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La aglomeración molecular estabiliza la estructura de ARN plegado por el efecto de volumen excluido.
Duncan Kilburn1, Joon Ho Roh, Liang Guo
1T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|June 5, 2010
Resumen
La aglomeración molecular con polietilenglicol (PEG) favorece las estructuras compactas de ARN al alterar el equilibrio de la solución. Este estudio muestra que PEG-1000 induce estados más compactos en una ribozima bacteriana, impactando la termodinámica de plegado.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- La biofísica es la biofísica.
Sus antecedentes:
- El plegamiento macromolecular está influenciado por las condiciones de la solución, incluida la presencia de moléculas de crowder.
- Comprender el plegamiento del ARN in vivo requiere tener en cuenta los efectos de aglomeración molecular.
- El polietilenglicol (PEG) es un agrupador molecular común utilizado para estudiar estos efectos.
Objetivo del estudio:
- Para investigar el impacto del polietilenglicol 1000 (PEG-1000) en el plegamiento de un grupo bacteriano I. ribozima.
- Para cuantificar el efecto de volumen excluido de PEG-1000 en la estructura del ARN.
- Para determinar cómo PEG-1000 influye en la termodinámica del plegamiento del ARN.
Principales métodos:
- Los experimentos de dispersión de rayos X de ángulo pequeño (SAXS) se realizaron en un grupo bacteriano de 64 kDa I ribozima.
- Los experimentos se llevaron a cabo en presencia de diferentes concentraciones de PEG-1000 (0-20% de peso/volumen).
- Se midieron los cambios en el agua y las actividades iónicas, y se aplicaron modelos teóricos para evaluar los efectos de volumen excluidos.
Principales resultados:
- Se encontró que PEG-1000 favorece estructuras de ARN más compactas, consistentes con los efectos de volumen excluidos.
- La transición al estado plegado se produjo a concentraciones más bajas de MgCl2 en presencia de PEG.
- El radio de giro del ARN desplegado disminuyó de 76 a 64 Å a medida que aumentaba la concentración de PEG.
Conclusiones:
- El efecto dominante de PEG-1000 como un crowder molecular en el plegamiento del ARN es el efecto de volumen excluido.
- PEG-1000 promueve las conformaciones compactas de ARN impidiendo estéricamente los estados desplegados.
- Estos hallazgos resaltan la importancia de considerar la aglomeración molecular en los procesos de plegamiento del ARN celular.
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