As SanG controls the transcription of sanN and sanO, SabR regulates the transcription of sanN and sanO via directly modulating the transcription of sanG. Figure 4 EMSA analysis of SabR binding to the upstream of sanG , sabR , sanN , sanO and sanF. A, Purification of the SabR-His6 from E. coli. M, protein marker; 1 and 2, purified SabR-His6 protein. B, The upstream region of sanG, sabR, sanN, sanO or sanF was incubated with or without increasing amounts of SabR-His6 (lanes 1-10 contain

0, 52, 104, 130, 208, 260, 390, 520, 650 and 780 nM, respectively). C, Competition assays using unlabeled specific DNA EG1 and nonspecific competitor DNA EG0. Lanes 3-9, EMSA of 208 nM SabR-His6 with labeled probe and unlabeled specific competitor EG1. Lanes 10-13, EMSA of 208 nM SabR-His6 with labeled probe and nonspecific competitor EG0. The arrows indicate the free probe and SabR -DNA complexes. Eltanexor in vitro https://www.selleckchem.com/products/Fedratinib-SAR302503-TG101348.html D, The gene organization of sanG, sanNO, sanF and sabR. Detection of the SabR-binding sites To identify the specific binding sites of SabR in the upstream region of sanG, DNase 1 footprinting assay was carried out using [γ-32P]-labeled probe. One region at positions -64 to -29 nucleotides was protected by SabR from DNase 1 digestion, its sequence was 5′-CTTTAAGTCACCTGGCTCATTCGCGTTCGCCCAGCT-3′ (Figure 5A and 5B). This sequence showed resemblance

to the reported ARE which were bound by γ-butyrolactone receptors described Astemizole previously (Figure 5C), and it was designated as SARE. These results confirmed that SabR regulated nikkomycin biosynthesis by interaction with SARE sequences upstream of sanG directly. Figure 5 DNase 1 footprinting analysis of SabR binding to the upstream of sanG. A, DNase 1 footprinting experiments. The amounts of SabR-His6 used in lane 1 to 7 were 0, 208, 260, 390, 520, 650 and 780 nM, respectively. The region protected against DNase 1 digestion by SabR was indicated by solid line. B, Nucleotide sequence of sanG promoter and SabR-binding sites. The transcription start point (TSP) of sanG is indicated by an arrow. The nucleotide sequence of SARE protected against DNase 1 digestion

by SabR is underlined. C, Comparison of SARE with the ARE consensus sequence recognized by the Streptomyces γ-butyrolactone receptors. Identical residues are highlighted in black. Arrows indicate the position of the 22 bp inverted repeat sequence identified as a consensus sequence (ARE box) recognized by the γ-butyrolactone autoregulator receptor protein ArpA[39]. The function of SARE upstream of sanG In order to know the function of SARE and its relationship with SabR in vivo, SARE deletion mutant (SAREDM) was constructed. The bioassay showed that nikkomycin Smoothened Agonist production was delayed in the SAREDM as that in the SabRDM from 48 h to 96 h fermentation. After 96 h, the nikkomycin production in SAREDM gradually restored to the level of WT, even slightly higher at 120 h (Figure 6).