New Insights into Glycopeptide Antibiotic Binding to Cell Wall Precursors using SPR and NMR Spectroscopy |
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| Authors: | Juan Treviño Carlos Bayón Ana Ardá Flavia Marinelli Raffaella Gandolfi Francesco Molinari Jesús Jimenez‐Barbero María J. Hernáiz |
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| Affiliation: | 1. Departamento de Química Orgánica y Farmacéutica, Universidad Complutense de Madrid, Pz/Ramón y Cajal s/n. 28040 Madrid (Spain);2. Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid (Spain);3. Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Via J.?H. Dunant 3, Varese 21100 (Italy);4. “The Protein Factory” Research Center, Politecnico of Milano, ICRM CNR Milano and University of Insubria, Varese (Italy);5. Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Venezian 21, 20133 Milano (Italy);6. Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano (Italy) |
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| Abstract: | Glycopeptide antibiotics, such as vancomycin and teicoplanin, are used to treat life‐threatening infections caused by multidrug‐resistant Gram‐positive pathogens. They inhibit bacterial cell wall biosynthesis by binding to the D ‐Ala‐D ‐Ala C‐terminus of peptidoglycan precursors. Vancomycin‐resistant bacteria replace the dipeptide with the D ‐Ala‐D ‐Lac depsipeptide, thus reducing the binding affinity of the antibiotics with their molecular targets. Herein, studies of the interaction of teicoplanin, teicoplanin‐like A40926, and of their semisynthetic derivatives (mideplanin, MDL63,246, dalbavancin) with peptide analogues of cell‐wall precursors by NMR spectroscopy and surface plasmon resonance (SPR) are reported. NMR spectroscopy revealed the existence of two different complexes in solution, when the different glycopeptides interact with Ac2Kd AlaD AlaOH. Despite the NMR experimental conditions, which are different from those employed for the SPR measurements, the NMR spectroscopy results parallel those deduced in the chip with respect to the drastic binding difference existing between the D ‐Ala and the D ‐Lac terminating analogues, confirming that all these antibiotics share the same primary molecular mechanism of action and resistance. Kinetic analysis of the interaction between the glycopeptide antibiotics and immobilized AcKd AlaD AlaOH by SPR suggest a dimerization process that was not observed by NMR spectroscopy in DMSO solution. Moreover, in SPR, all glycopeptides with a hydrophobic acyl chain present stronger binding with a hydrophobic surface than vancomycin, indicating that additional interactions through the employed surface are involved. In conclusion, SPR provides a tool to differentiate between vancomycin and other glycopeptides, and the calculated binding affinities at the surface seem to be more relevant to in vitro antimicrobial activity than the estimations from NMR spectroscopy analysis. |
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| Keywords: | antibiotics glycopeptides NMR spectroscopy surface plasmon resonance teicoplanin |
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