title: Enhanced selenium tolerance and accumulation in transgenic Arabidopsis expressing a mouse selenocysteine lyase.
abstract: Selenium (Se) toxicity is thought to be due to nonspecific incorporation of selenocysteine (Se-Cys) into proteins, replacing Cys. In an attempt to direct Se flow away from incorporation into proteins, a mouse (Mus musculus) Se-Cys lyase (SL) was expressed in the cytosol or chloroplasts of Arabidopsis. This enzyme specifically catalyzes the decomposition of Se-Cys into elemental Se and alanine. The resulting SL transgenics were shown to express the mouse enzyme in the expected intracellular location, and to have SL activities up to 2-fold (cytosolic lines) or 6-fold (chloroplastic lines) higher than wild-type plants. Se incorporation into proteins was reduced 2-fold in both types of SL transgenics, indicating that the approach successfully redirected Se flow in the plant. Both the cytosolic and chloroplastic SL plants showed enhanced shoot Se concentrations, up to 1.5-fold compared with wild type. The cytosolic SL plants showed enhanced tolerance to Se, presumably because of their reduced protein Se levels. Surprisingly, the chloroplastic SL transgenics were less tolerant to Se, indicating that (over) production of elemental Se in the chloroplast is toxic. Expression of SL in the cytosol may be a useful approach for the creation of plants with enhanced Se phytoremediation capacity.
authors.affiliation: Department of Biology, Colorado State University, Anatomy/Zoology Building, Fort Collins, Colorado 80523, USA.
authors.forename: Marinus
authors.initials: M
authors.lastname: Pilon
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Owen
authors.forename: Gulnara F
authors.initials: GF
authors.lastname: Garifullina
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kurihara
authors.forename: Hisaaki
authors.initials: H
authors.lastname: Mihara
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Esaki
authors.forename: Elizabeth A H
authors.initials: EA
authors.lastname: Pilon-Smits
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology*; D000409:Alanine / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008190:Lyases / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D030821:Plants, Genetically Modified; D012643:Selenium / Q000378:metabolism / Q000633:toxicity*; D017279:Selenocysteine / Q000378:metabolism
chemical_list: D017279:Selenocysteine; D008190:Lyases; C034278:selenocysteine lyase; D012643:Selenium; D000409:Alanine