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Una desaminasa de citidina edita C a U en ARN de transferencia en las arqueas

Lennart Randau¹, Bradford J Stanley, Andrew Kohlway

¹Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA. lennart.randau@yale.edu

Science (New York, N.Y.)

|May 2, 2009

Resumen

La arquea hipertermófila Methanopyrus kandleri utiliza citidina en la posición 8 del tRNA. Los investigadores descubrieron una enzima citidina desaminasa, CDAT8, que edita la citidina a la uridina, asegurando el plegamiento y la función adecuados del tRNA.

Área de la Ciencia:

Biología Molecular Biología Molecular
Biología Estructural Biología estructural.
Genómica de las arqueas.

Sus antecedentes:

Los ARN de transferencia canónicos (ARNt) poseen uridina en la posición 8, crucial para la estructura terciaria.
El arqueón hipertermófilo Methanopyrus kandleri presenta de manera única la citidina en la posición 8 en la mayoría de sus genes de ARNt.

Objetivo del estudio:

Para investigar el mecanismo detrás de la citidina inusual en la posición 8 en M. kandleri tRNAs.
Para identificar y caracterizar la enzima responsable de modificar esta posición.
Para aclarar la base estructural de la actividad y la especificidad de la enzima.

Principales métodos:

Demostración de la edición de C a U en la posición 8 del tRNA.
Cristalografía de rayos X para determinar la estructura de la enzima citidina desaminasa CDAT8.8.
Pruebas bioquímicas para evaluar la actividad enzimática y la especificidad del sustrato.

Principales resultados:

Se identificó una nueva citidina desaminasa específica para el ARNt, CDAT8.
CDAT8 posee una estructura única con un dominio de citidina desaminasa fusionado con un dominio THUMP de unión al tRNA.
La enzima desamina específicamente la citidina en la posición 8, requiriendo solo la horquilla del tallo aceptador para la actividad.
CDAT8 pertenece a una familia distinta dentro de la superfamilia parecida a la citidina desaminasa.

Conclusiones:

La edición de C a U por CDAT8 es esencial para el plegamiento y la funcionalidad adecuados de todos los tRNA de M. kandleri.
Este mecanismo de edición asegura la integridad del tRNA en un entorno hipertermófilo.
CDAT8 representa una solución enzimática única para mantener la estructura y la función del tRNA.

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