title: A gain-of-function phenotype conferred by over-expression of functional subunits of the COP9 signalosome in Arabidopsis.
abstract: The COP9 signalosome is a conserved cellular regulator present in diverse organisms. To understand the structural and functional relationship of the COP9 signalosome with its subunits, we expressed in wild-type and mutant Arabidopsis backgrounds two orthologues of subunit 1, rice FUS6 (rFUS6) and human GPS1, and Arabidopsis subunit 8 (COP9). In Arabidopsis, rFUS6 can functionally replace Arabidopsis endogenous FUS6 to form the COP9 signalosome complex and rescue the null fus6-1 mutant phenotype. Moreover, light-grown rFUS6 over-expression seedlings displayed longer hypocotyls and reduced anthocyanin accumulation in comparison to wild-type seedlings, which is opposite to the fus6/cop11 mutant phenotype. The long-hypocotyl phenotype was also observed in transgenic seedlings over-expressing Arabidopsis COP9. This finding indicates that over-expression of a functional subunit 1 or subunit 8 of the COP9 signalosome confers a gain-of-function phenotype relative to the complex. Human GPS1, when expressed in the fus6-1 null mutant of Arabidopsis, can assemble into a chimeric COP9 signalosome at low efficiency, demonstrating the structural conservation of the complexes between human and Arabidopsis. This low-abundancy chimeric complex is insufficient to fully rescue the mutant but is able to attenuate the mutant severity.
authors.affiliation: Peking-Yale Joint Center for Plant Molecular Genetics and Agribiotechnology, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: D
authors.initials: D
authors.lastname: Kang
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Cao
authors.forename: C
authors.initials: C
authors.lastname: Sun
authors.forename: X W
authors.initials: XW
authors.lastname: Deng
authors.forename: N
authors.initials: N
authors.lastname: Wei
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins; D000075686:COP9 Signalosome Complex; D019204:GTP-Binding Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008027:Light; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D012275:Oryza; D010447:Peptide Hydrolases; D010641:Phenotype; D021122:Protein Subunits; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C086322:CSN1 protein, Arabidopsis; C103315:GPS1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D011506:Proteins; D012097:Repressor Proteins; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D019204:GTP-Binding Proteins