Beilstein Arch. 2023, 202362. https://doi.org/10.3762/bxiv.2023.62.v1
Published 15 Dec 2023
Several under-explored Aspergillus sp. produce intriguing heptapeptides containing a g-aminobutyric acid (GABA) residue with as yet unknown biological functions. In this study a new GABA-containing heptapeptide – unguisin J (1) – along with known unguisin B (2) were isolated from a solid culture of Aspergillus heteromorphus CBS 117.55. The structure of compound 1 was elucidated by extensive 1D and 2D NMR spectroscopic analysis including HSQC, HMBC, COSY, and 2D-NOESY as well as HRESIMS. The stereochemistry of 1 and 2 was determined by Marfey’s method. A biosynthetic gene cluster (BGC) encoding unguisins B and J was compared to characterized BGCs in other Aspergillus sp. Since the unguisin family of heptapetides incorporate different amino-acid residues at different positions of the peptide, the A and C domains of the UngA NRPS were analyzed in an attempt to understand the lack of substrate specificity observed.
Keywords: Several under-explored Aspergillus sp. produce intriguing heptapeptides containing a g-aminobutyric acid (GABA) residue with as yet unknown biological functions. In this study a new GABA-containing heptapeptide – unguisin J (1) – along with known unguisin B (2) were isolated from a solid culture of Aspergillus heteromorphus CBS 117.55. The structure of compound 1 was elucidated by extensive 1D and 2D NMR spectroscopic analysis including HSQC, HMBC, COSY, and 2D-NOESY as well as HRESIMS. A biosynthetic gene cluster (BGC) encoding unguisins B and J was compared to characterized BGCs in other Aspergillus sp. Since the unguisin family of heptapetides incorporate different amino-acid residues at different positions of the peptide, the A and C domains of the UngA NRPS were analyzed in an attempt to understand the lack of substrate specificity observed.
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Neupane, S.; Rodrigues de Amorim, M.; Skellam, E. Beilstein Arch. 2023, 202362. doi:10.3762/bxiv.2023.62.v1
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