title: Regulation of tylosin production: role of a TylP-interactive ligand.
abstract: Gamma-butyrolactones regulate secondary metabolism and, sometimes, sporulation in actinomycetes by binding to specific receptor proteins, causing their dissociation from DNA targets and releasing the latter from transcriptional repression. Previously, in engineered strains of Streptomyces lividans, we showed that TylP, a deduced gamma-butyrolactone receptor, downregulated reporter gene expression driven by tylP, tylQ or tylS promoter DNA. These genes all control tylosin production in Streptomyces fradiae. Thus, at early stages of fermentation, TylQ represses tylR whereas TylS is needed for transcriptional activation of tylR. Importantly, TylR is the key activator of tylosin-biosynthetic genes. Here, we show that HIS-tagged TylP binds to specific DNA sequences, similar to the targets for authentic gamma-butyrolactone receptors, in the promoters of tylP, tylQ and tylS. Moreover, such binding is disrupted by material produced in S. fradiae and extractable by organic solvent. That putative gamma-butyrolactone material was not produced when orf18 * was disrupted within the S. fradiae genome and only about 1% of that activity survived inactivation of orf16 *, suggesting roles for the respective gene products in gamma-butyrolactone synthesis. Continued synthesis of tylosin by the disrupted strains contrasts with other reports that loss of gamma-butyrolactones abolishes antibiotic production.
authors.affiliation: Department of Biochemistry, University of Leicester, Leicester LE1 9HN, UK.
authors.forename: Dawn R D
authors.initials: DR
authors.lastname: Bignell
authors.forename: Neil
authors.initials: N
authors.lastname: Bate
authors.forename: Eric
authors.initials: E
authors.lastname: Cundliffe
mesh_terms: D015107:4-Butyrolactone / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015536:Down-Regulation; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D008024:Ligands; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D011963:Receptors, GABA-A / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional; D013302:Streptomyces / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015645:Tylosin / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D008024:Ligands; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D015107:4-Butyrolactone; D015645:Tylosin