Exploring conformational preferences of proteins: ionic liquid effects on the energy landscape of avidin.

Autor:	Shmool TA; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388., Martin LK; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388.; Imperial College Centre for Synthetic Biology, Imperial College London London SW7 2AZ UK., Clarke CJ; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388., Bui-Le L; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388., Polizzi KM; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388.; Imperial College Centre for Synthetic Biology, Imperial College London London SW7 2AZ UK., Hallett JP; Department of Chemical Engineering, Imperial College London London SW7 2AZ UK j.hallett@imperial.ac.uk +44 (0)20 7594 5388.
Jazyk:	angličtina
Zdroj:	Chemical science [Chem Sci] 2020 Oct 23; Vol. 12 (1), pp. 196-209. Date of Electronic Publication: 2020 Oct 23.
DOI:	10.1039/d0sc04991c
Abstrakt:	In this work we experimentally investigate solvent and temperature induced conformational transitions of proteins and examine the role of ion-protein interactions in determining the conformational preferences of avidin, a homotetrameric glycoprotein, in choline-based ionic liquid (IL) solutions. Avidin was modified by surface cationisation and the addition of anionic surfactants, and the structural, thermal, and conformational stabilities of native and modified avidin were examined using dynamic light scattering, differential scanning calorimetry, and thermogravimetric analysis experiments. The protein-surfactant nanoconjugates showed higher thermostability behaviour compared to unmodified avidin, demonstrating distinct conformational ensembles. Small-angle X-ray scattering data showed that with increasing IL concentration, avidin became more compact, interpreted in the context of molecular confinement. To experimentally determine the detailed effects of IL on the energy landscape of avidin, differential scanning fluorimetry and variable temperature circular dichroism spectroscopy were performed. We show that different IL solutions can influence avidin conformation and thermal stability, and we provide insight into the effects of ILs on the folding pathways and thermodynamics of proteins. To further study the effects of ILs on avidin binding and correlate thermostability with conformational heterogeneity, we conducted a binding study. We found the ILs examined inhibited ligand binding in native avidin while enhancing binding in the modified protein, indicating ILs can influence the conformational stability of the distinct proteins differently. Significantly, this work presents a systematic strategy to explore protein conformational space and experimentally detect and characterise 'invisible' rare conformations using ILs. Competing Interests: There are no conflicts to declare. (This journal is © The Royal Society of Chemistry.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu