Department of Biology, University of Ljubljana, Slovenia.
J Membr Biol. 2010 Feb;233(1-3):63-72. doi: 10.1007/s00232-010-9225-x. Epub 2010 Feb 10.
Desaturases that introduce double bonds into the fatty acids are involved in the adaptation of membrane fluidity to changes in the environment. Besides, polyunsaturated fatty acids (PUFAs) are increasingly recognized as important pharmaceutical and nutraceutical compounds. To successfully engineer organisms with increased stress tolerance or the ability to synthesize valuable PUFAs, detailed knowledge about the complexity of the desaturase family as well as understanding of the coevolution of desaturases and their cytochrome b5 electron donors is needed. We have constructed phylogenies of several hundred desaturase sequences from animals, plants, fungi and bacteria and of the cytochrome b5 domains that are fused to some of these enzymes. The analysis demonstrates the existence of three major desaturase acyl-CoA groups that share few similarities. Our results indicate that the fusion of Delta(6)-desaturase-like enzymes with their cytochrome b5 electron donor was a single event that took place in the common ancestor of all eukaryotes. We also propose the Delta(6)-desaturase-like enzymes as the most probable donor of the cytochrome b5 domain found in fungal Delta(9)-desaturases and argue that the recombination most likely happened soon after the separation of the animal and fungal ancestors. These findings answer some of the previously unresolved questions and contribute to the quickly expanding field of research on desaturases.
将双键引入脂肪酸的去饱和酶参与了膜流动性对环境变化的适应。此外，多不饱和脂肪酸（PUFAs）越来越被认为是重要的药物和营养化合物。为了成功地工程化具有增加的应激耐受性或合成有价值的 PUFAs 的能力的生物体，需要详细了解去饱和酶家族的复杂性以及去饱和酶与其细胞色素 b5 电子供体的共同进化。我们已经构建了来自动物、植物、真菌和细菌的数百种去饱和酶序列以及与其中一些酶融合的细胞色素 b5 结构域的系统发育。该分析表明存在三个主要的去饱和酶酰基辅酶 A 基团，它们之间很少有相似之处。我们的结果表明，Delta(6)-去饱和酶样酶与其细胞色素 b5 电子供体的融合是一个单一事件，发生在所有真核生物的共同祖先中。我们还提出 Delta(6)-去饱和酶样酶是真菌 Delta(9)-去饱和酶中发现的细胞色素 b5 结构域的最可能供体，并认为这种重组很可能发生在动物和真菌祖先分离后不久。这些发现回答了一些以前未解决的问题，并为去饱和酶的快速扩展研究领域做出了贡献。
