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Alostería de proteínas en la interfaz sólido-líquido: la unión de la endoglucanasa a la celulosa afecta el
Yuchun Lin1, Jordi Silvestre-Ryan, Michael E Himmel
1Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California, USA.
Journal of the American Chemical Society
|September 1, 2011
Resumen
Las interacciones enzimáticas en las interfaces son clave para la biocatálisis. Las simulaciones de dinámica molecular revelan cómo la endoglucanasa I (Cel7B) que se une a la celulosa afecta su actividad, descubriendo un mecanismo de acoplamiento alostérico.
Área de la Ciencia:
- Biocatálisis y mecanismos enzimáticos.
- Interacciones de la superficie de las proteínas.
- La deconstrucción de la biomasa y la deconstrucción de la biomasa.
Sus antecedentes:
- Las enzimas como los cócteles de celulosa son cruciales para descomponer la biomasa en azúcares.
- Comprender los pasos físicos de la acción enzimática en las interfaces es un desafío.
- La endoglucanasa I (Cel7B) de Trichoderma reesei hidroliza aleatoriamente los enlaces glucósidos en la celulosa.
Objetivo del estudio:
- Para dilucidar los mecanismos moleculares del dominio catalítico (CD) de Cel7B que interactúa con la celulosa.
- Para investigar el acoplamiento alostérico entre la unión enzima-superficie y la unión al sustrato.
- Para explorar la importancia funcional de los residuos conservados en la interacción de Cel7B con la celulosa.
Principales métodos:
- Se utilizaron simulaciones de dinámica molecular (DM) de todos los átomos para modelar el dominio catalítico de Cel7B.
- Las simulaciones analizaron los complejos Cel7B-glucano y Cel7B-microfibril.
- Las redes de acoplamiento mecánico se calcularon para comprender los efectos alostéricos.
Principales resultados:
- Se identificó un acoplamiento alostérico previamente no resuelto en la interfaz sólido-líquido.
- La adhesión de Cel7B a la superficie de celulosa influye en el apretamiento de la cadena de glucanos en su hendidura de unión.
- Los segmentos de fijación superficial con residuos conservados mostraron un vínculo funcional con los residuos del sitio activo.
Conclusiones:
- Las simulaciones de MD y las redes de acoplamiento mecánico pueden revelar la alostería de la enzima en las interfaces.
- Los residuos conservados en los segmentos de fijación superficial son funcionalmente importantes para el biocatálisis.
- El estudio proporciona información sobre la base física de la acción de las enzimas sobre la celulosa cristalina.
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