Antimalarial effects of peptide inhibitors of a Plasmodium falciparum cysteine proteinase.

Rosenthal, Philip J.; Wollish, Wendy S.; Palmer, James T.; Rasnick, David

doi:10.1172/jci115456

Cited by 175 publications

(130 citation statements)

References 24 publications

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“…Similar discrepancies, attributed to inefficient uptake of compounds into the parasite, have been reported with inhibitors of the P. falciparum cysteine proteases (55) or dihydroorotate dehydrogenase (56). Limited cell permeability could equally be a cause for the discrepancy between whole-cell and enzyme inhibition values observed with triclosan and its analogs, particularly in view of the requirement for apicoplast inhibitors to traverse four membranes surrounding this organelle (4,24) in addition to the host cell and parasite membranes.…”

Section: Journal Of Biological Chemistry 25439mentioning

confidence: 60%

X-ray Structural Analysis of Plasmodium falciparum Enoyl Acyl Carrier Protein Reductase as a Pathway toward the Optimization of Triclosan Antimalarial Efficacy

Freundlich

Wang

Tsai

et al. 2007

Journal of Biological Chemistry

115

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The x-ray crystal structures of five triclosan analogs, in addition to that of the isoniazid-NAD adduct, are described in relation to their integral role in the design of potent inhibitors of the malarial enzyme Plasmodium falciparum enoyl acyl carrier protein reductase (PfENR). Many of the novel 5-substituted analogs exhibit low micromolar potency against in vitro cultures of drug-resistant and drug-sensitive strains of the P. falciparum parasite and inhibit purified PfENR enzyme with IC 50 values of <200 nM. This study has significantly expanded the knowledge base with regard to the structure-activity relationship of triclosan while affording gains against cultured parasites and purified PfENR enzyme. In contrast to a recent report in the literature, these results demonstrate the ability to improve the in vitro potency of triclosan significantly by replacing the suboptimal 5-chloro group with larger hydrophobic moieties. The biological and x-ray crystallographic data thus demonstrate the flexibility of the active site and point to future rounds of optimization to improve compound potency against purified enzyme and intracellular Plasmodium parasites.

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Section: Journal Of Biological Chemistry 25439mentioning

confidence: 60%

X-ray Structural Analysis of Plasmodium falciparum Enoyl Acyl Carrier Protein Reductase as a Pathway toward the Optimization of Triclosan Antimalarial Efficacy

Freundlich

Wang

Tsai

et al. 2007

Journal of Biological Chemistry

115

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“…Considering the role of this enzyme in a unique and essential metabolic pathway, it warrants further investigation. FLN may be a worthy drug target as it has been shown that inhibition of hemoglobin catabolism is lethal to parasites [14,15]. In this study, we show that FLN, unlike other food vacuole proteases, does not have a propiece.…”

mentioning

confidence: 56%

Plasmodium falciparum falcilysin: an unprocessed food vacuole enzyme

Murata

Goldberg

2003

Molecular and Biochemical Parasitology

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Five hundred million infections and nearly two million deaths each year are attributed to the protozoan Plasmodium falciparum, a causative agent of human malaria. With the increasing prevalence of drug resistant strains, there is an urgent need to identify new drug targets. Examination of the parasite's unique metabolic pathways, such as hemoglobin degradation, provides candidates for chemotherapeutic development. Intraerythrocytic development of the parasite is dependent upon degradation of red blood cell hemoglobin. A semi-ordered pathway of proteases mediates this catabolism, which occurs in the acidic organelle called the food vacuole. The aspartic proteases, plasmepsins I and II, are proposed to be responsible for initial cleavage of hemoglobin in a conserved hinge region of the alpha chain [1,2]. Plasmepsins, and a family of cysteine proteases, falcipain-2 and 3, then carry out further degradation of the denatured globin [2][3][4][5]. The resulting small globin peptides serve as substrates for falcilysin (FLN) [6].FLN was first identified in 1999 when analysis of degraded globin fragments from the food vacuole revealed several peptides with cleavage sites that could not be attributed to the known proteases [7]. Specifically, a protease preferring to cleave substrates at polar or charged residues was implicated; this stands in contrast to the other hemoglobin-degrading proteases, which favor cleavage at hydrophobic residues. Purification of the native enzyme from food vacuoles revealed that it is a monomeric enzyme with a molecular weight of 130,000, by far the largest hemoglobin catabolic protease. FLN is a member of the M16 family of metalloproteases, enzymes character- * Corresponding author.

