Le protéasome et le fer : rôles et/ou régulations dans le nucléole d’Arabidopsis thaliana

Abstract : The aim of this thesis work is to highlight the impact of both nucleolus content and structure on nucleolar functions in A. thaliana. For this I followed two approaches: 1- I performed nucleolus proteome and characterized one of its non-ribosomal activity / 2- I studied nucleolar iron impact on ribosomes biogenesis.Firstly, the A. thaliana nucleolar proteome allowed me to identify nucleolar proteins with non-ribosomal functions. Among these, I showed that 26S proteasome activity can be regulated by nucleolus. More precisely, proteasome activity decreases with nucleolus disorganization. Moreover, I also showed that 26S proteasome, together with Nucleolin, might play a role in ribosomal RNA transcription and/or maturation.Secondly, I proved that loss of nucleolar iron (in nas1,2,4 mutant plants) induces an increase of nucleolar transcriptional structures (fibrillar centers). This observation is correlated with the transcription of normally silenced rDNA from NOR2 and, interestingly, with hypermethylation of rDNA promoters in CHH context. And so, iron might regulate factors implicated in epigenetic pathways responsible of either rDNA transcription or repression.
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Charlotte Montacié. Le protéasome et le fer : rôles et/ou régulations dans le nucléole d’Arabidopsis thaliana. Biologie végétale. Université de Perpignan, 2019. Français. ⟨NNT : 2019PERP0002⟩. ⟨tel-02145634⟩

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