摘要
△6脂肪酸脱饱和酶是在长链脂肪酸18C位置上引入双键的关键酶。本文分析硅藻门、绿藻门和蓝藻门等藻类的△6脂肪酸脱饱和酶基因密码子偏好及碱基位置偏好,同时比较藻类△6脂肪酸脱饱和酶基因与大肠杆菌、酵母及拟南芥基因组的密码子偏爱性。结果发现,硅藻门T.pseudonana与P.tricornutum及绿藻门Ostreococcus tauri△6脂肪酸脱饱和酶基因明显偏爱使用以G或C结尾的密码子,GC含量高达61.61%。蓝藻门三种藻△6脂肪酸脱饱和酶基因与之相反,偏爱A或U结尾的密码子,GC含量仅为39.1%。所选9条不同藻类的△6脱饱和酶基因密码子偏好不明显,说明藻类物种间差异对△6脱饱和酶基因密码子偏好性的影响较小,在进化上较为保守。然而,藻类△6脱饱和酶基因密码子用法与大肠杆菌、酵母和拟南芥的△6脱饱和酶基因密码子用法差异较大,若要实现该基因在以上宿主中的高效表达则需对部分密码子进行改造。
Delta-6 desaturases are the key enzymes required for the synthesis of unsaturated fatty acids, which introduce dou- ble bond at the position of 18C in algae. In this study, the authors investigate codon usage bias and base composition variations in nine available complete desaturase gene sequences from Bacillariophyta, Chlorophyta and Cyanophyta. The results showed that △6 desaturase genes of T. pseudonana and P. tricornutum （Bacillariophyta） as well as Ostreococcus tauri （Chlorophyta） prefer to use the codons ended with G or C, with GC content as high as 61.61%; while △6 desaturase genes of three algae of Cyanophyta prefer to use the codons ended with A or U, with GC content 39.1%. Codon usage bias in alga △6 desaturase gene was very small, which was mainly determined by base compositions on the third codon position and the value of effective number of codons （ENC）. It was implied that △6 desaturase genes were phylogenetically conservative. The results of com- paring algae △6 desaturase genes to genomic codon usage of E.coli, yeast and Arabidopsis thaliana preference revealed that codon usage pattern among them was significantly different. In order to significantly increase the efficiency of algae △6 desaturase gene expression, partial codon in gene＇s open reading frame needs to be reconstituted. The findings presented in this study offer guidance for expressing algae △6 desaturase gene in prokaryotic and eukaryotic expression systems.
出处
《热带海洋学报》
CAS
CSCD
北大核心
2010年第3期126-134,共9页
Journal of Tropical Oceanography
基金
福建省教育厅项目(JA09061)
福建省科技厅重点项目(2007I0039,2008I0047)
教育部留学回国人员科研启动基金资助项目
