University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
J Agric Food Chem. 2010 Feb 10;58(3):1870-7. doi: 10.1021/jf902684v.
Two full-length cDNA clones PoleFAD7 and PoleFAD8, encoding plastidial omega-3 fatty acid desaturases were isolated from purslane (Portulaca oleracea). The encoded enzymes convert linoleic to alpha-linolenic acid (C18:3n-3). Three histidine clusters characteristic of fatty acid desaturases, a putative chloroplast transit peptide in the N-terminal, and three putative transmembrane domains were identified in the sequence. Both genes were expressed in all analyzed tissues showing different levels of expression. PoleFAD7 was up-regulated by wounding but not by low temperature. PoleFAD8 was up-regulated by cold stress but not by wounding. Total fatty acid and linolenic acid content were higher both, in wounded and intact leaves of plants exposed to low temperature.
从马齿苋（Portulaca oleracea）中分离到编码质体ω-3 脂肪酸去饱和酶的全长 cDNA 克隆 PoleFAD7 和 PoleFAD8。编码的酶将亚油酸转化为α-亚麻酸（C18:3n-3）。在该序列中鉴定出三个脂肪酸去饱和酶特征的组氨酸簇、N 端的推定叶绿体转运肽和三个推定跨膜结构域。这两个基因在所有分析的组织中均有表达，表达水平不同。PoleFAD7 被低温而非低温诱导，而 PoleFAD8 被低温而非低温诱导。在低温下，无论是受伤的还是完整的叶片，总脂肪酸和亚麻酸的含量都更高。
