不同转录频率的酵母基因启动子序列结构差异性分析

Analysis of structure differences of promoter sequences for yeast genes with different transcriptional frequencies

不同基因的转录效率一般会有差异,启动子序列的组织结构可能是造成差异的原因之一。本文分别基于出现频率、Markov模型以及加权Markov模型计算出所有6碱基片段(6-mer)在不同转录频率的酵母基因启动子序列中的分布,然后利用最大最小贴近度方法分析这些基因启动子序列结构的差异情况。结果表明,酵母基因的转录频率与启动子序列结构的确有关联,转录频率相差较大的基因,它们的启动子序列结构差异一般也较大。统计分析还表明,高阶(3阶和4阶)加权Markov模型可以更有效地反映基因启动子序列的结构特征。

The transcriptional frequencies of different genes are generally distinct.The organizations of promoter sequences may be one of the causes leading to such distinction.In this paper,the distributions of 6-base words（6-mer） in yeast genes with different transcriptional frequencies are calculated based on 6-mer occurrence frequencies,Markov model and weighted Markov model,respectively.Then the differences of the sequence structures of these genes are analyzed through the method of Max-min close degree.The results show that the transcriptional frequencies of yeast genes are indeed correlated to their promoter sequence structures.In general,the greater the difference between the transcriptional frequencies of two genes,the more the difference of their promoter sequence structures.In addition,statistical analysis suggests that the weighted Markov model of higher order（3th and 4th order） could better characterize the sequence organizations of gene promoters.