Research on Non-linear Relationship among Histone Modifications in Yeast Genome

Abstract

In the process of we studied chromosome modifications, we found the previous studies only focused on linear relationship between chemical modifications. So we interfered the data sets of the Yeast histone Methylation modification and Acetylation which are measured by Pothook et al. We got 16 kinds of protein modification date sets in the whole genome. Then we processed the each of data sets by aligning, averaging and normalizing data around the TSS (about 1000bp from upstream or downstream).After we grouped the whole genome histone modification data sets according to the Yeast genome transcription level data : one modified groups promote transcription, and the other modified groups inhibit transcription or are independent of transcription. In order to reveal the complex relationships between different transcriptional activity of genetically modified, we calculated the correlation among several modifications with two by algorithms–Pearson correlation analysis and MINE proposed by David N. Reshelf et al. We analyzed the results and got some non-linear relationship between histone modifications. We also found that the association between histone modifications stronger in the same modified group. Introduction Histone is a major element of the nucleosome which is the basic structure of the chromosome. Nucleosome consists of four kinds of histones which are H2A, H2B, H3 and H4, each of two molecules to form a group of histone octamer, its outside coiled by the DNA molecules whose length is about 146 bp. Each Core Histone’s N terminal amino acid residues can react with the effect of acetylation, methylation, phosphorylation, ubiquitin and many kinds of covalent modification [3]. Histone modification plays a very important role in life process, and the occurrence of many diseases and Histone modifications have a close relation [4, 5]. Different histone modification plays a different role in the gene expression, including histone code, signal network and charge neutralization model and other different models which have been proposed to illustrate the function of histone modifications [6, 7, 8, 9], but a single histone modification cannot independently work [6], and this trait show that there is relevance among the Histone modification, and have an influence on the gene expression. Therefore, there is biological significance to research the correlation of the Histone modification. But previous research of chromatin modification only focused on the linear relation between the chemical modification, but nonlinear relationship was not fully focused. However, there are complex relationships between the modify, and often cannot simplified only with linear, so there are a more important meaning to research the nonlinear relationship of modify.