Functional characterization of an alternative [lactate dehydrogenase-like] malate dehydrogenase in Plasmodium falciparum.
The catalysis of malate dehydrogenase (MDH) in Plasmodium falciparum (pfMDH) which involves NAD/NADH coupling is crucial for the parasite's pathogenicity. Primers were designed based on the P. falciparum genome resource, and these facilitated the cloning of a gene coding for pfMDH from a local clinical isolate. The DNA sequence of the cloned gene revealed an open-reading frame that encodes a protein of 313 amino acids. After induction in Escherichia coli BL21, enzyme assays of the expressed pfMDH purified by affinity chromatography exhibited significant enzyme activity of about 50 U/mg, where one unit (U) of enzyme activity is defined as the amount of enzyme oxidising 1 microol NADH/min. Based on its phylogenetic status amongst MDHs and lactate dehydrogenases (LDHs), the cloned gene was clearly defined as belonging to the NADH-dependent [LDH-like] MDHs. It is noteworthy that pfMDH harbours unique structural characteristics potentially useful for screening drugs specific for disabling parasitic enzymes.
Department of Microbiology, Faculty of Medicine, National University of Singapore, Block MD4, 5 Science Drive 2, 117597, Singapore.
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D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D009243:NAD; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase