Superoxide dismutases (SODs, EC 1.15.1.1) belong to an important group of antioxidant metalloenzymes. Multiple SODs exist for scavenging of reactive oxygen species (ROS) in different cellular compartments to maintain an intricate ROS balance. The present study deals with molecular and biochemical characterization of CuZn SOD encoded by LOC_Os03g11960 (referred to as OsCSD3), which is the least studied among the four rice isozymes. The OsCSD3 showed higher similarity to peroxisomal SODs in plants. The OsCSD3 transcript was up-regulated in response to salinity, drought, and oxidative stress. Full-length cDNA encoding OsCSD3 was cloned and expressed in Escherichia coli and analyzed for spectral characteristics. UV (ultraviolet)–visible spectroscopic analysis showed evidences of d–d transitions, while circular dichroism analysis indicated high β-sheet content in the protein. The OsCSD3 existed as homodimer (∼36 kDa) with both Cu2+ and Zn2+ metal cofactors and was substantially active over a wide pH range (7.0–10.8), with optimum pH of 9.0. The enzyme was sensitive to diethyldithiocarbamate but insensitive to sodium azide, which are the characteristics features of CuZn SODs. The enzyme also exhibited bicarbonate-dependent peroxidase activity. Unlike several other known CuZn SODs, OsCSD3 showed higher tolerance to hydrogen peroxide and thermal inactivation. Heterologous overexpression of OsCSD3 enhanced tolerance of E. coli sod double-knockout (ΔsodA ΔsodB) mutant and wild-type strain against methyl viologen-induced oxidative stress, indicating the in vivo function of this enzyme. The results show that the locus LOC_Os03g11960 of rice encodes a functional CuZn SOD with biochemical characteristics similar to the peroxisomal isozymes.
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Cover Image
Cover Image
In this issue, Keith Willison reviews of the structure and evolution of eukaryotic CCT (chaperonin-containing TCP-1) and how it effects actin folding. The cover image shows a space-fill model of the CCT3/γ apical domain with its solvent-accessible-binding surface highlighted in brown and a stretch of bound poly-Gln β-strand occupying the long stretch of anchoring sites. For further details, see pages 3009–3034. Image kindly provided by Miriam Eisenstein (Weizmann Institute for Science).
Biochemical and functional characterization of OsCSD3, a novel CuZn superoxide dismutase from rice
Ravi Prakash Sanyal, Amol Samant, Vishal Prashar, Hari Sharan Misra, Ajay Saini; Biochemical and functional characterization of OsCSD3, a novel CuZn superoxide dismutase from rice. Biochem J 15 October 2018; 475 (19): 3105–3121. doi: https://doi.org/10.1042/BCJ20180516
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