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La comparación de la solución y las estructuras cristalinas del riboswitch preQ1 revela cambios inducidos por el
Qi Zhang1, Mijeong Kang, Robert D Peterson
1Department of Chemistry and Biochemistry , University of California, Los Angeles, California 90095-1569, USA.
Journal of the American Chemical Society
|March 18, 2011
Resumen
El aptamer de riboswitch de Bacillus subtilis preQ(1) exhibe flexibilidad intrínseca en su estado ligando. Los iones de calcio, presentes en las estructuras cristalinas, no son esenciales para su función en solución.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Los riboswitches son elementos genéticos que regulan la expresión génica a través de la unión de metabolitos.
- Los dominios aptamero de los riboswitches se unen a metabolitos específicos, induciendo cambios conformacionales.
- Existen discrepancias entre la solución y las estructuras cristalinas del aptamer de riboswitch de Bacillus subtilis preQ(1).
Objetivo del estudio:
- Para caracterizar estructural y dinámicamente el Bacillus subtilis preQ(1) riboswitch aptamer en su estado ligando-unido utilizando la solución de RMN.
- Para investigar el papel de los iones calcio en la estructura y función del aptamer.
- Para conciliar las diferencias entre la solución reportada y las estructuras cristalinas.
Principales métodos:
- Espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución. espectroscopia de Resonancia Magnética Nuclear (RMN) en Solución.
- Caracterización estructural y dinámica del complejo aptamer-preQ(1).
- Mediciones de afinidad de unión de ligandos para iones de calcio.
Principales resultados:
- El complejo aptamer-preQ(1) es intrínsecamente flexible en solución, con movimientos distintos en diferentes regiones.
- Un ion de calcio específico se une a una bolsa inducida por ligando con afinidad micromolar.
- Los iones de calcio inducen cambios conformacionales, pero no son necesarios para la unión de ligandos o el plegamiento en solución.
Conclusiones:
- El aptamer de riboswitch de Bacillus subtilis preQ(1) exhibe una flexibilidad conformacional significativa en solución, incluso cuando está unido a su ligando.
- Las diferencias observadas entre las estructuras de cristal y solución se atribuyen a las interacciones de iones de calcio.
- Los iones de calcio no son esenciales para la función fundamental de este aptamer de riboswitch en solución.
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