Voltage clamp studies on S-layer-supported tetraether lipid membranes.
Isolated subunits from the cell surface proteins (S-layer) of Bacillus coagulans E38-66 have been recrystallized on a glycerol dialkyl nonitol tetraether lipid (GDNT)-monolayer and the electrophysical features of this biomimetic membrane have been investigated in comparison to unsupported GDNT-monolayers. The GDNT-monolayer, spread on a Langmuir-Blodgett trough, was clamped with the tip of a glass patch pipette. In order to investigate the barrier function and potential to incorporate functional molecules, voltage-clamp examinations on plain and S-layer-supported GDNT-monolayers were per-formed. Our results indicate the formation of a tight GDNT-monolayer sealing the tip of the glass pipette, and a decrease in conductance of the GDNT-monolayer upon recrystallization of the S-layer protein. Thus, the S-layer protein, apparently, did not penetrate or rupture the lipid monolayer. The valinomycin-mediated increase in conductance was less pronounced for the S-layer-supported than for the plain GDNT-monolayer, indicating differences in the accessibility and/or in the fluidity of the lipid membranes. Furthermore. in contrast to plain GDNT-monolayers. S-layer supported GDNT-monolayers with high valinomycin-mediated conductance persisted over long, periods of time, indicating enhanced stability. These composite S-layer/lipid films may constitute a new tool for electrophysical and electrophysiological studies on membrane-associated and membrane-integrated biomolecules.
Schuster
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Center for Ultrastructure Research, Universität für Bodenkultur Wien, Austria. sleytr@edvl.boku.ac.at
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Sleytr
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D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001407:Bacillus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D003460:Crystallization; D004075:Diglycerides; D004553:Electric Conductivity; D004563:Electrochemistry; D008563:Membrane Lipids / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D018408:Patch-Clamp Techniques; D014634:Valinomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004075:Diglycerides; D008563:Membrane Lipids; D008565:Membrane Proteins; C085775:glycerol dialkyl nonitol tetraethyl ether; D014634:Valinomycin