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Communication Dans Un Congrès Année : 2018

Structure-function analysis of the box C/D snoRNP assembly factor Bcd1p

Marc Quinternet
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Cosmin Saveanu

Résumé

In eukaryotes, numerous trans-acting factors orchestrate the various steps of ribosome biogenesis, among which hundreds of box C/D and box H/ACA small nucleolar ribonucleoproteins (snoRNPs) are catalysts of rRNA 2'-O-methylation and pseudouridylation, respectively. In addition, a subset of snoRNPs, e.g. U3, is required for endo-ribonucleolytic cleavages in pre-rRNAs. C/D snoRNPs each contain a set of four core proteins (Snu13, Nop58, Nop56, Nop1) and a specific non coding C/D snoRNA which contains guide sequences that base-pair with a target sequence to specify the site to modify. Assembly of C/D snoRNPs is a complex process involving the HSP90 co-chaperone R2TP which is composed of an RPAP3/Tah1p-PIH1D1/Pih1p heterodimer associated with the two essential AAA+ ATPases RUVBL1/Rvb1p/Pontin and RUVBL2/Rvb2p/Reptin (human/yeast). The platform protein NUFIP1/Rsa1p plays a central role in R2TP recruitment on pre-snoRNPs. Finally, protein ZNHIT6/Bcd1 appeared as a leading actor of the assembly process but its precise function is poorly characterized. By chromatin, RNA and protein immunoprecipitation assays we show that Bcd1p is recruited co-transcriptionally on pre-snoRNAs and directs the loading of the core protein Nop58 on RNA. We found unexpectedly that Bcd1p is able to interact with histone chaperone Rtt106p, which is involved in nucleosome formation associated with replication and in the control of heterochromatin formation. We report the structural characterization of the Bcd1p-Rtt106p interaction by X-ray crystallography and a combination of biophysical techniques. Moreover, we found Rtt106p associated with C/D snoRNAs in a Bcd1p- and Rsa1p-dependent manner. This interaction may highlight a functional relation between snoRNPs biogenesis and chromatin remodeling.
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Dates et versions

hal-03543598 , version 1 (26-01-2022)

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  • HAL Id : hal-03543598 , version 1

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Benoit Bragantini, Arnaud Paul, Christophe Charron, Decebal Tiotiu, Marc Quinternet, et al.. Structure-function analysis of the box C/D snoRNP assembly factor Bcd1p. Levures, Modèles, Outils, Sep 2018, Rheinau, Switzerland. ⟨hal-03543598⟩
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