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La flexibilidad conformal de las fibrillas amiloides de la proteína priónica humana Y145Stop probadas por
Jonathan J Helmus1, Krystyna Surewicz, Witold K Surewicz
1Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, USA.
Journal of the American Chemical Society
|February 4, 2010
Resumen
El dominio N-terminal de la proteína priónica humana (huPrP23-144) amiloide es flexible y tiene forma de bobina aleatoria. Los residuos del núcleo muestran movimiento restringido, pero algunas dinámicas lentas dentro del núcleo amiloide sugieren posibles fenómenos de intercambio químico.
Área de la Ciencia:
- La biofísica es la biofísica.
- Biología Estructural Biología estructural.
- La neurociencia es la neurociencia.
Sus antecedentes:
- Los agregados amiloides de una proteína priónica humana truncada en C (huPrP23-144) mutante están vinculados a la angiopatía amiloide hereditaria.
- Estos agregados presentan un núcleo amiloide rígido y rico en hojas beta cerca del extremo C.
- Los residuos N-terminales de huPrP23-144 exhiben una flexibilidad conformacional significativa.
Objetivo del estudio:
- Para observar y caracterizar directamente el dominio N-terminal flexible del amiloide huPrP23-144.
- Para investigar los movimientos moleculares potenciales dentro del núcleo amiloide de huPrP23-144.4.
- Para medir cuantitativamente la dinámica de los residuos del núcleo utilizando RMN en estado sólido (RMNSA).
Principales métodos:
- Se emplearon técnicas SSNMR de hilado de ángulo mágico (MAS) basadas en acoplamiento 2D J. Se emplearon técnicas SSNMR.
- Se analizaron espectros 3D SSNMR basados en polarización cruzada (CP) para intensidades de señal.
- Los parámetros de orden dipolar de la columna vertebral y las tasas de relajación de giro transversal se midieron cuantitativamente para los residuos del núcleo.
Principales resultados:
- El dominio N-terminal del amiloide huPrP23-144 fue observado directamente, mostrando conformaciones aleatorias en forma de bobina.
- Los residuos del núcleo demostraron movimientos restringidos y uniformes en la escala de tiempo submicrosegundo, similares a las proteínas microcristalinas.
- Las variaciones en las tasas de relajación transversal dentro del núcleo sugieren fenómenos de intercambio químico lentos, en una escala de tiempo de microsegundos a milisegundos.
Conclusiones:
- El dominio N-terminal del amiloide huPrP23-144 es muy flexible.
- Si bien el núcleo amiloide es en gran parte rígido, la evidencia sugiere movimientos moleculares lentos y un potencial intercambio químico dentro de esta región.
- Estos hallazgos proporcionan información sobre la naturaleza dinámica de las estructuras amiloides de las proteínas priónicas.
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