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Ion transport and osmotic adjustment in Escherichia coli in response to ionic and non-ionic osmotica
journal contribution
posted on 2023-05-16, 22:16 authored by Svetlana ShabalaSvetlana Shabala, John BowmanJohn Bowman, Janelle BrownJanelle Brown, Thomas RossThomas Ross, Thomas McMeekinThomas McMeekin, Sergey ShabalaSergey ShabalaBacteria respond to osmotic stress by a substantial increase in the intracellular osmolality, adjusting their cell turgor for altered growth conditions. Using Escherichia coli as a model organism we demonstrate here that bacterial responses to hyperosmotic stress specifically depend on the nature of osmoticum used. We show that increasing acute hyperosmotic NaCl stress above ∼1.0 Os kg-1 causes a dose-dependent K+ leak from the cell, resulting in a substantial decrease in cytosolic K+ content and a concurrent accumulation of Na+ in the cell. At the same time, isotonic sucrose or mannitol treatment (non-ionic osmotica) results in a gradual increase of the net K+ uptake. Ion flux data are consistent with growth experiments showing that bacterial growth is impaired by NaCl at the concentration resulting in a switch from net K+ uptake to efflux. Microarray experiments reveal that about 40% of upregulated genes shared no similarity in their responses to NaCl and sucrose treatment, further suggesting specificity of osmotic adjustment in E. coli to ionic and non-ionic osmotica. The observed differences are explained by the specificity of the stress-induced changes in the membrane potential of bacterial cells highlighting the importance of voltage-gated K+ transporters for bacterial adaptation to hyperosmotic stress. © 2008 The Authors.
History
Publication title
Environmental MicrobiologyVolume
11Pagination
137-148ISSN
1462-2912Department/School
Tasmanian Institute of Agriculture (TIA)Publisher
Blackwell Publishing LtdPlace of publication
United KingdomRepository Status
- Restricted