Arabidopsis FUSCA5 encodes a novel phosphoprotein that is a component of the COP9 complex

Baruch Karniol, Przemyslaw Malec, Daniel A. Chamovitz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The COP9 complex is a regulator essential for repression of light-mediated development in Arabidopsis. Using partial amino acid sequence data generated from purified COP9 complexes, we cloned the Arabidopsis cDNA encoding the 27-kD subunit of the COP9 complex and showed that it is encoded by the previously identified FUSCA5 (FUS5) locus. fus5 mutants exhibit constitutive photomorphogenic phenotypes similar to those of cop9 and fus6. Point mutations in FUSS that led to a loss of FUS5 protein were detected in four fuss allelic strains. FUS5 contains the PCI/PINT and mitogen-activated protein kinase kinase activation loop motifs and is highly conserved with the mammalian COP9 complex subunit 7 and the Aspergillus nidulans AcoB proteins. FUS5 is present in both complex and monomeric forms. In the COP9 complex, FUS5 may interact directly with FUS6 and COP9. Mutations in FUS6 and COP9 result in a shift in the electrophoretic mobility of FUS5. This shift can be mimicked by in vitro phosphorylation of FUS5 by plant extracts. These findings further support the hypothesis that the COP9 complex is a central and common regulator that may interact with multiple signaling pathways.

Original languageEnglish
Pages (from-to)839-848
Number of pages10
JournalPlant Cell
Issue number5
StatePublished - May 1999
Externally publishedYes


Dive into the research topics of 'Arabidopsis FUSCA5 encodes a novel phosphoprotein that is a component of the COP9 complex'. Together they form a unique fingerprint.

Cite this