title: Discovery of factors linked to antimony resistance in Leishmania panamensis through differential proteome analysis.
abstract: The rate of treatment failure to antileishmanial chemotherapy in Latin America is up to 64%. Parasite drug resistance contributes to an unknown proportion of treatment failures. Identification of clinically relevant molecular mechanisms responsible for parasite drug resistance is critical to the conservation of available drugs and to the discovery of novel targets to reverse the resistant phenotype. We conducted comparative proteomic-based analysis of Leishmania (Viannia) panamensis lines selected in vitro for resistance to trivalent antimony (Sb(III)) to identify factors associated with antimony resistance. Using 2-dimensional gel electrophoresis, two distinct sub-proteomes (soluble in NP-40/urea and Triton X-114, respectively) of promastigotes of WT and Sb(III)-resistant lines were generated. Overall, 9 differentially expressed putative Sb-resistance factors were detected and identified by mass spectrometry. These constituted two major groups: (a) proteins involved in general stress responses and (b) proteins with highly specific metabolic and transport functions, potentially directly contributing to the Sb-resistance mechanism. Notably, the sulfur amino acid-metabolizing enzymes S-adenosylmethionine synthetase (SAMS) and S-adenosylhomocysteine hydrolase (SAHH) were over-expressed in Sb(III)-resistant lines and Sb(III)-resistant clinical isolates. These enzymes play a central role in the upstream synthesis of precursors of trypanothione, a key molecule involved in Sb-resistance in Leishmania parasites, and suggest involvement of epigenetic regulation in response to drug exposure. These data re-enforce the importance of thiol metabolism in Leishmania Sb resistance, reveal previously unrecognized steps in the mechanism(s) of Sb tolerance, and suggest a cross-talk between drug resistance, metabolism and virulence.
authors.affiliation: Centro Internacional de Entrenamiento e Investigaciones Medicas, Carrera 125, No. 19-225, Cali, Colombia.
authors.forename: John
authors.initials: J
authors.lastname: Walker
authors.forename: Rafael
authors.initials: R
authors.lastname: Gongora
authors.forename: Juan-José
authors.initials: JJ
authors.lastname: Vasquez
authors.forename: Jolyne
authors.initials: J
authors.lastname: Drummelsmith
authors.forename: Richard
authors.initials: R
authors.lastname: Burchmore
authors.forename: Gaetan
authors.initials: G
authors.lastname: Roy
authors.forename: Marc
authors.initials: M
authors.lastname: Ouellette
authors.forename: Maria Adelaida
authors.initials: MA
authors.lastname: Gomez
authors.forename: Nancy G
authors.initials: NG
authors.lastname: Saravia
mesh_terms: D043383:Adenosylhomocysteinase / Q000302:isolation & purification / Q000378:metabolism; D000965:Antimony / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D015180:Electrophoresis, Gel, Two-Dimensional; D015870:Gene Expression; D005978:Glutathione / Q000031:analogs & derivatives / Q000096:biosynthesis; D006801:Humans; D007843:Latin America; D018334:Leishmania guyanensis / Q000737:chemistry* / Q000187:drug effects*; D013058:Mass Spectrometry; D008716:Methionine Adenosyltransferase / Q000302:isolation & purification / Q000378:metabolism; D020543:Proteome / Q000032:analysis*; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism*; D013095:Spermidine / Q000031:analogs & derivatives / Q000096:biosynthesis
chemical_list: D000981:Antiprotozoal Agents; D020543:Proteome; D015800:Protozoan Proteins; C044809:trypanothione; D000965:Antimony; D008716:Methionine Adenosyltransferase; D043383:Adenosylhomocysteinase; D005978:Glutathione; D013095:Spermidine