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Un evento estocástico de una sola molécula desencadena el cambio de fenotipo de una célula bacteriana
Paul J Choi1, Long Cai, Kirsten Frieda
1Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Science (New York, N.Y.)
|October 18, 2008
Resumen
El monitoreo de una sola molécula revela cómo las células de Escherichia coli cambian de fenotipos. Los eventos estocásticos de la disociación del represor de lactosa del ADN desencadenan la expresión de la permeasa, lo que determina el comportamiento celular.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Genética La genética.
- La biofísica es la biofísica.
Sus antecedentes:
- El operón lac en Escherichia coli regula el metabolismo de la lactosa.
- La expresión génica puede exhibir cambios fenotípicos incluso en células genéticamente idénticas.
- Comprender la base molecular de esta conmutación es crucial para la biología celular.
Objetivo del estudio:
- Para investigar el mecanismo molecular detrás de la conmutación fenotípica en Escherichia coli.
- Para aclarar cómo las transiciones lac operon entre estados inducidos y no inducidos.
- Para identificar el papel de los eventos de una sola molécula en la determinación del fenotipo celular.
Principales métodos:
- Se utilizó microscopía de fluorescencia de una sola molécula para monitorear la permeasa de lactosa.
- Observación en tiempo real de proteínas etiquetadas con fluorescencia en células individuales.
- Análisis de la dinámica de la expresión génica a nivel de una sola molécula.
Principales resultados:
- A concentraciones intermedias de inductores, las células mostraron fenotipos bimodales: alta y baja expresión de permeasa.
- La expresión a nivel basal está relacionada con la disociación parcial del represivo de la lactosa del ADN.
- Los eventos infrecuentes de disociación completa del represor causaron grandes ráfagas de expresión de permeasa, lo que desencadenó la inducción.
Conclusiones:
- La conmutación fenotípica en el operón lac está impulsada por eventos estocásticos a nivel de una sola molécula.
- La dinámica de disociación del represor de lactosa dicta el fenotipo celular.
- Un solo evento estocástico puede determinar el destino de la expresión génica de una célula.
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