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La estructura cristalina del transportador MgtE Mg2+ del transportador MgtE Mg2+ tiene una estructura cristalina
Motoyuki Hattori1, Yoshiki Tanaka, Shuya Fukai
1Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.
Nature
|August 19, 2007
Resumen
Los transportadores de magnesio como el MgtE son cruciales para la homeostasis celular del magnesio. Los estudios estructurales revelan cómo MgtE puede regular el transporte de iones de magnesio mediante la detección de los niveles intracelulares de Mg2+.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Fisiología Molecular Fisiología Molecular
Sus antecedentes:
- El ion magnesio (Mg2+) es esencial para numerosos procesos fisiológicos.
- Los transportadores de Mg2+ facilitan la absorción de Mg2+, pero sus mecanismos, especialmente la deshidratación del Mg2+ hidratado, aún no están claros.
- La familia MgtE de transportadores de Mg2+ está muy extendida, con homólogos humanos involucrados en la homeostasis del magnesio.
Objetivo del estudio:
- Para aclarar la base estructural de la función del transportador MgtE Mg2+.
- Para caracterizar la estructura de Thermus thermophilus MgtE de longitud completa y sus cambios conformacionales dependientes de Mg2+.
Principales métodos:
- La cristalografía de rayos X se utilizó para determinar las estructuras de MgtE de longitud completa y su dominio citosólico.
- Las estructuras se resolvieron a resoluciones de 3,5 Å, 2,3 Å y 3,9 Å, en presencia y ausencia de Mg2+.
Principales resultados:
- El transportador MgtE exhibe una arquitectura homodimérica con dominios transmembranales y citosólicos.
- Un poro a través de los dominios transmembranares muestra posibles sitios de unión de Mg2+, incluido Asp 432.
- La unión de Mg2+ a los dominios citosólicos induce cambios conformacionales en las hélices de conexión, lo que podría regular la apertura de los poros.
Conclusiones:
- La unión de Mg2+ a los dominios citosólicos de MgtE parece regular el flujo de Mg2+.
- Esto sugiere un mecanismo de homeostasis donde MgtE detecta la concentración intracelular de Mg2+ para controlar el transporte.
- El mecanismo preciso del portal de los poros (canal iónico frente al transporte activo secundario) requiere una mayor investigación.
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