The cis/trans isomerization of the double bond of a fatty acid as a strategy for adaptation to changes in ambient temperature in the psychrophilic bacterium, Vibrio sp. strain ABE-1.
The major phospholipid, phosphatidylethanolamine (PE), of Vibrio sp. strain ABE-1 contains a unique trans-unsaturated fatty acid, 9-trans-hexadecenoic acid (16:1(9t], at the sn-2 position of the glycerol moiety. The major molecular species of PE that contain 16:1(9t) at the sn-2 position have either 9-cis-hexadecenoic acid (16:1(9c] or hexadecanoic acid (16:0) at the sn-1 position. The transition temperatures of the liquid-crystal to the gel phase of 16:1(9c)/16:1(9t)-PE and 16:0/16:1(9t)-PE were -3 degrees C and 38 degrees C, respectively, temperatures that were 31 degrees C and 18 degrees C higher than the corresponding temperatures for 16:1(9c)/16:1(9c)-PE and 16:0/16:1(9c)-PE. The proportion of 16:1(9c)/16:1(9t)-PE and 16:0/16:1(9t)-PE increased significantly in cells grown at 20 degrees C over that in cells grown at 5 degrees C. When cells grown at 5 degrees C were incubated at 20 degrees C in the presence of cerulenin, an inhibitor of the synthesis de novo of fatty acids, the level of 16:1(9t) increased almost in parallel with a concomitant decrease in the level of 16:1(9c) at the sn-2 position. These results suggest that 16:1(9c) is converted to 16:1(9t) by the cis/trans isomerization of the double bond in the fatty acid. This conversion is discussed as a possible strategy for adaptation by bacteria to changes in temperature.
Okuyama
H
H
Department of Botany, Faculty of Science, Hokkaido University, Sapporo, Japan.
Okajima
N
N
Sasaki
S
S
Higashi
S
S
Murata
N
N
D000222:Adaptation, Physiological; D002569:Cerulenin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005227:Fatty Acids / Q000032:analysis*; D005454:Fluorescence Polarization; D008055:Lipids / Q000302:isolation & purification; D010714:Phosphatidylethanolamines / Q000302:isolation & purification; D013237:Stereoisomerism; D013696:Temperature; D014733:Vibrio / Q000187:drug effects / Q000254:growth & development*
D005227:Fatty Acids; D008055:Lipids; D010714:Phosphatidylethanolamines; D002569:Cerulenin