Polyamines cause plasma membrane depolarization, activate Ca²⁺-, and modulate H⁺-ATPase pump activity in pea roots
Date
2014
Authors
Pottosin, I.
Velarde-Buendía, A.
Bose, J.
Fuglsang, A.
Shabala, S.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Journal of Experimental Botany, 2014; 65(9):2463-2472
Statement of Responsibility
Igor Pottosin, Ana María Velarde-Buendía, Jayakumar Bose, Anja T. Fuglsang and Sergey Shabala
Conference Name
Abstract
Polyamines regulate a variety of cation and K⁺ channels, but their potential effects on cation-transporting ATPases are underexplored. In this work, noninvasive microelectrode ion flux estimation and conventional microelectrode techniques were applied to study the effects of polyamines on Ca²⁺ and H⁺ transport and membrane potential in pea roots. Externally applied spermine or putrescine (1mM) equally activated eosin yellow (EY)-sensitive Ca²⁺ pumping across the root epidermis and caused net H⁺ influx or efflux. Proton influx induced by spermine was suppressed by EY, supporting the mechanism in which Ca²⁺ pump imports 2 H⁺ per each exported Ca²⁺. Suppression of the Ca²⁺ pump by EY diminished putrescine-induced net H⁺ efflux instead of increasing it. Thus, activities of Ca²⁺ and H⁺ pumps were coupled, likely due to the H⁺-pump inhibition by intracellular Ca²⁺. Additionally, spermine but not putrescine caused a direct inhibition of H⁺ pumping in isolated plasma membrane vesicles. Spermine, spermidine, and putrescine (1mM) induced membrane depolarization by 70, 50, and 35 mV, respectively. Spermine-induced depolarization was abolished by cation transport blocker Gd³⁺, was insensitive to anion channels' blocker niflumate, and was dependent on external Ca²⁺. Further analysis showed that uptake of polyamines but not polyamine-induced cationic (K⁺+Ca²⁺+H⁺ fluxes were a main cause of membrane depolarization. Polyamine increase is a common component of plant stress responses. Activation of Ca²⁺ efflux by polyamines and contrasting effects of polyamines on net H⁺ fluxes and membrane potential can contribute to Ca²⁺ signalling and modulate a variety of transport processes across the plasma membrane under stress.
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Dissertation Note
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Description
Advance Access publication 10 April, 2014
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Rights
© The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.