Molecular cloning and stress-dependent expression of a gene encoding Δ12-fatty acid desaturase in the Antarctic microalga Chlorella vulgaris NJ-7

Springer Science and Business Media LLC - Tập 13 - Trang 875-884 - 2009
Yandu Lu1,2,3, Xiaoyuan Chi4, Qingli Yang4, Zhaoxin Li5, Shaofang Liu2,3, Qinhua Gan6, Song Qin1
1Yantai Institute of Coastal Zone Research for Sustainable Development, Chinese Academy of Sciences, Yantai, People’s Republic of China
2Institute of Oceanology, Chinese Academy of Sciences, Qingdao, People’s Republic of China
3Graduate School of the Chinese Academy of Sciences, Beijing, People’s Republic of China
4Shandong Peanut Research Institute, Qingdao, People’s Republic of China
5Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, People’s Republic of China
6Shandong Entry-Exit Inspection and Quarantine Bureau, Qingdao, People’s Republic of China

Tóm tắt

The psychrotrophic Antarctic alga, Chlorella vulgaris NJ-7, grows under an extreme environment of low temperature and high salinity. In an effort to better understand the correlation between fatty acid metabolism and acclimation to Antarctic environment, we analyzed its fatty acid compositions. An extremely high amount of Δ12 unsaturated fatty acids was identified which prompted us to speculate about the involvement of Δ12 fatty acid desaturase in the process of acclimation. A full-length cDNA sequence, designated CvFAD2, was isolated from C. vulgaris NJ-7 via reverse transcription polymerase chain reaction (RT-PCR) and RACE methods. Sequence alignment and phylogenetic analysis showed that the gene was homologous to known microsomal Δ12-FADs with the conserved histidine motifs. Heterologous expression in yeast was used to confirm the regioselectivity and the function of CvFAD2. Linoleic acid (18:2), normally not present in wild-type yeast cells, was detected in transformants of CvFAD2. The induction of CvFAD2 at an mRNA level under cold stress and high salinity is detected by real-time PCR. The results showed that both temperature and salinity motivated the upregulation of CvFAD2 expression. The accumulation of CvFAD2 increased 2.2-fold at 15°C and 3.9-fold at 4°C compared to the alga at 25°C. Meanwhile a 1.7- and 8.5-fold increase at 3 and 6% NaCl was detected. These data suggest that CvFAD2 is the enzyme responsible for the Δ12 fatty acids desaturation involved in the adaption to cold and high salinity for Antarctic C. vugaris NJ-7.

Tài liệu tham khảo

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