title: Plants contain two SCO proteins that are differentially involved in cytochrome c oxidase function and copper and redox homeostasis.
abstract: Two Arabidopsis thaliana genes (HCC1 and HCC2), resulting from a duplication that took place before the emergence of flowering plants, encode proteins with homology to the SCO proteins involved in copper insertion during cytochrome c oxidase (COX) assembly in other organisms. Heterozygote HCC1 mutant plants produce 25% abnormal seeds with defective embryos arrested at the heart or torpedo stage. These embryos lack COX activity, suggesting that the requirement of HCC1 during the early stages of plant development is related with its COX assembly function. Homozygote HCC2 mutant plants develop normally and do not show changes in COX2 levels. These plants display increased sensitivity of root growth to increased copper and a higher expression of miR398 and other genes that respond to copper limitation, in spite of the fact that they have a higher copper content than the wild type. HCC2 mutant plants also show increased expression of stress-responsive genes. The results suggest that HCC1 is the protein involved in COX biogenesis and that HCC2, that lacks the cysteines and histidine putatively involved in copper binding, functions in copper sensing and redox homeostasis. In addition, plants that overexpress HCC1 have an altered response of root elongation to changes in copper in the growth medium and increased expression of two low-copper-responsive genes, suggesting that HCC1 may also have a role in copper homeostasis.
authors.affiliation: Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina.
authors.forename: Carolina V
authors.initials: CV
authors.lastname: Attallah
authors.forename: Elina
authors.initials: E
authors.lastname: Welchen
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Martin
authors.forename: Silvana V
authors.initials: SV
authors.lastname: Spinelli
authors.forename: Geraldine
authors.initials: G
authors.lastname: Bonnard
authors.forename: Javier F
authors.initials: JF
authors.lastname: Palatnik
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Gonzalez
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000079922:Copper Transport Proteins; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017343:Genes, Plant / Q000235:genetics; D006706:Homeostasis / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000378:metabolism; D012639:Seeds / Q000201:enzymology; D013312:Stress, Physiological / Q000235:genetics; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; C556505:HCC1 protein, Arabidopsis; C568347:HCC2 protein, Arabidopsis; D007527:Isoenzymes; D024101:Mitochondrial Proteins; D003300:Copper; D013482:Superoxide Dismutase; D003576:Electron Transport Complex IV