{"doi":"10.1073/pnas.96.22.12655","title":"Characterization of the\n                    <i>Saccharomyces cerevisiae ERG27</i>\n                    gene encoding the 3-keto reductase involved in C-4 sterol demethylation","abstract":"<jats:p>\n                    The last unidentified gene encoding an enzyme involved in ergosterol biosynthesis in\n                    <jats:italic>Saccharomyces cerevisiae</jats:italic>\n                    has been cloned. This gene, designated\n                    <jats:italic>ERG27</jats:italic>\n                    , encodes the 3-keto sterol reductase, which, in concert with the C-4 sterol methyloxidase (\n                    <jats:italic>ERG25</jats:italic>\n                    ) and the C-3 sterol dehydrogenase (\n                    <jats:italic>ERG26</jats:italic>\n                    ), catalyzes the sequential removal of the two methyl groups at the sterol C-4 position. We developed a strategy to isolate a mutant deficient in converting 3-keto to 3-hydroxy-sterols. An ergosterol auxotroph unable to synthesize sterol or grow without sterol supplementation was mutagenized. Colonies were then selected that were nystatin-resistant in the presence of 3-ketoergostadiene and cholesterol. A new ergosterol auxotroph unable to grow on 3-ketosterols without the addition of cholesterol was isolated. The gene (YLR100w) was identified by complementation. Segregants containing the YLR100w disruption failed to grow on various types of 3-keto sterol substrates. Surprisingly, when\n                    <jats:italic>erg27</jats:italic>\n                    was grown on cholesterol- or ergosterol-supplemented media, the endogenous compounds that accumulated were noncyclic sterol intermediates (squalene, squalene epoxide, and squalene dioxide), and there was little or no accumulation of lanosterol or 3-ketosterols. Feeding experiments in which\n                    <jats:italic>erg27</jats:italic>\n                    strains were supplemented with lanosterol (an upstream intermediate of the C-4 demethylation process) and cholesterol (an end-product sterol) demonstrated accumulation of four types of 3-keto sterols identified by GC/MS and chromatographic properties: 4-methyl-zymosterone, zymosterone, 4-methyl-fecosterone, and ergosta-7,24 (28)-dien-3-one. In addition, a fifth intermediate was isolated and identified by\n                    <jats:sup>1</jats:sup>\n                    H NMR as a 4-methyl-24,25-epoxy-cholesta-7-en-3-one. Implications of these results are discussed.\n                  </jats:p>","journal":"Proceedings of the National Academy of Sciences","year":1999,"id":687305,"datarank":0.6937459219926407,"base_score":4.624972813284271,"endowment":4.624972813284271,"self_citation_contribution":0.6937459219926407,"citation_network_contribution":0.0,"self_endowment_contribution":0.6937459219926407,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":101,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1795570,"name":"S. E. Sen","orcid":null,"position":1,"is_corresponding":false},{"id":1795571,"name":"J. Eckstein","orcid":null,"position":2,"is_corresponding":false},{"id":1795572,"name":"R. Barbuch","orcid":null,"position":3,"is_corresponding":false},{"id":1795574,"name":"M. Krieger","orcid":null,"position":4,"is_corresponding":false},{"id":1795576,"name":"B. D. Ray","orcid":null,"position":5,"is_corresponding":false},{"id":526134,"name":"M. Bard","orcid":null,"position":6,"is_corresponding":false},{"id":1795569,"name":"D. Gachotte","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Characterization of the\n                    <i>Saccharomyces cerevisiae ERG27</i>\n                    gene encoding the 3-keto reductase involved in C-4 sterol demethylation","abstract":"<jats:p>\n                    The last unidentified gene encoding an enzyme involved in ergosterol biosynthesis in\n                    <jats:italic>Saccharomyces cerevisiae</jats:italic>\n                    has been cloned. This gene, designated\n                    <jats:italic>ERG27</jats:italic>\n                    , encodes the 3-keto sterol reductase, which, in concert with the C-4 sterol