On the interaction of neomycin with the slow vacuolar channel of Arabidopsis thaliana

This study investigates the interaction of the aminoglycoside antibiotic neomycin with the slow vacuolar (SV) channel in vacuoles from Arabidopsis thaliana mesophyll cells. Patch-clamp experiments in the excised patch configuration revealed a complex pattern of neomycin effects on the channel: appli...

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Bibliographic Details
Published in:The Journal of general physiology 2006-03, Vol.127 (3), p.329-340
Main Authors: Scholz-Starke, Joachim, Carpaneto, Armando, Gambale, Franco
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents - administration & dosage
Antibiotics
Arabidopsis - drug effects
Arabidopsis - metabolism
Biochemistry
Cations - metabolism
Cells, Cultured
Cellular biology
Dose-Response Relationship, Drug
Flowers & plants
Ion Channel Gating
Ion Channels - drug effects
Ion Channels - physiology
Membrane Potentials - drug effects
Membrane Potentials - physiology
Neomycin - administration & dosage
Signal transduction
Vacuoles - drug effects
Vacuoles - metabolism
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Summary:This study investigates the interaction of the aminoglycoside antibiotic neomycin with the slow vacuolar (SV) channel in vacuoles from Arabidopsis thaliana mesophyll cells. Patch-clamp experiments in the excised patch configuration revealed a complex pattern of neomycin effects on the channel: applied at concentrations in the submicromolar to millimolar range neomycin (a) blocked macroscopic SV currents in a voltage- and concentration-dependent manner, (b) slowed down activation and deactivation kinetics of the channel, and most interestingly, (c) at concentrations above 10 muM, neomycin shifted the SV activation threshold towards negative membrane potentials, causing a two-phasic activation at high concentrations. Single channel experiments showed that neomycin causes these macroscopic effects by combining a decrease of the single channel conductance with a concomitant increase of the channel's open probability. Our results clearly demonstrate that the SV channel can be activated at physiologically relevant tonoplast potentials in the presence of an organic effector molecule. We therefore propose the existence of a cellular equivalent regulating the activity of the SV channel in vivo.
ISSN:0022-1295
1540-7748
DOI:10.1085/jgp.200509402