Energy-transducing properties of primary proton pumps reconstituted into archaeal bipolar lipid vesicles.
Archaeal lipids differ considerably from eubacterial and eukaryotic lipids in their structure and physical properties. From the membranes of the extreme thermophilic archaea Sulfolobus acidocaldarius a tetraether lipid fraction was isolated, which can form closed and stable monolayer liposomes in aqueous media. The function of three different primary proton pumps originating from archaeal, bacterial and eukaryotic lipid sources have been studied after reconstitution in these liposomes: bacteriorhodopsin from the archaea Halobacterium halobium; cytochrome-c oxidase from the thermophilic bacterium Bacillus stearothermophilus and cytochrome-c oxidase from beef heart mitochondria. Liposomes composed of tetraether lipids form a competent matrix for all three exogenous proton pumps. Bacteriorhodopsin was inserted inside-out in these liposomes, as normally observed in bilayer-forming lipid. The activities of the two oxidases were inhibited at high tetraether-lipid concentration, probably due to the low fluidity of these membranes. Only bacteriorhodopsin, which originates from diether archaeal lipids is fully functional in the tetraether membranes.
Department of Microbiology, University of Groningen, Haren, The Netherlands.
M G
MG
Elferink
J G
JG
De Wit
A J
AJ
Driessen
W N
WN
Konings
D001436:Bacteriorhodopsins / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D001411:Geobacillus stearothermophilus / Q000378:metabolism; D019617:Halobacterium salinarum / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D008055:Lipids / Q000494:pharmacology*; D008560:Membrane Fluidity; D009206:Myocardium / Q000201:enzymology; D011510:Proteolipids; D017494:Proton Pumps / Q000187:drug effects* / Q000502:physiology*; D016945:Sulfolobus acidocaldarius / Q000737:chemistry*; D014475:Uncoupling Agents / Q000494:pharmacology
D007476:Ionophores; D008055:Lipids; D011510:Proteolipids; D017494:Proton Pumps; D014475:Uncoupling Agents; C020485:proteoliposomes; D001436:Bacteriorhodopsins; D003576:Electron Transport Complex IV