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Positive and negative regulation of GlnR in validamycin A biosynthesis by binding to different loci in promoter region.
- Source :
- Applied Microbiology & Biotechnology; Jun2015, Vol. 99 Issue 11, p4771-4783, 13p
- Publication Year :
- 2015
-
Abstract
- Validamycin A (VAL-A) is a CN aminocyclitol antibiotic produced by Streptomyces hygroscopicus var. jinggangensis 5008, which has been widely used as antifungal agent against rice sheath blight disease. VAL-A biosynthesis has been proven to be affected by γ-butyrolactone and temperature. Herein, we showed that GlnR, a global regulator in nitrogen metabolism, is specifically associated with valK-valA intergenic promoter region by DNA-affinity chromatography and MS-based protein identification. Subsequent EMSA and DNase I footprinting assays revealed two GlnR binding sites in this promoter region. Targeted disruption of glnR in S. hygroscopicus 5008 led to a significant increase in the transcription of VAL-A structural genes, albeit the VAL-A production was reduced by 80 % and the sporulation of the mutant was impaired. Compared with the wild-type 5008, site-specific mutagenesis of GlnR binding site I enhanced VAL-A production by 2.5-fold, whereas the mutation of GlnR binding site II resulted in a 50 % reduction of VAL-A yield. Moreover, tandem mutation of site I in the site II mutant led to a 66 % increase of VAL-A production. The result suggested that GlnR not only serves as an inhibitor by binding site I but also as an activator by binding site II for VAL-A biosynthesis. Furthermore, overexpression of glnR in the site I mutant JG45 improved VAL-A production for 41 % compared with the control strain containing the vector. Therefore, the obtained data illustrate a novel regulatory feature of the global regulator GlnR. GlnR is firstly proved to act simultaneously as an activator and a repressor in validamycin biosynthesis by binding to different loci within a promoter region of the gene cluster. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01757598
- Volume :
- 99
- Issue :
- 11
- Database :
- Complementary Index
- Journal :
- Applied Microbiology & Biotechnology
- Publication Type :
- Academic Journal
- Accession number :
- 102702232
- Full Text :
- https://doi.org/10.1007/s00253-015-6437-0