|M.Sc Thesis||Department of Biology|
|Supervisor:||Prof. Glickman Michael|
The COP9 signalosome (CSN complex), the lid subcomplex of the proteasome and translational initiation factor 3 (eIF3) are often referred to as the PCI family of complexes. This family of genetically and structurally similar complexes mediates different regulatory pathways. The CSN complex was originally described as an essential regulator of photomorphogenesis in Arabidopsis. Later on, the COP9 signalosome was purified from animal cells and found to be remarkably similar to the complex in plants. Recently, a CSN-like complex was identified and characterized in the group of M. Glickman at the Technion. The work describe in the accompanying thesis focuses on the biological roles of this CSN complex in budding yeast and a comparison to documented roles in other Organisms.
Deletants for individual subunits enhance pheromone response, increase mating efficiency and increase sporulation efficiency compared with the wild type strain. Overexpression of individual subunits, or of a human homologue, mitigates Dsst2-induced pheromone sensitivity. csi1, a novel CSN interactor, exhibits opposite phenotypes on these pathways. Deletants of most csn genes accumulate Cdc53/cullin in a Rub1-modified form. csn10 exhibits a distinct synthetic phenotype together with rub1 in mating or sporulation. Together, these results suggest that the role of the CSN in mediating Cdc53/cul1 Rubylation is distinct from that in the mating and sporulation pathways.