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DNAzyme-dependent Analysis of rRNA 2’-O-Methylation
Published on: September 16, 2019
RlmN y Cfr son enzimas SAM radicales involucradas en la metilación del ARN ribosomal
Feng Yan1, Jacqueline M LaMarre, Rene Röhrich
1Department of Cellular and Molecular Pharmacology, University of California, San Francisco, 600 16th Street, San Francisco, California 94158, USA.
Journal of the American Chemical Society
|February 27, 2010
Resumen
Este estudio revela cómo las enzimas bacterianas RlmN y Cfr metilan el ARN ribosomal (ARNr), un paso clave en la resistencia a los antibióticos. Estas enzimas SAM radicales metilan el ARNr 23S durante el ensamblaje del ribosoma, lo que afecta la eficacia del fármaco.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Microbiología Microbiología.
Sus antecedentes:
- Las modificaciones posttranscripcionales del ARN ribosomal (ARNr) son cruciales para la función del ribosoma y la resistencia bacteriana a los antibióticos.
- La metilación de la adenosina en el centro de la peptidil transferasa por las enzimas RlmN y Cfr es un mecanismo clave de resistencia.
- RlmN y Cfr pertenecen a la superfamilia SAM Radical, que utiliza la S-adenosilmetionina (SAM) como donante de metilo y iniciador de radicales.
Objetivo del estudio:
- Para caracterizar la actividad de transferencia de metilo in vitro de las enzimas RlmN y Cfr.
- Para aclarar los requisitos de sustrato y los elementos de reconocimiento de ARNr para estas metiltransferasas.
- Comprender las implicaciones del tiempo de metilación del ARNr y la especificidad del sustrato para la resistencia a los antibióticos.
Principales métodos:
- Ensayos in vitro para demostrar la transferencia de metilo catalizada por las enzimas Radical SAM.
- Análisis de los requisitos de ARNr 23S, incluido el ARNr libre de proteínas frente a las subunidades ribosómicas ensambladas.
- Identificación de los elementos estructurales clave del ARNr (hélices 90-92 y A2503) involucrados en el reconocimiento de sustratos.
Principales resultados:
- Demostró la primera transferencia de metilo in vitro por un miembro de la superfamilia SAM Radical.
- Se demostró que RlmN y Cfr utilizan el ARNr 23S libre de proteínas, no la subunidad ribosómica grande completa.
- Se identificaron elementos estructurales específicos de ARNr esenciales para el reconocimiento de enzimas y la catálisis.
- Confirmó SAM como el donante de metilo y la fuente de radicales.
Conclusiones:
- Este estudio amplía las funciones catalíticas conocidas de la superfamilia de enzimas Radical SAM.
- La metilación del RRNA por RlmN y Cfr ocurre durante el ensamblaje del ribosoma, no en los ribosomas maduros.
- Los hallazgos proporcionan información crítica sobre el mecanismo de la resistencia a los antibióticos conferida por la modificación del ARNr.
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