methyloxidase (\n                    <jats:italic>ERG25</jats:italic>\n                    ) and the C-3 sterol dehydrogenase (\n                    <jats:italic>ERG26</jats:italic>\n                    ), catalyzes the sequential removal of the two methyl groups at the sterol C-4 position. We developed a strategy to isolate a mutant deficient in converting 3-keto to 3-hydroxy-sterols. An ergosterol auxotroph unable to synthesize sterol or grow without sterol supplementation was mutagenized. Colonies were then selected that were nystatin-resistant in the presence of 3-ketoergostadiene and cholesterol. A new ergosterol auxotroph unable to grow on 3-ketosterols without the addition of cholesterol was isolated. The gene (YLR100w) was identified by complementation. Segregants containing the YLR100w disruption failed to grow on various types of 3-keto sterol substrates. Surprisingly, when\n                    <jats:italic>erg27</jats:italic>\n                    was grown on cholesterol- or ergosterol-supplemented media, the endogenous compounds that accumulated were noncyclic sterol intermediates (squalene, squalene epoxide, and squalene dioxide), and there was little or no accumulation of lanosterol or 3-ketosterols. Feeding experiments in which\n                    <jats:italic>erg27</jats:italic>\n                    strains were supplemented with lanosterol (an upstream intermediate of the C-4 demethylation process) and cholesterol (an end-product sterol) demonstrated accumulation of four types of 3-keto sterols identified by GC/MS and chromatographic properties: 4-methyl-zymosterone, zymosterone, 4-methyl-fecosterone, and ergosta-7,24 (28)-dien-3-one. In addition, a fifth intermediate was isolated and identified by\n                    <jats:sup>1</jats:sup>\n                    H NMR as a 4-methyl-24,25-epoxy-cholesta-7-en-3-one. Implications of these results are discussed.\n                  </jats:p>","is_dataset_classified":null,"base_score":4.624972813284271,"endowment":4.624972813284271,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"10535978","pmcid":"PMC23033","openalex_id":"https://openalex.org/W2020912981","authors":[],"funders":[{"funder_name":"NIDA NIH HHS","grant_id":"R01 DA038598","title":null},{"funder_name":"NIAID NIH HHS","grant_id":"1RO1 AI38598","title":null}],"total_grants":2,"fwci":1.5871,"citation_percentile":0.82569959,"influential_citations":0,"citation_trend":[{"year":2012,"count":2},{"year":2013,"count":1},{"year":2014,"count":1},{"year":2015,"count":2},{"year":2016,"count":4},{"year":2017,"count":3},{"year":2018,"count":5},{"year":2019,"count":5},{"year":2020,"count":2},{"year":2021,"count":1},{"year":2022,"count":1},{"year":2023,"count":4},{"year":2024,"count":5},{"year":2025,"count":2},{"year":2026,"count":2}],"oa_status":"green","license":null,"oa_locations":[{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/23033","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/23033","host_type":"repository"},{"url":"https://pnas.org/doi/pdf/10.1073/pnas.96.22.12655","host_type":"publisher"},{"url":"https://doi.org/10.1073/pnas.96.22.12655","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/10535978","host_type":"repository"}],"fields_of_study":["Steroid Chemistry and Biochemistry","Fungal Biology and Applications","Plant biochemistry and biosynthesis","Amino Acid Sequence","Base Sequence","Cloning, Molecular","DNA, Fungal","Genes, Fungal","Lanosterol","Magnetic Resonance Spectroscopy","Methylation","Molecular Sequence Data","Mutation","Saccharomyces cerevisiae"],"mesh_terms":["Amino Acid Sequence","Base Sequence","Cloning, Molecular","DNA, Fungal","Genes, Fungal","Lanosterol","Methylation","Molecular Sequence Data","Mutation","Magnetic Resonance Spectroscopy","Saccharomyces cerevisiae"],"keywords":["Sterol","Ergosterol","Lanosterol","Biochemistry","Squalene","Saccharomyces cerevisiae","Demethylation","Squalene monooxygenase","Biology","Auxotrophy","Reductase","Cholesterol","Mutant","Biosynthesis","Enzyme","Gene","Gene expression"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-18T21:44:43.369525Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}