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El gamma-TuSC de nucleación de microtúbulos ensambla estructuras con una simetría de 13 veces similar a la de los
Justin M Kollman1, Jessica K Polka, Alex Zelter
1Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, and Keck Advanced Microscopy Center, University of California, San Francisco, San Francisco, California 94158, USA.
Nature
|July 16, 2010
Resumen
El núcleo del pequeño complejo gamma-tubulina (gamma-TuSC) forma anillos que sirven como plantillas de microtúbulos, incluso sin proteínas adicionales. La levadura Spc110 estabiliza estos anillos en filamentos, revelando una estructura de 13 gamma-tubulinas que coincide con la simetría de los microtúbulos.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Los microtúbulos son esenciales para la estructura y división celular.
- Los complejos de gamma-tubulina nuclean la formación de microtúbulos in vivo.
- El pequeño complejo gamma-tubulina (gamma-TuSC) es el componente central de la maquinaria de nucleación de microtúbulos.
Objetivo del estudio:
- Investigar la capacidad de autoensamblaje del pequeño complejo gamma-tubulina (gamma-TuSC).
- Para determinar la estructura de los anillos y filamentos gamma-TuSC.
- Comprender el papel de las proteínas accesorias en la nucleación de microtúbulos.
Principales métodos:
- Microscopía criolectrónica (resolución de 8 Å).
- La reconstitución bioquímica de los filamentos gamma-TuSC.
- Análisis de las interacciones de Saccharomyces cerevisiae gamma-TuSC y Spc110.
Principales resultados:
- Saccharomyces cerevisiae gamma-TuSC se autoensambla en anillos sin otros componentes gamma-TuRC.
- La proteína adaptadora de la levadura Spc110 estabiliza estos anillos en filamentos extendidos.
- Cryo-EM reveló una estructura de filamento con 13 gamma-tubulinas por turno, coincidiendo con la simetría de los microtúbulos y exponiendo los extremos más.
Conclusiones:
- El propio gamma-TuSC puede formar una plantilla de microtúbulos.
- Spc110 es crucial para estabilizar el gamma-TuSC en filamentos nucleantes funcionales.
- La estructura proporciona información sobre la regulación de la nucleación de los microtúbulos y la función de las proteínas específicas de gamma-TuRC.
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