Engineering Copper Hyperaccumulation in Plants by Expressing a Prokaryotic copC Gene

• Published in: Environmental science & technology 2012-11, Vol.46 (21), p.12088-12097
• Main Authors: Rodríguez-Llorente, Ignacio D, Lafuente, Alejandro, Doukkali, Bouchra, Caviedes, Miguel A, Pajuelo, Eloisa
• Format: Article
• Language: English
• Subjects: Applied sciences; Arabidopsis - genetics; Arabidopsis - metabolism; Bacterial Proteins - genetics; Biodegradation, Environmental; Biological and medical sciences; Biotechnology; Copper - metabolism; Decontamination. Miscellaneous; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gene expression; Gram-negative bacteria; Homeostasis; Industrial applications and implications. Economical aspects; Miscellaneous; Plant Roots - metabolism; Plant Shoots - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Pollution; Pollution, environment geology; Prokaryotes; Proteins; Pseudomonas - genetics; Soil and sediments pollution; Soil Pollutants - metabolism; Transgenic plants
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es300842s

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.