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Molecular dynamics simulation of the antiamoebin ion channel: linking structure and conductance

Wilson, M. and Wei, C. and Bjelkmar, P. and Wallace, Bonnie A. and Pohorille, A. (2011) Molecular dynamics simulation of the antiamoebin ion channel: linking structure and conductance. Biophysical Journal 100 (10), pp. 2394-2402. ISSN 0006-3495.

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Official URL: http://dx.doi.org/10.1016/j.bpj.2011.03.054

Abstract

Molecular-dynamics simulations were carried out to ascertain which of the potential multimeric forms of the transmembrane peptaibol channel, antiamoebin, is consistent with its measured conductance. Estimates of the conductance obtained through counting ions that cross the channel and by solving the Nernst-Planck equation yield consistent results, indicating that the motion of ions inside the channel can be satisfactorily described as diffusive. The calculated conductance of octameric channels is markedly higher than the conductance measured in single channel recordings, whereas the tetramer appears to be nonconducting. The conductance of the hexamer was estimated to be 115 ± 34 pS and 74 ± 20 pS, at 150 mV and 75 mV, respectively, in satisfactory agreement with the value of 90 pS measured at 75 mV. On this basis, we propose that the antiamoebin channel consists of six monomers. Its pore is large enough to accommodate K+ and Cl− with their first solvation shells intact. The free energy barrier encountered by K+ is only 2.2 kcal/mol whereas Cl− encounters a substantially higher barrier of nearly 5 kcal/mol. This difference makes the channel selective for cations. Ion crossing events are shown to be uncorrelated and follow Poisson statistics.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 18 May 2011 11:03
Last Modified: 17 Apr 2013 12:20
URI: http://eprints.bbk.ac.uk/id/eprint/3285

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