Publication details

Dynamics of major urinary protein-pheromone interactions: Insight by NMR and MD simulations



Year of publication 2007
Type Article in Proceedings
Conference ISMAR 2007, Program and Abstracts
MU Faculty or unit

Faculty of Science

Field Biophysics
Keywords NMR; relaxation; protein-ligand interactions; internal dynamics; N-15; MD simulations;
Description Binding of mouse pheromones to major urinary proteins (MUPs) represents a typical example of interactions between lipocalins and their small hydrophobic ligands. Previously, based on the model-free analysis of 15N relaxation data, we observed that the backbone flexibility of MUP-I increased slightly upon pheromone binding, in contrast to the decreased flexibility expected for induced-fit interactions. To shed the light on this unusual observation, we have performed an independent study adopting different methodology. Backbone dynamics of mouse major urinary protein I (MUP-I) was studied by 15N NMR relaxation at multiple temperatures for a complex of MUP-I with its natural pheromonal ligand, 2-sec-4,5-dihydrothiazole, and for the free protein. Graphical analysis of the reduced spectral density values provided an unbiased qualitative picture of the internal motions. Quantitative parameters were obtained using a simultaneous data fitting at multiple temperatures to several models of different complexity. The relaxation data were complemented by the molecular dynamics simulations. Correlation functions and frequency-dependent order parameters were calculated from the simulated motions of the amide NH vectors. Comparison of the experimental and simulated order parameters and the information about slow conformational exchanges provided a picture of the molecular motions and offered a structural explanation for the observed difference in the dynamics of the free and bound MUP-I.
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