用图论方法研究核酸序列的密码子使用与基因表达水平的关系

研究了Escherichiacoli（115个基因）和SacharomycesYeast（97个基因）核酸序列的密码子使用频率与基因表达水平的关系．将同义密码子按使用频率统计值分成三种特性的密码子：最适密码子（H）、非最适密码子（L）和稀有密码子（R），对每一基因序列的编码区，算出它们各自出现的概率P（H），P（L）和P（R）．以P（H）和P（R）为指标，用图论法聚类，发现每种生物的高低表达基因明显分开，基因表达水平被分为四级：甚高表达基因（VH）、高表达基因（H）、较低表达基因（LM）和低表达基因（LL）．每类基因的表达水平与实验结果保持了很好的相关性，与E．coli和Yeast的现有资料相比，符合很好．

Study on the Relation Between Codon Usage of Nucleic Acids Sequence and Gene Expression Level by Graph Theory Method

The relations between codon usage and gene expression level for E.coli(115genes) and Yeast(97 genes) were discussed.According to the frequency of synonymous codons in a particular class of genes,the codons were classified into three groups optimal codon (H),nonoptimal codon (L) and rare codon ( R ).For each protein-coding sequence,the probabilities of the three groups of codons,P(H),P(L) and P(R),were calculated.Then according to P(H) and P( R ),genes were classfied by graph Theory method.It was found that genes for each species can be class-ified into four dstinct groups:very high-expressed genes (VH),high-expressed genes (H),moderate-expressed genes (LM) and low-expressed genes (LL).The results were consistent with experimental data and other method.