title: Molecular cloning and functional characterization of MnSOD from Dunaliella salina.
abstract: Dunaliella salina, a unicellular green alga, has the potential to grow in hypersaline environments via one of its gene products, superoxide dismutase (SOD). The superoxide radicals (O2 (-) ) produced by environmental stresses can cause damage to cells, and SOD catalyzes the turnover of such free radicals to protect cells. In this study, the gene coding for SOD in D. salina was cloned and the product was further identified and characterized. The open reading frame of this gene was 651 bp long, encoding for 217 amino acids. According to the sequence alignment using BLAST, native polyacrylamide electrophoresis for SOD activity analysis, and atomic absorption spectroscopy analysis, this protein belongs to the manganese-containing superoxide dismutase (MnSOD) family. Complementation analysis, performed by introducing plasmids carrying an inducible version of the D. salina gene encoding for MnSOD into an SOD-deficient mutant of E.coli, revealed that this gene could not only complement the defects in SOD activity, but was also capable of providing a stronger tolerance to restrictive growth conditions, such as high salt and prolonged UV exposure, compared to the tolerance of wild-type strains.
authors.affiliation: Microbiology and Metabolic Engineering Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan 610065, P. R. China.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Xin Ran
authors.initials: XR
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Yu
authors.initials: Y
authors.lastname: Cao
authors.forename: Shu Han
authors.initials: SH
authors.lastname: Ma
authors.forename: Yi
authors.initials: Y
authors.lastname: Cao
authors.forename: Dairong
authors.initials: D
authors.lastname: Qiao
mesh_terms: D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D016366:Open Reading Frames; D010957:Plasmids; D016415:Sequence Alignment; D013054:Spectrophotometry, Atomic; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism*; D016823:Volvocida / Q000201:enzymology* / Q000235:genetics
chemical_list: D013482:Superoxide Dismutase
keywords: Complementation analysis; Dunaliella salina; Manganese-containing Superoxide Dismutase; Oxidative stress