Cyanochelins, an overlooked class of widely distributed cyanobacterial siderophores, discovered by silent gene cluster awakening.

0552516 - BC 2022 RIV US eng J - Journal Article
Galica, T. - Borbone, N. - Mareš, Jan - Kust, Andreja - Caso, A. - Esposito, G. - Saurav, K. - Hajek, J. - Řeháková, Klára - Urajová, P. - Costantino, V. - Hrouzek, P.
Cyanochelins, an overlooked class of widely distributed cyanobacterial siderophores, discovered by silent gene cluster awakening.
Applied and Environmental Microbiology. Roč. 87, č. 17 (2021), č. článku e03128-20. ISSN 0099-2240. E-ISSN 1098-5336
Institutional support: RVO:60077344
Keywords : cyanobacteria * iron acquisition * lipopeptides * secondary metabolism * siderophores
OECD category: Microbiology
Impact factor: 5.005, year: 2021
Method of publishing: Limited access
https://doi.org/10.1128/AEM.03128-20

Cyanobacteria require iron for growth and often inhabit iron-limited habitats, yet only a few siderophores are known to be produced by them. We report that cyanobacterial genomes frequently encode polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) biosynthetic pathways for synthesis of lipopeptides featuring beta-hydroxyaspartate (beta-OH-Asp), a residue known to be involved in iron chelation. Iron starvation triggered the synthesis of beta-OH-Asp lipopeptides in the cyanobacteria Rivularia sp. strain PCC 7116, Leptolyngbya sp. strain NIES-3755, and Rubidibacter lacunae strain KORDI 51-2. The induced compounds were confirmed to bind iron by mass spectrometry (MS) and were capable of Fe3+ to Fe2+ photoreduction, accompanied by their cleavage, when exposed to sunlight. The siderophore from Rivularia, named cyanochelin A, was structurally characterized by MS and nuclear magnetic resonance (NMR) and found to contain a hydrophobic tail bound to phenolate and oxazole moieties followed by five amino acids, including two modified aspartate residues for iron chelation. Phylogenomic analysis revealed 26 additional cyanochelin-like gene clusters across a broad range of cyanobacterial lineages. Our data suggest that cyanochelins and related compounds are widespread beta-OH-Asp-featuring cyanobacterial siderophores produced by phylogenetically distant species upon iron starvation. Production of photolabile siderophores by phototrophic cyanobacteria raises questions about whether the compounds facilitate iron monopolization by the producer or, rather, provide Fe2+ for the whole microbial community via photoreduction.
Permanent Link: http://hdl.handle.net/11104/0327626