Comparative metabolomic profiling of Cupriavidus necator B-4383 revealed production of cupriachelin siderophores, one with activity against Cryptococcus neoformans

Mohammed M A Ahmed; Siddarth K Tripathi; Paul D Boudreau

doi:10.3389/fchem.2023.1256962

Comparative metabolomic profiling of Cupriavidus necator B-4383 revealed production of cupriachelin siderophores, one with activity against Cryptococcus neoformans

Front Chem. 2023 Aug 24:11:1256962. doi: 10.3389/fchem.2023.1256962. eCollection 2023.

Authors

Mohammed M A Ahmed^{1

2}, Siddarth K Tripathi³, Paul D Boudreau¹

Affiliations

¹ Boudreau Lab, Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, Oxford, MS, United States.
² Department of Pharmacognosy, Al-Azhar University, Cairo, Egypt.
³ National Center for Natural Products Research, School of Pharmacy, University of Mississippi, Oxford, MS, United States.

Abstract

Cupriavidus necator H16 is known to be a rich source of linear lipopeptide siderophores when grown under iron-depleted conditions; prior literature termed these compounds cupriachelins. These small molecules bear β-hydroxyaspartate moieties that contribute to a photoreduction of iron when bound as ferric cupriachelin. Here, we present structural assignment of cupriachelins from C. necator B-4383 grown under iron limitation. The characterization of B-4383 cupriachelins is based on MS/MS fragmentation analysis, which was confirmed by 1D- and 2D-NMR for the most abundant analog (1). The cupriachelin congeners distinguish these two strains with differences in the preferred lipid tail; however, our rigorous metabolomic investigation also revealed minor analogs with changes in the peptide core, hinting at a potential mechanism by which these siderophores may reduce biologically unavailable ferric iron (4-6). Antifungal screening of the C. necator B-4383 supernatant extract and the isolated cupriachelin analog (1) revealed inhibitory activity against Cryptococcus neoformans, with IC₅₀ values of 16.6 and 3.2 μg/mL, respectively. This antifungal activity could be explained by the critical role of the iron acquisition pathway in the growth and pathogenesis of the C. neoformans fungal pathogen.

Keywords: Cupriavidus necator; cupriachelin; mass spectrometry; metabolomics (LC-MS); siderophore.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. Support for this work came from a startup package provided by the University of Mississippi Provost’s office and the Department of BioMolecular Sciences in the School of Pharmacy to PB. MA was supported, in part, by a Graduate Student Research Grant from the University of Mississippi Graduate Student Council. The biological screening work by ST was supported by USDA-ARS SCA grant # 58-6060-6-015 at the National Center for Natural Products Research.