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El factor anfitrión de integración estimula la interacción de la ARN polimerasa con NIFA, el activador
T R Hoover1, E Santero, S Porter
1Department of Plant Pathology, University of California, Berkeley 94720.
Cell
|October 5, 1990
Resumen
El factor de acogida de integración (IHF) mejora sinérgicamente la activación de la transcripción del gen de fijación de nitrógeno (nif) por la proteína NIFA y la ARN sigma 54 polimerasa. La flexión del ADN inducida por IHF facilita las interacciones esenciales proteína-ADN para la expresión del operón nif.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
Sus antecedentes:
- La fijación de nitrógeno (nif) es crucial para el crecimiento de las plantas, regulada por NIFA y sigma 54 ARN polimerasa.
- Se sabe que el factor de acogida de integración (IHF, por sus siglas en inglés) se une a las regiones reguladoras del ADN.
Objetivo del estudio:
- Investigar el efecto sinérgico de IHF y NIFA en la activación de la transcripción de nifH.
- Aclarar el mecanismo por el cual la IHF influye en la transcripción mediada por NIFA.
Principales métodos:
- Pruebas de transcripción in vitro con el promotor de Klebsiella pneumoniae nifH.
- Ensayos de desplazamiento de movilidad por electroforesis (EMSA) para estudiar las interacciones proteína-ADN.
- Microscopía electrónica para visualizar la flexión del ADN.
Principales resultados:
- IHF estimula significativamente la activación mediada por NIFA de la transcripción de nifH in vitro.
- IHF induce la flexión del ADN dentro de la región reguladora del promotor nifH.
- La estimulación de la IHF no se debe a la mejora directa de la unión de la holoenzima sigma 54.
Conclusiones:
- IHF y NIFA exhiben una sinergia funcional en la activación de la transcripción de nifH.
- La curvatura del ADN mediada por IHF probablemente facilita las interacciones productivas entre NIFA y la holoenzima sigma 54.
- La IHF generalmente puede estimular la transcripción nif mediada por NIFA a través de bacterias púrpuras.
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