Expression profiles of glyceraldehyde-3-phosphate dehydrogenase from Clonorchis sinensis : a glycolytic enzyme with plasminogen binding capacity

Globally, 15–20 million people are infected with Clonorchis sinensis ( C. sinensis ) which results in clonorchiasis. In China, clonorchiasis is considered to be one of the fastest-growing food-borne parasitic diseases. That more key molecules of C. sinensis are characterized will be helpful to understand biology and pathogenesis of the carcinogenic liver fluke. Glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) from many species have functions other than their catalytic role in glycolysis. In the present study, we analyzed the sequence and structure of GAPDH from C. sinensis ( Cs GAPDH) by using bioinformatics tools and obtained its recombinant protein by prokaryotic expression system, to learn its expression profiles and molecular property. Cs GAPDH could bind to human intrahepatic biliary epithelial cell in vivo and in vitro by the method of immunofluorescence assays. Cs GAPDH also disturbed in lumen of biliary tract near to the parasite in the liver of infected rat. Western blotting analysis together with immunofluorescence assay indicated that Cs GAPDH was a component of excretory/secretory proteins ( Cs ESPs) and a surface-localized protein of C. sinensis . Quantitative real-time PCR (Q-PCR) and Western blotting demonstrated that Cs GAPDHs are expressed at the life stages of adult worm, metacercaria, and egg, but the expression levels were different from each other. Recombinant Cs GAPDH (r Cs GAPDH) was confirmed to have the capacity to catalyze the conversion of glyceraldehyde 3-phosphate to D-glycerate 1,3-bisphosphate which was inhibited by AMP in a dose-dependent manner. In addition, r Cs GAPDH was able to interact with human plasminogen in a dose-dependent manner by ELISA. The interaction could be inhibited by lysine. The plasminogen binding capacity of r Cs GAPDH along with the distribution of Cs GAPDH in vivo and in the liver of C. sinensis -infected rat hinted that surface-localized Cs GAPDH might play an important role in host invasion of the worm besides its glycolytic activity. Our work will be a cornerstone for getting more messages about Cs GAPDH and its role in biology and parasitism of C. sinensis .