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Cation-permeable vacuolar ion channels in the moss Physcomitrella patens: a patch-clamp study
Mateusz Koselski1, Kazimierz Trebacz, Halina Dziubinska
1Department of Biophysics, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, Lublin, Poland. mateusz.koselski@poczta.umcs.lublin.pl
Planta
|May 30, 2013
Summary
This study identified two cation-selective ion channels in moss tonoplast: slowly activated (SV) channels and fast-activated potassium channels. SV channels transport monovalent and divalent cations, while fast channels are selective for potassium.
Area of Science:
- Plant Cell Physiology
- Ion Transport Mechanisms
- Membrane Biophysics
Background:
- The tonoplast, or vacuolar membrane, plays a crucial role in maintaining cellular homeostasis and ion gradients in plants.
- Understanding the ion channels present in the tonoplast is essential for elucidating plant physiological processes.
Purpose of the Study:
- To characterize the electrophysiological properties and ion selectivity of cation-selective channels in the tonoplast of the moss Physcomitrella patens.
- To investigate the regulation of these channels by calcium ions and their permeability to various cations.
Main Methods:
- Patch-clamp electrophysiology was employed on whole-vacuole and cytoplasm-out membrane patches of Physcomitrella patens.
- Experiments utilized symmetrical and asymmetrical ionic gradients (KCl, NaCl) and varying calcium concentrations.
Main Results:
- Two types of cation-selective channels were identified: slowly activated (SV) channels and fast-activated potassium-selective channels.
- SV channels exhibited permeability to K+, Na+, Ca2+, and Mg2+, with transport direction from cytoplasm to vacuole. Cytoplasmic Ca2+ activated SV channels, while vacuolar Ca2+ inhibited them.
- Fast-activated channels were highly selective for K+ and their activity was modulated by cytoplasmic Ca2+.
Conclusions:
- Physcomitrella patens tonoplast possesses distinct SV and fast-activated K+ channels with different ion permeabilities and regulatory mechanisms.
- These findings contribute to the understanding of vacuolar ion transport in plants and highlight the role of calcium in channel modulation.
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In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
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