• Alamethicin

    Alamethicin single channel conductances, measured on the Port-a-Patch. Recordings from a GUV prepared bilayer

Alamethicin

Family:
Non-ribosomally Synthesized Channels

Description:
Proteins belonging to this family form oligomeric trans-membrane channels. Voltage may induce channel formation by promoting assembly of the oligomeric pore-forming structure. These "depsipeptides" are often made by bacteria and fungi and are used as agents of biological warfare. Other substances, completely lacking amino acids, may also be involved in channel formation

Subgroups:
Over 100 subgroups belong to the "Non-ribosomally Synthesized Channels" family, including amongst others:
The Gramicidin A (Gramicidin A) Channel Family
The Alamethicin or Peptaibol Antibiotic Channel-forming (Alamethicin) Family 
The Saponin (Saponin) Family
The Ceramide-forming Channel (Ceramide) Family

Alamethicin Background Information


Overview:

Alamethicin was the first isolated and is the best characterized member of the peptaibol class of natural linear depsipeptide antibiotics. It is a channel-forming peptide, produced by the fungus Trichoderma viride. As a member of the peptaibol peptide family, it contains the non-proteinogenic amino acid residue Aib (2-aminoisobutyric acid). It adopts helical secondary monomeric and dimeric helix-bend-helix structures that self assemble in membranes into ion conducting helix bundles.


Data Sheet:

Topology:
Chemically, the peptaibol Alamethicin is a peptide of 20 amino acids and forms a alpha-helical structure. In cell membranes, it forms voltage-dependent ion channels by aggregation of four to six molecules.

Channel Function:
Peptaibol compounds are characterized by acetylated N-termini, a high percentage of α-amino-isobutyrate (AIB), and a C-terminal amino alcohol. Most contain 18-20 residues. Because of their high proportion of AIB, they form α-helical structures. Voltage causes them to autoassociate to form ion channels. The alamethicin pore is of the barrel-stave type consisting of eight alamethicin helices. The channels formed conduct ions in a non-saturable fashion, suggesting that transport occurs in a diffusional process without ion binding at discrete sites in the channel. The channels are mildly cation-selective.

Sequence:
Ac-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phe-ol

Assays:
Bilayer Recordings on the Orbit Product family or on the Port-a-Patch

Reviews and Links

Data and Applications

Alamethicin - Parallel recordings

Alamethicin IoneraIcon Orbit   Orbit 16 data and applications: 
Data courtesy of Dr. Gerhard Baaken, University of Freiburg / Ionera.

The data image shows parallel recordings from reconstituted alamethicin channels. See also the paper: "Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR", Salnikov et al. (2016) Biophysical Journal 111(11): 2450-2459.

Alamethicin - Bilayer Recordings

application alameticin 2icon pap   Port-a-Patch and   icon vpp   Vesicle Prep Pro data and applications:
Data were kindly provided by M. Sondermann/Prof. Behrends, Univ. Freiburg.

Alamethicin is a channel forming peptide and, when patch clamped, reveals multiple non-equidistant conductance levels due to formation of alamethicin oligomers in the bilayer. Alamethicin single channel conductances. Recordings from a GUV prepared bilayer in 85 mM KCl at -140 mV.

Publications

2016 - Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR

Icon Orbit  Orbit 16 publication in Biophysical Journal (2016)

Authors: 
Salnikov E.S., Raya J., De Zotti M., Zaitseva E., Peggion C., Ballano G., Toniolo C., Raap J., Bechinger B.

2012 - Natural and artificial ion channels for biosensing platforms

icon pap   Port-a-Patch,   icon pl   Patchliner,   icon sp96   SyncroPatch 96 ((a predecessor model of SyncroPatch 384PE) and   icon vpp   Vesicle Prep Pro publication in Analytical and Bioanalytical Chemistry (2012)

Authors: 
Steller L., Kreir M., Salzer R.

2008 - Planar microelectrode-cavity array for high-resolution and parallel electrical recording of membrane ionic currents

Icon Orbit  Orbit 16 publication in Lab on a Chip (2008)

Authors:
Baaken G., Sondermann M., Schlemmer C., Rühe J., Behrends J.C.

2006 - High-resolution electrophysiology on a chip: Transient dynamics of alamethicin channel formation

icon pap  Port-a-Patch and   icon vpp   Vesicle Prep Pro publication in Biochimica et Biophysica Acta - Biomembranes (2006)

Authors: 
Sondermann M., George M., Fertig N., Behrends J.C.

 

 

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