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Molecular characterization and expression analysis of copper‐zinc superoxide dismutases from the freshwater alga Closterium ehrenbergii under metal stress
Author(s) -
Wang Hui,
Ki JangSeu
Publication year - 2020
Publication title -
environmental toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.813
H-Index - 77
eISSN - 1522-7278
pISSN - 1520-4081
DOI - 10.1002/tox.22837
Subject(s) - superoxide dismutase , reactive oxygen species , biology , gene , botany , oxidative stress , algae , phylogenetic tree , antioxidant , metal toxicity , biochemistry , zinc , green algae , photosynthesis , gene expression , microbiology and biotechnology , chemistry , environmental chemistry , heavy metals , organic chemistry
Abstract Superoxide dismutase (SOD) acts as the first line of defense against reactive oxygen species (ROS) within cells. In the present study, we determined two novel CuZnSOD genes (designated as CeCSD1 and CeCSD2 ) from the toxicity‐testing freshwater algae Closterium ehrenbergii and examined their structural features, phylogenetic relationships, and gene expression under exposure to different metals. Putative CeCSD1 (204 aa, 20.6 kDa) and CeCSD2 (155 aa, 15.3 kDa) proteins had conserved CuZnSOD family motifs and metal (Cu, Zn) binding sites, but different N‐terminus structures, that is, CeCSD1 has a signal peptide to chloroplasts. Phylogenetic analysis of each protein revealed that C. ehrenbergii was well clustered with other green algae and plants. Real‐time PCR results showed that the gene expression obviously increased with heavy metal exposure. In addition, excess copper considerably increased the SOD activity and ROS generation but decreased the photosynthetic efficiency in treated cells. These results suggest that CeCSDs are involved in the antioxidant defense system and can be regarded as potential biomarkers for monitoring metal contaminants in aquatic environments.