Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water

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Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water, Angew. Chem. Int. Ed. 2017, 56, 389 –392

 

Intrinsically disordered proteins (IDPs) constitute a class of physiologically active proteins that lack stable secondary and tertiary structures. The highly dynamic nature of these proteins endows them with an inherent ability to interact simultaneously with multiple binding partners in the cellular environment. IDPs thus frequently constitute important hubs in protein interaction networks. The malfunction of IDPs often leads to severe diseases associated with deregulation of the cellular machinery. Since intrinsically disordered proteins or regions constitute approximately 30% of the human proteome, understanding their functionality and structure–function relationships is clearly desirable, especially with a view to developing novel therapeutic strategies for the treatment and prevention of diseases related to IDP malfunction.

 

The inherent dynamics and flexibility of IDPs explain their astonishingly rich interactome. Nuclear magnetic resonance (NMR) spectroscopy has developed into a key method for the study of IDPs. Multidimensional techniques and high field NMR spectrometers give access to residue-resolved dynamics of IDPs at ambient temperature and low pH. However, under physiological conditions, the spectra typically suffer from strong signal overlap and broadening, thus leading to peak intensities below the detection threshold. To the best of our knowledge, only one study has been published so far that employs 1H-15N correlation spectra of IDPs under physiological conditions at pH 7.4 and 37°C.

 

 

These limitations in the study of IDPs can be overcome by using hyperpolarized HDO produced through dissolution dynamic nuclear polarization (D-DNP). Because exchange between hyperpolarized HDO and amide HN protons only enhances a limited set of solvent-exposed residues under near-physiological conditions,[8] the 1H-15N correlation spectra are sparse and can be assigned despite the poor dispersion of their chemical shifts. Such sparse spectra are reminiscent of “spectral dilution” techniques that rely on 13C labelling of selected amino acids. Felli and co-workers have advocated the use of 13C direct detection techniques that allow the observation of IDPs under physiological conditions in 13C-15N correlation spectra but do not show any proton signals, which are the object of our work.

 

N'hésitez pas à consuter le communiqué de presse associé à cet article : L’eau hyperpolarisée pour éclairer les protéines intrinsèquement désordonnées

 

 

Résumé: 

Angew. Chem. Int. Ed2017, 56, 389 –392

 

Hyperpolarized water can selectively enhance NMR signals of rapidly exchanging protons in osteopontin (OPN), a metastasis-associated intrinsically disordered protein (IDP), at near-physiological pH and temperature. The transfer of magnetization from hyperpolarized water is limited to solventexposed residues and therefore selectively enhances signals in 1H-15N correlation spectra. Binding to the polysaccharide heparin was found to induce the unfolding of preformed structural elements in OPN.

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Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water

 

Dennis Kurzbach, Estel Canet, Andrea G. Flamm, Aditya Jhajharia, Emmanuelle M. M. Weber, Robert Konrat, and Geoffrey Bodenhausen

 

Angew. Chem. Int. Ed. 2017, 56, 389 –392

 

DOI: 10.1002/anie.201608903