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遗传密码子是生命信息的基本遗传单位,每种氨基酸对应1～6个同义密码子.特定物种在长期进化中形成了适应自身基因组环境的密码子使用偏性.运用CHIPS、CUSP和CodonW程序分析自主克隆的籽粒苋NAD-ME基因的密码子偏好性,并与马铃薯等7种植物的ME基因密码子偏好性进行比较,以期为该基因在作物遗传改良中选择合适的受体植物提供依据.结果表明,籽粒苋NAD-ME基因偏好于以A或T结尾的密码子,其它几种被比较作物的ME基因也有同样的趋势,但双子叶植物的偏好性更强.基于NAD-ME基因的密码子使用偏性的系统聚类分析表明,籽粒苋与马铃薯、拟南芥、葡萄、蓖麻、毛果杨等双子叶植物聚为1类,玉米和高粱这2个单子叶植物聚为1类,预示籽粒苋NAD-ME基因更适合导入马铃薯等双子叶植物.对籽粒苋NAD-ME基因的密码子偏好性与大肠杆菌和酵母的基因组密码子偏好性进行比较,发现均存在差异,与大肠杆菌的差异高于酵母,表明酵母表达系统要优于大肠杆菌表达系统.若要进一步提高籽粒苋NAD-ME基因在大肠杆菌或酵母中的表达水平,尚需对其密码子进行优化.
Genetic code is the basic genetic unit of life information, each amino acid corresponds to 1 ~ 6 synonymous codons.Specific species in the long-term evolution to adapt to their own genome environment codon usage bias.Using CHIPS, CUSP and CodonW program The codon preference of NAD-ME gene was analyzed and compared with the codon preference of ME gene of seven plants such as potato in order to provide a basis for the selection of suitable recipient plants for crop genetic improvement The results showed that NAD-ME gene of Amaranthus indicus favored the codon ending with A or T. Similar trends were observed for the ME genes of other crops, but the preference of dicotyledonous plants was stronger.According to the NAD-ME gene The cluster analysis of codon usage bias indicated that amaranthus was clustered into 1 class with dicotyledonous plants such as potato, Arabidopsis thaliana, grape, castor bean and Populus trichocarpa. The two monocotyledonous plants such as maize and sorghum clustered 1, indicating that the NAD-ME gene of amaranth was more suitable for introducing dicotyledonous plants such as potato etc. The codon preference of NAD-ME gene of amaranth was compared with the codon preference of genome of E. coli and yeast, Were higher than that of yeast, indicating that the yeast expression system is superior to the E. coli expression system.To further improve the expression of amaranth NAD-ME gene in E. coli or yeast, its password Sub-optimization.