Transformation with human dihydrofolate reductase renders malaria parasites insensitive to WR99210 but does not affect the intrinsic activity of proguanil
Open Access
- 30 September 1997
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 94 (20), 10931-10936
- https://doi.org/10.1073/pnas.94.20.10931
Abstract
Increasing resistance of Plasmodium falciparum malaria parasites to chloroquine and the dihydrofolate reductase (DHFR) inhibitors pyrimethamine and cycloguanil have sparked renewed interest in the antimalarial drugs WR99210 and proguanil, the cycloguanil precursor. To investigate suggestions that WR99210 and proguanil act against a target other than the reductase moiety of the P. falciparum bifunctional DHFR–thymidylate synthase enzyme, we have transformed P. falciparum with a variant form of human DHFR selectable by methotrexate. Human DHFR was found to fully negate the antiparasitic effect of WR99210, thus demonstrating that the only significant action of WR99210 is against parasite DHFR. Although the human enzyme also resulted in greater resistance to cycloguanil, no decrease was found in the level of susceptibility of transformed parasites to proguanil, thus providing evidence of intrinsic activity of this parent compound against a target other than DHFR. The transformation system described here has the advantage that P. falciparum drug-resistant lines are uniformly sensitive to methotrexate and will complement transformation with existing pyrimethamine-resistance markers in functional studies of P. falciparum genes. This system also provides an approach for screening and identifying novel DHFR inhibitors that will be important in combined chemotherapeutic formulations against malaria.Keywords
This publication has 58 references indexed in Scilit:
- Analysis in yeast of antimalaria drugs that target the dihydrofolate reductase of Plasmodium falciparumMolecular and Biochemical Parasitology, 1997
- High frequencies of CYP2C19 mutations and poor metabolism of proguanil in VanuatuThe Lancet, 1997
- Recombinant Plasmodium falciparum dihydrofolate reductase-based in vitro screen for antifolate antimalarialsMolecular and Biochemical Parasitology, 1996
- Japanese poor metabolizers of proguanil do not have an increased risk of malaria chemoprophylaxis breakthroughTransactions of the Royal Society of Tropical Medicine and Hygiene, 1995
- Stable Transfection of Malaria Parasite Blood StagesScience, 1995
- Molecular genetics of drug resistance in Plasmodium faiciparum malariaParasitology Today, 1991
- Heterologous expression of active thymidylate synthase-dihydrofolate reductase from Plasmodium falciparumBiochemistry, 1990
- A histidine-rich protein gene marks a linkage group favored strongly in a genetic cross of Plasmodium falciparumCell, 1987
- Purification and characterization of the bifunctional thymidylate synthetase-dihydrofolate reductase from methotrexate-resistant Leishmania tropicaBiochemistry, 1985
- Human Malaria Parasites in Continuous CultureScience, 1976