Shockey Jay, Parchuri Prasad, Thyssen Gregory N, Bates Philip D
United States Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA, USA, 70124.
Institute of Biological Chemistry, Washington State University, Pullman, WA, USA, 99164.
Plant Physiol Biochem. 2023 Mar;196:940-951. doi: 10.1016/j.plaphy.2023.02.040. Epub 2023 Feb 27.
The chemical and physical properties of vegetable oils are largely dictated by the ratios of 4-6 common fatty acids contained within each oil. However, examples of plant species that accumulate from trace amounts to >90% of certain unusual fatty acids in seed triacylglycerols have been reported. Many of the general enzymatic reactions that drive both common and unusual fatty acid biosynthesis and accumulation in stored lipids are known, but which isozymes have evolved to specifically fill this role and how they coordinate in vivo is still poorly understood. Cotton (Gossypium sp.) is the very rare example of a commodity oilseed that produces biologically relevant amounts of unusual fatty acids in its seeds and other organs. In this case, unusual cyclopropyl fatty acids (named after the cyclopropane and cyclopropene moieties within the fatty acids) are found in membrane and storage glycerolipids (e.g. seed oils). Such fatty acids are useful in the synthesis of lubricants, coatings, and other types of valuable industrial feedstocks. To characterize the role of cotton acyltransferases in cyclopropyl fatty acid accumulation for bioengineering applications, we cloned and characterized type-1 and type-2 diacylglycerol acyltransferases from cotton and compared their biochemical properties to that of litchi (Litchi chinensis), another cyclopropyl fatty acid-producing plant. The results presented from transgenic microbes and plants indicate both cotton DGAT1 and DGAT2 isozymes efficiently utilize cyclopropyl fatty acid-containing substrates, which helps to alleviate biosynthetic bottlenecks and enhances total cyclopropyl fatty acid accumulation in the seed oil.
植物油的化学和物理性质很大程度上取决于每种油中所含4 - 6种常见脂肪酸的比例。然而，已有报道称某些植物物种在种子三酰甘油中积累痕量至超过90%的某些不寻常脂肪酸。许多驱动常见和不寻常脂肪酸生物合成以及在储存脂质中积累的一般酶促反应是已知的，但哪些同工酶已经进化以专门发挥这一作用以及它们在体内如何协调仍知之甚少。棉花（棉属）是一种非常罕见的商品油料作物，其种子和其他器官能产生具有生物学意义数量的不寻常脂肪酸。在这种情况下，不寻常的环丙基脂肪酸（以脂肪酸中的环丙烷和环丙烯部分命名）存在于膜和储存甘油脂质（如种子油）中。此类脂肪酸在润滑剂、涂料和其他类型有价值的工业原料的合成中很有用。为了表征棉花酰基转移酶在环丙基脂肪酸积累中对于生物工程应用的作用，我们克隆并表征了来自棉花的1型和2型二酰甘油酰基转移酶，并将它们的生化特性与荔枝（荔枝）——另一种产生环丙基脂肪酸的植物——的生化特性进行了比较。转基因微生物和植物的结果表明，棉花DGAT1和DGAT2同工酶都能有效利用含环丙基脂肪酸的底物，这有助于缓解生物合成瓶颈并提高种子油中环丙基脂肪酸的总积累量。
