Novel aspects of COP9 signalosome functions revealed through analysis of hypomorphic csn mutants.
The COP9 signalosome (CSN) is a conserved eukaryotic protein complex implicated in the regulation of cullin-RING type E3 ubiquitin ligases by cleaving the small peptide RUB/Nedd8 from cullins. However, detailed analysis of CSN physiological functions in Arabidopsis has been hampered by the early seedling-lethality of csn null mutants. We and others have now identified a number of viable hypomorphic csn mutants which start to reveal novel CSN-dependent activities in adult Arabidopsis plants. Here, we present a detailed comparative analysis of the csn5a-1 and csn2-5 mutants as a mean to improve understanding of CSN functions in plant cells. Our observations point to CSN-independent activities of CSN5 and suggest a role of the CSN in cytoskeleton assembly/organization.
Institut de Biologie Environnementale et Biotechnologie, UMR 6191 CNRS-CEA-Université de la méditerranée Aix-Marseille II, CEN Cadarache, Saint Paul-lez-Durance, France. stuttman@mpiz-koeln.mpg.de
Johannes
J
Stuttmann
Jane E
JE
Parker
Laurent D
LD
Noël