title: Protection of tobacco cells from oxidative copper toxicity by catalytically active metal-binding DNA oligomers.
abstract: The impact of copper ions on the oxidative and calcium signal transductions, leading to cell death in plant cells, have been documented. Copper induces a series of biological and chemical reactions in plant cells including the oxidative burst reflecting the production of reactive oxygen species and the stimulation of calcium channel opening allowing a transient increase in cytosolic calcium concentrations. These early events, completed within a few minutes after the contact with copper, are known to trigger the development of cell death. The effects of DNA fragments with copper-binding motifs as novel plant cell-protecting agents were assessed using cell suspension cultures of transgenic tobacco (Nicotiana tabacum L., cell line BY-2) expressing the aequorin gene. The addition of GC-rich double-stranded DNA fragments, prior to the addition of copper ions, effectively blocked both the copper-induced calcium influx and cell death. In addition, the DNA-Cu complex examined was shown to possess superoxide-scavenging catalytic activity, suggesting that DNA-mediated protection of the cells from copper toxicity is due to the removal of superoxide. Lastly, a possible mechanism of DNA-Cu interaction and future applications of these DNA fragments in the protection of plant roots from metal toxicity or in aid of phyto-remediation processes are discussed.
authors.affiliation: Graduate School of Environmental Engineering, The University of Kitakyushu, Kitakyushu, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Iwase
authors.forename: Hiroka
authors.initials: H
authors.lastname: Furukawa
authors.forename: Takuya
authors.initials: T
authors.lastname: Hiramatsu
authors.forename: François
authors.initials: F
authors.lastname: Bouteau
authors.forename: Stefano
authors.initials: S
authors.lastname: Mancuso
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Okazaki
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kawano
mesh_terms: D000331:Aequorin / Q000378:metabolism*; D000975:Antioxidants / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death; D003300:Copper / Q000633:toxicity*; D018744:DNA, Plant / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; D018744:DNA, Plant; D000331:Aequorin; D003300:Copper; D010100:Oxygen; D002118:Calcium
keywords: Aequorin; ROS; Z-DNA.; cell death; copper phytotoxicity; metal toxicity; nucleozyme