An eight-subunit COP9 signalosome with an intact JAMM motif is required for fungal fruit body formation
- Silke Busch†,
- Elke U. Schwier†,
- Krystyna Nahlik†,
- Özür Bayram†,
- Kerstin Helmstaedt†,‡,
- Oliver W. Draht†,
- Sven Krappmann†,
- Oliver Valerius†,
- William N. Lipscomb§,¶, and
- Gerhard H. Braus†,¶
- †Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstrasse 8, D-37077 Göttingen, Germany;
- ‡Research Center for Molecular Physiology of the Brain, Deutsche Forschungsgemeinschaft, D-37073 Göttingen, Germany; and
- §Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138
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Contributed by William N. Lipscomb, March 7, 2007 (received for review November 17, 2006)
Abstract
Fruit body formation in filamentous fungi is a complex and yet hardly understood process. We show here that protein turnover control is crucial for Aspergillus nidulans development. Deletion of genes encoding COP9 signalosome (CSN) subunits 1, 2, 4, or 5 resulted in identical blocks in fruit body formation. The CSN multiprotein complex controls ubiquitin-dependent protein degradation in eukaryotes. Six CSN subunits interacted in a yeast two-hybrid analysis, and the complete eight-subunit CSN was recruited by a functional tandem affinity purification tag fusion of subunit 5 (CsnE). The tagged CsnE was unable to recruit any CSN subunit in a strain deleted for subunit 1 or subunit 4. Mutations in the JAMM metalloprotease core of CsnE resulted in mutant phenotypes identical to those of csn deletion strains. We propose that a correctly assembled CSN including a functional JAMM links protein turnover to fungal sexual development.
Footnotes
- ¶To whom correspondence may be addressed. E-mail: lipscomb{at}chemistry.harvard.edu or gbraus{at}gwdg.de
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Author contributions: S.B., E.U.S., K.N., K.H., O.W.D., S.K., O.V., and G.H.B. designed research; S.B., E.U.S., K.N., Ö.B., K.H., and O.W.D. performed research; S.B., E.U.S., K.N., Ö.B., K.H., S.K., O.V., and G.H.B. analyzed data; and S.B., W.N.L., and G.H.B. wrote the paper.
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The authors declare no conflict of interest.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0702108104/DC1.
- Abbreviation:
- CSN,
- COP9 signalosome.
- © 2007 by The National Academy of Sciences of the USA
