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C-diazeniumdiolate siderophores are a small class of photoactive bacterial Fe(III) chelators. Driven by genome mining, we discovered a new C-type diazeniumdiolate siderophore, pandorachelin, produced by the rhizospheric bacterium, Pandoraea norimbergensis DSM 11628. The biosynthetic gene cluster encoding the production of pandorachelin is conserved across several Pandoraea species. Pandoraea spp. are environmentally widespread and are increasingly prevalent clinical pathogens, spurring new interest in their metabolites. UV irradiation photolytically cleaves the N–N bonds within the diazeniumdiolate-containing graminine constituents of pandorachelin. With EPR spin trapping, we directly detect nitric oxide released from the two C-diazeniumdiolate ligands of pandorachelin upon UV irradiation. Additionally, we show that nitric oxide can react with the intermediates during the photoreaction to re-construct the diazeniumdiolate groups via exchange of the distal NO, and thereby recover Fe(III)-binding capacity. The photochemistry of this class of siderophores points to a broader biological role, both in their propensity to release the biological signaling molecule, nitric oxide, and in their ability to undergo photoinduced NO exchange.
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This content will become publicly available on June 16, 2026
Nitrite Causes Nitrosative Stress to Iron Sulfur Clusters
Nitric oxide (NO), produced by nitrite reductases or nitric oxide synthases, performs vital roles in signaling and the immune response. Iron sulfur (FeS) clusters are known targets for NO induced degradation, serving as sensors to trigger cellular responses. However, this FeS reactivity is proposed as NO specific, with no demonstrated reactivity toward nitrite, a soluble NO storage molecule. We demonstrate that synthetic FeS clusters supported by various ligands undergo facile nitrosylation by nitrite in the presence of a reductant, evidencing the nitrite reductase reactivity for FeS clusters. Moreover, a mononitrosylated Fe4S4 cluster, [tempS3Fe4S4(NO)]2–, can be readily synthesized by this approach, enabling further investigation into the FeS cluster repair and decomposition under NO induced oxidative stress.
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- Award ID(s):
- 2102098
- PAR ID:
- 10609376
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Journal of the American Chemical Society
- ISSN:
- 0002-7863
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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