The properties of ion channels formed by zervamicins |
| |
Authors: | P Balaram K Krishna M Sukumar I R Mellor Mark S P Sansom |
| |
Institution: | (1) Molecular Biophysics Unit, Indian Institute of Science, 560 012 Bangalore, India;(2) Department of Life Science, University of Nottingham, University Park, NG7 2RD Nottingham, UK;(3) Laboratory of Molecular Biophysics, The Rex Richards Building, University of Oxford, South Parks Road, OX1 3QU Oxford, UK |
| |
Abstract: | The zervamicins (Zrv) are a family of 16 residue peptaibol channel formers, related to the 20 residue peptaibol alamethicin (Alm), but containing a higher proportion of polar sidechains. Zrv-1113 forms multi-level channels in planar lipid (diphytanoyl phosphatidylcholine) bilayers in response to cis positive voltages. Analysis of the voltage and concentration dependence of macroscopic conductances induced by Zrv-IIB suggests that, on average, channels contain ca. 13 peptide monomers. Analysis of single channel conductance levels suggests a similar value. The pattern of successive conductance levels is consistent with a modified helix bundle model in which the higher order bundle are distorted within the plane of the bilayer towards a torpedo shaped cross-section. The kinetics of intro-burst switching between adjacent conductance levels are shown to be approximately an order of magnitude faster for Zrv-IIB than for Alm. The channel forming properties of the related naturally occurring peptaibols, Zrv-Leu and Zrv-IC, have also been demonstrated, as have those of the synthetic apolar analogue Zrv-Al-16. The experimental studies on channel formation are combined with the known crystallographic structures of Zrv-Al-16 and Zrv-Leu to develop a molecular model of Zrv-II3 channels.Abbreviations Alm
Alamethicin
- Zrv
Zervamicin
- CFP
Channel forming peptide
- Aib
-aminoisobutyric acid
Correspondence to: M. S. P. Sansom |
| |
Keywords: | Ion channel Peptaibol Channel forming peptide Planar bilayer |
本文献已被 SpringerLink 等数据库收录! |
|