{"doi":"10.1128/jb.173.7.2319-2327.1991","title":"Further inducibility of a constitutive system: ultrainduction of the gal operon","abstract":"<jats:p>In wild-type Escherichia coli, expression of the gal operon is negatively regulated by the Gal repressor and is induced 10- to 15-fold when the repressor is inactivated by an inducer. In strains completely deleted for galR, the gene which encodes the Gal repressor, the operon is derepressed by only 10-fold without an inducer. But this derepression is increased further by threefold during cell growth in the presence of an inducer, D-galactose or D-fucose. This phenomenon of extreme induction in the absence of Gal repressor is termed ultrainduction--a manifestation of further inducibility in a constitutive setup. Construction and characterization of gene and operon fusion strains between galE and lacZ, encoding beta-galactosidase as a reporter gene, show that ultrainduction occurs at the level of transcription and not translation. Transcription of the operon, from both the cyclic AMP-dependent P1 and the cyclic nucleotide-independent P2 promoters, is subject to ultrainduction. The wild-type galR+ gene has an epistatic effect on ultrainducibility: ultrainduction is observed only in cells devoid of Gal repressor protein. Titration experiments show the existence of an ultrainducibility factor that acts like a repressor and functions by binding to DNA segments (operators) to which Gal repressor also binds to repress the operon.</jats:p>","journal":"Journal of Bacteriology","year":1991,"id":15027,"datarank":1.0639232292190728,"base_score":3.091042453358316,"endowment":3.091042453358316,"self_citation_contribution":0.4636563680037475,"citation_network_contribution":0.6002668612153254,"self_endowment_contribution":0.4636563680037475,"citer_contribution":0.6002668612153254,"corpus_percentile":null,"corpus_rank":null,"citation_count":21,"citer_count":10,"citers_with_citation_signal":8,"citers_with_endowment":8,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":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":116194,"name":"S Garges","orcid":null,"position":1,"is_corresponding":false},{"id":116195,"name":"S Adhya","orcid":null,"position":2,"is_corresponding":false},{"id":116193,"name":"J P Tokeson","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":3.091042453358316,"endowment":3.091042453358316,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"2007555","pmcid":null,"openalex_id":"https://openalex.org/W1877291914","authors":[],"funders":[],"total_grants":0,"fwci":1.3604,"citation_percentile":0.81266694,"influential_citations":2,"citation_trend":[{"year":2012,"count":3},{"year":2014,"count":2},{"year":2016,"count":1}],"oa_status":"bronze","license":"https://journals.asm.org/non-commercial-tdm-license","oa_locations":[{"url":"https://jb.asm.org/content/jb/173/7/2319.full.pdf","host_type":"journal"},{"url":"https://jb.asm.org/content/jb/173/7/2319.full.pdf","host_type":"BRONZE"},{"url":"https://jb.asm.org/content/jb/173/7/2319.full.pdf","host_type":"publisher"},{"url":"https://journals.asm.org/doi/pdf/10.1128/jb.173.7.2319-2327.1991","host_type":"publisher"},{"url":"https://doi.org/10.1128/jb.173.7.2319-2327.1991","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/2007555","host_type":"repository"},{"url":"http://europepmc.org/pmc/articles/PMC207785","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/207785","host_type":"repository"}],"fields_of_study":["Bacterial Genetics and Biotechnology","Escherichia coli research studies","Polyamine Metabolism and Applications","Biology","Medicine","DNA Mutational Analysis","Enzyme Induction","Epistasis, Genetic","Escherichia coli","Escherichia coli Proteins","Galactokinase","Galactose","Gene Expression Regulation, Bacterial","Operator Regions, Genetic","Operon","Promoter Regions, Genetic","Protein Biosynthesis","Repressor Proteins","Transcription, Genetic"],"mesh_terms":["DNA Mutational Analysis","Enzyme Induction","Epistasis, Genetic","Escherichia coli","Galactokinase","Galactose","Operator Regions, Genetic","Operon","Promoter Regions, Genetic","Repressor Proteins","Transcription, Genetic","Protein Biosynthesis","Gene Expression Regulation, Bacterial","Escherichia coli Proteins"],"keywords":["Operon","Repressor","gal operon","Derepression","Biology","trp operon","Inducer","L-arabinose operon","Lac repressor","lac operon","Transcription (linguistics)","Gene","Molecular biology","YY1","Genetics","Promoter","Escherichia coli","Transcription factor","Gene expression","Psychological repression"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-01T16:04:27.434477Z","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":[]}