Molecular characterization and inhibition of a Plasmodium falciparum aspartic hemoglobinase.

Francis, Susan E.; Gluzman, Ilya Y.; Oksman, Anna; Knickerbocker, Aron; Mueller, Rita U.; Bryant, Martin L.; Sherman, David R.; Russell, David G.; Goldberg, Daniel E.

doi:10.1002/j.1460-2075.1994.tb06263.x

Cited by 263 publications

(216 citation statements)

References 52 publications

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“…13. The V-ATPase responsible for acidifying the FV is present in the parasite surface membranes (Marchesini et al, 2005) and FV-resident proteases were shown to localize to the cytostome (Francis et al, 1994;Klemba et al, 2004). FV components are, therefore, present in membranes contiguous with the cytostome.…”

Section: A New Model For Hemoglobin Transportmentioning

confidence: 99%

A new model for hemoglobin ingestion and transport by the human malaria parasite Plasmodium falciparum

Lazarus

Schneider

Taraschi

2008

Journal of Cell Science

108

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The current model for hemoglobin ingestion and transport by intraerythrocytic Plasmodium falciparum malaria parasites shares similarities with endocytosis. However, the model is largely hypothetical, and the mechanisms responsible for the ingestion and transport of host cell hemoglobin to the lysosome-like food vacuole (FV) of the parasite are poorly understood. Because actin dynamics play key roles in vesicle formation and transport in endocytosis, we used the actin-perturbing agents jasplakinolide and cytochalasin D to investigate the role of parasite actin in hemoglobin ingestion and transport to the FV. In addition, we tested the current hemoglobin trafficking model through extensive analysis of serial thin sections of parasitized erythrocytes (PE) by electron microscopy. We find that actin dynamics play multiple, important roles in the hemoglobin transport pathway, and that hemoglobin delivery to the FV via the cytostomes might be required for parasite survival. Evidence is provided for a new model, in which hemoglobin transport to the FV occurs by a vesicle-independent process.

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Section: A New Model For Hemoglobin Transportmentioning

confidence: 99%

A new model for hemoglobin ingestion and transport by the human malaria parasite Plasmodium falciparum

Lazarus

Schneider

Taraschi

2008

Journal of Cell Science

108

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“…Hemoglobinolysis was also monitored at 410 nm using a spectrophotometer and reversed phase (RP)-HPLC. 1 …”

Section: Determination Of Subsite Preferences Using Positional Scannimentioning

confidence: 99%

A Multi-enzyme Cascade of Hemoglobin Proteolysis in the Intestine of Blood-feeding Hookworms

Williamson¹,

Lecchi

Turk

et al. 2004

Journal of Biological Chemistry

157

115

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Blood-feeding pathogens digest hemoglobin (Hb) as a source of nutrition, but little is known about this process in multicellular parasites. The intestinal brush border membrane of the canine hookworm, Ancylostoma caninum, contains aspartic proteases (APR-1), cysteine proteases (CP-2), and metalloproteases (MEP-1), the first of which is known to digest Hb. We now show that Hb is degraded by a multi-enzyme, synergistic cascade of proteolysis. Recombinant APR-1 and CP-2, but not MEP-1, digested native Hb and denatured globin. MEP-1, however, did cleave globin fragments that had undergone prior digestion by APR-1 and CP-2. Proteolytic cleavage sites within the Hb ␣ and ␤ chains were determined for the three enzymes, identifying a total of 131 cleavage sites. By scanning synthetic combinatorial peptide libraries with each enzyme, we compared the preferred residues cleaved in the libraries with the known cleavage sites within Hb. The semi-ordered pathway of Hb digestion described here is surprisingly similar to that used by Plasmodium to digest Hb and provides a potential mechanism by which these hemoglobinases are efficacious vaccines in animal models of hookworm infection.

