Vol 9: The C-Terminal Random Coil Region Tunes the Ca2 -Binding Affinity of S100A4 through Conformational Activation.Reportar como inadecuado



 Vol 9: The C-Terminal Random Coil Region Tunes the Ca2 -Binding Affinity of S100A4 through Conformational Activation.


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This article is from PLoS ONE, volume 9.AbstractS100A4 interacts with many binding partners upon Ca2+ activation and is strongly associated with increased metastasis formation. In order to understand the role of the C-terminal random coil for the protein function we examined how small angle X-ray scattering of the wild-type S100A4 and its C-terminal deletion mutant residues 1–88, Δ13 changes upon Ca2+ binding. We found that the scattering intensity of wild-type S100A4 changes substantially in the 0.15–0.25 Å−1 q-range whereas a similar change is not visible in the C-terminus deleted mutant. Ensemble optimization SAXS modeling indicates that the entire C-terminus is extended when Ca2+ is bound. Pulsed field gradient NMR measurements provide further support as the hydrodynamic radius in the wild-type protein increases upon Ca2+ binding while the radius of Δ13 mutant does not change. Molecular dynamics simulations provide a rational explanation of the structural transition: the positively charged C-terminal residues associate with the negatively charged residues of the Ca2+-free EF-hands and these interactions loosen up considerably upon Ca2+-binding. As a consequence the Δ13 mutant has increased Ca2+ affinity and is constantly loaded at Ca2+ concentration ranges typically present in cells. The activation of the entire C-terminal random coil may play a role in mediating interaction with selected partner proteins of S100A4.



Autor: Duelli, Annette; Kiss, Bence; Lundholm, Ida; Bodor, Andrea; Petoukhov, Maxim V.; Svergun, Dmitri I.; Nyitray, Laszlo; Katona, Gergely

Fuente: https://archive.org/







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