Leishmania major:Molecular Modeling of Cysteine Proteases and Prediction of New Nonpeptide Inhibitors

Department of Pathology, University of California, San Francisco 94143, USA.
Experimental Parasitology (Impact Factor: 1.64). 12/1997; 87(3):212-21. DOI: 10.1006/expr.1997.4220
Source: PubMed


The crystal structures of papain, cruzain, and human liver cathepsin B were used to build homology-based enzyme models of a cathepsin L-like cysteine protease (cpL) and a cathepsin B-like cysteine protease (cpB) from the protozoan parasite Leishmania major. Although structurally a member of the cathepsin B subfamily, the L. major cpB is not able to cleave synthetic substrates having an arginine in position P2. This biochemical property correlates with the prediction of a glycine instead of a glutamic acid at position 205 (papain numbering). The modeled active sites of the L. major cpB and cpL were used to screen the Available Chemicals Directory (a database of about 150,000 commercially available compounds) for potential cysteine protease inhibitors, using DOCK3.5. Based on both steric and force field considerations, 69 compounds were selected. Of these, 18 showed IC50's between 50 and 100 microM and 3 had IC50's below 50 microM. A secondary library of compounds, originally derived from a structural screen against the homologous protease of Plasmodium falciparum (falcipain), and subsequently expanded by combinatorial chemistry, was also screened. Three inhibitors were identified which were not only effective against the L. major protease but also inhibited parasite growth at 5-50 microM.

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    • "Papain-like cysteine proteases have been identified in T. cruzi (cruzain) [8], T. brucei (trypanopain, TbCatB) [9] and different Leishmania spp. (CPA, CPB, CPC) [10,11] and inhibition of these peptidases has led to promising results both in vitro [12], in tissue culture models [13-15] and in vivo [15-17]. This study has focused on finding inhibitors of CPB, a cathepsin L-like cysteine protease thought to be crucial in the infectivity of Leishmania mexicana and encoded as a tandem array of 19 similar genes [18]. "
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    ABSTRACT: Cysteine proteases of the papain superfamily are present in nearly all eukaryotes. They play pivotal roles in the biology of parasites and inhibition of cysteine proteases is emerging as an important strategy to combat parasitic diseases such as sleeping sickness, Chagas' disease and leishmaniasis. Homology modeling of the mature Leishmania mexicana cysteine protease CPB2.8 suggested that it differs significantly from bovine cathepsin B and thus could be a good drug target. High throughput screening of a compound library against this enzyme and bovine cathepsin B in a counter assay identified four novel inhibitors, containing the warhead-types semicarbazone, thiosemicarbazone and triazine nitrile, that can be used as leads for antiparasite drug design. Covalent docking experiments confirmed the SARs of these lead compounds in an effort to understand the structural elements required for specific inhibition of CPB2.8. This study has provided starting points for the design of selective and highly potent inhibitors of L. mexicana cysteine protease CPB that may also have useful efficacy against other important cysteine proteases.
    Full-text · Article · Oct 2013 · PLoS ONE
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    • "Cysteine proteinases are among the most important enzymes in many microorganisms and are known to play essential roles in pathogenesis of such organisms (8, 9). From known Cysteine proteinases, CP1 and CP5 exist in E. histolytica and not in E. dispar (10, 11). "
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    ABSTRACT: Background: We examined a molecular method with a single-PCR for amplification of a part of CP5 gene enabling us to differentiate the pathogenic species, Entamoeba histolytica, from the non-pathogenic species, E. dispar. Methods: We developed a single PCR method for this purpose. After investigation of GenBank, primer pairs were designed from highly conserved regions of cysteine proteinase (CP5) gene. The primers were utilized in PCR using isolated genomic DNA template of E. histolytica and the PCR products were then sequenced. The same primer and method for PCR was used for isolated genomic DNA template of E. dispar. Results: A fragment of about 950 bp was isolated in PCR by using DNA from E. histolytica, however, no banding pattern was produced by using the same primers for E. dispar. We characterized CP5 gene at molecular level in E. histolytica isolates from 22 positive; including 20 non-dysentery samples isolated from both cities as well as two dysentery samples isolated only from Tabriz. Nucleotide sequence comparison in gene data banks (NCBI, NIH) revealed significant homology with CP5 gene in E. histolytica isolates Conclusion: We developed a PCR method, which could detect simply and rapidly E. histolytica by amplifying a specific PCR fragment.
    Full-text · Article · Dec 2010 · Iranian Journal of Public Health
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    • "Indeed, because of the CPBE deletion, CPBE misses a potential B-cell epitope in position 153–169. Furthermore, the protease activity of all papain-like proteases is associated with the catalytic triad consisting of a nucleophilic cysteine, a histidine and an asparagine (for example Cys 25 -His 163 -Asn 183 for Leishmania) (Selzer et al. 1997 ; Juliano et al. 2004). Our study has revealed that, because of CPBE deletion, His 163 is absent, as is 1 disulfide bond (absence of Cys 156 ). "
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    ABSTRACT: Leishmania infantum and Leishmania donovani both pertain to the L. (L.) donovani complex and are responsible for visceral leishmaniasis. To explore the L. donovani complex, we focused our study on cysteine protease B (cpb) and especially on 2 cpb copies: cpbE and cpbF. We selected cpb genes because of their phylogenetic interest and host-parasite interaction involvement. Sequencing these 2 copies revealed (i) that cpbE is specific to L. infantum and cpbF is specific to L. donovani and (ii) that these 2 copies are different in length and sequence. Phylogenetic analysis and protein predictions were carried out in order to compare these copies (i) with other trypanosomatid cpb, especially L. mexicana, and (ii) within the L. donovani complex. Our results revealed patterns specific to the L. donovani complex such as the COOH-terminal extension, potential epitopes and N-glycosylation sites. Moreover, phylogenetic analysis revealed different levels of polymorphism between L. infantum and L. donovani and confirmed the ancestral status of the latter. L. infantum has a shorter sequence and a deleted sequence responsible for modifications in protein conformation and catalytic triad. Considering the clinical aspect, L. infantum dermotropic strains appeared more polymorphic than L. infantum viscerotropic strains.
    Full-text · Article · Apr 2007 · Parasitology
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