Proteasome- and SCF-dependent degradation of yeast adenine deaminase upon transition from proliferation to quiescence requires a new F-box protein named Saf1p. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Molecular Microbiology Année : 2006

Proteasome- and SCF-dependent degradation of yeast adenine deaminase upon transition from proliferation to quiescence requires a new F-box protein named Saf1p.

Résumé

In response to nutrient limitation, Saccharomyces cerevisiae cells enter into a nonproliferating state termed quiescence. This transition is associated with profound changes in gene expression patterns. The adenine deaminase encoding gene AAH1 is among the most precociously and tightly down-regulated gene upon entry into quiescence. We show that AAH1 down regulation is not specifically due to glucose exhaustion but is a more general response to nutrient limitation. We also found that Aah1p level is tightly correlated to RAS activity indicating thus an important role for the proteine kinase A pathway in this regulation process. We have isolated three deletion mutants, srb10, srb11 and saf1 (ybr280c) affecting AAH1 expression during post-diauxic growth and in early stationary phase. We show that the Srb10p cyclin-dependent kinase and its cyclin, Srb11p, regulate AAH1 expression at the transcriptional level. By contrast, Saf1p, a previously uncharacterized F-box protein, acts at a post-transcriptional level by promoting degradation of Aah1p. This post-transcriptional regulation is abolished by mutations affecting the proteasome or constant subunits of the SCF (Skp1-Cullin-F-box) complex. We propose that Saf1p targets Aah1p for proteasomedependent degradation upon entry into quiescence. This work provides the first direct evidence for active degradation of proteins in quiescent yeast cells.
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Dates et versions

hal-00023448 , version 1 (27-04-2007)

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Stéphanie Escusa, Jurgi Camblong, Jean-Marc Galan, Benoît Pinson, Bertrand Daignan-Fornier. Proteasome- and SCF-dependent degradation of yeast adenine deaminase upon transition from proliferation to quiescence requires a new F-box protein named Saf1p.. Molecular Microbiology, 2006, 60(4), pp.1014-25. ⟨10.1111/j.1365-2958.2006.05153.x⟩. ⟨hal-00023448⟩
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