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Los datos experimentales de NOE, cambio químico e isomerización de prolina proporcionan información detallada sobre

Sai Chaitanya Chiliveri¹, Yang Shen¹, James L Baber¹

¹Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States.

Journal of the American Chemical Society

|August 7, 2023

Resumen

La amelotina, una proteína intrínsecamente desordenada, forma oligómeros ordenados involucrados en la mineralización. La RMN de salto de presión reveló su cinética de oligomerización y cambios estructurales, incluida una hélice naciente y una hoja beta, que ofrecen información sobre la formación de hidroxiapatita.

Área de la Ciencia:

La bioquímica
Biología estructural
La biofísica

Sus antecedentes:

La amelotina es una proteína intrínsecamente desordenada (IDP) crucial para la mineralización de la hidroxiapatita.
Los PDI exhiben estructuras dinámicas y se oligomerizan en condiciones fisiológicas.

Objetivo del estudio:

Investigar los cambios estructurales y dinámicos de la amelotina durante la oligomerización.
Elucidar la cinética de la oligomerización y disociación de la amelotina a un nivel específico del residuo.

Principales métodos:

Se empleó la espectroscopia de RMN de salto de presión para sondear los contactos de NOE de largo alcance en el estado oligomérico.
Análisis de los equilibrios cis/trans de los residuos de prolina y los desplazamientos químicos secundarios del 13C.

Principales resultados:

La oligomerización se inicia en la mitad C-terminal de un segmento de residuo 105, que se ordena después de la oligomerización.
Un alfa-hélice de 11 residuos naciente y una forma de hoja beta en el estado oligomérico, con residuos específicos de prolina que muestran preferencias alteradas cis/trans.
Los modelos AlphaFold-Multimer de hexámeres de amelotina mostraron consistencia con los datos experimentales.

Conclusiones:

La oligomerización de la amelotina implica un ordenamiento estructural significativo y configuraciones específicas de prolina.
La RMN de salto de presión es eficaz para el estudio de la dinámica de la oligomerización del PDI.
Los hallazgos proporcionan una base para el modelado atómico de oligómeros de amelotina y su papel en la mineralización.

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