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Báo cáo khoa học: Molecular and biochemical characterization ofD-phosphoglycerate dehydrogenase fromEntamoeba histolytica A unique enteric protozoan parasite that possesses both phosphorylated and nonphosphorylated serine metabolic pathways

A putative phosphoglycerate dehydrogenase (PGDH), which catalyzes the oxidation ofD-phosphoglycerate to 3-phosphohydroxypyruvate in the so-called phosphorylated serine metabolic pathway, from the enteric protozoan parasite Entamoeba histolytica was characterized. The E. histolyticaPGDH gene (EhPGDH) encodes a protein of 299 amino acids with a calculated molecular mass of 33.5 kDa and an isoelectric point of8.11. EhPGDHshowed high homology to PGDH from bacteroides and another enteric protozoan ciliate,Entodinium caudatum. . | Eur. J. Biochem. 271 2670-2681 2004 FEBS 2004 doi 10.1111 j.1432-1033.2004.04195.x Molecular and biochemical characterization of D-phosphoglycerate dehydrogenase from Entamoeba histolytica A unique enteric protozoan parasite that possesses both phosphorylated and nonphosphorylated serine metabolic pathways Vahab Ali1 Tetsuo Hashimoto2 Yasuo Shigeta1 and Tomoyoshi Nozaki1 3 1 Department of Parasitology National Institute of Infectious Diseases Tokyo Japan 2Institute of Biological Sciences University of Tsukuba Japan 3 Precursory Research for Embryonic Science and Technology Japan Science and Technology Agency Tokyo Japan A putative phosphoglycerate dehydrogenase PGDH which catalyzes the oxidation of D-phosphoglycerate to 3-phosphohydroxypyruvate in the so-called phosphorylated serine metabolic pathway from the enteric protozoan parasite Entamoeba histolytica was characterized. The E. histolytica PGDH gene EhPGDH encodes a protein of 299 amino acids with a calculated molecular mass of 33.5 kDa and an isoelectric point of 8.11. EhPGDHshowed high homology to PGDH from bacteroides and another enteric protozoan ciliate Entodinium caudatum. EhPGDH lacks both the carboxyl-terminal serine binding domain and the 13-14 amino acid regions containing the conserved Trp139 of Escherichia coli PGDH in the nucleotide binding domain shown to be crucial for tetramerization which are present in other organisms including higher eukaryotes. EhPGDH catalyzed reduction of phosphohydroxypynivate to phosphoglycerate utilizing NADH and less efficiently NADPH EhPGDH did not utilize 2-oxoglutarate. Kinetic parameters of EhPGDH weee similar to tho of mamma lian PGDH for example the preference of NADH cofactor substrate specificities and salt-reversible substrate inhibition. In contrast to PGDH from bacteria plants and mammals the EhPGDH protein is present as a homodimer as demonstrated by gel filtration chromatography. The E. histolytica lysate contained PGDH activity of 26 nmol NADH utilized .