title: Cyclic-nucleotide- and Ca2+/calmodulin-regulated channels in plants: targets for manipulating heavy-metal tolerance, and possible physiological roles.
abstract: Recently we discovered a tobacco protein (designated NtCBP4) that modulates heavy-metal tolerance in transgenic plants. Structurally, NtCBP4 is similar to mammalian cyclic-nucleotide-gated non-selective cation channels containing six putative transmembrane domains, a predicted pore region, a conserved cyclic-nucleotide-binding domain, and a high-affinity calmodulin-binding site that coincides with its cyclic-nucleotide-binding domain. Transgenic tobacco expressing the plasma-membrane-localized NtCBP4 exhibit improved tolerance to Ni(2+) and hypersensitivity to Pb(2+), which are associated with a decreased accumulation of Ni(2+) and an enhanced accumulation of Pb(2+) respectively. Transgenic plants expressing a truncated version of NtCBP4, from which regulatory domains had been removed, have a different phenotype. Here we describe our approach to studying the involvement of NtCBP4 in heavy-metal tolerance and to elucidate its physiological role.
authors.affiliation: The Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: T
authors.initials: T
authors.lastname: Arazi
authors.forename: B
authors.initials: B
authors.lastname: Kaplan
authors.forename: R
authors.initials: R
authors.lastname: Sunkar
authors.forename: H
authors.initials: H
authors.lastname: Fromm
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002412:Cations; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence; D007473:Ion Channels / Q000737:chemistry* / Q000378:metabolism; D007854:Lead / Q000378:metabolism / Q000493:pharmacokinetics; D019216:Metals, Heavy / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009532:Nickel / Q000378:metabolism / Q000493:pharmacokinetics; D009712:Nucleotides, Cyclic / Q000378:metabolism*; D010641:Phenotype; D018521:Plant Physiological Phenomena; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014026:Nicotiana / Q000737:chemistry
chemical_list: C402668:CBP4 protein, Nicotiana tabacum; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D002412:Cations; D007473:Ion Channels; D019216:Metals, Heavy; D009712:Nucleotides, Cyclic; D010940:Plant Proteins; D007854:Lead; D009532:Nickel; D002118:Calcium