2. Academic Validation
  3. Identification of small molecules affecting the interaction between human hemoglobin and Staphylococcus aureus IsdB hemophore

Identification of small molecules affecting the interaction between human hemoglobin and Staphylococcus aureus IsdB hemophore

  • Sci Rep. 2024 Apr 9;14(1):8272. doi: 10.1038/s41598-024-55931-8.
Monica Cozzi # 1,  Mariacristina Failla # 2,  Eleonora Gianquinto 2,  Sandra Kovachka 2 3,  Valeria Buoli Comani 1,  Carlotta Compari 1,  Omar De Bei 4,  Roberta Giaccari 1,  Francesco Marchesani 4,  Marialaura Marchetti 4,  Luca Ronda 4 5,  Barbara Rolando 2,  Massimo Baroni 6,  Gabriele Cruciani 7,  Barbara Campanini 1,  Stefano Bettati 4 5,  Serena Faggiano 8 9,  Loretta Lazzarato 2,  Francesca Spyrakis 10
Affiliations

Affiliations

  • 1 Department of Food and Drug, University of Parma, Parma, Italy.
  • 2 Department of Drug Science and Technology, University of Turin, Turin, Italy.
  • 3 The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, Jupiter, FL, USA.
  • 4 Department of Medicine and Surgery, University of Parma, Parma, Italy.
  • 5 Institute of Biophysics, National Research Council, Pisa, Italy.
  • 6 Molecular Discovery Ltd, Kisnetic Business Centre, Elstree, Borehamwood, Hertfordshire, UK.
  • 7 Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy.
  • 8 Department of Food and Drug, University of Parma, Parma, Italy. serena.faggiano@unipr.it.
  • 9 Institute of Biophysics, National Research Council, Pisa, Italy. serena.faggiano@unipr.it.
  • 10 Department of Drug Science and Technology, University of Turin, Turin, Italy. francesca.spyrakis@unito.it.
  • # Contributed equally.
PMID: 38594253 DOI: 10.1038/s41598-024-55931-8
Abstract

Human hemoglobin (Hb) is the preferred iron source of Staphylococcus aureus. This pathogenic bacterium exploits a sophisticated protein machinery called Iron-regulated surface determinant (Isd) system to bind Hb, extract and internalize heme, and finally degrade it to complete iron acquisition. IsdB, the surface exposed Hb receptor, is a proven virulence factor of S. aureus and the inhibition of its interaction with Hb can be pursued as a strategy to develop new classes of antimicrobials. To identify small molecules able to disrupt IsdB:Hb protein-protein interactions (PPIs), we carried out a structure-based virtual screening campaign and developed an ad hoc immunoassay to screen the retrieved set of commercially available compounds. Saturation-transfer difference (STD) NMR was applied to verify specific interactions of a sub-set of molecules, chosen based on their efficacy in reducing the amount of Hb bound to IsdB. Among molecules for which direct binding was verified, the best hit was submitted to ITC analysis to measure the binding affinity to Hb, which was found to be in the low micromolar range. The results demonstrate the viability of the proposed in silico/in vitro experimental pipeline to discover and test IsdB:Hb PPI inhibitors. The identified lead compound will be the starting point for future SAR and molecule optimization campaigns.

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