Molecular cloning and characterization of important stress and redox regulatory genes from Hydra vulgaris

In this research, important stress and redox regulatory genes present in Hydra vulgaris were isolated and characterized to facilitate our understanding of the evolution and mechanisms of stress response. H. vulgaris heat shock protein 70 (HvHSP70), extracellular copper zinc superoxide dismutase (HvECCuZnSOD), manganese superoxide dismutase (HvMnSOD), phospholipid peroxidase glutathione peroxidase (HvPHGPx) and monofunctional catalase (HvCatalase) were cloned and characterized with regard to stress response, phylogeny and molecular structure. The HSP70 gene isolated from H. vulgaris encodes a polypeptide of 650 amino acids (Mw=710,037) and is interrupted by three intron sequences. The 5' non-coding region of the HvHSP70 possessed the canonical heat shock elements. Phylogenetically HvHSP70 formed a distinct lineage. A molecular model generated for the N-terminal fragment of the HvHSP70 displayed the heat shock protein fold and domains of phosphotransferases. The EC-CuZnSOD cDNA isolated from H. vulgaris encodes a protein of 189 amino acids (Mw=20959.73); the first 19 amino acids constitute the presumed signal peptide. Phylogenetically HvEC-CuZnSOD is grouped with ECCuZnSODs from several organisms. A molecular model generated for the HvEC-CuZnSOD displayed the CuZnSOD (beta)-barrel fold. The MnSOD cDNA isolated from H. vulgaris encodes a protein of 219 amino acids (Mw=24348.75); the first 21 amino acids constitute the presumed mitochondria-targeting signal peptide. Phylogenetically HvMnSOD is clustered with mollusk and crustacean MnSODs. A molecular model generated for the HvMnSOD displayed the N-terminal long alpha antiparallel hairpin and the Cterminal mixed alpha/beta fold characteristic of MnSODs. The PHGPx gene isolated from H. vulgaris encodes a polypeptide of 168 amino acids (Mw=18746.51) including a TGA-encoded selenocysteine at residue 44 and lacks any intron. Phylogenetically HvPHGPx is grouped with PHGPxs from several organisms. A molecular model generated for the HvPHGPx displayed the thioredoxin fold. The 3'-end of a cDNA sequence encoding for 168 amino acids of the Cterminal end of a catalase was isolated from H. vulgaris. Phylogenetically HvCatalase is grouped with heme-containing monofunctional catalases. Hydrae exposed to thermal, starvation, oxidative and metal stress responded by regulating respective mRNA transcriptions suggesting that these genes are involved in stress and (anti)oxidative processes and may have potential as molecular biomarkers for assessing aquatic environment quality.