Biosynthetic Diversification of Fidaxomicin Aglycones by Heterologous Expression and Promoter Refactoring

Fidaxomicin (Dificid) is a commercial macrolide antibiotic for treating Clostridium difficile infection. Total synthesis of fidaxomicin and its aglycone had been achieved through different synthetic schemes. In this study, an alternative biological route to afford the unique 18-membered macrolactone aglycone of fidaxomicin was developed. The promoter refactored fidaxomicin biosynthetic gene cluster from Dactylosporangium aurantiacum was expressed in the commonly used host Streptomyces albus J1074, thereby delivering five structurally diverse fidaxomicin aglycones with the corresponding titers ranging from 4.9 to 15.0 mg L–1. In general, these results validated a biological strategy to construct and diversify fidaxomicin aglycones on the basis of promoter refactoring and heterologous expression

Additional file 1 of Spatiotemporal distribution of migraine in China: analyses based on baidu index

Supplementary Material

Tandem Hydration of Diisonitriles Triggered by Isonitrile Hydratase in Streptomyces thioluteus

The biosynthetic pathway of diisonitrile chalkophore SF2768 was identified in Streptomyces thioluteus through heterologous expression recently. Isolation and structure elucidation of the N-substituted formamides that coexisted with the diisonitriles implied that a hydration event was involved. <i>In vitro</i> enzymatic assays of an endogenous isonitrile hydratase suggested a rare sequential-hydration of the diisonitriles. Additionally, the results of Cu-CAS assays indicate that both partial and complete hydration led to the loss of the copper-chelating ability of SF2768

Additional file 3: of Human-induced pluripotent stem cell-derived macrophages and their immunological function in response to tuberculosis infection

Figure S3. Immunofluorescence images showing the positive expression of Mφ lineage markers CD40 in iPS-Mφ (A), THP-1-Mφ (B) and ES-Mφ (C). Nuclei are labeled with DAPI. Bar = 100 μm. (TIFF 1548 kb

Additional file 5: of Human-induced pluripotent stem cell-derived macrophages and their immunological function in response to tuberculosis infection

Figure S5. Immunofluorescence images showing the positive expression of Mφ lineage markers MHC-II in iPS-Mφ (A), THP-1-Mφ (B) and ES-Mφ (C). Nuclei are labeled with DAPI. Bar = 100 μm. (TIFF 1462 kb

Additional file 2: of Human-induced pluripotent stem cell-derived macrophages and their immunological function in response to tuberculosis infection

Figure S2. Immunofluorescence images showing the positive expression of Mφ lineage markers CD14 in iPS-Mφ (A), THP-1-Mφ (B) and ES-Mφ (C). Nuclei are labeled with DAPI. Bar = 100 μm. (TIFF 1337 kb

Diisonitrile Natural Product SF2768 Functions As a Chalkophore That Mediates Copper Acquisition in <i>Streptomyces thioluteus</i>

A nonribosomal peptide synthetase (NRPS) gene cluster (<i>sfa</i>) was identified in <i>Streptomyces thioluteus</i> to direct the biosynthesis of the diisonitrile antibiotic SF2768. Its biosynthetic pathway was reasonably proposed based on bioinformatics analysis, metabolic profiles of mutants, and the elucidation of the intermediate and shunt product structures. Bioinformatics-based alignment found a putative ATP-binding cassette (ABC) transporter related to iron import within the biosynthetic gene cluster, which implied that the product might be a siderophore. However, characterization of the metal-binding properties by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), metal–ligand titration, thin-layer chromatography (TLC), and chrome azurol S (CAS) assays revealed that the final product SF2768 and its diisonitrile derivatives specifically bind copper, rather than iron, to form stable complexes. Inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed that the intracellular cupric content of <i>S</i>. <i>thioluteus</i> significantly increased upon incubation with the copper–SF2768 complex, direct evidence for the copper acquisition function of SF2768. Further <i>in vivo</i> functional characterization of the transport elements for the copper–SF2768 complexes not only confirmed the chalkophore identity of the compound but also gave initial clues into the copper uptake mechanism of this nonmethanotrophic microorganism