Certain cyanobacteria of the secondary metabolite-rich order Nostocales can establish permanent symbioses with a large number of cycads, by accumulating in their coralloid roots and shifting their metabolism to dinitrogen fixation. Here, we report the discovery of two new lipoglycopeptides, desmamides A (1) and B (2), together with their aglycone desmamide C (3), from the nostocalean cyanobacterium Desmonostoc muscorum LEGE 12446 isolated from a cycad (Cycas revoluta) coralloid root. The chemical structures of the compounds were elucidated using a combination of 1D and 2D NMR spectroscopy and mass spectrometry. The desmamides are decapeptides featuring O-glycosylation of tyrosine (in 1 and 2) and an unusual 3,5-dihydroxy-2-methyldecanoic acid residue. The biosynthesis of the desmamides was studied by substrate incubation experiments and bioinformatics. We describe herein the dsm biosynthetic gene cluster and propose it to be associated with desmamide production. The discovery of this class of very abundant (>1.5% d.w.) bacterial lipoglycopeptides paves the way for exploration of their potential role in root endosymbiosis.
structure, NMR spectroscopy, mass spectrometry, cyanobacteria, marine, lipoglycopeptides, Desmonostoc muscorum
NCBI PubMed ID: 35793792Publication DOI: 10.1021/acs.jnatprod.2c00162Journal NLM ID: 7906882Publisher: American Society of Pharmacognosy
Correspondence: P.N. Leão
Institutions: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Avenida General Norton de Matos, s/n, 4450-208 Matosinhos, Portugal, Department of Biology, Faculty of Sciences, University of Porto Rua do Campo Alegre, Porto, Portugal, GEOMAR Centre for Marine Biotechnology (GEOMAR-Biotech), Research Unit Marine Natural Product Chemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Am Kiel Kanal 44, 24106 Kiel, Germany, Kiel University, Christian-Albrechts-Platz 4, 24118 Kiel, Germany
Methods: 13C NMR, 1H NMR, NMR-2D, FTIR, HPLC, extraction, optical rotation measurement, bioinformatic analysis, HR-ESI-MS, antibacterial assay, cell viability assay, flash chromatography, genome sequencing, Marfey’s method, LC-HR-ESI-MS
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