Analysis for the Combinations of Histone Modifications in S.Cerevisiae

ABSTRACTIt is known that multiple histone modifications act in a combinatorial fashion to form a ‘histone code’. In this study, the pathways within Bayesian networks of histone modifications constructed indicated the combinatorial and causative relationships among 12 histone modifications studied at the region TSS + 1 kb in S. cerevisiae. After Bayesian networks for the genes with high transcript levels and low transcript levels were constructed, all combinations of histone modifications that the two networks indicated were analyzed. The results showed that four combinations were necessary for gene transcription. Other combinations played different roles in the regulation of gene transcription. In addition, our analysis suggested that the combinations in the top layer within the networks might affect the downstream histone modifications and associate with Pol II.