title: Functional manipulations of the tetramycin positive regulatory gene ttmRIV to enhance the production of tetramycin A and nystatin A1 in Streptomyces ahygroscopicus.
abstract: A putative regulatory gene ttmRIV located in the tetramycin biosynthetic gene cluster was found in Streptomyces ahygroscopicus. In-frame deletion of ttmRIV led to abolishment of tetramycin and significant enhancement of nystatin A1, whose production reached 2.1-fold of the H42 parental strain. Gene complementation by an integrative plasmid carrying ttmRIV restored tetramycin biosynthesis revealed that ttmRIV was indispensable to tetramycin biosynthesis. Gene expression analysis of the H42 strain and its mutant strain ΔttmRIV via reverse transcriptase-PCR of the tetramycin gene cluster demonstrated that the expression levels of most biosynthetic genes were reduced in ΔttmRIV. Results of electrophoretic mobility shift assays showed that TtmRIV bound the putative promoters of several genes in the tetramycin pathway. Thus, TtmRIV is a pathway-specific positive regulator activating the transcription of the tetramycin gene cluster in S. ahygroscopicus. Providing an additional copy of ttmRIV under the control of the ermEp* promoter in the H42 strain boosted tetramycin A production to 3.3-fold.
authors.affiliation: School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical Univerisity, Shenhe District, Wenhua Road 103, 110016, Shenyang, Liaoning, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Cui
authors.forename: Xianpu
authors.initials: X
authors.lastname: Ni
authors.forename: Wei
authors.initials: W
authors.lastname: Shao
authors.forename: Jian
authors.initials: J
authors.lastname: Su
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Su
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
authors.forename: Huanzhang
authors.initials: H
authors.lastname: Xia
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D019149:Bioreactors; D053898:Biosynthetic Pathways; D016384:Consensus Sequence; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D018942:Macrolides / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009761:Nystatin / Q000096:biosynthesis*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; C000593605:tetramycin; D009761:Nystatin