title: Critical role of the plasma membrane for expression of mammalian mitochondrial side chain cleavage activity in yeast.
abstract: Engineered yeast cells efficiently convert ergosta-5-eneol to pregnenolone and progesterone provided that endogenous pregnenolone acetylase activity is disrupted and that heterologous sterol delta7-reductase, cytochrome P450 side chain cleavage (CYP11A1) and 3beta hydroxysteroid dehydrogenase/isomerase (3beta-HSD) activities are present. CYP11A1 activity requires the expression of the mammalian NADPH-adrenodoxin reductase (Adrp) and adrenodoxin (Adxp) proteins as electron carriers. Several parameters modulate this artificial metabolic pathway: the effects of steroid products; the availability and delivery of the ergosta-5-eneol substrate to cytochrome P450; electron flux and protein localization. CYP11A1, Adxp and Adrp are usually located in contact with inner mitochondrial membranes and are directed to the outside of the mitochondria by the removal of their respective mitochondrial targeting sequences. CYP11A1 then localizes to the plasma membrane but Adrp and Adxp are detected in the endoplasmic reticulum and cytosol as expected. The electron transfer chain that involves several subcellular compartments may control side chain cleavage activity in yeast. Interestingly, Tgl1p, a potential ester hydrolase, was found to enhance steroid productivity, probably through both the availability and/or the trafficking of the CYP11A1 substrate. Thus, the observation that the highest cellular levels of free ergosta-5-eneol are found in the plasma membrane suggests that the substrate is freely available for pregnenolone synthesis.
authors.affiliation: Laboratoire d'Ingénierie des Protéines Membranaires, CGM du CNRS, Gif sur Yvette, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Duport
authors.forename: Barbara
authors.initials: B
authors.lastname: Schoepp
authors.forename: Elise
authors.initials: E
authors.lastname: Chatelain
authors.forename: Roberto
authors.initials: R
authors.lastname: Spagnoli
authors.forename: Bruno
authors.initials: B
authors.lastname: Dumas
authors.forename: Denis
authors.initials: D
authors.lastname: Pompon
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism; D000325:Adrenodoxin / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002451:Cell Compartmentation / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000031:analogs & derivatives / Q000378:metabolism; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D004875:Ergosterol / Q000031:analogs & derivatives / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008322:Mammals; D008928:Mitochondria / Q000201:enzymology*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism; D011284:Pregnenolone / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013256:Steroids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D011994:Recombinant Proteins; D013256:Steroids; C473558:ergosta-5-eneol; D000325:Adrenodoxin; D011284:Pregnenolone; D002784:Cholesterol; D010088:Oxidoreductases; D015096:3-Hydroxysteroid Dehydrogenases; D002786:Cholesterol Side-Chain Cleavage Enzyme; D005287:Ferredoxin-NADP Reductase; C407913:DWF5 protein, Arabidopsis; D004950:Esterases; D004875:Ergosterol