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“…Disruption of the FP2 gene led to the accumulation of undegraded hemoglobin in trophozoites, confirming a critical role for this enzyme in hemoglobin hydrolysis (10). Inhibition of FP2 and related proteases led to a block in parasite development (11,12) and cured mice with murine malaria (13,14), and efforts to develop falcipain inhibitors as new antimalarial agents are underway. These efforts will be facilitated by a detailed understanding of the biochemical properties of FP2.…”

mentioning

confidence: 92%

The Plasmodium falciparum cysteine protease falcipain-2 captures its substrate, hemoglobin, via a unique motif

Pandey

Wang

Sijwali

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

122

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Falcipain-2 (FP2) is a papain family cysteine protease and important hemoglobinase of erythrocytic Plasmodium falciparum parasites. Inhibitors of FP2 block hemoglobin hydrolysis and parasite development, suggesting that this enzyme is a promising target for antimalarial chemotherapy. FP2 and related plasmodial cysteine proteases have an unusual 14-aa motif near the C terminus of the catalytic domain. Recent solution of the structure of FP2 showed this motif to form a ␤-hairpin that is distant from the enzyme active site and protrudes out from the protein. To evaluate the function of this motif, we compared the activity of the wild-type enzyme with that of a mutant lacking 10 aa of the motif ( ⌬10 FP2). ⌬10 FP2 had nearly identical activity to that of the wild-type enzyme against peptide substrates and the protein substrates casein and gelatin. However, ⌬10 FP2 demonstrated negligible activity against hemoglobin or globin. FP2 that was inhibited with trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (FP2 E-64 ) formed a complex with hemoglobin, but ⌬10 FP2 E-64 did not, indicating that the motif mediates binding to hemoglobin independent of the active site. A peptide encoding the motif blocked hemoglobin hydrolysis, but not the hydrolysis of casein. Kinetics for the inhibition of ⌬10 FP2 were very similar to those for FP2 with peptidyl and protein inhibitors, but ⌬10 FP2 was poorly inhibited by the inhibitory prodomain of FP2. Our results indicate that FP2 utilizes an unusual motif for two specific functions, interaction with hemoglobin, its natural substrate, and interaction with the prodomain, its natural inhibitor.M alaria is one of the most important infectious diseases in the world. Plasmodium falciparum, the most virulent human malaria parasite, is believed to cause hundreds of millions of illnesses and over a million deaths each year (1). The control of malaria has been hindered by increasing resistance of malaria parasites to available drugs (2). New antimalarial drugs, ideally directed against new targets, are urgently needed (3). Among potential new targets for antimalarial therapy are proteases that hydrolyze hemoglobin. Intraerythrocytic malaria parasites break down hemoglobin in an acidic food vacuole to supply amino acids for parasite protein synthesis and to maintain osmotic stability (4, 5). Multiple proteases appear to participate in hemoglobin processing (6). Cysteine protease inhibitors block hemoglobin hydrolysis, indicating that cysteine proteases play a key role in this process (7). Falcipain-2 (FP2) and falcipain-3 (FP3) are papain-family cysteine proteases of erythrocytic stages of P. falciparum that localize to the food vacuole and readily hydrolyze hemoglobin (8, 9). Disruption of the FP2 gene led to the accumulation of undegraded hemoglobin in trophozoites, confirming a critical role for this enzyme in hemoglobin hydrolysis (10). Inhibition of FP2 and related proteases led to a block in parasite development (11, 12) and cured mice with murine malaria (13, 14), and efforts to develop...

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Antimalarial effects of peptide inhibitors of a Plasmodium falciparum cysteine proteinase.

Cited by 175 publications

References 24 publications

X-ray Structural Analysis of Plasmodium falciparum Enoyl Acyl Carrier Protein Reductase as a Pathway toward the Optimization of Triclosan Antimalarial Efficacy

X-ray Structural Analysis of Plasmodium falciparum Enoyl Acyl Carrier Protein Reductase as a Pathway toward the Optimization of Triclosan Antimalarial Efficacy

Plasmodium falciparum falcilysin: an unprocessed food vacuole enzyme

The Plasmodium falciparum cysteine protease falcipain-2 captures its substrate, hemoglobin, via a unique motif

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