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No hay retroalimentación de transcripción-traducción en el ritmo circadiano de la fosforilación de KaiC
Jun Tomita1, Masato Nakajima, Takao Kondo
1Division of Biological Science, Graduate School of Science, Nagoya University, and Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Science (New York, N.Y.)
|November 20, 2004
Resumen
El reloj circadiano de las cianobacterias, impulsado por la fosforilación de KaiC, funciona independientemente de la nueva transcripción y traducción. Este ritmo robusto demuestra la compensación de la temperatura, incluso sin la acumulación de ARN mensajero.
Área de la Ciencia:
- * Biología circadiana.
- * Los mecanismos moleculares de los relojes biológicos.
- * Fisiología cianobacteriana.
Sus antecedentes:
- * Los circuitos de retroalimentación autorreguladores de transcripción-traducción se consideran esenciales para la generación del ritmo circadiano en la mayoría de los organismos.
- * Se planteó la hipótesis de que la proteína KaiC en el Synechococcus elongatus formaba parte de ese ciclo de retroalimentación negativa.
- * Comprender los componentes centrales del reloj circadiano es crucial para descifrar la regulación temporal en la vida.
Objetivo del estudio:
- * Investigar la necesidad de transcripción y traducción para la ritmicidad circadiana en Synechococcus elongatus.
- * Para determinar si el ciclo de fosforilación de KaiC está compensado por la temperatura y es robusto bajo condiciones que inhiben la expresión génica.
- * Para aclarar los mecanismos fundamentales que subyacen a la cronometraje cianobacteriano.
Principales métodos:
- * Monitoreo del ciclo de fosforilación de KaiC bajo condiciones continuas de oscuridad.
- * Evaluación de la persistencia del ritmo en presencia de inhibidores de la transcripción y la traducción.
- * Análisis cinético in vitro de las relaciones de autofosforilación-desfosforilación de KaiC.
Principales resultados:
- * Se observó un ciclo circadiano robusto y compensado por la temperatura de la fosforilación KaiC sin acumulación de ARN mensajero kaiBC.
- * El ritmo observado persistió incluso cuando se inhibió la transcripción o la traducción.
- * Estudios cinéticos in vitro confirmaron la compensación de la temperatura en la autofosforilación-desfosforilación de KaiC.
Conclusiones:
- * El reloj circadiano de las cianobacterias puede mantener un cronometraje robusto y compensado por la temperatura, independiente de la transcripción y la traducción de novo.
- * Los ritmos circadianos en Synechococcus elongatus no dependen exclusivamente de los circuitos de retroalimentación autorreguladores de transcripción-traducción.
- * Estos hallazgos desafían el requisito universal de retroalimentación transcripcional-traducional para la generación del ritmo circadiano.
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