NMR-based approach to measure the free energy of transmembrane helix–helix interactions

• Published in: Biochimica et biophysica acta 2014-01, Vol.1838 (1), p.164-172
• Main Authors: Mineev, Konstantin S., Lesovoy, Dmitry M., Usmanova, Dinara R., Goncharuk, Sergey A., Shulepko, Mikhail A., Lyukmanova, Ekaterina N., Kirpichnikov, Mikhail P., Bocharov, Eduard V., Arseniev, Alexander S.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Binding Sites; Detergent micelle; Detergents - chemistry; Dimerization; Escherichia coli - genetics; Escherichia coli - metabolism; Free energy; Humans; Kinetics; Micelles; Models, Chemical; Molecular Sequence Data; NMR spectroscopy; Nuclear Magnetic Resonance, Biomolecular - methods; Oligopeptides - chemistry; Oligopeptides - genetics; Oligopeptides - metabolism; Protein Binding; Protein Multimerization; Protein Structure, Secondary; Protein Structure, Tertiary; Receptor, Fibroblast Growth Factor, Type 3 - chemistry; Receptor, Fibroblast Growth Factor, Type 3 - genetics; Receptor, Fibroblast Growth Factor, Type 3 - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Solutions; Thermodynamics; Transmembrane helix; Vascular Endothelial Growth Factor Receptor-2 - chemistry; Vascular Endothelial Growth Factor Receptor-2 - genetics; Vascular Endothelial Growth Factor Receptor-2 - metabolism
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2013.08.021

Knowledge of the energetic parameters of transmembrane helix–helix interactions is necessary for the establishment of a structure–energy relationship for α-helical membrane domains. A number of techniques have been developed to measure the free energies of dimerization and oligomerization of transmembrane α-helices, and all of these have their advantages and drawbacks. In this study we propose a methodology to determine the magnitudes of the free energy of interactions between transmembrane helices in detergent micelles. The suggested approach employs solution nuclear magnetic resonance (NMR) spectroscopy to determine the population of the oligomeric states of the transmembrane domains and introduces a new formalism to describe the oligomerization equilibrium, which is based on the assumption that both the dimerization of the transmembrane domains and the dissociation of the dimer can occur only upon the collision of detergent micelles. The technique has three major advantages compared with other existing approaches: it may be used to analyze both weak and relatively strong dimerization/oligomerization processes, it works well for the analysis of complex equilibria, e.g. when monomer, dimer and high-order oligomer populations are simultaneously present in the solution, and it can simultaneously yield both structural and energetic characteristics of the helix–helix interaction under study. The proposed methodology was applied to investigate the oligomerization process of transmembrane domains of fibroblast growth factor receptor 3 (FGFR3) and vascular endothelium growth factor receptor 2 (VEGFR2), and allowed the measurement of the free energy of dimerization of both of these objects. In addition the proposed method was able to describe the multi-state oligomerization process of the VEGFR2 transmembrane domain. [Display omitted] •Oligomerization of transmembrane helices in detergent micelles was studied.•NMR spectroscopy was used to determine the populations of oligomeric states.•New model to calculate the free energy from state populations was presented.•Model was tested on the membrane domains of VEGFR2 and FGFR3 receptors.•The applicability of the technique to weak and strong dimers/oligomers was shown.