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Plasmidos mitocondriales de Neurospora: integración en el ADN mitocondrial y evidencia para la transcripción inversa
Cell
|November 21, 1986
Resumen
Los plásmidos mitocondriales de Neurospora pueden causar defectos de crecimiento al integrarse en el ADN mitocondrial. Estos plásmidos supresores, posiblemente generados por transcripción inversa, conducen a un ADN mitocondrial defectuoso en los mutantes.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La micología de la micología.
- Genética La genética.
Sus antecedentes:
- Los plásmidos mitocondriales Mauriceville y Varkud en Neurospora son moléculas circulares de ADN.
- Su composición genética sugiere un vínculo con elementos genéticos móviles como retrotransposones e intrones.
Objetivo del estudio:
- Para investigar los efectos perjudiciales de estos plásmidos mitocondriales en el crecimiento de Neurospora.
- Para caracterizar la base molecular del deterioro del crecimiento inducido por plásmidos.
Principales métodos:
- Aislamiento y caracterización de mutantes de Neurospora que exhiben un deterioro del crecimiento debido a la actividad plasmítica.
- Análisis de secuencias de ADN plasmítico y mitocondrial (ADNmt) en cepas mutantes.
- Investigación de la estructura del plásmido, incluyendo inserciones y sitios de integración.
Principales resultados:
- Se identificaron doce mutantes con trastornos del crecimiento, todos los cuales albergaban plásmidos variantes supresoras.
- Diez de estos mutantes también mostraron ADN mitocondrial defectuoso (ADNmt).
- Los plásmidos supresores contenían inserciones, que a menudo incluían secuencias de tRNA, cerca del sitio de inicio del ARN 5 ', lo que sugiere la participación de la transcripción inversa.
- Se encontraron secuencias de plásmidos mitocondriales integradas en el ADNmt de al menos tres mutantes, con uniones indicativas de integración mediada por ARN.
Conclusiones:
- El estudio demuestra que los plásmidos mitocondriales de Neurospora pueden exhibir un comportamiento perjudicial, lo que lleva a un deterioro del crecimiento y un ADNmt defectuoso.
- Los hallazgos sugieren un mecanismo que involucra intermediarios de ARN y transcripción inversa en la generación e integración de estos plásmidos supresores.
- Estos plásmidos representan un ejemplo único de elementos genéticos móviles que afectan la integridad del genoma mitocondrial del huésped.
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