Abstract
Pyrophosphate-dependent phosphofructokinase (PPi-PFK) from Entamoeba histolytica (HM-1) was purified from trophozoites. Oligonucleotide probes based on partial amino acid sequence were used to clone and sequence the gene and the cDNA of the enzyme. The molecular mass of the subunit was greater than, and the derived sequence significantly different from, that of the product of the PPi-PFK gene previously cloned from E. histolytica [Huang, Albach, Chang, Tripathi and Kemp (1995) Biochim. Biophys. Acta 1260, 215-217; Bruchhaus, Jacobs, Denart and Tannich (1996) Biochem. J. 316, 57-63]. The sequence identity between the two proteins was 17%. The sequence bore greater identity with the more phylogenetically advanced plant PPi-PFKs than with bacterial PPi-PFKs. The cloned cDNA was expressed and the protein purified. The kinetic properties were identical with those of the enzyme isolated from the organism. Furthermore, the specific activity was more than three orders of magnitude higher than that described for the product of the previously cloned E. histolytica PFK gene [Bruchhaus et al. (1996)]. The pH-dependence and apparent substrate affinities of the cloned enzyme were identical with those of the PPi-PFK in trophozoite extracts, indicating that the product of the cloned gene accounts for most if not all of the PFK activity in E. histolytica trophozoites.