title: Arabidopsis SUMO E3 ligase SIZ1 is involved in excess copper tolerance.
abstract: The reversible conjugation of the small ubiquitin-like modifier (SUMO) to protein substrates occurs as a posttranslational regulatory process in eukaryotic organisms. In Arabidopsis (Arabidopsis thaliana), several stress-responsive SUMO conjugations are mediated mainly by the SUMO E3 ligase SIZ1. In this study, we observed a phenotype of hypersensitivity to excess copper in the siz1-2 and siz1-3 mutants. Excess copper can stimulate the accumulation of SUMO1 conjugates in wild-type plants but not in the siz1 mutant. Copper accumulated to a higher level in the aerial parts of soil-grown plants in the siz1 mutant than in the wild type. A dramatic difference in copper distribution was also observed between siz1 and wild-type Arabidopsis treated with excess copper. As a result, the shoot-to-root ratio of copper concentration in siz1 is nearly twice as high as that in the wild type. We have found that copper-induced Sumoylation is involved in the gene regulation of metal transporters YELLOW STRIPE-LIKE 1 (YSL1) and YSL3, as the siz1 mutant is unable to down-regulate the expression of YSL1 and YSL3 under excess copper stress. The hypersensitivity to excess copper and anomalous distribution of copper observed in the siz1 mutant are greatly diminished in the siz1ysl3 double mutant and slightly in the siz1ysl1 double mutant. These data suggest that SIZ1-mediated sumoylation is involved specifically in copper homeostasis and tolerance in planta.
authors.affiliation: Agricultural Biotechnology Research Center , Academia Sinica, Taipei, Taiwan 11529.
authors.forename: Chyi-Chuann
authors.initials: CC
authors.lastname: Chen
authors.forename: Yong-Yi
authors.initials: YY
authors.lastname: Chen
authors.forename: I-Chien
authors.initials: IC
authors.lastname: Tang
authors.forename: Hong-Ming
authors.initials: HM
authors.lastname: Liang
authors.forename: Chong-Cheong
authors.initials: CC
authors.lastname: Lai
authors.forename: Jeng-Min
authors.initials: JM
authors.lastname: Chiou
authors.forename: Kuo-Chen
authors.initials: KC
authors.lastname: Yeh
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects* / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D008025:Ligases / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D058207:Sumoylation / Q000187:drug effects; D013997:Time Factors; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D003300:Copper; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; C502552:SIZ1 protein, Arabidopsis