Cis/trans isomerisation of unsaturated fatty acids in a cardiolipin synthase knock-out mutant of Pseudomonas putida P8.
The gene encoding cardiolipin synthase ( cls) from the phenol-degrading bacterium Pseudomonas putida P8, which rapidly adapts its membrane lipids to the presence of organic solvents by cis/trans isomerisation of unsaturated fatty acids, was isolated and completely sequenced. The functionality of the predicted gene product was proven by constructing a knock-out mutant that was significantly reduced in its growth rate both at elevated temperatures and in the presence of membrane-active solvents. Though the mutant showed a clear phenotype it was still able to synthesise trace amounts of cardiolipin. As an increase in cardiolipin (diphosphatidylglycerol) content is known to function as a long term membrane adaptation mechanism in pseudomonads, we tested whether the mutant compensates for the lack of the Cls by increased cis/trans isomerisation of unsaturated fatty acids. Increase in cis/trans isomerisation of unsaturated fatty acids was observed for the mutant at zero and low concentrations of 4-chlorophenol; however, cis/trans isomerisation is not able to fully compensate for the lack of cardiolipin production. Possibly, other long-term adaptation mechanisms are instrumental in compensating for the missing cardiolipin synthesis. As the cis/trans isomerase is activated similarly in the mutant and the wildtype, cis/trans isomerisation and cardiolipin production do not display mutual dependency.
von Wallbrunn
A
A
Institut für Mikrobiologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, Germany.
Heipieper
H J
HJ
Meinhardt
F
F
D015139:Blotting, Southern; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D008560:Membrane Fluidity; D008565:Membrane Proteins; D016366:Open Reading Frames; D016958:Pseudomonas putida / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017421:Sequence Analysis; D013237:Stereoisomerism; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism*
D005231:Fatty Acids, Unsaturated; D008565:Membrane Proteins; D017855:Transferases (Other Substituted Phosphate Groups); C100091:cardiolipin synthetase