酵母核小体中心序列局域偏好和连接序列的多样性

The local preference of nucleosome core sequences and the diversity of linker sequences in yeast

基于酵母单碱基精度的核小体位置数据,提取核小体中心及连接序列分析两类序列的精细结构和模体偏好。结果显示,区分两类序列最主要的是稀有模体(GCG、CGC、CGG和CCG),其次是富含模体(AAA和TTT)。将核小体中心序列等分为3个单元,发现中单元与核小体中心序列相对偏差的分布相似,两翼单元分布部分类似于连接序列,表明中单元的核小体定位信号强而两翼具有连接序列的部分序列特征。通过分析11个核小体连接序列长度组的G+C含量发现其长度与G+C含量成负相关,而MEME模体搜索结果显示11个长度组主要有4类保守模体,意味着连接序列的多样性。

Based on the yeast＇s nucleosome positions with single-base-pair accuracy, nucieosome core sequences and linker sequences extracted were used to discuss their fine structures and pre- ferred motifs. Analyzing relative deviations （RD） of 3-mer relative frequency between core/linker sequences and genome-wide found that rare motifs （GCG, CGC, CGG and CCG） were the most important factor to distinguish two kinds of sequences, and the most abundant motifs （AAA and TTT） closely followed. After core sequences equally divided into three units, the RD distribution of the central unit was similar to that of core sequences, and the RD distributions of the flanking units were partially similar to that of linker sequences, which showed the flanking units have transition regions toward linker sequences. Based on the analysis of G＋C contents in 11 groups with different length, it was found that the length was negatively correlated with the G＋C con- tent,while four main types of conserved motifs were found in these groups through search of MEME suite,indicating that linker sequence possesses diversity.