title: A nystatin-resistant mutant of Rhodotorula gracilis. Transport properties and sterol content.
abstract: A nystatin-resistant mutant of Rhodotorula gracilis was obtained by treatment of the wild strain cells with N-methyl-N-nitro-N-nitrosoguanidine and selected on agar plates containing 150 micrograms nystatin/ml. Three important transport functions of the plasma membrane of mutant cells: the accumulation of monosaccharides, the generation and maintenance of the pH-gradient and of the membrane potential, as well as the cell respiration were insensitive to at least 10(-5) M nystatin. This concentration of nystatin inhibited completely all these processes in wild strain cells. Analysis of cellular sterols revealed a defect of ergosterol biosynthesis in the mutant, which was localized at the last oxidative step between 5,6-dihydroergosterol and ergosterol.
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004875:Ergosterol / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects; D003904:Mitosporic Fungi / Q000378:metabolism*; D009005:Monosaccharides / Q000378:metabolism*; D009154:Mutation; D009761:Nystatin / Q000494:pharmacology*; D012248:Rhodotorula / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D009005:Monosaccharides; D009761:Nystatin; D004875:Ergosterol