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Les sous unités spécifiques de l'ARN polymérase I

Abstract : Rpa34 and Rpa49 are non-catalytic subunits of RNA polymerase I (Pol I) conserved from yeast to man. Rpa34 binds a conserved domain between positions 63 and 119 of Rpa49 and this stabilises Rpa49 onto Pol I. Conversely, the rpa49-119,416 N-terminal deletion, with no binding domain, fails to recruit Rpa34 onto Pol I. rpa34Δ grows like a wild type but is synthetic lethal with top1Δ (lacking a type I DNA topoisomerase) and with rpa135-L656P or rpa135-D398N, two viable but mycophenolate-sensitive Pol I mutants. These defects are suppressed by over-expressing Rpa49, further arguing for a close functional interaction between Rpa34 and Rpa49. in vivo, Rpa49 is critical for regulating the binding and release of Rrn3 during initiation and elongation. rpa49Δ (or an rpa49::HIS3 mutant lacking the conserved C-terminal end of Rpa49) partly impairs the recruitment of Rrn3 to the rDNA promoter, but this defect is bypassed by the rpa43 35,326 N-terminal deletion. These rpa49 mutants are also unable to release the Rrn3 initiation factor from the elongating Pol I, and fully dissociate the elongating Pol I from its rDNA template. Rpa49, combined with Rpa34, therefore appears to facilitate Pol I recruitment and to convert it into an elongation-competent form lacking Rrn3.
Mots-clés : polymérase
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Submitted on : Thursday, January 6, 2011 - 3:57:16 PM
Last modification on : Monday, February 10, 2020 - 6:12:52 PM
Long-term archiving on: : Thursday, April 7, 2011 - 3:08:08 AM


  • HAL Id : tel-00553144, version 1



Frédéric Beckouet. Les sous unités spécifiques de l'ARN polymérase I. Sciences du Vivant [q-bio]. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00553144⟩



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