Plasmodium falciparum:Stage-Related Expression of Topoisomerase I

Tosh, Kerrie; Cheesman, Sandie; Horrocks, Paul; Kilbey, Brian J.

doi:10.1006/expr.1998.4362

Cited by 28 publications

(13 citation statements)

References 40 publications

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“…This also seems to correspond with the low level of plasmodial topoisomerase I activity that was observed in the youngest stages of intraerythrocytic development of the parasite, which was in contrast to the high nitidine activity observed at the same stage [24]. …”

Section: Discussionmentioning

confidence: 99%

Biological activities of nitidine, a potential anti-malarial lead compound

Bouquet

Rivaud

Chevalley

et al. 2012

Malar J

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BackgroundNitidine is thought to be the main active ingredient in several traditional anti-malarial remedies used in different parts of the world. The widespread use of these therapies stresses the importance of studying this molecule in the context of malaria control. However, little is known about its potential as an anti-plasmodial drug, as well as its mechanism of action.MethodsIn this study, the anti-malarial potential of nitidine was evaluated in vitro on CQ-sensitive and -resistant strains. The nitidine's selectivity index compared with cancerous and non-cancerous cell lines was then determined. In vivo assays were then performed, using the four-day Peter's test methodology. To gain information about nitidine's possible mode of action, its moment of action on the parasite cell cycle was studied, and its localization inside the parasite was determined using confocal microscopy. The in vitro abilities of nitidine to bind haem and to inhibit β-haematin formation were also demonstrated.ResultsNitidine showed similar in vitro activity in CQ-sensitive and resistant strains, and also a satisfying selectivity index (> 10) when compared with a non-cancerous cells line. Its in vivo activity was moderate; however, no sign of acute toxicity was observed during treatment. Nitidine's moment of action on the parasite cycle showed that it could not interfere with DNA replication; this was consistent with the observation that nitidine did not localize in the nucleus, but rather in the cytoplasm of the parasite. Nitidine was able to form a 1-1 complex with haem in vitro and also inhibited β-haematin formation with the same potency as chloroquine.ConclusionNitidine can be considered a potential anti-malarial lead compound. Its ability to complex haem and inhibit β-haematin formation suggests a mechanism of action similar to that of chloroquine. The anti-malarial activity of nitidine could therefore be improved by structural modification of this molecule to increase its penetration of the digestive vacuole in the parasite, where haemoglobin metabolization takes place.

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Section: Discussionmentioning

confidence: 99%

Biological activities of nitidine, a potential anti-malarial lead compound

Bouquet

Rivaud

Chevalley

et al. 2012

Malar J

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“…Parasite extracts were obtained from 5 ϫ 10 8 log-phase promastigotes and subjected to the Topo-I activity assays (20,35). Briefly, the parasites were resuspended in 100 to 200 l of Topo-I assay buffer (10 mM Tris-HCl [pH 7.9], 1 mM EDTA, 150 mM NaCl, 0.1% bovine serum albumin, 0.1 mM spermidine, 5% glycerol) and lysed by repeated passage through a 25-gauge needle.…”

Section: Methodsmentioning

confidence: 99%

Topoisomerase I Amino Acid Substitutions, Gly185Arg and Asp325Glu, Confer Camptothecin Resistance in Leishmania donovani

Marquis

Hardy

Olivier

2005

Antimicrob Agents Chemother

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The antitumor compound camptothecin (CPT) is also recognized for its specific activity against Leishmania donovani topoisomerase I (Topo-I). In consequence, defining CPT resistance mechanisms represents an important strategic tool in the acquisition of a better understanding of its mode of action. In the present study, we selected a single highly resistant L. donovani strain termed LdRCPT.160 by stepwise exposure to CPT. Gene sequencing revealed two single nucleotide mutations in the LdRCPT.160 LdTOP1A gene, resulting in two amino acid substitutions (Gly185Arg and Asp325Glu) in the protein. Moreover, these two substitutions observed in the LdTOP1A protein were correlated with a decreased Topo-I DNA relaxation activity in these resistant parasites. Nevertheless, there was no change in the LdTOP1A gene expression level. Interestingly, transfection studies of the LdRCPT.160 LdTOP1A gene in its wild-type counterpart showed that it induced CPT resistance. Sitedirected mutagenesis studies demonstrated that, despite a substantial level of resistance conferred by the Gly185Arg and Asp325Glu substitutions separately, both were essential to reach a high-resistance phenotype. Of interest, the amino acid substitutions observed in LdRCPT.160 LdTOP1A protein occurred near the amino acids previously predicted to interact with CPT, providing new insight into the mechanism of CPT molecular action.

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“…Some chemical mutagens have been used to study nucleotide or base excision repair (NER or BER, respectively) (25)(26)(27). CPT, which generates DSBs by trapping the topoisomerase I (TopI) reaction intermediate during relaxation of supercoiled DNA and blocks the progression of the replisome, has been shown to inhibit P. falciparum TOP1 (PlasmoDB gene identifier PF3D7_0510500) function in vitro (28) and is active against parasite cultures, with a half-maximal inhibitory concentration (IC 50 ) of ϳ1 M in a 72-h drug assay (our unpublished results).…”

Section: Causes Of Double-strand Breaksmentioning

confidence: 99%

DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

Lee

Fidock

2014

Microbiol Mol Biol Rev

101

103

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SUMMARY Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium . Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium . Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum . These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen.

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Plasmodium falciparum:Stage-Related Expression of Topoisomerase I

Cited by 28 publications

References 40 publications

Biological activities of nitidine, a potential anti-malarial lead compound

Biological activities of nitidine, a potential anti-malarial lead compound

Topoisomerase I Amino Acid Substitutions, Gly185Arg and Asp325Glu, Confer Camptothecin Resistance in Leishmania donovani

DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

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