title: Engineering copper hyperaccumulation in plants by expressing a prokaryotic copC gene.
abstract: In this work, engineering Cu-hyperaccumulation in plants was approached. First, the copC gene from Pseudomonas sp. Az13, encoding a periplasmic Cu-binding protein, was expressed in Arabidopsis thaliana driven by the CaMV35S promoter (transgenic lines 35S-copC). 35S-copC lines showed up to 5-fold increased Cu accumulation in roots (up to 2000 μg Cu. g(-1)) and shoots (up to 400 μg Cu. g(-1)), compared to untransformed plants, over the limits established for Cu-hyperaccumulators. 35S lines showed enhanced Cu sensitivity. Second, copC was engineered under the control of the cab1 (chlorophyll a/b binding protein 1) promoter, in order to drive copC expression to the shoots (transgenic lines cab1-copC). cab1-copC lines showed increased Cu translocation factors (twice that of wild-type plants) and also displayed enhanced Cu sensitivity. Finally, subcellular targeting the CopC protein to plant vacuoles was addressed by expressing a modified copC gene containing specific vacuole sorting determinants (transgenic lines 35S-copC-V). Unexpectedly, increased Cu-accumulation was not achieved-neither in roots nor in shoots-when compared to 35S-copC lines. Conversely, 35S-copC-V lines did display greatly enhanced Cu-hypersensitivity. Our results demonstrate the feasibility of obtaining Cu-hyperaccumulators by engineering a prokaryotic Cu-binding protein, but they highlight the difficulty of altering the exquisite Cu homeostasis in plants.
authors.affiliation: Departamento de Microbiología, Facultad de Farmacia, Universidad de Sevilla, 41012-Sevilla, Spain.
authors.forename: Ignacio D
authors.initials: ID
authors.lastname: Rodríguez-Llorente
authors.forename: Alejandro
authors.initials: A
authors.lastname: Lafuente
authors.forename: Bouchra
authors.initials: B
authors.lastname: Doukkali
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Caviedes
authors.forename: Eloisa
authors.initials: E
authors.lastname: Pajuelo
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics*; D001673:Biodegradation, Environmental; D003300:Copper / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011549:Pseudomonas / Q000235:genetics; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C071265:CopC protein, Bacteria; D012989:Soil Pollutants; D003300:Copper