Étude chez la levure Saccharomyces cerevisiae des relations entre la structure du petit ARN nucléolaire U3, ses interactions avec les protéines de la particule nucléolaire snoRNP U3 et sa fonction dans la biogenèse des ribosomes

Abstract : U3 snoRNA contains two conserved pairs of boxes C'/D and B/C needed to bind the stably associated proteins. Binding of protein Snu13p/15.5 kD to each of the conserved motifs is a prerequisite for recruitment of the 4 other U3 snoRNP proteins, namely: Nop1p, Nop56p and Nop58p on the C'/D motif and the Rrp9p U3 specific protein on the B/C motif. We used the known 3D structure of a human G protein containing 7 WD-40 motifs and 3D structure homology modeling methods to build a 3D structure model for Rrp9p. In parallel, by production of variant U3 snoRNAs, and by testing their in vivo stabilities and activities, we identified the C'/D determinants needed for association of proteins Snu13p, Nop1p, Nop56p and Nop58p to U3 snoRNA. Based on a 3D structure model of U3 C/D box RNP built by C Charron, we then formulated hypotheses on the possible interactions between the C'/D motif and amino acids from Snu13p and Nop58p and verified the hypotheses by site-directed mutagenesis of yeast cell components. The data also revealed that very low amounts of U3 snoRNA are sufficient to ensure yeast growth. By site directed mutagenesis, I also studied how the C'/D and B/C motifs should be positioned one relative to the other in order to be functional. Taken together, my work brings important information on the architecture of yeast U3 snoRNP and its functional constraints
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http://docnum.univ-lorraine.fr/prive/DDOC_T_2012_0317_ROLLAND.pdf
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https://hal.univ-lorraine.fr/tel-01749658
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Submitted on : Thursday, March 29, 2018 - 12:22:31 PM
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Nicolas Rolland. Étude chez la levure Saccharomyces cerevisiae des relations entre la structure du petit ARN nucléolaire U3, ses interactions avec les protéines de la particule nucléolaire snoRNP U3 et sa fonction dans la biogenèse des ribosomes. Médecine humaine et pathologie. Université de Lorraine, 2012. Français. ⟨NNT : 2012LORR0317⟩. ⟨tel-01749658⟩

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