title: Inactivation of the extracytoplasmic function sigma factor Sig6 stimulates avermectin production in Streptomyces avermitilis.
abstract: The role of the extracytoplasmic function (ECF) σ factor Sig6 (SAV663) in avermectin production by Streptomyces avermitilis was investigated by gene-deletion, complementation and over-expression experiments. Inactivation of Sig6 had no major effect on growth, stress responses, or morphology. Avermectin yield was increased 2- to 2.7-fold (~680 μg/ml) relative to the wild-type strain by deletion of the sig6 gene, and was restored to the wild-type level by introduction of a single copy of sig6. Introduction of extra multi-copy or integrative sig6 vectors into the wild-type decreased avermectin yield by 56-63%. Taken together, these findings indicate that Sig6 plays a negative regulatory role in avermectin production in S. avermitilis. RT-PCR analysis demonstrated that this role of Sig6 is mediated by the pathway-specific activator gene aveR.
authors.affiliation: State Key Laboratories for Agro-biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, People's Republic of China. jianglibin1984@163.com
authors.forename: Libin
authors.initials: L
authors.lastname: Jiang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Liu
authors.forename: Pan
authors.initials: P
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Wen
authors.forename: Yuan
authors.initials: Y
authors.lastname: Song
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Jilun
authors.initials: J
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000378:metabolism; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D014157:Transcription Factors; D007559:Ivermectin; C019264:avermectin