Los D A, Ray M K, Murata N
National Institute for Basic Biology, Okazaki, Japan.
Mol Microbiol. 1997 Sep;25(6):1167-75. doi: 10.1046/j.1365-2958.1997.5641912.x.
Cyanobacteria are capable of desaturating the fatty acids in their membrane lipids in response to decreases in temperature. The cyanobacterium, Synechocystis sp. PCC 6803, contains four desaturases, which specifically catalyse desaturation at the delta6, delta9, delta12 and omega3 positions of fatty acids. The levels of the mRNAs transcribed from the genes that encode the delta6, delta12 and omega3 desaturases increased about 10-fold, but at different rates, upon a decrease in temperature from 34 degrees C to 22 degrees C, whereas the level of the mRNA for the delta9 desaturase remained constant. The increases in the levels of mRNAs were caused both by the enhanced transcription and by the increased stability of the mRNAs at the low temperature. Western blotting analysis demonstrated that levels of the delta6, delta12 and omega3 desaturases increased at different rates at the low temperature, while that of the delta9 desaturase remained constant. These observations indicate that the expression of the genes for the four desaturases is regulated by temperature in different ways.
蓝细菌能够根据温度降低对其膜脂中的脂肪酸进行去饱和。蓝细菌集胞藻PCC 6803含有四种去饱和酶，它们特异性地催化脂肪酸在δ6、δ9、δ12和ω3位置的去饱和。当温度从34℃降至22℃时，编码δ6、δ12和ω3去饱和酶的基因转录的mRNA水平增加了约10倍，但速率不同，而δ9去饱和酶的mRNA水平保持不变。mRNA水平的增加是由转录增强和低温下mRNA稳定性增加共同引起的。蛋白质印迹分析表明，δ6、δ12和ω3去饱和酶的水平在低温下以不同速率增加，而δ9去饱和酶的水平保持不变。这些观察结果表明，四种去饱和酶基因的表达受温度的不同方式调控。
