title: Identification and characterization of chromosomal relBE toxin-antitoxin locus in Streptomyces cattleya DSM46488.
abstract: The relBE family of Type II toxin-antitoxin (TA) systems have been widely reported in bacteria but none in Streptomyces. With the conserved domain searches for TA pairs in the sequenced Streptomyces genomes, we identified two putative relBE loci, relBE1sca and relBE2sca, on the chromosome of Streptomyces cattleya DSM 46488. Overexpression of the S. cattleya toxin RelE2sca caused severe growth inhibition of E. coli and S. lividans, but RelE1sca had no toxic effect. The toxicity of RelE2sca could be abolished by the co-expression of its cognate RelB2sca antitoxin. Moreover, the RelBE2sca complex, or the antitoxin RelB2sca alone, specifically interacted with the relBE2sca operon and repressed its transcription. The relBE2sca operon transcription was induced under osmotic stress, along with the ClpP proteinase genes. The subsequent in vivo analysis showed that the antitoxin was degraded by ClpP. Interestingly, the E. coli antitoxin RelBeco was able to alleviate the toxicity of S. cattleya RelE2sca while the mutant RelB2sca(N61V&M68L) but not the wild type could alleviate the toxicity of E. coli RelEeco as well. The experimental demonstration of the relBEsca locus might be helpful to investigate the key roles of type II TA systems in Streptomyces physiology and environmental stress responses.
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Cui
authors.initials: C
authors.lastname: Tai
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Gan
authors.affiliation: Department of Genetics, University of Leicester, Leicester, UK.
authors.forename: Marco R
authors.initials: MR
authors.lastname: Oggioni
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Ou
mesh_terms: D000595:Amino Acid Sequence; D000992:Antitoxins / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D002875:Chromosomes / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D049071:Endopeptidase Clp / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism; D005798:Genes, Bacterial; D056426:Genetic Loci; D016296:Mutagenesis; D009997:Osmotic Pressure; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D013302:Streptomyces / Q000235:genetics*
chemical_list: D000992:Antitoxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D012329:RNA, Bacterial; D049071:Endopeptidase Clp