A gate mechanism indicated in the selectivity filter of the potassium channel KscA |
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Authors: | J Kóňa M Minozzi V Torre P Carloni |
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Institution: | (1) International School for Advanced Studies (SISSA), Via Beirut 4, 34014 Trieste, Italy |
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Abstract: | Classical molecular dynamics (MD) and non-equilibrium steered molecular dynamics (SMD) simulations were performed on the molecular
structure of the potassium channel KcsA using the GROMOS 87 force fields. Our simulations focused on mechanistic and dynamic
properties of the permeation of potassium ions through the selectivity filter of the channel. According to the SMD simulations
a concerted movement of ions inside the selectivity filter from the cavity to extracellular side depends on the conformation
of the peptide linkage between Val76 and Gly77 residues in one subunit of the channel. In SMD simulations, if the carbonyl
oxygen of Val76 is positioned toward the ion bound at the S3 site (gate-opened conformation) the net flux of ions through
the filter is observed. When the carbonyl oxygen leaped out from the filter (gate-closed conformation), ions were blocked
at the S3 site and no flux occurred. A reorientation of the Thr75-Val76 linkage indicated by the CHARMM-based MD simulations
performed Berneche and Roux (2005) Structure 13:591–600; (2000) Biophys J 78:2900–2917] as a concomitant process of the Val76-Gly77
conformational interconversion was not observed in our GROMOS-based MD simulations. |
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Keywords: | Channels Ion transport Molecular dynamics simulations Computer modeling GROMOS |
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