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Holo-Ni ((II) HpNikR es un tetramero asimétrico que contiene dos sitios de unión de níquel diferentes
Abby L West1, Franz St John, Pedro E M Lopes
1Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201-1180, USA.
Journal of the American Chemical Society
|September 25, 2010
Resumen
La proteína metalorreguladora NikR de Helicobacter pylori se une a los iones de níquel de dos maneras distintas. Esta visión estructural de HpNikR enlazado al níquel puede explicar su especificidad de unión al ADN.
Área de la Ciencia:
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
- Las metaloproteínas son proteínas metálicas.
Sus antecedentes:
- Helicobacter pylori NikR (HpNikR) es una proteína metalorreguladora que controla la expresión génica basada en la disponibilidad de níquel.
- La comprensión de los mecanismos de unión de níquel de HpNikR es crucial para aclarar sus funciones regulatorias.
Objetivo del estudio:
- Para determinar la estructura cristalina de Ni (II) HpNikR.
- Para investigar los entornos de coordinación de níquel dentro de HpNikR.
Principales métodos:
- Cristalografía de rayos X (resolución de 2,37 Å) del holo HpNikR.
- Cálculos de la Teoría Funcional de la Densidad (DFT).
Principales resultados:
- La estructura revela cuatro iones de níquel en dos entornos de coordinación distintos.
- Dos iones de níquel adoptan una geometría cuadrada plana de cuatro coordenadas predicha.
- Dos iones de níquel exhiben geometrías inesperadas de cinco o seis coordenadas que involucran residuos de histidina y moléculas de agua.
- Los cálculos de DFT indican la favorabilidad energética de las geometrías de cinco/seis coordenadas.
Conclusiones:
- HpNikR posee sitios únicos de coordinación de níquel, con la geometría de un sitio siendo energéticamente favorable.
- La presencia de distintos entornos de coordinación de níquel probablemente influye en la especificidad y afinidad de unión al ADN de HpNikR.
- Esta caracterización estructural proporciona una base para comprender el papel de HpNikR en la regulación de genes dependientes del níquel.
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