Entamoeba histolytica, the agent of amebic dysentery and amebic liver abscess, is the third leading cause of death from parasitic diseases worldwide. Invasive E. histolytica infection is treated with the drug metronidazole, but concerns about the mutagenic effects of metronidazole, and the development of metronidazole resistance in a number of organisms, has fueled a search for alternative agents to treat amebiasis. E histolytica lack mitochondria, and obtain energy from the fermentation of glucose to CO2, acetate and ethanol. This glycolytic pathway is an attractive target for anti-amebic chemotherapy because it is essential for parasite existence, and it appears to utilize several enzymes lacking from most other eukaryotic organisms. Recently, we isolated the native protein, and cloned the gene encoding a key enzyme in this pathway, a bifunctional NAD-dependent alcohol dehydrogenase/acetyl-coA reductase responsible for the conversion of acetyl-coA to acetaldehyde and acetaldehyde to ethanol. This enzyme, which we have designated E. histolytica alcohol dehydrogenase 2 (EhADH2), has a unique structure containing both alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) domains, and does not have any homologues among known eukaryotic enzymes. The critical position of the EhADH2 enzyme in the amebic glycolytic pathway, and its fundamental differences from human ADH and ALDH enzymes, appear to make it an ideal target for chemotherapy. The goal of this proposal is to identify specific inhibitors of the EhADH2 enzyme. We will accomplish this by studying the structure and function of the EhADH2 enzyme at the molecular level to learn about this new class of enzymes, and to provide the data base necessary for the rational design of inhibitors of the EhADH2 molecule. At the same time, we will develop an assay system which will allow us to rapidly, simply, and inexpensively screen compounds for EhADH2 inhibitory activity. Inhibitors identified by this screen, and by molecular modeling, will then be assayed for their effects on E. histolytica growth and virulence. Compounds capable of selectively inhibiting the EhADH2 enzyme could represent a new class of agents effective against certain anaerobic protozoa and some anaerobic bacteria.

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Washington University
Saint Louis
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Davis, Paul H; Chen, Minghe; Zhang, Xiaochun et al. (2009) Proteomic comparison of Entamoeba histolytica and Entamoeba dispar and the role of E. histolytica alcohol dehydrogenase 3 in virulence. PLoS Negl Trop Dis 3:e415
Davis, Paul H; Schulze, Jochen; Stanley Jr, Samuel L (2007) Transcriptomic comparison of two Entamoeba histolytica strains with defined virulence phenotypes identifies new virulence factor candidates and key differences in the expression patterns of cysteine proteases, lectin light chains, and calmodulin. Mol Biochem Parasitol 151:118-28
Davis, Paul H; Zhang, Xiaochun; Guo, Jianhua et al. (2006) Comparative proteomic analysis of two Entamoeba histolytica strains with different virulence phenotypes identifies peroxiredoxin as an important component of amoebic virulence. Mol Microbiol 61:1523-32
Espinosa, A; Yan, L; Zhang, Z et al. (2001) The bifunctional Entamoeba histolytica alcohol dehydrogenase 2 (EhADH2) protein is necessary for amebic growth and survival and requires an intact C-terminal domain for both alcohol dahydrogenase and acetaldehyde dehydrogenase activity. J Biol Chem 276:20136-43
Ben Mamoun, C; Gluzman, I Y; Hott, C et al. (2001) Co-ordinated programme of gene expression during asexual intraerythrocytic development of the human malaria parasite Plasmodium falciparum revealed by microarray analysis. Mol Microbiol 39:26-36
Denny, P W; Gokool, S; Russell, D G et al. (2000) Acylation-dependent protein export in Leishmania. J Biol Chem 275:11017-25
Hill, K L; Hutchings, N R; Russell, D G et al. (1999) A novel protein targeting domain directs proteins to the anterior cytoplasmic face of the flagellar pocket in African trypanosomes. J Cell Sci 112 Pt 18:3091-101
Selzer, P M; Pingel, S; Hsieh, I et al. (1999) Cysteine protease inhibitors as chemotherapy: lessons from a parasite target. Proc Natl Acad Sci U S A 96:11015-22
Schaible, U E; Schlesinger, P H; Steinberg, T H et al. (1999) Parasitophorous vacuoles of Leishmania mexicana acquire macromolecules from the host cell cytosol via two independent routes. J Cell Sci 112 ( Pt 5):681-93
Tyas, L; Gluzman, I; Moon, R P et al. (1999) Naturally-occurring and recombinant forms of the aspartic proteinases plasmepsins I and II from the human malaria parasite Plasmodium falciparum. FEBS Lett 454:210-4

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