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“…In P. falciparum several proteases have been identified in the food vacuole that are involved in hemoglobin degradation, including a family of aspartic proteases known as the plasmepsins (2,3). The four plasmepsins found in the food vacuole of P. falciparum are PfPM1, PfPM2, PfPM4, and the histoaspartic protease (HAP) (3,4). It is now believed that the enzymes from P. vivax (PvPM4), P. ovale (PoPM4), and P. malariae (PmPM4) are orthologs of PfPM4 (5 (3,(6)(7)(8)(9).…”

Section: Introductionmentioning

confidence: 99%

“…The four plasmepsins found in the food vacuole of P. falciparum are PfPM1, PfPM2, PfPM4, and the histoaspartic protease (HAP) (3,4). It is now believed that the enzymes from P. vivax (PvPM4), P. ovale (PoPM4), and P. malariae (PmPM4) are orthologs of PfPM4 (5 (3,(6)(7)(8)(9). Therefore, the PfPM4 orthologs would be excellent targets for a single drug therapy directed at all four plasmodium species (4).…”

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Analysis of Binding Interactions of Pepsin Inhibitor-3 To Mammalian and Malarial Aspartic Proteases

et al. 2007

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The nematode Ascaris suum primarily infects pigs, but also causes disease in humans. As part of its survival mechanism in the intestinal tract of the host, the worm produces a number of protease inhibitors, including pepsin inhibitor-3 (PI3), a 17 kDa protein. Recombinant PI3 expressed in E. coli has previously been shown to be a competitive inhibitor of a sub-group of aspartic proteinases: pepsin, gastricsin and cathepsin E. The previously determined crystal structure of the complex of PI3 with porcine pepsin (p. pepsin) showed that there are two regions of contact between PI3 and the enzyme. The first three N-terminal residues (QFL) bind into the prime side of the active site cleft and a polyproline helix (139)(140) in the C-terminal domain of PI3 packs against residues 289-295 that form a loop in p. pepsin. Mutational analysis of both inhibitor regions was conducted to assess their contributions to the binding affinity for p. pepsin, human pepsin (h. pepsin) and several malarial aspartic proteases, the plasmepsins. Overall, the polyproline mutations have a limited influence on the K i values for all the enzymes tested, with the values for p. pepsin remaining in the low nanomolar range. The largest effect was seen with a Q1L mutant, with a 200-fold decrease in K i for plasmepsin 2 from Plasmodium falciparum (PfPM2). Thermodynamic measurements of the binding of PI3 to p. pepsin and PfPM2 showed that inhibition of the enzymes is an entropy-driven reaction. Further analysis of the Q1L mutant showed that the increase in binding affinity to PfPM2 was due to improvements in both entropy and enthalpy.There are over 300 million cases of malaria every year, resulting in at least one million deaths annually (World Health Organization, 2006). Malaria is found in tropical and sub-tropical regions of the world and is caused by one of four species of the plasmodium parasite: P. falciparum, P. vivax, P. ovale, and P. malariae. P. falciparum is the deadliest of the four species and P. vivax is the most common, responsible for 40% to 50% of cases in Latin America and Asia.During the intraerythrocytic stage of the plasmodium parasite's lifecycle in the human host, up to 75% of host cell hemoglobin is degraded (1). In P. falciparum several proteases have been identified in the food vacuole that are involved in hemoglobin degradation, including a family of aspartic proteases known as the plasmepsins (2,3). The four plasmepsins found in the food vacuole of P. falciparum are PfPM1, PfPM2, PfPM4, and the histoaspartic protease (HAP) (3,4). It is now believed that the enzymes from P. vivax (PvPM4), P. ovale (PoPM4), and P. malariae (PmPM4) are orthologs of PfPM4 (5 (3,(6)(7)(8)(9). Therefore, the PfPM4 orthologs would be excellent targets for a single drug therapy directed at all four plasmodium species (4).Most large, proteinaceous inhibitors of aspartic proteases have been isolated from plants (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). For this study, we have analyzed the inhibition of aspartic proteases by a 17 kD inhi...

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Molecular characterization and inhibition of a Plasmodium falciparum aspartic hemoglobinase.

Cited by 263 publications

References 52 publications

A new model for hemoglobin ingestion and transport by the human malaria parasite Plasmodium falciparum

A new model for hemoglobin ingestion and transport by the human malaria parasite Plasmodium falciparum

A Multi-enzyme Cascade of Hemoglobin Proteolysis in the Intestine of Blood-feeding Hookworms

Analysis of Binding Interactions of Pepsin Inhibitor-3 To Mammalian and Malarial Aspartic Proteases

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