LuxR-Type SCO6993 Negatively Regulates Antibiotic Production at the Transcriptional Stage by Binding to Promoters of Pathway-Specific Regulatory Genes in Streptomyces coelicolor

Abstract

SCO6993 (606 amino acids) inStreptomyces coelicolor belongs to the large ATP-binding regulators of the LuxR family regulators having one DNA-binding motif. Our previous findings predicted that SCO6993 may suppress the production of pigmented antibiotics, actinorhodin, and undecylprodigiosin, in S. coelicolor, resulting in the characterization of its properties at the molecular level. SCO6993-disruptant, S. coelicolor ΔSCO6993 produced excess pigments in R2YE plates as early as the third day of culture and showed 9.0-fold and 1.8-fold increased production of actinorhodin and undecylprodigiosin in R2YE broth, respectively, compared with that by the wild strain and S. coelicolor ΔSCO6993/SCO6993 + . Real-time polymerase chain reaction analysis showed that the transcription of actA and actII-ORF4 in the actinorhodin biosynthetic gene cluster and that of redD and redQ in the undecylprodigiosin biosynthetic gene cluster were significantly increased by SCO6993-disruptant. Electrophoretic mobility shift assay and DNase footprinting analysis confirmed that SCO6993 protein could bind only to the promoters of pathway-specific transcriptional activator genes, actII-ORF4 and redD, and a specific palindromic sequence is essential for SCO6993 binding. Moreover, SCO6993 bound to two palindromic sequences on its promoter region. These results indicate that SCO6993 suppresses the expression of other biosynthetic genes in the cluster by repressing the transcription of actII-ORF4 and redD and consequently negatively regulating antibiotic production.

Molecular and Biochemical Characterization of Xylanase Produced by Streptomyces viridodiastaticus MS9, a Newly Isolated Soil Bacterium

“…The strain with the highest xylanase activity was named MS9 and used in this study. For 16S rRNA coding gene analysis, a genomic DNA extracted from strain MS9 (template) and bacterial universal primers [ 4 ], 27F (5'-AGAGTTTGATCCTGGCTCAG- 3') and 1492R (5'-GGTTACCTTGTTACGACTT-3'), were used to perform PCR, as described previously [ 31 ]. The 16S rRNA gene sequence of the MS9 strain was obtained using Basic Local Alignment Search Tool (BLAST) program [ 1 ] at NCBI, and was submitted to the GenBank database; gene sequences of the related strains were collected from the EzTaxon server [ 9 ].…”

Overexpression of SAV111 in Streptomyces avermitilis increases avermectin production by binding to aveA1 gene promoter

“…In the wild type S. rapamycinicus, overexpression of LAL gene rapH increased rapamycin production by 46.5% (He et al 2022). In S. coelicolor, the LAL regulator SCO6993 inhibits the production of actinomycin and undecylprodigiosin (Tsevelkhoroloo et al 2022).…”