Lipid membranes from halophilic and alkali-halophilic Archaea have a low H+ and Na+ permeability at high salt concentration.
The influence of pH and the salt concentration on the proton and sodium ion permeability of liposomes formed from lipids of the halophile Halobacterium salinarum and the haloalkaliphile Halorubrum vacuolatum were studied. In contrast with liposomes formed from Escherichia coli lipids, liposomes formed from halophilic lipids remained stable up to 4M of NaCl and KCl. The proton permeability of the liposomes from lipids of halophiles was independent of the salt concentration and was essentially constant between pH 7 and pH 9. The sodium ion permeability increased with the salt concentration but was 10- to 100 fold lower than the proton permeability. It is concluded that the membranes of halophiles are stable over a wide range of salt concentrations and at elevated pH values and are well adapted to the halophilic conditions.
van de Vossenberg
J L
JL
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
Driessen
A J
AJ
Grant
W D
WD
Konings
W N
WN
D001105:Archaea / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology*; D002463:Cell Membrane Permeability; D004926:Escherichia coli / Q000502:physiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008563:Membrane Lipids / Q000502:physiology*; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D011522:Protons; D012964:Sodium / Q000378:metabolism*
D008563:Membrane Lipids; D011522:Protons; D012964:Sodium; D011188:Potassium