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Papel funcional de la entropía del disolvente y la entropía conformacional de la unión del metal en un sistema

Daiana A Capdevila¹, Katherine A Edmonds¹, Gregory C Campanello¹

¹Department of Chemistry , Indiana University , Bloomington , Indiana 47405-7102 United States.

Journal of the American Chemical Society

|June 29, 2018

Resumen

Allostery involucra la dinámica de las proteínas y las moléculas de disolvente circundantes. Este estudio revela que la dinámica proteica alterada en los mutantes de CzrA tiene un impacto significativo en la entropía del disolvente, afectando la regulación alosterica.

Área de la Ciencia:

La bioquímica
Biología molecular
Biología estructural

Sus antecedentes:

El alosterio es un mecanismo regulador clave en los sistemas biológicos, donde la unión de ligandos en un sitio afecta a otro.
La base física de la regulación alostérica, particularmente la alostería impulsada dinámicamente, no se entiende completamente.
La contribución de la dinámica de las proteínas y la entropía del disolvente a la regulación alosterica es un área de investigación activa.

Objetivo del estudio:

Investigar la interacción entre la dinámica de las proteínas y la entropía del disolvente en la regulación alostérica.
Para diseccionar las contribuciones relativas de la entropía del disolvente y la dinámica específica del residuo a la inhibición alostérica de la unión al ADN por Zn en CzrA.
Para entender el papel de las moléculas de agua en la alostería impulsada dinámicamente.

Principales métodos:

Cristalografía de rayos X para obtener nuevas estructuras cristalinas.
Estudios calorimétricos para evaluar los cambios termodinámicos.
Estudios de la dinámica específica de los residuos en un rango de escalas de tiempo y temperaturas.
Análisis de los mutantes CzrA con alteraciones alostéricas.

Principales resultados:

Se observó una dinámica específica de residuos no nativos en los mutantes de CzrA.
Estas dinámicas se asociaron con perturbaciones significativas en la entropía del disolvente.
Estos cambios en la entropía del disolvente no podían predecirse solo a partir de las estructuras cristalinas.
Se investigó la inhibición alostérica de la unión al ADN por Zn en CzrA.

Conclusiones:

La dinámica funcional en la alostería se extiende más allá de los residuos de proteínas para incluir moléculas de agua de superficie.
Las perturbaciones mediadas por ligandos en los movimientos internos de las proteínas influyen en la entropía del disolvente.
La regulación alostérica involucra el conjunto conformacional, no solo los cambios estructurales importantes.

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