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A Conserved Glycine Is Identified to be Essential for Desaturase Activity of IpFAD2s by Analyzing Natural Variants from <i>Idesia polycarpa</i>

By Pan Wu, Lingling Zhang, Tao Feng, Wenying Lu, Huayan Zhao, Jianzhong Li and Shiyou Lü

Abstract

High amounts of polyunsaturated fatty acids (PUFAs) in vegetable oil are not desirable for biodiesel or food oil due to their lower oxidative stability. The oil from <i>Idesia polycarpa</i> fruit contains 65&#8315;80% (mol%) linoleic acid (C18:2). Therefore, development of <i>Idesia polycarpa</i> cultivars with low PUFAs is highly desirable for <i>Idesia polycarpa</i> oil quality. Fatty acid desaturase 2 (FAD2) is the key enzyme converting oleic acid (C18:1) to C18:2. We isolated four FAD2 homologs from the fruit of <i>Idesia polycarpa</i>. Yeast transformed with <i>IpFAD2-1</i>, <i>IpFAD2-2</i> and <i>IpFAD2-3</i> can generate appreciable amounts of hexadecadienoic acid (C16:2) and C18:2, which are not present in wild-type yeast cells, revealing that the proteins encoded by these genes have &#916;<sup>12</sup> desaturase activity. Only trace amounts of C18:2 and little C16:2 were detected in yeast cells transformed with <i>IpFAD2-4</i>, suggesting IpFAD2-4 displays low activity. We also analyzed the activity of several FAD2 natural variants of <i>Idesia polycarpa</i> in yeast and found that a highly conserved Gly376 substitution caused the markedly reduced products catalyzed by IpFAD2-3. This glycine is also essential for the activity of IpFAD2-1 and IpFAD2-2, but its replacement in other plant FAD2 proteins displays different effects on the desaturase activity, suggesting its distinct roles across plant FAD2s proteins

Topics: <i>Idesia polycarpa var</i>, glycine, FAD2, linoleic acid, oleic acid, Biology (General), QH301-705.5, Chemistry, QD1-999
Publisher: MDPI AG
Year: 2018
DOI identifier: 10.3390/ijms19123932
OAI identifier: oai:doaj.org/article:d5233ce339574bffaccda74962367d03
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