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Las propiedades de unión al Ni (II) de la metalochaperona SlyD
Harini Kaluarachchi1, Duncan E K Sutherland, Alex Young
1Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6.
Journal of the American Chemical Society
|December 2, 2009
Resumen
La metallochaperona SlyD de Escherichia coli se une a hasta siete iones de níquel con una alta afinidad. Este níquel que se une influye en SlyDD.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Investigación de las metaloproteínas.
- Biología molecular La biología molecular.
Sus antecedentes:
- Las metalochaperonas facilitan la entrega de cofactores metálicos a las proteínas.
- El níquel es esencial para los procesos celulares pero tóxico en exceso.
- La proteína SlyD de Escherichia coli está involucrada en la homeostasis del níquel y el ensamblaje de la [Ni-Fe]-hidrogenasa.
Objetivo del estudio:
- Para investigar las propiedades de unión de níquel de Escherichia coli SlyD.
- Para aclarar el papel de SlyD en la acumulación de níquel y el metabolismo.
- Comprender el impacto estructural y funcional de la unión de níquel en SlyD.
Principales métodos:
- Espectrometría de masas de ionización por electrospray (ESI-MS) para el análisis de complejos metal-proteína no covalentes.
- Técnicas de análisis estructural para observar cambios conformacionales inducidos por el metal.
- Espectroscopia de absorción de rayos X (XAS) para determinar las geometrías de coordinación de los iones de níquel.
- Caracterización de los mutantes SlyD para identificar los residuos clave para la unión del níquel.
Principales resultados:
- SlyD se une a hasta siete iones de níquel de manera no cooperativa con una afinidad submicromolar.
- La unión de níquel induce cambios estructurales sutiles en SlyD, que afectan tanto a los dominios N-terminal y C-terminal.
- Los sitios de unión de níquel implican la formación de beta-turn, y los residuos de cisteína mejoran la afinidad y capacidad de unión.
- SlyD exhibe diversas geometrías y números de coordinación de iones de níquel.
Conclusiones:
- SlyD funciona como una metallochaperona de unión de iones de níquel múltiple en Escherichia coli.
- La proteína juega un papel crítico en la homeostasis del níquel y en el ensamblaje de las metalloenzimas.
- La flexibilidad estructural y los residuos específicos contribuyen a las capacidades de unión de níquel de SlyD.
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