摘要
二氢吡啶二羧酸合成酶(DHDPS)是赖氨酸生物合成途径的关键酶,探讨DHDPS在不同植物中所受到的选择压力及其功能分歧,以期为阐明赖氨酸积累的分子机制奠定基础,并为植物逆境适应性研究提供线索。利用模式植物基因组数据库,通过生物信息学手段,鉴定并获得水稻、拟南芥和大豆等11个物种的DHDPS基因的核酸和蛋白全序列;利用Clustal X、PAML和DIVERGE等工具剖析了21条DHDPS基因的序列、功能分歧、选择压力及进化关系,并计算了相关参数。系统进化树揭示了植物DHDPS基因能被划分为5个类群,其中,杨树的2个DHDPS蛋白单独形成了E类群,剩余的4个类群至少包括2个物种的DHDPS蛋白。基于位点模型的选择压力检测显示,M8模型虽然能签定出正选择位点,但这些位点均未达到显著水平,说明植物DHDPS基因主要受控于纯净选择。类群间功能分歧研究显示:类群之间存在Ⅰ型功能分歧,不存在Ⅱ型功能分歧;总共鉴定了273个功能分歧位点,其中,Ⅰ型功能分歧位点214个,Ⅱ型功能分歧位点59个;似然比检测表明,Ⅰ型功能分歧位点均达到显著水平,但Ⅱ型功能分歧位点均不显著。因此,在长期进化过程中,DHDPS基因类群间发生Ⅰ型功能分化,同时,单个类群内纯净选择起着主导作用。
Dihydrodipicolinate synthase（DHDPS） is the key enzyme for the pathway of lysine biosynthesis.This paper aimed at investigation of selective pressure and functional divergence in DHDPS proteins in different plants,which would pave the way for adequate understanding of molecular mechanism for lysine accumulation,and provide useful clues for stress tolerance in plants.Based on in silico methods,nucleic acid and protein sequences of DHDPS genes in 11 model plants,including rice,Arabidopsis,soybean,and so on,were identified from the corresponding genome databases.The sequence alignment,functional divergence,selective pressure,and phylogenetic relationship of 21 DHDPS genes were analyzed using Clustal X,PAML and DIVERGE,and the related parameters were estimated.All the DHDPS genes were classified into five groups based on the phylogenetic tree,among which E group only included two DHDPS genes in Populus,but other groups included DHDPS genes from at least two plants.The site specific model implemented in Codeml from PAML package revealed that DHDPS genes in each of five groups were mainly controlled by purifying selection,and there were no significant positive sites.Functional divergent analyses between five groups indicated that there was type Ⅰ but no type Ⅱ functional divergence and there were 273 functional divergence sites including 214 type Ⅰ and 59 type Ⅱ functional divergence sites.Likelihood ratio test showed that 59 type Ⅱ functional divergence sites were not significant at 0.05 level,but 214 type I functional divergence sites were significant at 0.01 level.Taken together,there was type I functional divergence between five groups,and purifying selection played a dominant role in each of five groups during DHDPS gene evolutionary process.
出处
《河南农业科学》
CSCD
北大核心
2012年第4期34-37,共4页
Journal of Henan Agricultural Sciences
基金
河南省政府决策研究招标课题(B578)
关键词
植物
基因
功能分歧
适应性进化
分歧时间
选择压力
plant
gene
functional divergence
adaptive evolution
divergence time
selective pres sure
