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El autoensamblaje de las proteínas de la seda de araña está controlado por un relé sensible al pH
Glareh Askarieh1, My Hedhammar, Kerstin Nordling
1Department of Chemistry, Oslo University, 1033 Blindern, 0315 Oslo, Norway.
Nature
|May 14, 2010
Resumen
Las proteínas de la seda de araña, las spidroins, se almacenan en un estado fluido. El dominio amino-terminal (NT) de las arañas controla el autoensamblaje, evitando la agregación prematura y permitiendo la formación de seda.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Ciencia de los materiales Ciencia de los materiales.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La seda de araña es un biopolímero de alto rendimiento producido a partir de arañas, almacenado como una droga fluida.
- Las arañas poseen segmentos repetitivos y conservan dominios no repetitivos cruciales para las propiedades de la seda.
- El mecanismo que impide la agregación prematura de spidroin antes del autoensamblaje sigue sin estar claro.
Objetivo del estudio:
- Investigar el papel del dominio amino-terminal (NT) en el autoensamblaje y la agregación de la spidroina.
- Para dilucidar los detalles moleculares del almacenamiento de spidroin y la formación de la seda.
- Para entender cómo las arañas controlan la agregación de proteínas durante la producción de seda.
Principales métodos:
- Cristalografía de rayos X para determinar la estructura del dominio NT.
- Mini-arañas de ingeniería que incorporan el dominio NT.
- Evaluación de las propiedades de autoensamblaje y agregación de las arañas de araña de ingeniería a diferentes pH.
Principales resultados:
- El dominio NT forma un homodímero de haces antiparalelas de cinco hélices con una estructura única.
- La incorporación de NT en mini-spidroins permite un autoensamblaje dependiente del pH alrededor del pH 6.3.
- NT retrasa la agregación a pH neutro (por encima de 7) y acelera el ensamblaje a pH más bajo.
Conclusiones:
- El dominio NT actúa como un interruptor molecular, regulando el ensamblaje de las spidroínas.
- Un mecanismo similar a un relé que involucra a NT controla la agregación de spidroin durante el almacenamiento y la extrusión.
- Es probable que la estructura dimérica y la distribución de la carga de NT se conserven en todas las arañas.
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