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Cambio de marco autorregulador en la decodificación de la ornitina decarboxilasa antienzima de los mamíferos
S Matsufuji1, T Matsufuji, Y Miyazaki
1Howard Hughes Medical Institute, University of Utah, Salt Lake City 84112.
Cell
|January 13, 1995
Resumen
La expresión génica del antienzima de la rata se basa en el cambio de marco ribosómico programado, modulado por los niveles de poliamina. Este mecanismo autorregulador controla la síntesis de poliaminas mediante la degradación de la ornitina descarboxilasa.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Regulación genética Reglamento genético.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La expresión génica antienzimática de la rata está regulada por el cambio de marco ribosomal programado.
- Las poliaminas son moléculas esenciales involucradas en el crecimiento y la proliferación celular.
- La ornitina descarboxilasa es una enzima clave en la síntesis de poliaminas.
Objetivo del estudio:
- Para dilucidar el nuevo mecanismo autorregulador que controla la expresión génica de antienzimas en ratas.
- Investigar el papel de las poliaminas en la modulación del cambio de marco ribosómico.
- Para caracterizar el sitio de desplazamiento de fotogramas y sus secuencias asociadas.
Principales métodos:
- Experimentos in vitro en los que se utilizaron lisados de reticulocitos.
- Construcción de construcciones de fusión para estudiar la eficiencia del cambio de marco.
- Análisis de secuencias de ARNm, incluidos los codones de terminación y los pseudonodos aguas abajo.
Principales resultados:
- Las poliaminas, específicamente la espermidina, modulan la eficiencia de cambio de marco de una manera dependiente de la concentración (19% en la concentración óptima).
- Un desplazamiento de cuadro +1 ocurre aguas arriba del codón terminador del cuadro inicial.
- El codón de terminación y un pseudonodo aguas abajo estimulan el cambio de marco.
- La secuencia del sitio de desplazamiento de marco (UCC-UGA-U) es única y puede implicar un nuevo mecanismo más allá del nuevo emparejamiento del tRNA.
Conclusiones:
- La expresión génica antienzimática de la rata está autorregulada por un mecanismo de cambio de marco ribosómico dependiente de la poliamina.
- Este mecanismo ajusta los niveles de poliamina mediante el control de la síntesis de antienzimas.
- El sitio único de desplazamiento de fotogramas sugiere un nuevo mecanismo de control traslacional que implica la lectura u oclusión de una cuarta base.
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