Expression and characterization of a phospholipid hydroperoxide glutathione peroxidase gene inSchistosoma japonicum

SUMMARYPhospholipid hydroperoxide glutathione peroxidase (PHGPx, GPx4) is a major antioxidant enzyme, which plays unique roles in the protection of cells against oxidative stress by catalysing reduction of lipid hydroperoxides. We isolated and characterized a full-length cDNA sequence encodingGPxgene from a blood fluke,Schistosoma japonicum(designatedSjGPx), which contained an in-frame TGA codon for selenocysteine (Sec) and a concurrent Sec insertion sequence in its 3′-untranslated region. Protein encoded bySjGPxdemonstrated a primary structure characteristic to the PHGPx family, including preservation of catalytic domains and absence of the subunit interaction domains. Semi-quantitative reverse transcription PCR and Western blotting showed that the SjGPx was mainly expressed in the female adults and eggs. RNA interference approach was employed to investigate the effects of knockdown ofSjGPx. SjGPx expression level was significantly reduced on the 5th day post-RNAi. Significantly reduction in GPx enzyme activities, as well as obvious changes in morphology of intrauterine eggs followed the reduction inSjGPxtranscript level. We observed a 63·04% reduction in GPx activity and the eggs severely deformed. Our results revealed that SjGPx protein might be involved in the provision of enzyme activity during egg production.