The COP9 signalosome (CSN) is a eukaryotic multiprotein complex that connects various signals with multiple downstream molecular pathways controlling cellular differentiation and development. In higher eukaryotes, disfunction of the CSN is embryonic lethal, whereas in Aspergillus nidulans deletion of CSN subunits leads to viable strains with severe developmental defects. We want to understand the molecular networks controlled by CSN action in A. nidulans as a genetically amaneable eukaryotic model system. In higher eukaryotes, the CSN is composed of eight conserved subunits. We identified proposed open reading frames for all of them in the A. nidulans genome sequence. Using the tandem affinity purification method (TAP) we purified a complex containing several CSN subunits as proven by mass spectrometry. We are currently improving the method to additionally identify CSN associated proteins. Function of the CSN involves 26S proteasome-dependent regulation of cellular protein levels, mainly by the signalosome's intrinsic deneddylation and associated kinase activities. Accordingly, we observed a different protein expression pattern in a wild-type compared to a csn deletion strain in 2D gel analyses. Differentially expressed proteins were identified by mass spectrometry. These potential downstrem targets of CSN action hint at a CSN function in regulation of metabolism, cytoskeleton composition and stress response.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)