A conserved parasite serine protease processes the Plasmodium falciparum merozoite surface protein-1

Blackman, Michael J.; Chappel, Jonathan A.; Shai, Shafrira; Holder, Anthony A.

doi:10.1016/0166-6851(93)90182-w

Cited by 52 publications

(56 citation statements)

References 37 publications

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“…We currently favor the former possibility since we have found that the addition of high concentrations of rp31 to P. falciparum cultures has no effect on the efficiency of erythrocyte invasion, and extensive experiments have indicated that rPfSUB-1 has no detectable capacity to modify surface proteins of the intact merozoite or the host red blood cell under nondenaturing conditions. 2 In light of the findings described here, rp31 could be used to regulate the activity of PfSUB-1 in a specific and informative manner; it may be possible, for example, to subtly and specifically downregulate levels of functional PfSUB-1 in the parasite by constitutive overexpression of the propeptide from a suitable transgene (42). The demonstration that rp31 inhibits both authentic and baculovirus-derived PfSUB-1 validates the use of the recombinant protease as a tool for high throughput screening for low molecular mass inhibitors (21).…”

Section: Discussionmentioning

confidence: 99%

“…The life cycle of the malaria parasite in the human is complex, involving intracellular replication in both hepatocytes and erythrocytes, with the pathophysiological manifestations closely allied to intraerythrocytic replication. Plasmodium merozoites actively penetrate erythrocytes via a tightly regulated series of events involving proteolytic processing and release of proteins from the apical organelles and surface of the parasite (2)(3)(4). Functional maturation of many invasion-related proteins requires their proteolytic modification and, in some cases, their eventual removal from the parasite surface.…”

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confidence: 99%

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Functional Characterization of the Propeptide of Plasmodium falciparum Subtilisin-like Protease-1

Jean¹,

Hackett²,

Martin³

et al. 2003

Journal of Biological Chemistry

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Erythrocyte invasion by the malaria merozoite is prevented by serine protease inhibitors. Various aspects of the biology of Plasmodium falciparum subtilisin-like protease-1 (PfSUB-1), including the timing of its expression and its apical location in the merozoite, suggest that this enzyme is involved in invasion. Recombinant PfSUB-1 expressed in a baculovirus system is secreted in the p54 form, noncovalently bound to its cognate propeptide, p31. To understand the role of p31 in PfSUB-1 maturation, we examined interactions between p31 and both recombinant and native enzymes. CD analyses revealed that recombinant p31 (rp31) possesses significant secondary structure on its own, comparable with that of folded propeptides of some bacterial subtilisins. Kinetic studies demonstrated that rp31 is a fast binding, high affinity inhibitor of PfSUB-1. Inhibition of two bacterial subtilisins by rp31 was much less effective, with inhibition constants 49 -60-fold higher than that for PfSUB-1. Single (at the P4 or P1 position) or double (at P4 and P1 positions) point mutations of residues within the C-terminal region of rp31 had little effect on its inhibitory activity, and truncation of 11 residues from the rp31 C terminus substantially reduced, but did not abolish, inhibition. None of these modifications prevented binding to the PfSUB-1 catalytic domain or rendered the propeptide susceptible to proteolytic digestion by PfSUB-1. These studies provide new insights into the function of the propeptide in PfSUB-1 activation and shed light on the structural requirements for interaction with the catalytic domain.Parasites of the genus Plasmodium are responsible for the debilitating disease malaria, which affects 300 -500 million people each year, mostly in subtropical regions (1). The continued emergence of drug-resistant parasites imposes an urgent need for a new generation of control measures. The life cycle of the malaria parasite in the human is complex, involving intracellular replication in both hepatocytes and erythrocytes, with the pathophysiological manifestations closely allied to intraerythrocytic replication. Plasmodium merozoites actively penetrate erythrocytes via a tightly regulated series of events involving proteolytic processing and release of proteins from the apical organelles and surface of the parasite (2-4). Functional maturation of many invasion-related proteins requires their proteolytic modification and, in some cases, their eventual removal from the parasite surface. These processing events can occur both in the apical organelles and at the parasite surface (4 -6), suggesting a role for proteases in different compartments of the parasite. Specific inhibitors of cysteine and serine proteases can block invasion, providing compelling evidence that these classes of parasite proteases play a major role in the invasion process (6, 7). In the case of Plasmodium falciparum, the species responsible for most fatal cases of malaria, two subtilisin-like serine proteases (subtilases) have been identified, called PfSUB-...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Functional Characterization of the Propeptide of Plasmodium falciparum Subtilisin-like Protease-1

Jean¹,

Hackett²,

Martin³

et al. 2003

Journal of Biological Chemistry

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“…The C-terminal MSP-1 19 fragment produced by a series of protease-mediated reactions most likely participates in the process of red cell invasion by merozoites (31,32). Several lines of evidence suggest that MSP-1 and MSP-1 19 may be efficacious in a malaria vaccine.…”

