title: Streptomyces clavuligerus relA-null mutants overproduce clavulanic acid and cephamycin C: negative regulation of secondary metabolism by (p)ppGpp.
abstract: The (p)ppGpp synthetase gene, relA, of Streptomyces clavuligerus was cloned, sequenced and shown to be located in a genomic region that is highly conserved in other Streptomyces species. relA-disrupted and relA-deleted mutants of S. clavuligerus were constructed, and both were unable to form aerial mycelium or to sporulate, but regained these abilities when complemented with wild-type relA. Neither ppGpp nor pppGpp was detected in the S. clavuligerus relA-deletion mutant. In contrast to another study, clavulanic acid and cephamycin C production increased markedly in the mutants compared to the wild-type strain; clavulanic acid production increased three- to fourfold, while that of cephamycin C increased about 2.5-fold. Complementation of the relA-null mutants with wild-type relA decreased antibiotic yields to approximately wild-type levels. Consistent with these observations, transcription of genes involved in clavulanic acid (ceaS2) or cephamycin C (cefD) production increased dramatically in the relA-deleted mutant when compared to the wild-type strain. These results are entirely consistent with the growth-associated production of both cephamycin C and clavulanic acid, and demonstrate, apparently for the first time, negative regulation of secondary metabolite biosynthesis by (p)ppGpp in a Streptomyces species of industrial interest.
authors.affiliation: Área de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Gomez-Escribano
authors.affiliation: Instituto de Biotecnología (INBIOTEC), Parque Científico de León, Av. Real 1, 24006 León, Spain.|Área de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Martín
authors.affiliation: Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
authors.forename: A
authors.initials: A
authors.lastname: Hesketh
authors.affiliation: Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bibb
authors.affiliation: Instituto de Biotecnología (INBIOTEC), Parque Científico de León, Av. Real 1, 24006 León, Spain.|Área de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Liras
mesh_terms: D001483:Base Sequence; D002513:Cephamycins / Q000096:biosynthesis*; D019818:Clavulanic Acid / Q000096:biosynthesis*; D003001:Cloning, Molecular; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology*; D005816:Genetic Complementation Test; D006158:Guanosine Pentaphosphate / Q000378:metabolism; D008025:Ligases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D017422:Sequence Analysis, DNA; D013171:Spores, Bacterial / Q000235:genetics / Q000254:growth & development; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D024363:Transcription Initiation Site; D015533:Transcriptional Activation
chemical_list: D002513:Cephamycins; D019818:Clavulanic Acid; D006158:Guanosine Pentaphosphate; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases; C024925:cephamycin C