DS0401 -

Function of pre-60S pre-ribosomal particle components in rDNA transcription by RNA polymerase I – CHROMRIB

Submission summary

Ribosome biogenesis in eukaryotes involves the transcription of the ribosomal DNA (rDNA) units by RNA polymerase I (Pol I) and the assembly of the resulting nascent transcripts (pre-rRNAs) with numerous ribosomal proteins and ribosome assembly factors (RAFs). These early steps generate pre-ribosomal particles hosting the complex pre-rRNA maturation process and which will evolve into the mature ribosomal subunits. In recent years, it has become clear that pre-ribosome assembly and pre-rRNA processing start during rDNA transcription by Pol I and that rDNA transcription, pre-ribosome assembly and pre-rRNA processing are functionally coupled. The mode of coupling and the factors involved remain largely unknown. We propose to explore the functional coupling of pre-rRNA processing and rDNA transcription using the yeast S. cerevisiae as model system. Our preliminary results indicate that the Rpf2-Rrs1 heterodimer, which associates co-transcriptionally with the nascent pre-rRNA and functions as pre-60S assembly module, seems also involved in the regulation of Pol I transcription. Both proteins interact with several chromatin modifying or remodeling factors, bind themselves to rDNA and Pol I subunits and their absence induces rapid defects in Pol I transcription. We thus hypothesize that Rpf2 and Rrs1, and possibly also other pre-60S RAFs, are directly involved in Pol I transcription. The aim of this project is to elucidate the molecular mechanisms underlying the function of pre-60S particle assembly factors (pre-60S RAFs) in Pol I transcription. Using transcriptional run-on assays, we will identify the pre-60S RAFs in addition to Rpf2 and Rrs1 required for Pol I transcription and characterize their function in transcription by ChIP and Miller spread analyses. The precise interactome of the identified factors (proteins and nucleic acids) will be characterized using a combination of in vivo approaches (immunoprecipitations, CRAC, ChIP-Seq and ChIP-exo). The direct binding partners will be identified in vitro and the molecular determinant of these interactions will be characterized through structural studies. The functional importance of these interactions for rDNA organization and Pol I transcription as well as pre-ribosome assembly and pre-rRNA processing will be assessed in yeast cells. Altogether, our studies should determine how components of pre-60S particles participate in a functional coupling between Pol I transcription, pre-ribosome assembly and pre-rRNA processing.

Project coordination

Anthony HENRAS (Centre National de la Recherche Scientifique / Laboratoire de Biologie Moléculaire Eucaryote)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

UPD-UMR 8015 Laboratoire de Cristallographie et RMN Biologiques
CNRS/LBME/UMR5099 Centre National de la Recherche Scientifique / Laboratoire de Biologie Moléculaire Eucaryote

Help of the ANR 465,755 euros
Beginning and duration of the scientific project: October 2016 - 48 Months

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