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Sedimentation Equilibrium of a Small Oligomer-forming Membrane Protein: Effect of Histidine Protonation on Pentameric Stability
Published on: April 2, 2015
Un enlace de hidrógeno C-alfa-H...O en una proteína de membrana no se estabiliza
Sarah Yohannan1, Salem Faham, Duan Yang
1Department of Chemistry and Biochemistry, UCLA-DOE Center for Genomics and Proteomics, Molecular Biology Institute, 655 Boyer Hall, University of California, Los Angeles, Los Angeles, California 90095-1570, USA.
Journal of the American Chemical Society
|February 26, 2004
Resumen
La evidencia experimental sugiere que los enlaces Calpha-H...O no estabilizan significativamente las proteínas. La mutación de un residuo clave en la bacteriorhodopsina no mostró pérdida de estabilidad, lo que desafía el papel propuesto de estos enlaces en la estructura de las proteínas.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- El plegamiento de las proteínas.
Sus antecedentes:
- Los enlaces Calpha-H...O son comunes en las estructuras de las proteínas y se proponen estabilizar las proteínas, especialmente las proteínas de membrana.
- Los cálculos de energía sugieren que estos enlaces tienen la mitad de fuerza que los enlaces de hidrógeno tradicionales.
- El papel estabilizador de los enlaces Calpha-H...O en las proteínas no ha sido verificado experimentalmente.
Objetivo del estudio:
- Para probar experimentalmente la importancia de los enlaces Calpha-H...O para la estabilidad de las proteínas.
- Para investigar la contribución de una interacción específica Calpha-H...O en la bacteriorhodopsina a la estabilidad de las proteínas.
Principales métodos:
- Se utilizó la mutagenesis dirigida al sitio para alterar Thr24 en la bacteriorhodopsina a Ala, Val y Ser.
- Se midió la estabilidad termodinámica de las proteínas de tipo salvaje y mutantes.
- Se determinaron las estructuras cristalinas de los mutantes.
Principales resultados:
- La mutación de Thr24 a Ala, Val o Ser no redujo significativamente la estabilidad de la proteína.
- El mutante T24A exhibió una mayor estabilidad en comparación con la proteína de tipo salvaje.
- El análisis estructural reveló cambios mínimos en T24A, con T24S y T24V mostrando algunas alteraciones, ninguno explicando los cambios de estabilidad.
Conclusiones:
- Los enlaces Calpha-H...O no son un contribuyente importante a la estabilidad de la bacteriorhodopsina.
- El residuo de Thr24 investigado parece desestabilizar, en lugar de estabilizar, la proteína.
- Los hallazgos experimentales desafían la hipótesis de que los enlaces Calpha-H...O juegan un papel importante en la estabilización de las proteínas.
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