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Published on: February 21, 2019
Surfactin activity depends on the membrane dipole potential
Olga S Ostroumova1, Valery V Malev, Maxim G Ilin
1Institute of Cytology of the Russian Academy of Sciences, St. Petersburg 194064, Russia. ostroumova@mail.cytspb.rssi.ru
Altering membrane dipole potential with agents like phloretin and RH 421 modifies surfactin-induced membrane channels. This suggests dipole potential influences surfactin
Area of Science:
- Biophysics
- Membrane Biophysics
- Lipid Bilayer Studies
Background:
- Surfactin, a lipopeptide antibiotic from Bacillus subtilis, forms voltage-independent channels in lipid bilayers.
- These surfactin-induced channels exhibit varying conductance levels and selectivity based on pore size.
Purpose of the Study:
- To investigate the impact of membrane dipole potential on surfactin-induced channel activity.
- To elucidate the role of dipole modifying agents (phloretin and RH 421) in modulating membrane conductance.
Main Methods:
- Utilized diphytanoylphosphocholine lipid bilayers in 1 M KCl.
- Incorporated dipole modifying agents phloretin (decreases dipole potential) and RH 421 (increases dipole potential).
- Measured membrane conductance changes induced by surfactin under varying dipole potential conditions.
Main Results:
- Phloretin decreased surfactin-induced membrane conductance.
- RH 421 increased surfactin-induced membrane conductance, number of open channels, and channel conductance.
- Large surfactin channels showed reduced K(+)/Cl(-) selectivity compared to small channels.
Conclusions:
- Membrane dipole potential significantly influences surfactin channel formation and activity.
- Changes in lipopeptide partitioning between lipid and aqueous phases may explain the observed effects.
- Dipole potential modulation offers a mechanism to control membrane channel properties.
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