Water and potassium dynamics inside the KcsA K(+) channel.
Molecular dynamics simulations and electrostatic modeling are used to investigate structural and dynamical properties of the potassium ions and of water molecules inside the KcsA channel immersed in a membrane-mimetic environment. Two potassium ions, initially located in the selectivity filter binding sites, maintain their position during 2 ns of dynamics. A third potassium ion is very mobile in the water-filled cavity. The protein appears engineered so as to polarize water molecules inside the channel cavity. The resulting water induced dipole and the positively charged potassium ion within the cavity are the key ingredients for stabilizing the two K(+) ions in the binding sites. These two ions experience single file movements upon removal of the potassium in the cavity, confirming the role of the latter in ion transport through the channel.
Guidoni
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L
Istituto Nazionale per la Fisica della Materia, Italy and International School for Advanced Studies, Via Beirut 4, 34014 Trieste, Italy.
Torre
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V
Carloni
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P
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002414:Cations, Monovalent / Q000378:metabolism; D003198:Computer Simulation; D008958:Models, Molecular; D009038:Motion; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D055672:Static Electricity; D013302:Streptomyces / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000378:metabolism*
D001426:Bacterial Proteins; D002414:Cations, Monovalent; D015221:Potassium Channels; C107790:prokaryotic potassium channel; D014867:Water; D011188:Potassium