Cloning of the gene for phosphoglycerate kinase from Schistosoma mansoni and characterization of its gene product.

As molecules on the surface or associated with the outer covering (tegument) of Schistosoma mansoni are a major focus as potential vaccine candidates, affinity purified antibodies which are specific to the tegumental antigens were used to immunoscreen a lambda gt11 S. mansoni cercarial cDNA library. One of the identified clones was found to encode the glycolytic enzyme phosphoglycerate kinase (PGK, EC 2.7.2.3). The 1.5-kb cDNA clone has a single open reading frame encoding 416 amino acids and exhibits over 60% identity to PGKs from a number of eukaryotic species. Recombinant S. mansoni PGK (SmPGK) was overexpressed in Escherichia coli, purified, and shown to have PGK enzyme activity. Native protein affinity purified from S. mansoni adult worms was shown by microsequencing to have the same amino-acid sequence as deduced from the cDNA sequence, thus confirming the cDNA clone we identified encodes S. mansoni phosphoglycerate kinase. Antibodies localize the native SmPGK to various tissues including the tegument of 3-h schistosomula and 42-day adult worms.