Thermal Response of Inner and Outer Transmembrane Segments of Cora Protein by a Coarse-Grain Monte Carlo Simulation

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Physics and Astronomy


Inner (i.corA) and outer (o.corA) transmembrane (TM) components of CorA protein perform specific functions in transport of Mg2+ across the ion channels. The monomer protein (with 351 residues) consists of its outer (o.corA, residues 1-290) and an inner (i.corA, residues 291-351) segments that form the pore. We investigated the structure and dynamics of CorA protein and its inner (i.corA) and outer (o.corA) TM components as a function of temperature by a coarse-grained Monte Carlo simulation in an implicit solvent. We found that the thermal response of i.corA differed considerably from that of the outer component o.corA. Analysis of the radius of gyration revealed that the inner TM component underwent a continuous transition from a globular conformation to a random coil structure on raising the temperature. In contrast, the outer transmembrane component exhibited an abrupt (almost discontinuous) thermal response in a narrow range of temperature. Scaling of the structure factor showed a globular structure of i.corA at low temperature with an effective dimension D ∼ 3 and random coil at high temperature with D ∼ 2. The residue distribution in o.corA is slightly sparser than that of i.corA in a narrow thermos-responsive regime. The difference in thermo-response characteristics of these components (i.corA, o.corA) may reflect their unique transmembrane functions. Attempts are being made to incorporate such realistic features as explicit solvent and membrane; corresponding results may also be presented as data become available.

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Biophysical Journal




3, Supplement 1

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