| Title | Identification and Functional Analysis of Acyl‑Acyl Carrier Protein Δ9 Desaturase from Nannochloropsis oceanica |
|---|---|
| Author | Ruigang Yang1,2, Hui Wang3, Lingyun Zhu1, Lvyun Zhu1, Tianzhong Liu2*, and Dongyi Zhang4* |
| Address | 1Department of Biology and Chemistry, College of Sciences, National University of Defense Technology, Changsha 410073, People’s Republic of China, 2Key Laboratory of Biofuels, Key Laboratory of Shandong Energy Biological Genetic Resources, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, People’s Republic of China, 3Functional Laboratory of Solar Energy, Shandong Energy Institute, Qingdao 266101, People’s Republic of China, 4Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan 411201, People’s Republic of China |
| Bibliography | Journal of Microbiology, 61(1),95-107, 2023, |
| DOI | 10.1007/s12275-022-00001-9 |
| Key Words | Acyl-ACP desaturase · Nannochloropsis oceanica · Fatty acid biosynthesis · Monounsaturated fatty acids |
| Abstract | The oleaginous marine microalga Nannochloropsis oceanica strain IMET1 has attracted increasing attention as a promising photosynthetic cell factory due to its unique excellent capacity to accumulate large amounts of triacylglycerols and eicosapentaenoic acid. To complete the genomic annotation for genes in the fatty acid biosynthesis pathway of N. oceanica, we conducted the present study to identify a novel candidate gene encoding the archetypical chloroplast stromal acyl-acyl carrier protein Δ9 desaturase. The full-length cDNA was generated using rapid-amplification of cDNA ends, and the structure of the coding region interrupted by four introns was determined. The RT-qPCR results demonstrated the upregulated transcriptional abundance of this gene under nitrogen starvation condition. Fluorescence localization studies using EGFP-fused protein revealed that the translated protein was localized in chloroplast stroma. The catalytic activity of the translated protein was characterized by inducible expression in Escherichia coli and a mutant yeast strain BY4389, indicating its potential desaturated capacity for palmitoyl-ACP (C16:0-ACP) and stearoyl-ACP (C18:0-ACP). Further functional complementation assay using BY4839 on plate demonstrated that the expressed enzyme restored the biosynthesis of oleic acid. These results support the desaturated activity of the expressed protein in chloroplast stroma to fulfill the biosynthesis and accumulation of monounsaturated fatty acids in N. oceanica strain IMET1. |