Transcriptional interactions between RNA polymerases II and III

  • Ysaline Lebrun

Student thesis: Master typesMaster en biochimie et biologie moléculaire et cellulaire à finalité approfondie


Transcription by the RNA polymerase III (Pol III) is one of the key determinants affecting protein synthesis regulation,among other things. However, the regulation of this polymerase remains poorly understood. In order to open new leads on Pol III regulation paths, experiments were performed based on a Pol III mutant showing a marked growth defect and reduced amount of one type of Pol III transcripts, transfer RNA precursors. As this mutant particularity arises from addition of a peptide on the Pol III subunit Rpc25, we studied the role of this subunit in transcription. On the basis of our results and of Pol III complex structure, the role of this subunit was elucidated and its mutation was linked to a defect in transcription initiation. We also show that its mutation has no significant impact on the activity of a particular complex, TORC1, despite that this complex is supposed to be regulated by the concentration of transfer RNA precursors. Reversely, mutation of Rpc25 causes a sensibility of this strain to overexpression of a protein stabilizing transfer RNA precursors, Sla1.

In parallel, naturally emerging suppressors of the growth defect phenotype of this mutant were isolated and sequenced in order to precisely map the acquired suppressive mutations. Based on the identified mutations, we show that some Pol II related actors have an impact on Pol III transcription.Thus, we propose the existence of a trans-polymerases regulation impacting Pol III.
la date de réponse18 janv. 2019
langue originaleAnglais
L'institution diplômante
  • Universite de Namur
SuperviseurDamien Hermand (Promoteur)

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