Using the perturbation-response scanning (PRS) technique, we study a set of 23 proteins that disp... more Using the perturbation-response scanning (PRS) technique, we study a set of 23 proteins that display a variety of conformational motions upon ligand binding (e.g. shear, hinge, allosteric). In most cases, PRS determines residues that may be manipulated to achieve the resulting conformational change. PRS reveals that for some proteins, binding induced conformational change may be achieved through the perturbation of residues scattered throughout the protein, whereas in others, perturbation of specific residues confined to a highly specific region are necessary. Correlations between the experimental and calculated atomic displacements are always better or equivalent to those obtained from a modal analysis of elastic network models. Furthermore, best correlations obtained by the latter approach do not always appear in the most collective modes. We show that success of the modal analysis depends on the lack of redundant paths that exist in the protein. PRS thus demonstrates that several relevant modes may simultaneously be induced by perturbing a single select residue on the protein. We also illustrate the biological relevance of applying PRS on the GroEL and ADK structures in detail, where we show that the residues whose perturbation lead to the precise conformational changes usually correspond to those experimentally determined to be functionally important.
The dynamics of a folded protein is studied in water and glycerol at a series of temperatures bel... more The dynamics of a folded protein is studied in water and glycerol at a series of temperatures below and above their respective dynamical transition. The system is modeled in two distinct states whereby the protein is decoupled from the bulk solvent at low temperatures, and communicates with it through a vicinal layer at physiological temperatures. A linear viscoelastic model elucidates the less-than-expected increase in the relaxation times observed in the backbone dynamics of the protein. The model further explains the increase in the flexibility of the protein once the transition takes place and the differences in the flexibility under the different solvent environments. Coupling between the vicinal layer and the protein fluctuations is necessary to interpret these observations. The vicinal layer is postulated to form once a threshold for the volumetric fluctuations in the protein to accommodate solvents of different sizes is reached. Compensation of entropic-energetic contributions from the protein-coupled vicinal layer quantifies the scaling of the dynamical transition temperatures in various solvents. The protein adapts different conformational routes for organizing the required coupling to a specific solvent, which is achieved by adjusting the amount of conformational jumps in the surface-group dihedrals.
Using the perturbation-response scanning (PRS) technique, we study a set of 23 proteins that disp... more Using the perturbation-response scanning (PRS) technique, we study a set of 23 proteins that display a variety of conformational motions upon ligand binding (e.g. shear, hinge, allosteric). In most cases, PRS determines residues that may be manipulated to achieve the resulting conformational change. PRS reveals that for some proteins, binding induced conformational change may be achieved through the perturbation of residues scattered throughout the protein, whereas in others, perturbation of specific residues confined to a highly specific region are necessary. Correlations between the experimental and calculated atomic displacements are always better or equivalent to those obtained from a modal analysis of elastic network models. Furthermore, best correlations obtained by the latter approach do not always appear in the most collective modes. We show that success of the modal analysis depends on the lack of redundant paths that exist in the protein. PRS thus demonstrates that several relevant modes may simultaneously be induced by perturbing a single select residue on the protein. We also illustrate the biological relevance of applying PRS on the GroEL and ADK structures in detail, where we show that the residues whose perturbation lead to the precise conformational changes usually correspond to those experimentally determined to be functionally important.
The dynamics of a folded protein is studied in water and glycerol at a series of temperatures bel... more The dynamics of a folded protein is studied in water and glycerol at a series of temperatures below and above their respective dynamical transition. The system is modeled in two distinct states whereby the protein is decoupled from the bulk solvent at low temperatures, and communicates with it through a vicinal layer at physiological temperatures. A linear viscoelastic model elucidates the less-than-expected increase in the relaxation times observed in the backbone dynamics of the protein. The model further explains the increase in the flexibility of the protein once the transition takes place and the differences in the flexibility under the different solvent environments. Coupling between the vicinal layer and the protein fluctuations is necessary to interpret these observations. The vicinal layer is postulated to form once a threshold for the volumetric fluctuations in the protein to accommodate solvents of different sizes is reached. Compensation of entropic-energetic contributions from the protein-coupled vicinal layer quantifies the scaling of the dynamical transition temperatures in various solvents. The protein adapts different conformational routes for organizing the required coupling to a specific solvent, which is achieved by adjusting the amount of conformational jumps in the surface-group dihedrals.
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