title: The antimycin-A-insensitive respiratory pathway of Candida parapsilosis: evidence for a second quinone involved specifically in its functioning.
abstract: The involvement of a quinone in the antimycin A-insensitive electron transfer from NADH-dehydrogenase to cytochrome c via the alternative respiratory chain of Candida parapsilosis, by-passing complex II, has been studied. After a partial extraction of quinones, the residual respiration was fully antimycin-A-sensitive, but reincorporation of the organic extract partially restored an antimycin A-insensitive respiration. Analysis of quinone content by HPLC, after purification by thin-layer chromatography, evidenced another quinone species in a very low amount. Myxothiazol and stigmatellin were shown to inhibit the alternative pathway but at a higher concentration than required to inhibit the classical pathway. Cytochrome spectra analysis showed that, in the presence of high myxothiazol concentrations, cytochromes c and aa3 were not reduced, while they were in the presence of antimycin A. It is suggested that the secondary pathway of C. parapsilosis involved a specific quinone pool which can be displaced from its binding site by high concentrations of myxothiazol or analogous compounds.
authors.affiliation: Institut de Biochimie Cellulaire et Neurochimie du CNRS, Université de Bordeaux II, France.
authors.forename: N M
authors.initials: NM
authors.lastname: Camougrand
authors.forename: S
authors.initials: S
authors.lastname: Zniber
authors.forename: M G
authors.initials: MG
authors.lastname: Guérin
mesh_terms: D000968:Antimycin A / Q000494:pharmacology*; D016227:Benzoquinones; D002175:Candida / Q000187:drug effects* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004579:Electron Transport; D008689:Methacrylates; D009252:NADPH Dehydrogenase / Q000378:metabolism; D010084:Oxidation-Reduction; D011809:Quinones / Q000032:analysis*; D012119:Respiration; D013844:Thiazoles
chemical_list: D016227:Benzoquinones; D008689:Methacrylates; D011809:Quinones; D013844:Thiazoles; D000968:Antimycin A; C030517:myxothiazol; D009252:NADPH Dehydrogenase; C034257:duroquinone