Isolation and characterization of the gene encoding glyceraldehyde-3-phosphate dehydrogenase

A 1.2-kb full-length cDNA sequence of a glyceraldehyde-3-phosphate dehydrogenase (GPD) gene was isolated from the mushroom, Pleurotus sajor-caju. The full-length cDNA of the GPD gene consists of 1248 nucleotides, predicted to encode a 36-kDa polypeptide consisting of 335 amino acid residues. Sequence analysis revealed that the GPD gene has more than 72-78% amino acid sequence homology with those of other Basidiomycetes. Expression of the GPD gene increased when P. sajor-caju was treated with various abiotic stresses, such as salt, cold, heat, and drought. There was an eightfold induction by drought treatment. Salt and cold stress induced four- and twofold induction of GPD gene expression, respectively. There was also a fivefold induction by heat stress. The GPD gene exhibits different expression patterns under different stress conditions. It reached its maximum expression level within two hours under cold or heat treatment. The mRNA levels of this gene increased proportionally to increasing treatment time under salt or dry conditions. Because the expression of GPD was significantly increased, we tested whether GPD could confer abiotic stress resistance when it was introduced into yeast cells. For this, a transgenic yeast harboring P. sajor-caju GPD was generated under the control of a constitutively expressed GAL promoter. The results from biofunctional analyses with GPD yeast transformants showed that GPD yeast transformants had significantly higher resistance to cold, salt, heat, and drought stresses.