y se regula durante el ciclo celular.
Objetivo del estudio:
- Investigar el mecanismo por el cual la condensina 13S induce la condensación cromosómica.
- Identificar los factores reguladores y las vías involucradas en la activación de la condensina 13S durante la mitosis.
Principales métodos:
- Purificación de la condensina 13S a partir de extractos de huevo de Xenopus.
- Ensayos in vitro para evaluar la actividad de superenrolamiento del ADN en presencia de ATP y topoisomerasa I.
- Experimentos de fosforilación específicos de la mitosis y estudios de inmunodepleción.
- Mapeo de péptidos para identificar sitios de fosforilación en la subunidad XCAP-D2.
Principales resultados:
- Se demostró que la condensina 13S purificada introduce superbobinas positivas en el ADN in vitro.
- Se encontró que la actividad de superenrolamiento de la condensina 13S estaba regulada por la fosforilación específica de la mitosis.
- La quinasa Cdc2 fue identificada como la enzima probable responsable de la fosforilación y activación de la condensina 13S.
- Se localizaron múltiples sitios de fosforilación de Cdc2 en el dominio carboxilo-terminal de la subunidad XCAP-D2.
Conclusiones:
- La fosforilación de la condensina 13S por la cinasa Cdc2 es un evento regulador clave.
- Se propone que este evento de fosforilación desencadene el inicio de la condensación del cromosoma mitótico in vitro.
- Los hallazgos aclaran un paso crítico en el proceso de segregación cromosómica durante la división celular.
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