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La coordinación de manganeso de alta afinidad por la calprotectina humana es dependiente del calcio y requiere el
Joshua A Hayden1, Megan Brunjes Brophy, Lisa S Cunden
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|January 2, 2013
Resumen
La calprotectina (CP) secuestra el manganeso (Mn(II)) en un sitio específico de His(4), mejorado por el calcio. Esta proteína quela metales para inhibir el crecimiento microbiano, especialmente en respuesta a los gradientes de calcio.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Microbiología Microbiología.
Sus antecedentes:
- La calprotectina (CP) es una proteína antimicrobiana producida por los neutrófilos.
- La CP inhibe el crecimiento microbiano mediante la quelación de iones metálicos de transición como el manganeso y el zinc.
- La interfaz de dímeros S100A8/S100A9 de CP forma distintas zonas de unión de los metales.
Objetivo del estudio:
- Para investigar las propiedades de unión al manganeso de la Calprotectina (CP).
- Para caracterizar el sitio específico de coordinación del manganeso dentro del S100A8/S100A9 dimer.
- Comprender el papel del calcio en la modulación de la afinidad y la selectividad de unión a los metales de la CP.
Principales métodos:
- Espectroscopia de resonancia paramagnética de electrones (EPR) de baja temperatura para detectar la unión de Mn (II).
- Mutagénesis dirigida al sitio para identificar los principales residuos coordinadores.
- Ensayos de selectividad de iones metálicos comparando la unión de zinc y manganeso.
Principales resultados:
- El motivo His(4) en la interfaz de dímeros S100A8/S100A9 es el sitio de unión Mn(II) de alta afinidad.
- El análisis espectroscópico reveló una esfera de coordinación octaédrica de Mn (II) en este sitio.
- La unión de calcio aumenta significativamente la afinidad de Mn{\displaystyle Mn} , mientras que la CP muestra una mayor selectividad para Zn{\displaystyle Zn} .
Conclusiones:
- El CP utiliza el sitio His para la coordinación de MnII de alta afinidad, influenciada por los niveles de calcio.
- Se favorece la formación de complejos mixtos Zn:Mn:CP.
- CP actúa como un quelador metálico de alta afinidad regulado por el calcio para inhibir el crecimiento microbiano extracelularmente.
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