title: Delta24(25)-sterol methenyltransferase: intracellular localization and azasterol sensitivity in Leishmania major promastigotes overexpressing the enzyme.
abstract: Trypanosomatids contain predominantly ergostane-based sterols, which differ from cholesterol, the main sterol in mammalian cells, in the presence of a methyl group in the 24 position. The methylation is initiated by S-adenosyl-L-methionine:Delta(24 (25))-sterol methenyltransferase, an enzyme present in protozoa, but absent in mammals. The importance of this enzyme is underscored by its potential as a drug target in the treatment of the leishmaniases. Here, we report studies concerning the intracellular distribution of sterol methenyltransferase in Leishmania major promastigotes and overexpressing cells using a specific antibody raised against highly purified recombinant protein. It was found by immunofluorescence and electron microscopy studies that in L. major wild-type cells sterol methenyltransferase was primarily associated to the endoplasmic reticulum. In addition to this location, the protein was incorporated into translucent vesicles presumably of the endocytic pathway. We also found in this study that cells overproducing the enzyme do not have increased resistance to the sterol methenyltransferase inhibitor 22, 26 azasterol.
authors.affiliation: Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18100 Armilla, Granada, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Jiménez-Jiménez
authors.forename: Juana
authors.initials: J
authors.lastname: Carrero-Lérida
authors.forename: Marco
authors.initials: M
authors.lastname: Sealey-Cardona
authors.forename: Luis Miguel
authors.initials: LM
authors.lastname: Ruiz Pérez
authors.forename: Julio Alberto
authors.initials: JA
authors.lastname: Urbina
authors.forename: Dolores
authors.initials: D
authors.lastname: González Pacanowska
mesh_terms: D000818:Animals; D004083:Cholestanol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004351:Drug Resistance; D004721:Endoplasmic Reticulum / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology; D018320:Leishmania major / Q000187:drug effects* / Q000201:enzymology* / Q000648:ultrastructure; D008780:Methyltransferases / Q000302:isolation & purification*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011994:Recombinant Proteins / Q000302:isolation & purification; D014162:Transfection; D022161:Transport Vesicles / Q000201:enzymology; D014344:Trypanocidal Agents / Q000494:pharmacology
chemical_list: C103731:22,26-azasterol; D011994:Recombinant Proteins; D014344:Trypanocidal Agents; D004083:Cholestanol; D008780:Methyltransferases; C022670:delta 24-sterol methyltransferase