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.
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Abbreviations
- Alm:
-
Alamethicin
- Zrv:
-
Zervamicin
- CFP:
-
Channel forming peptide
- Aib:
-
α-aminoisobutyric acid
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Correspondence to: M. S. P. Sansom
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Balaram, P., Krishna, K., Sukumar, M. et al. The properties of ion channels formed by zervamicins. Eur Biophys J 21, 117–128 (1992). https://doi.org/10.1007/BF00185426
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DOI: https://doi.org/10.1007/BF00185426