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Zinc ions block H + /OH ‐ channels in Chara australis
Author(s) -
AL KHAZAALY SABAH,
BEILBY MARY J.
Publication year - 2012
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02496.x
Subject(s) - chara , conductance , zinc , saline , chemistry , membrane , ion , biophysics , ion transporter , membrane potential , biochemistry , botany , biology , physics , endocrinology , organic chemistry , condensed matter physics
Chara australis cells exposed to media of pH 10 and above exhibit high conductance, arising from the opening of H + /OH ‐ channels in the plasma membrane. This high conductance can be totally inhibited by 1.0 m m ZnCl 2 and restored by 0.5 m m 2‐mercaptoethanol (ME). Important for carbon fixation, H + /OH ‐ channels play a key role in cell pH banding. Banding was also shown to be abolished by 1.0 m m ZnCl 2 and restored in some cells by ME. The proton pump is also involved in banding, but was little affected by ZnCl 2 over the periods needed for the inhibition of H + /OH ‐ channels. Previously, we postulated that H + /OH ‐ channels open transiently at the onset of saline stress in salt‐sensitive C. australis, causing membrane potential difference (PD) noise; and remain open in latter stages of saline stress, contributing to cell deterioration. ZnCl 2 totally inhibited the saline noise and the upwardly concave I/V characteristics associated with the putative H + /OH ‐ currents. Again, ME reversed both these effects. We discuss the mode of action of zinc ions and ME with reference to animal voltage‐gated H + channels and water channels.