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Antiamoebin can function as a carrier or as a pore-forming peptaibol
H Duclohier1, C F Snook, B A Wallace
1UMR 6522 CNRS-Université de Rouen (IFRMP 23), Boulevard M. de Broglie, 76821 Mont-Saint-Aignan, France. Herve.Duclohier@univ-rouen.fr
Abstract:
Antiamoebin is a 16-residue polypeptide whose crystal structure and lytic activity in membrane vesicles have recently been reported. It is a bent helical molecule and a member of the peptaibol family of antibiotics. Under conditions which produce voltage-dependent conductance activity by other members of the family, no single-channel conductance was detected for antiamoebin, and a carrier-like mechanism was put forward to account for its mode of action. We now present evidence for pore formation that is largely voltage-insensitive, with large amplitude single-channel events on top of a background conductance that may account for the previously proposed carrier-like activity. Thus, antiamoebin may be the first instance of a peptide which can function both as an ion carrier and a pore former.
Insights
Antiamoebin, a peptaibol antibiotic, forms voltage-insensitive pores and exhibits background conductance, suggesting a dual mechanism. This peptide may act as both an ion carrier and a pore former.
Area of Science:
- Biochemistry
- Molecular Biology
- Biophysics
Background:
- Antiamoebin is a 16-residue helical polypeptide antibiotic belonging to the peptaibol family.
- Previous studies reported its crystal structure and lytic activity, suggesting a carrier-like mechanism due to lack of voltage-dependent conductance.
Purpose of the Study:
- To investigate the mechanism of action of antiamoebin in membrane vesicles.
- To determine if antiamoebin forms ion channels or acts solely as a carrier.
Main Methods:
- Electrophysiological recordings of membrane vesicles treated with antiamoebin.
- Analysis of single-channel conductance events and background conductance.
Main Results:
- Evidence for largely voltage-insensitive pore formation by antiamoebin was observed.
- Large amplitude single-channel events were detected on top of a background conductance.
- The background conductance may explain the previously proposed carrier-like activity.
Conclusions:
- Antiamoebin exhibits pore-forming activity that is largely independent of voltage.
- This peptide may represent the first instance of a molecule functioning as both an ion carrier and a pore former.
- Antiamoebin's dual mechanism offers new insights into peptaibol antibiotic function.