Evolutive and structural characterization of Nostoc commune iron-superoxide dismutase that is fit for modification

Abstract

ABSTRACT. Superoxide dismutase (SOD) has extensive clinical applications for protecting organisms from toxic oxidation. In this study, the integrated iron-superoxide dismutase gene (fe-sod) coding sequence of Nostoc commune stain CHEN was cloned from genomic DNA and compared to sods from other reported algae. These analyses of immunology and phylogenetics indicated that this Fe-SOD is considerably homologous with SODs from lower prokaryotes (Fe-SOD or Mn-SOD) but not those from higher animals (Cu/Zn-SOD). In addition, the N. commune Fe-SOD shows 67 to 93% protein sequence identity to 10 other algal Fe-SODs (or Mn-SODs) and 69 to 93% gene sequence identity. Rare nonsynonymous substitutions imply that algal SODs are being subjected to strong natural selection. Interestingly, the N. commune Fe-SOD enzyme molecule has a compact active center that is highly conserved (38.1% of residues are absolutely conserved), and 2 loose ends localized outside the molecule and inclined to mutate (only 11.5% of residues are absolutely conserved). Based on associative analyses of evolution, structure, and function, this special phenomenon is attributed to function- dependent evolution through negative natural selection. Under strong natural selection, although the mutation is random on the gene level, the exterior region is inclined to mutate on the protein level owing to more nonsynonymous substitutions in the exterior region, which demonstrates the theoretical feasibility of modifying Fe-SOD on its ends to overcome its disadvantages in clinical applications.

Transcriptomic and Physiological Responses of Chlorella pyrenoidosa during Exposure to 17α-Ethinylestradiol

“…SODs are the first antioxidant defense system of the cell when plants are exposed to oxygen stress. The three most common types of SODs in plants are Mn-SOD, Cu/Zn-SOD, and Fe-SOD, the main function of which is to scavenge O 2− [ 40 ]. The increase in SOD activity may have occurred due to the progressive production of superoxide, which is thought to be a central component of signal transduction, the level of which increases with the activation of the enzyme pool or with increased SOD gene expression [ 41 ].…”