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Use of Stopped-Flow Fluorescence and Labeled Nucleotides to Analyze the ATP Turnover Cycle of Kinesins
Published on: October 17, 2014
Mecanismo de hidrólisis del trifosfato de adenosina en kinesin estudiado por simulaciones combinadas de mecánica
Matthew J McGrath1, I-F Will Kuo, Shigehiko Hayashi
1Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan. mcgrath@theory.biophys.kyoto-u.ac.jp
Journal of the American Chemical Society
|June 12, 2013
Resumen
La proteína motora de kinesin Eg5 utiliza un mecanismo de cadena de dos aguas para la hidrólisis de ATP, facilitada por un puente de sal roto. Este proceso es menos favorable en los estados vinculados al ADP, lo que sugiere un mecanismo motor común.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Química computacional es la química computacional.
Sus antecedentes:
- Las kinesinas son motores moleculares que convierten la energía química de la hidrólisis del trifosfato de adenosina (ATP) en trabajo mecánico.
- Si bien se conoce la estructura y la motilidad de la quinesina, el mecanismo preciso de la hidrólisis de ATP dentro del sitio activo sigue sin estar claro.
Objetivo del estudio:
- Para dilucidar el mecanismo de hidrólisis de ATP en la proteína quinetina-5 Eg5.
- Para identificar los pasos clave y los intermediarios involucrados en la hidrólisis de ATP utilizando simulaciones computacionales.
Principales métodos:
- Se emplearon simulaciones combinadas de mecánica cuántica / mecánica molecular (QM / MM) de metadinamía.
- Las superficies de energía libre se calcularon para aproximadamente 200 átomos en el sitio catalítico.
Principales resultados:
- Se identificó una vía de hidrólisis de baja barrera que involucra una cadena de dos aguas.
- La reacción es favorecida por un puente de sal transitoriamente roto entre Glu270 y Arg234.
- La hidrólisis de ATP es menos favorable en la conformación unida al ADP debido al obstáculo estérico y las interacciones de las moléculas de agua.
Conclusiones:
- El mecanismo identificado de la cadena de dos aguas proporciona información sobre la hidrólisis de ATP de Eg5.
- Los hallazgos sugieren un mecanismo de hidrólisis de ATP potencialmente conservado a través de diferentes motores moleculares como la miosina y la F1-ATPasa.
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