title: Asn112 in Plasmodium falciparum glutathione S-transferase is essential for induced reversible tetramerization by phosphate or pyrophosphate.
abstract: The glutathione S-transferase from Plasmodium falciparum presents distinct features which are absent from mammalian GST isoenzyme counterparts. Most apparent among these are the ability to tetramerize and the presence of a flexible loop. The loop, situated between the 113-119 residues, has been reported necessary for the tetramerization process. In this article, we report that a residue outside of this loop, Asn112, is a key to the process - to the point where the single Asn112Leu mutation prevents tetramerization altogether. We propose that a structural pattern involving the interaction of the Asn112 and Lys117 residues from two neighboring subunits plays a role in keeping the tetramer structure stable. We also report that, for the tetramerization of the wild-type PfGST to occur, phosphate or pyrophosphate anions must be present. In other words, tetramerization is a phosphate- or pyrophosphate-induced process. Furthermore, the presence of magnesium reinforces this induction. We present experimental evidence for these claims as well as a preliminary calorimetric and kinetic study of the dimeric Asn112Leu PfGST mutant. We also propose a putative binding site for phosphate or pyrophosphate anions through a comparative structural analysis of PfGST and pyrophosphatases from several organisms. Our results highlight the differences between PfGST and the human isoenzymes, which make the parasite enzyme a suitable antimalarial target.
authors.affiliation: Department of Chemistry and Physics, University of Almería, Research Center for Agrifood Biotechnology (BITAL), Agrifood Campus of International Excellence ceiA3, Ctra de Sacramento s/n, 04120 Almería, Spain.
authors.forename: Indalecio
authors.initials: I
authors.lastname: Quesada-Soriano
authors.affiliation: Department of Chemistry and Physics, University of Almería, Research Center for Agrifood Biotechnology (BITAL), Agrifood Campus of International Excellence ceiA3, Ctra de Sacramento s/n, 04120 Almería, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Barón
authors.affiliation: Department of Chemistry and Physics, University of Almería, Research Center for Agrifood Biotechnology (BITAL), Agrifood Campus of International Excellence ceiA3, Ctra de Sacramento s/n, 04120 Almería, Spain.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Téllez-Sanz
authors.affiliation: Department of Chemistry and Physics, University of Almería, Research Center for Agrifood Biotechnology (BITAL), Agrifood Campus of International Excellence ceiA3, Ctra de Sacramento s/n, 04120 Almería, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: García-Maroto
authors.affiliation: Department of Chemistry and Physics, University of Almería, Research Center for Agrifood Biotechnology (BITAL), Agrifood Campus of International Excellence ceiA3, Ctra de Sacramento s/n, 04120 Almería, Spain. Electronic address: lgarcia@ual.es.
authors.forename: Luis
authors.initials: L
authors.lastname: García-Fuentes
mesh_terms: D001216:Asparagine / Q000737:chemistry* / Q000378:metabolism; D002413:Cations, Divalent; D011756:Diphosphates / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005982:Glutathione Transferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D010710:Phosphates / Q000737:chemistry* / Q000378:metabolism; D010963:Plasmodium falciparum / Q000737:chemistry* / Q000201:enzymology; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D013816:Thermodynamics
chemical_list: D002413:Cations, Divalent; D011756:Diphosphates; D010710:Phosphates; D021122:Protein Subunits; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C107241:diphosphoric acid; D001216:Asparagine; D005982:Glutathione Transferase; D008274:Magnesium
keywords: Calorimetry; Glutathione S-transferase; Ligand-binding protein; Malaria; N112L mutant; Plasmodium falciparum