RNA polymerase I mutant affects ribosomal RNA processing and ribosomal DNA stability. Caractérisation d'un mutant de l'ARN polymérase I affecte le processing de l'ARN ribosomal et la stabilité de l'ADN ribosomal

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Normand, Christophe | Dez, Christophe | Dauban, Lise | Queille, Sophie | Danché, Sarah | Abderrahmane, Sarra | Beckouet, Frederic | Gadal, Olivier

Edité par CCSD ; Taylor & Francis -

International audience. Transcription is a major contributor to genomic instability. The ribosomal RNA (rDNA) gene locus consists of a head-to-tail repeat of the most actively transcribed genes in the genome. RNA polymerase I (RNAPI) is responsible for massive rRNA production, and nascent rRNA is co-transcriptionally assembled with early assembly factors in the yeast nucleolus. In Saccharomyces cerevisiae, a mutant form of RNAPI bearing a fusion of the transcription factor Rrn3 with RNAPI subunit Rpa43 (CARA-RNAPI) has been described previously. Here, we show that the CARA-RNAPI allele results in a novel type of rRNA processing defect, associated with rDNA genomic instability. A fraction of the 35S rRNA produced in CARA-RNAPI mutant escapes processing steps and accumulates. This accumulation is increased in mutants affecting exonucleolytic activities of the exosome complex. CARA-RNAPI is synthetic lethal with monopolin mutants that are known to affect the rDNA condensation.

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