Molecular cloning and characterization of the copper/zinc and manganese syperoxide distnutase genes from the human parasite Cionorchis sinensis

• Published in: Parasitology 2005-06, Vol.130 (6), p.687-697
• Main Authors: Li, AH, Kong, Y, Cho, SH, Lee, H W, Na, B K, Pak, J K, Kim, T S
• Format: Article
• Language: English
• Subjects: Cestoda; Clonorchis sinensis; Escherichia coli
• ISSN: 0031-1820
• DOI: 10.1017/S003118200400695X

A copper/zinc superoxide dismutase (Cu/ZnSOD) gene and a manganese superoxide dismutase (MnSOD) gene of the human parasite Clonorchis sinensis have been cloned and their gene products functionally characterized. Genes Cu/ZnSOD and MnSOD encode proteins of 16 kDa and 25 times 4 kDa, respectively. The deduced amino acid sequences of the two genes contained highly conserved residues required for activity and secondary structure formation of Cu/ZnSOD and MnSOD, respectively, and show up to 73 times 7% and 75 times 4% identities with their counterparts in other animals. The genomic DNA sequence analysis of Cu/ZnSOD gene revealed this as an intronless gene. Inhibitor studies with purified recombinant Cu/ZnSOD and MnSOD, both of which were functionally expressed in Escherichia coli, confirmed that they are copper/zinc and manganese-containing SOD, respectively. Immunoblots showed that both C. sinensis Cu/ZnSOD and MnSOD should be antigenic for humans, and both, especially the C. sinensis MnSOD, exhibit extensive cross-reactions with sera of patients infected by other trematodes or cestodes. RT-PCR and SOD activity staining of parasite lysates indicate that there are no significant differences in mRNA level or SOD activity for both species of SOD, indicating cytosolic Cu/ZnSOD and MnSOD might play a comparatively important role in the C. sinensis antioxidant system.