Characterization of a novel glutamate dehydrogenase gene and its response to heat stress in the sea urchin Strongylocentrotus intermedius

Abstract

Glutamate dehydrogenase (GDH), a key metabolic enzyme that is ubiquitous across almost all living species, is essential for cell survival. To elucidate the characteristics and functions of the GDH gene in the sea urchin, we cloned and characterized the full-length cDNA of a novel GDH homolog from Strongylocentrotus intermedius, herein designated SiGDH. The full-length SiGDH gene was 2499 bp, with an open reading frame (ORF) of 1635 bp, encoding 544 amino acids. Bioinformatic analyses revealed that the predicted SiGDH protein contained the conserved ELFV_dehydrog_N and ELFV_dehydrog domains and that this protein had the highest sequence identity with the GDH protein from Strongylocentrotus purpuratus. Tissue-specific differences in SiGDH relative expression patterns and enzyme activity levels were observed, and the highest relative expression and total enzyme activity of SiGDH were determined to be in the gonad. Changes in SiGDH relative expression and enzyme activity in the gonad were observed after both gradual and acute heat stress. Together, our observations help to clarify the characteristics of this GDH homolog, as well as its associations with heat resistance in echinoderms.