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Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 26, 2011
tRNA como un regulador positivo de la antiterminación de la transcripción en B. subtilis
1Department of Biochemistry and Molecular Biology, Albany Medical College, New York 12208.
Cell
|August 13, 1993
Resumen
Los genes de la sintetasa tRNA de Bacillus usan la antiterminación de la transcripción para la regulación. El cambio de un codón específico en el gen tyrS alteró su respuesta de aminoácidos, revelando tRNA.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología Molecular Biología Molecular
- Regulación genética Reglamento genético.
Sus antecedentes:
- La mayoría de los genes de la tRNA sintetasa de Bacillus están regulados por un mecanismo de antiterminación de transcripción compartido.
- Los genes individuales responden a las limitaciones en su aminoácido específico.
- Las regiones líderes de ARNm muestran estructuras conservadas con un único codón específico de aminoácidos.
Objetivo del estudio:
- Para investigar el mecanismo regulador de los genes de la tRNA sintetasa de Bacillus.
- Para determinar el papel del codón específico en la secuencia líder del ARNm.
- Para identificar la molécula efector involucrada en la regulación génica.
Principales métodos:
- Análisis comparativo de las secuencias líderes de ARNm en los genes de la tRNA sintetasa de Bacillus.
- Mutagenesis dirigida al sitio de la secuencia líder del gen tyrS para alterar el codón específico.
- Análisis fenotípico de la inducción génica bajo diferentes limitaciones de aminoácidos.
- Análisis de supresión utilizando mutantes supresores sin sentido de lisil-tRNA.
Principales resultados:
- La alteración del codón del gen tyrS de UAC (tirosina) a UUC (fenilalanina) abolió la inducción de limitación de tirosina y confirió la inducción de limitación de fenilalanina.
- La inserción de una base adicional aguas arriba del codón no afectó la regulación, lo que sugiere un mecanismo no traslacional.
- Un codón sin sentido en la secuencia líder dio como resultado un fenotipo no inducible, que fue suprimible por un mutante de ARNt lisilo.
Conclusiones:
- El codón específico en la secuencia líder del ARNm dicta la respuesta aminoácida de los genes de la tRNA sintetasa.
- La regulación se produce a través de un mecanismo no traslacional.
- El ARN de transferencia (ARNt) actúa como la molécula efector en esta vía reguladora.
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