Section: Discussionmentioning

confidence: 99%

Acquired Immune Responses to Plasmodium falciparum Merozoite Surface Protein-1 in the Human Fetus

King

Malhotra

Wamachi

et al. 2002

The Journal of Immunology

104

108

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Infants born in areas of stable malaria transmission are relatively protected against severe morbidity and high density Plasmodium falciparum blood-stage infection. This protection may involve prenatal sensitization and immunologic reactivity to malaria surface ligands that participate in invasion of red cells. We examined cord blood T and B cell immunity to P. falciparum merozoite surface protein-1 (MSP-1) in infants born in an area of stable malaria transmission in Kenya. T cell cytokine responses to the C-terminal 19-kDa fragment of MSP-1 (MSP-119) were detected in 24 of 92 (26%) newborns (4–192 IFN-γ and 3–88 IL-4-secreting cells per 106/cord blood lymphocytes). Peptide epitopes in the N-terminal block 3 region of MSP-1 also drove IFN-γ and/or IL-13 production. There was no evidence of prenatal T cell sensitization to liver-stage Ag-1. A total of 5 of 86 (6%) newborns had cord blood anti-MSP-119 IgM Abs, an Ig isotype that does not cross the placenta and is therefore of fetal origin. The frequency of neonatal B cell sensitization was higher than that indicated by serology alone, as 5 of 27 (18%) cord blood samples contained B cells that produced IgG when stimulated with MSP-119 in vitro. Neonatal B cell IgG responses were restricted to the Q-KNG allele of MSP-119, the major variant in this endemic area, whereas T cells responded to all four MSP-119 alleles evaluated. In utero sensitization to MSP-1 correlated with the presence of malaria parasites in cord blood (χ2 = 20, p < 0.0001). These data indicate that prenatal sensitization to blood-stage Ags occurs in infants born in malaria endemic areas.

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“…However, IEM studies have shown that a part of the dense granule contents also can be seen around the surface of merozoites during their entry (5). This event is both the time and place where MSP1-42 maturation is thought to occur (6,33). Hence, by analogy with other Apicomplexa parasites, it has been proposed that P. falciparum merozoites may have subpopulations of dense granules with different properties (13).…”

Section: Discussionmentioning

confidence: 99%

“…Two major roles have been attributed for these enzymes: (i) the proteolysis of the erythrocyte plasma membrane anion transporter band 3 by the chymotrypsin-like Pfgp76 participating in the formation of the parasitophorous vacuole (32), and (ii) the maturation of MSP1-42 by a merozoite membrane-bound and calcium-dependent serine protease (6,33). In addition to their difference of size and maturation pattern, because PfSUB2 has an active site similar to prokaryotic subtilisins and contains in its C terminus a transmembrane domain without any sequence typical of a glycosylphosphatidylinositol addition, it is unlikely that PfSUB2 corresponds to Pfgp76, which is a 76-kDa glycosylphosphatidylinositol-anchored merozoite serine protease with specificity for substrates with Arg at the P1 position and hydrophobic residues at the P3 and P4 positions (32,34).…”

Section: Discussionmentioning

confidence: 99%

Plasmodium falciparum subtilisin-like protease 2, a merozoite candidate for the merozoite surface protein 1–42 maturase

Barale

Blisnick

Fujioka

et al. 1999

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

103

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The process of human erythrocyte invasion by Plasmodium falciparum parasites involves a calciumdependent serine protease with properties consistent with a subtilisin-like activity. This enzyme achieves the last crucial maturation step of merozoite surface protein 1 (MSP1) necessary for parasite entry into the host erythrocyte. In eukaryotic cells, such processing steps are performed by subtilisinlike maturases, known as proprotein convertases. In an attempt to characterize the MSP1 maturase, we have identified a gene that encodes a P. falciparum subtilisin-like protease (PfSUB2) whose deduced active site sequence resembles more bacterial subtilisins. Therefore, we propose that PfSUB2 belongs to a subclass of eukaryotic subtilisins different from proprotein convertases. Pfsub2 is expressed during merozoite differentiation and encodes an integral membrane protein localized in the merozoite dense granules, a secretory organelle whose contents are believed to participate in a late step of the erythrocyte invasion. PfSUB2's subcellular localization, together with its predicted enzymatic properties, leads us to propose that PfSUB2 could be responsible for the late MSP1 maturation step and thus is an attractive target for the development of new antimalarial drugs.

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A conserved parasite serine protease processes the Plasmodium falciparum merozoite surface protein-1

Cited by 52 publications

References 37 publications

Functional Characterization of the Propeptide of Plasmodium falciparum Subtilisin-like Protease-1

Functional Characterization of the Propeptide of Plasmodium falciparum Subtilisin-like Protease-1

Acquired Immune Responses to Plasmodium falciparum Merozoite Surface Protein-1 in the Human Fetus

Plasmodium falciparum subtilisin-like protease 2, a merozoite candidate for the merozoite surface protein 1–42 maturase

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