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Moléculas de kinesinas individuales estudiadas con una pinza de fuerza molecular
K Visscher1, M J Schnitzer, S M Block
1Department of Molecular Biology, Princeton Materials Institute, Princeton University, New Jersey 08544, USA.
Nature
|July 17, 1999
Resumen
Las proteínas motoras de la kinesin usan ATP para moverse a lo largo de los microtúbulos. Una nueva investigación revela que la quinesina es una sustancia
Área de la Ciencia:
- La función de las proteínas motoras moleculares en la función motora.
- Mecanoquímica de los motores de quinesina de las máquinas.
- Mecanismos de transporte de las células.
Sus antecedentes:
- La kinesin es una proteína motora impulsada por ATP que se mueve a lo largo de los microtúbulos en pasos de 8 nm.
- El mecanismo de acoplamiento preciso entre la hidrólisis de ATP y el movimiento mecánico en la quinesina no se entiende completamente.
- Comprender este proceso es crucial para comprender el transporte intracelular.
Objetivo del estudio:
- Para investigar los detalles mecanoquímicos de la función de las proteínas motoras de la quinesina.
- Para dilucidar cómo la energía química del ATP se convierte en trabajo mecánico.
- Para analizar la respuesta de la quinesina a diferentes concentraciones de ATP y cargas externas.
Principales métodos:
- Desarrollo de un nuevo instrumento de pinza de fuerza que utiliza una trampa óptica accionada por retroalimentación.
- Medición del movimiento de un solo motor cinético bajo cargas controladas y constantes.
- Análisis del comportamiento mecanico-químico de la quinesina a través de diferentes concentraciones y fuerzas de ATP.
Principales resultados:
- El paso de la kinesin está estrechamente acoplado a la hidrólisis de ATP (una hidrólisis por paso de 8 nm) en un amplio rango de fuerzas.
- La fuerza de pérdida de quinesina depende de la concentración de ATP.
- El aumento de las cargas mecánicas reduce la velocidad máxima y aumenta la constante de Michaelis-Menten, lo que indica transiciones dependientes de la carga en el ciclo de kinesin.
Conclusiones:
- El ciclo del motor de la kinesin implica al menos una transición dependiente de la carga que afecta la unión de ATP y el compromiso de hidrólisis.
- Otra tasa dependiente de la carga probablemente influye en el número total de facturación.
- Estos hallazgos requieren una comprensión revisada de la mecánica y función del motor de la quinesina.
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