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Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 26, 2011
Una aminoacil tRNA sintetasa cuya secuencia no encaja en ninguna de las dos clases conocidas
C Fàbrega1, M A Farrow, B Mukhopadhyay
1The Skaggs Institute for Chemical Biology, The Scripps Research Institute, Beckman Center, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Nature
|May 3, 2001
Resumen
Los investigadores descubrieron una nueva ARN sintetasa de transferencia de cisteinilo en las arqueas, desafiando los modelos existentes de síntesis de proteínas. Esta antigua enzima carece de motivos canónicos, lo que sugiere una ruta evolutiva diferente para las reacciones esenciales de aminoacilación.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- Las sintetasas de ARN de transferencia de aminoácidos son enzimas esenciales para la síntesis de proteínas, catalizando la unión de aminoácidos a sus correspondientes ARNt.
- Estas enzimas se dividen en dos clases conservadas basadas en la arquitectura del sitio activo y los motivos de secuencia conservados.
- La ausencia de un gen reconocible para la cisteinil-tRNA sintetasa en algunas arqueas presentó un rompecabezas para la comprensión de la síntesis de proteínas.
Objetivo del estudio:
- Para identificar y caracterizar la cisteinil-tRNA sintetasa en las arqueas, específicamente Methanococcus jannaschii.
- Para investigar los orígenes evolutivos y las propiedades funcionales de esta potencialmente nueva sintetasa.
- Para resolver el mecanismo de incorporación de cisteína en el tRNA en arqueas que carecen de genes canónicos de sintetasa.
Principales métodos:
- Análisis bioinformático para identificar genes potenciales de la sintetasa.
- Ensayos bioquímicos in vitro para caracterizar la actividad enzimática y la especificidad del sustrato.
- Estudios in vivo en huéspedes arqueos para confirmar la función.
Principales resultados:
- Se identificó una nueva cisteinil-tRNA sintetasa en Methanococcus jannaschii y Deinococcus radiodurans.
- Esta enzima carece de los motivos de secuencia conservados característicos de las dos clases conocidas de tRNA sintetasas.
- La caracterización confirmó su capacidad para aminoacillar la cisteína a su tRNA cognado, tanto in vitro como in vivo.
- La estructura única de la enzima sugiere un origen antiguo, anterior a la divergencia de las clases canónicas de sintetasa.
Conclusiones:
- El descubrimiento de esta distinta cisteinil-tRNA sintetasa proporciona una nueva perspectiva sobre la evolución de la síntesis de proteínas.
- Desafía la noción de que la aminoacilación de cisteína en estas arqueas se basa en una enzima canónica modificada.
- Este hallazgo sugiere la existencia de vías evolutivas alternativas para las aminoacil-tRNA sintetasas esenciales.
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