title: Inhibition of p-aminobenzoate and folate syntheses in plants and apicomplexan parasites by natural product rubreserine.
abstract: Glutamine amidotransferase/aminodeoxychorismate synthase (GAT-ADCS) is a bifunctional enzyme involved in the synthesis of p-aminobenzoate, a central component part of folate cofactors. GAT-ADCS is found in eukaryotic organisms autonomous for folate biosynthesis, such as plants or parasites of the phylum Apicomplexa. Based on an automated screening to search for new inhibitors of folate biosynthesis, we found that rubreserine was able to inhibit the glutamine amidotransferase activity of the plant GAT-ADCS with an apparent IC(50) of about 8 μM. The growth rates of Arabidopsis thaliana, Toxoplasma gondii, and Plasmodium falciparum were inhibited by rubreserine with respective IC(50) values of 65, 20, and 1 μM. The correlation between folate biosynthesis and growth inhibition was studied with Arabidopsis and Toxoplasma. In both organisms, the folate content was decreased by 40-50% in the presence of rubreserine. In both organisms, the addition of p-aminobenzoate or 5-formyltetrahydrofolate in the external medium restored the growth for inhibitor concentrations up to the IC(50) value, indicating that, within this range of concentrations, rubreserine was specific for folate biosynthesis. Rubreserine appeared to be more efficient than sulfonamides, antifolate drugs known to inhibit the invasion and proliferation of T. gondii in human fibroblasts. Altogether, these results validate the use of the bifunctional GAT-ADCS as an efficient drug target in eukaryotic cells and indicate that the chemical structure of rubreserine presents interesting anti-parasitic (toxoplasmosis, malaria) potential.
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, Commissariat à l'Energie Atomique/CNRS UMR5168/INRA USC1200/Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France.
authors.forename: Djeneb
authors.initials: D
authors.lastname: Camara
authors.forename: Cordelia
authors.initials: C
authors.lastname: Bisanz
authors.forename: Caroline
authors.initials: C
authors.lastname: Barette
authors.forename: Jeroen
authors.initials: J
authors.lastname: Van Daele
authors.forename: Esmare
authors.initials: E
authors.lastname: Human
authors.forename: Bernice
authors.initials: B
authors.lastname: Barnard
authors.forename: Dominique
authors.initials: D
authors.lastname: Van der Straeten
authors.forename: Christophe P
authors.initials: CP
authors.lastname: Stove
authors.forename: Willy E
authors.initials: WE
authors.lastname: Lambert
authors.forename: Roland
authors.initials: R
authors.lastname: Douce
authors.forename: Eric
authors.initials: E
authors.lastname: Maréchal
authors.forename: Lyn-Marie
authors.initials: LM
authors.lastname: Birkholtz
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Cesbron-Delauw
authors.forename: Renaud
authors.initials: R
authors.lastname: Dumas
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rébeillé
mesh_terms: D010129:4-Aminobenzoic Acid / Q000494:pharmacology*; D000818:Animals; D000977:Antiparasitic Agents / Q000494:pharmacology; D016782:Apicomplexa / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D005492:Folic Acid / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008956:Models, Chemical; D010830:Physostigmine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014122:Toxoplasma / Q000378:metabolism
chemical_list: D000977:Antiparasitic Agents; D010936:Plant Extracts; D011994:Recombinant Proteins; C027950:rubreserine; D005492:Folic Acid; D010830:Physostigmine; D010129:4-Aminobenzoic Acid