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Role of a Mitogen-Activated Protein Kinase Cascade in Ion Flux-Mediated Turgor Regulation in Fungi


Lew, RR and Levina, NN and Shabala, L and Anderca, MI and Shabala, SN, Role of a Mitogen-Activated Protein Kinase Cascade in Ion Flux-Mediated Turgor Regulation in Fungi, Eukaryotic Cell, 5, (3) pp. 480-487. ISSN 1535-9778 (2006) [Refereed Article]

DOI: doi:10.1128/EC.5.3.480-487.2006


Fungi normally maintain a high internal hydrostatic pressure (turgor) of about 500 kPa. In response to hyperosmotic shock, there are immediate electrical changes: a transient depolarization (1 to 2 min) followed by a sustained hyperpolarization (5 to 10 min) prior to turgor recovery (10 to 60 min). Using ion-selective vibrating probes, we established that the transient depolarization is due to Ca2+ influx and the sustained hyperpolarization is due to H+ efflux by activation of the plasma membrane H+-ATPase. Protein synthesis is not required for H+-ATPase activation. Net K+ and Cl- uptake occurs at the same time as turgor recovery. The magnitude of the ion uptake is more than sufficient to account for the osmotic gradients required for turgor to return to its original level. Two osmotic mutants, os-1 and os-2, homologs of a two-component histidine kinase sensor and the yeast high osmotic glycerol mitogen-activated protein (MAP) kinase, respectively, have lower turgor than the wild type and do not exhibit the sustained hyperpolarization after hyperosmotic treatment. The os-1 mutant does not exhibit all of the wild-type turgor-adaptive ion fluxes (Cl- uptake increases, but net K+ flux barely changes and net H + efflux declines) (os-2 was not examined). Both os mutants are able to regulate turgor but at a lower level than the wild type. Our results demonstrate that a MAP kinase cascade regulates ion transport, activation of the H+-ATPase, and net K+ and Cl- uptake during turgor regulation. Other pathways regulating turgor must also exist. Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial ecology
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Food safety
UTAS Author:Shabala, L (Associate Professor Lana Shabala)
UTAS Author:Shabala, SN (Professor Sergey Shabala)
ID Code:36720
Year Published:2006
Web of Science® Times Cited:25
Deposited By:Agricultural Science
Deposited On:2006-08-01
Last Modified:2007-04-18

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