Clonorchis sinensis: molecular cloning and functional expression of a novel cytosolic glutathione transferase

Glutathione transferases (GSTs) represent a large family of enzymes. In the high throughput sequencing of the cDNA library constructed from the adult stage of Clonorchis sinensis (Cs), we isolate another cDNA clone encoding a novel cytosolic GST enzyme. To discriminate with our former reported CsGST, we designated this GST as CsGST1. This new cDNA contains 744 bp with a putative open reading frame of 213 amino acids. The deduced amino acid sequence exhibits 88% identity to Opisthorchis viverrini 28GST (Ov28GST), 60 and 52% identity to C. sinensis cytosolic 28-kDa GST (Cs28GST) and CsGST, respectively. The CsGST1 was expressed in Escherichia coli BL21(DE3) as a His-tag fusion protein and was purified by Ni-NTA agarose. The recombinant CsGST1 showed moderate GST activity of 0.79 U mg(-1). The average K (m) of the CsGST1 for 1-chloro-2, 4-dinitrobenzene is 150 microM. Cibacron blue F3GA and albendazole inhibited the CsGST1 activity with average IC(50) values of 9.1 and 265.4 muM, respectively. The nucleotide sequence reported in this paper was submitted to the GenBank Database with accession number DQ342327.