PMID: 9178266May 1, 1997Paper

Isolation and molecular characterization of the bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate synthase gene from Toxoplasma gondii

Molecular and Biochemical Parasitology
T V PashleyC J Delves

Abstract

Toxoplasma gondii is an important cause of AIDS-related opportunistic infection, manifest as toxoplasmic encephalitis. The clinical treatment of choice is the synergistic combination of antifolate agents, pyrimethamine and sulphadiazine, of which the latter targets the parasite's dihydropteroate synthase (DHPS) activity. Here, we describe the isolation of the gene encoding this activity in T. gondii. The nucleotide sequence contains an open reading frame interrupted by five introns, which encodes a protein of 664 amino acids with an M(r) of 72991. Sequence analysis revealed that, in addition to DHPS, the predicted protein contains a second enzyme function, hydroxymethyldihydropterin pyrophosphokinase (PPPK). This enzyme immediately precedes DHPS in the folate biosynthetic pathway. The bifunctional arrangement of the T. gondii pppk-dhps gene is the same as that observed in the related protozoan parasite, Plasmodium falciparum, and confirms previous biochemical data that these activities were inseparable. Recently, specific mutations within conserved motifs of the DHPS gene of P. falciparum have been identified which give rise to sulphonamide drug resistance. Analysis of seven clinical isolates of T. gondii did not reveal any sim...Continue Reading

Citations

Apr 12, 2002·International Journal for Parasitology·G H Coombs, S Müller
Jul 16, 2002·International Journal for Parasitology·Tanya V AspinallPaul F G Sims
Jul 18, 2002·Antimicrobial Agents and Chemotherapy·Karen HaytonDavid Walliker
Mar 19, 2013·Molecular and Biochemical Parasitology·Ingrid B Müller, John E Hyde
Nov 16, 2016·Journal of Biomolecular Structure & Dynamics·Parthiban MarimuthuVigneshwaran Namasivayam
Jun 6, 2020·International Journal of Molecular Sciences·Shaofeng LiJinshuang Sun

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