Impact of membrane fatty acid composition on the uncoupling sensitivity of the energy conservation of Comamonas testosteroni ATCC 17454.
The fatty acid composition of pyruvate-grown Comamonas testosteroni ATCC 17454 was analyzed after growth at 30 and 20 degrees C and after half-maximum growth inhibition caused by different membrane-active chemicals at 30 degrees C. Palmitic acid (16:0), palmitoleic acid (16:1 omega7c) and vaccenic acid (18:1 omega7c) were the dominant fatty acids. At 20 degrees C, the proportion of palmitic acid decreased and those of palmitoleic and vaccenic acid increased. Saturation degree was also lowered when half-maximum growth inhibition was caused by 4-chlorosalicylic acid, 2,4-dichlorophenoxyacetic acid and 2,4-dinitrophenol and, to a lesser extent, in the presence of 2,4-dichlorophenol, phenol and ethanol. It appeared that the dissociated forms of the former group of chemicals were preferentially incorporated near the head group region of the lipid bilayer, thereby somewhat extending the outer region of the membranes, and that the increased amount of bent, unsaturated fatty acids helped to maintain membrane integrity. Irrespective of how the decrease of the saturation degree was triggered, it caused electron transport phosphorylation (adenosine triphosphate synthesis driven by n-hexanol oxidation) to become more sensitive to uncoupling. Apparently, the viscosity and phase stability of the cytoplasmic membrane of C. testosteroni were maintained at the price of a reduced protection against energy toxicity.
Loffhagen
Norbert
N
Department of Environmental Microbiology, Centre for Environmental Research (UFZ), Leipzig-Halle, Permoserstrasse 15, 04318 Leipzig, Germany. norbert.loffhagen@ufz.de
Härtig
Claus
C
Harms
Hauke
H
D002462:Cell Membrane / Q000737:chemistry*; D020604:Comamonas testosteroni / Q000145:classification* / Q000166:cytology / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D004579:Electron Transport / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005227:Fatty Acids / Q000032:analysis*; D010766:Phosphorylation; D019289:Pyruvic Acid / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
D003470:Culture Media; D005227:Fatty Acids; D019289:Pyruvic Acid