The Molecular Characterization and Antioxidant Defense of a Novel Nrf2 from the Pacific Abalone Haliotis discus hannai Ino

The Nrf2/ARE pathway is considered the most important endogenous antioxidant signaling pathway in mammals, playing a crucial role in defending against external damage. This study investigated the functional characteristics of Nrf2 in the abalone, Haliotis discus hannai. The full-length cDNA sequence of the HdhNrf2 gene was cloned using rapid amplification of cDNA ends (RACE) technology and consists of 4568 base pairs encoding a protein of 694 amino acids. The predicted theoretical molecular weight was 77 kDa, with an isoelectric point of 4.72. Multiple sequence alignment analysis revealed the relative conservation of the HdhNrf2 amino acid sequence in H. discus hannai. The tissue expression pattern of the HdhNrf2 gene was analyzed using real-time fluorescence quantitative PCR, which showed the highest expression in the gills, followed by hemocytes, with the lowest levels in the foot and mantle. The inducible expression of HdhNrf2 and antioxidant genes in abalone under H2O2 stress was investigated at various time points. Furthermore, an expression vector, pET-28a(+)-rHdhNrf2, was constructed, and the recombinant protein rHdhNrf2 was obtained through induced expression and purification. These findings indicated that HdhNrf2 plays a crucial role in the defense of abalones against oxidative stress.