title: Point mutations in Arabidopsis Cullin1 reveal its essential role in jasmonate response.
abstract: The SKP1-Cullin/Cdc53-F-box protein ubiquitin ligases (SCF) target many important regulatory proteins for degradation and play vital roles in diverse cellular processes. In Arabidopsis there are 11 Cullin members (AtCUL). AtCUL1 was demonstrated to assemble into SCF complexes containing COI1, an F-box protein required for response to jasmonates (JA) that regulate plant fertility and defense responses. It is not clear whether other Cullins also associate with COI1 to form SCF complexes, thus, it is unknown whether AtCUL1, or another Cullin that assembles into SCF(COI1) (even perhaps two or more functionally redundant Cullins), plays a major role in JA signaling. We present genetic and physiological data to directly demonstrate that AtCUL1 is necessary for normal JA responses. The homozygous AtCUL1 mutants axr6-1 and axr6-2, the heterozygous mutants axr6/AXR6, and transgenic plants expressing mutant AtCUL1 proteins containing a single amino acid substitution from phenylalanine-111 to valine, all exhibit reduced responses to JA. We also demonstrate that ax6 enhances the effect of coi1 on JA responses, implying a genetic interaction between COI1 and AtCUL1 in JA signaling. Furthermore, we show that the point mutations in AtCUL1 affect the assembly of COI1 into SCF, thus attenuating SCF(COI1) formation.
authors.affiliation: College of Bio-Safety Science and Technology, Hunan Agricultural University, Changsha, 410128 China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Ren
authors.forename: Jianwei
authors.initials: J
authors.lastname: Pan
authors.forename: Wen
authors.initials: W
authors.lastname: Peng
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Lawrence
authors.initials: L
authors.lastname: Hobbie
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
authors.forename: Mark
authors.initials: M
authors.lastname: Estelle
authors.forename: Bida
authors.initials: B
authors.lastname: Gao
authors.forename: Jinrong
authors.initials: J
authors.lastname: Peng
authors.forename: Chuanqing
authors.initials: C
authors.lastname: Sun
authors.forename: Daoxin
authors.initials: D
authors.lastname: Xie
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D044842:Cullin Proteins / Q000235:genetics / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000502:physiology; D054883:Oxylipins; D010641:Phenotype; D010937:Plant Growth Regulators / Q000502:physiology*; D030821:Plants, Genetically Modified; D017354:Point Mutation; D014157:Transcription Factors / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D014157:Transcription Factors; C011006:jasmonic acid