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Conservación de complejos dominios de reconocimiento de ADN entre familias de enzimas de restricción
G M Cowan1, A A Gann, N E Murray
1Department of Molecular Biology, University of Edinburgh, Scotland.
Cell
|January 13, 1989
Resumen
El polipéptido S es el polipéptido S.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Enzimología Enzimología.
- Genética La genética.
Sus antecedentes:
- Las enzimas de restricción de tipo I multisubunitaria utilizan polipéptidos S para el reconocimiento de ADN específico de la secuencia.
- Dos familias de enzimas, K y A, reconocen diversos objetivos de ADN bipartito.
- Los polipéptidos S dentro de la familia K exhiben regiones de secuencia variable cruciales para el reconocimiento de objetivos.
Objetivo del estudio:
- Para aclarar el papel del dominio N-terminal de los polipéptidos S en el reconocimiento de secuencias de ADN.
- Para determinar la secuencia específica de ADN reconocida por la enzima de restricción de tipo I EcoE.
- Para comparar las secuencias de aminoácidos y nucleótidos de los genes S en diferentes familias de enzimas.
Principales métodos:
- Análisis de secuencia de genes S de EcoA y EcoE.
- Comparación de las secuencias de aminoácidos predichas con los miembros de la familia K.
- Determinación de la secuencia de ADN objetivo para EcoE.
Principales resultados:
- Los aminoácidos N-terminales 150 de los polipéptidos S de la familia K especifican el reconocimiento de un componente objetivo bipartito.
- EcoE reconoce la secuencia de ADN 5'GAG(N7) ATGC.
- Un dominio conservado que reconoce el GAG está presente en los polipéptidos S de las familias K y A, a pesar de la disimilaridad de la secuencia general.
- Se encontró una identidad de secuencia significativa (casi el 50%) entre el dominio específico de GAG de StySB (familia K) y la región amino variable de los polipéptidos S de EcoA y EcoE (familia A).
Conclusiones:
- Existe un dominio común de reconocimiento y metilación de GAG en las enzimas de restricción de tipo I de distintas familias.
- A pesar de la divergencia de la secuencia general, la conservación funcional de los dominios de reconocimiento de ADN es evidente.
- El estudio pone de relieve la naturaleza modular de los polipéptidos S para conferir especificidad de secuencia.
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