1 research outputs found
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