Conformational Ensembles from Experimental Data and Computer Simulations

Conformational Ensembles from Experimental Data and Computer Simulations

Poster Abstracts

105-POS Board 25 Critical Behaviors of Structural Fluctuations in the Native States of Proteins Wang Wei 1,2,3 , Qian-Yuan Tang 1 , Yang-Yang Zhang 1 , Jun Wang 1,2,3 , Dante Chialvo 4 . 1 Nanjing University, Nanjing, China, 2 National Lab of Solid State Microstructure, Nanjing, China, 3 Collaborative Innovation Center of Advanced Microstructures, Nanjing, China, 4 Universidad Nacional de San Martin, Buenos Aires, Argentina. The three-dimensional folded structures of proteins, known as native states, make proteins capable of performing related biological functions. To achieve such performance, the structure of the native state of a protein must be susceptible enough to sense the signal and switch to another structure, but also be stable enough to warrant functional specificity and structural robustness. This means a coexistence of high susceptibility and stability for the protein around its native state, which is apparently competing since high susceptibility implies large fluctuations and thus small stability in general, and vice versa. Does the balance of such competition result in a certain kind of critical behavior in proteins? Based on protein structural ensembles determined by NMR, we study the position fluctuations of residues by calculating distance-dependent correlations and conducting finite-size scaling analysis. The fluctuations exhibit high susceptibility and long- range correlations up to the protein sizes. The scaling relations between the correlations or susceptibility and protein sizes resemble those in other physical and biological systems near their critical points. These results indicate that, at the native states, motions of each residue are felt by every other one in the protein. We also find that proteins with larger susceptibility are more frequently observed in nature. Overall, our results suggest that the protein’s native state is critical.

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