Uchida Hidenobu, Sumimoto Koremitsu, Ferriols Victor Marco Emmanuel, Imou Kenji, Saga Kiyotaka, Furuhashi Kenichi, Matsunaga Shigeki, Okada Shigeru
Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan; Japan Science and Technology Agency-Core Research for Evolutional Science and Technology (CREST), Gobancho, Chiyoda, Tokyo 102-0076, Japan.
Laboratory of Aquatic Natural Products Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan; Institute of Aquaculture, University of the Philippines Visayas, Miagao, 5023 Iloilo, Philippines.
PLoS One. 2015 Apr 1;10(4):e0122649. doi: 10.1371/journal.pone.0122649. eCollection 2015.
The B race of the green microalga Botryococcus braunii produces triterpene hydrocarbons, botryococcenes and methylsqualenes that can be processed into jet fuels with high heating values. In this alga, squalene is also converted into membrane sterols after 2,3-epoxidation. In the present study, cDNA clones of two distinct squalene epoxidases (BbSQE-I and -II) were isolated. Predicted amino acid sequences encoded on these genes are 45% identical with each other. Introduction of BbSQE-I or -II into Saccharomyces cerevisie erg1 mutants resulted in the complementation of ergosterol auxotrophy. The relative expression level of SQE-II increased 3.5-fold from the early stage to the middle phase of a culture period of 42 days, while that of SQE-I was almost constant throughout the culture period. Southern blot analyses suggested that these genes are single-copied genes. This is the first report on the isolation of functional SQEs that are encoded in duplicated loci in the algal genome.
绿色微藻布朗葡萄藻的B族会产生三萜类碳氢化合物、葡萄藻烯和甲基角鲨烯，这些物质可被加工成具有高热值的喷气燃料。在这种藻类中，角鲨烯在2,3-环氧化后也会转化为膜甾醇。在本研究中，分离出了两种不同的角鲨烯环氧化酶（BbSQE-I和-II）的cDNA克隆。这些基因编码的预测氨基酸序列彼此有45%的同一性。将BbSQE-I或-II导入酿酒酵母erg1突变体中导致麦角甾醇营养缺陷型的互补。在42天的培养期内，从早期到中期，SQE-II的相对表达水平增加了3.5倍，而SQE-I的相对表达水平在整个培养期几乎保持不变。Southern印迹分析表明这些基因是单拷贝基因。这是关于在藻类基因组中重复位点编码的功能性SQEs分离的首次报道。
