Alamethicin

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

Recommended Reviews:

• Hancock et al. (1999) Peptide Antibiotics. Antimicrobial Agents and Chemotherapy. DOI: 10.1128/AAC.43.6.1317

Transporter classification database:

• 1.D.5 The Alamethicin or Peptaibol Antibiotic Channel-forming (Alamethicin) Family

PubChem:

• Alamethicin