25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Global and local parameters to characterize peptide-membrane mimetics interaction

Not scheduled
4h
Harnack House and Henry Ford Building

Harnack House and Henry Ford Building

Board: 425
Poster Posters

Speaker

Ms Fanni Sebák (Institute of Chemistry, Eötvös Loránd University)

Description

Understanding the physico-chemical basics of protein-membrane interactions are of key importance in functional characterization of the cell membrane. In order to simplify this complex system the best membrane mimetics are bicelles, which at q=0.5 (long chain/short chain lipid) ratio are ideal for solution state NMR studies1,2.
We chose biologically relevant protein fragments: the lysine-rich segments of the plant stress protein ERD14 and the C-terminal domain of a small Ca2+-binding, metastasis associated protein S100A4 to follow changes in size and morphology occurring upon interaction with neutral DHPC/DMPC and negatively charged DHPC/DMPC/DMPG bicelles under physiological conditions (pH=7.4; 150 mM NaCl).
Local environmental changes for both partners (typically 1mM/2mM unlabeled peptide and 150mM/300 mM lipids) were followed by 2D 1H-13C spectra, peptide amide environment using 1H-15N HSQC spectra, lipid phosphate headgroup environment by 31P NMR.
Translational diffusion experiments enable determination of the diffusion coefficient D that permits calculation of an effective hydration radius rH. SAXS measurements were performed on the same sample under the same experimental conditions. Fitting of a lentil core-shell model (with axis a,b,ta,tb) on the scattering curve enables a shape prediction and determination of gyration radius rG.
For all studied systems significant line broadening of the DMPC peak in the 31P spectra was detected upon peptide interaction; while peptide HN resonances shifted or broadened below detection limit. Diffusion coefficients were the same for the bicelle (followed on the DMPC methyl group) and for the peptide, showing that a peptide-bicelle complex was formed. Corresponding changes in rH and b axis parameters enable elucidation of morphology variation. The structural changes of peptides were also followed by CD spectroscopy

1Vold et al. J. Biomol. NMR 9 (1997) 329–335
2Bodor et al.Biochim. Biophys. Acta 1848 (2015) 760–766

Primary authors

Ms Fanni Sebák (Institute of Chemistry, Eötvös Loránd University) Ms Erika F. Dudás (Institute of Chemistry, Eötvös Loránd University) András Wacha (Research Centre for Natural Sciences, Hungarian Academy of Sciences) Dr Attila Bóta (Research Centre for Natural Sciences, Hungarian Academy of Sciences) Dr Andrea Bodor (Institute of Chemistry, Eötvös Loránd UniversityEötvös Loránd University)

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