title: Flux of sterol intermediates in a yeast strain deleted of the lanosterol C-14 demethylase Erg11p.
abstract: Lanosterol C-14 demethylase Erg11p of the yeast Saccharomyces cerevisiae catalyzes the enzymatic step following formation of lanosterol by the lanosterol synthase Erg7p in lipid particles (LP). Localization experiments employing microscopic inspection and cell fractionation revealed that Erg11p in contrast to Erg7p is associated with the endoplasmic reticulum (ER). An erg11Delta mutation in erg3Delta background, which is required to circumvent lethality of the erg11 defect, did not only change the sterol pattern but also the sterol distribution within the cell. Whereas in wild type the plasma membrane was highly enriched in ergosterol and LP harbored large amounts of sterol precursors in the form of steryl esters, sterol intermediates were more or less evenly distributed among organelles of erg11Delta erg3Delta. This distribution is not result of the erg3Delta background, because in the erg3Delta strain the major intermediate formed, ergosta-7,22-dienol, is also highly enriched in the plasma membrane similar to ergosterol in wild type. These results indicate that (i) exit of lanosterol from LP occurs independently of functional Erg11p, (ii) random supply of sterol intermediates to all organelles of erg11Delta erg3Delta appears to compensate for the lack of ergosterol in this mutant, and (iii) preferential sorting of ergosterol in wild type, but also of ergosta-7,22-dienol in erg3Delta, supplies sterol to the plasma membrane.
authors.affiliation: Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria.
authors.forename: René G
authors.initials: RG
authors.lastname: Ott
authors.forename: Karin
authors.initials: K
authors.lastname: Athenstaedt
authors.forename: Claudia
authors.initials: C
authors.lastname: Hrastnik
authors.forename: Erich
authors.initials: E
authors.lastname: Leitner
authors.forename: Helmut
authors.initials: H
authors.lastname: Bergler
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism; D017353:Gene Deletion; D010088:Oxidoreductases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D058886:Sterol 14-Demethylase; D013261:Sterols / Q000032:analysis / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D058886:Sterol 14-Demethylase