CLONING AND CHARACTERIZATION OF A CDNA-ENCODING PHOSPHOFRUCTOKINASE FROM SCHISTOSOMA-MANSONI

Schistosoma mansoni, a human parasitic worm, depends on anaerobic glyc olysis as the main source of energy. Phosphofructokinase (ATP: D-fruct ose-6-phosphase 1-phosphotransferase, EC 2.7.1.11; PFK) limits the rat e of glycolysis in these organisms and it has been found to be a targe t for some antischistosomal agents. A cDNA clone from this parasite ha s been isolated and characterized. The cDNA is 3046 base pairs long, c ontains an open reading frame of 2346 bp and codes for a deducted prot ein of 781 amino acids. The putative protein encoded by the clone has an exact match with the human muscle PFK of 58% and a 73% match when c onserved amino acid substitutions are considered. ATP and Fructose-6-P sites have been identified by crystallographic data in the Escherichi a coli and Bacillus stearothermophilus PFKs. There is excellent homolo gy between those PFKs and the schistosome PFK at those sites. The PFK- coding cDNA was expressed in insect cells and was shown to ben enzymat ically active. Western blot analysis of the recombinant protein in cel l extracts gave a positive band with the expected molecular weight of 86 kDa.