Various combinations of post-translational modifications of the N-terminal tails of nucleosomal histones serve as signals to govern chromatin-related processes. The relationship, however, among different types of histone modifications - most frequently acetylation, phosphorylation and methylation - and the order of their establishment has been explored only in a few cases. Here we show that a reduced level of histone H4 acetylated at Lys12 by the ATAC-HAT complex leads to a decrease in the histone H3 phosphorylation at Ser10 by the kinase JIL-1. As JIL-1 activity antagonizes histone H3 dimethylation at Lys9 by SU(VAR)3-9, our observations demonstrate the interdependent actions of an acetyltransferase, a kinase and a methyltransferase. We demonstrate that, in accord with the steps of modifications, mutations that affect ATAC subunits (such as dGcn5, dAda2a and dAda3) (1) decrease the level histone H3 phosphorylation at Ser10, (2) can be rescued partially by JIL-1 overproduction, (3) enhance the spread of histone H3 dimethylation at Lys9 and (4) are suppressed by mutations of Su(var)3-9. We propose that a reduced level of histone H4 acetylated at Lys12 by ATAC attenuates histone H3 phosphorylation at Ser10 by JIL-1 owing to reduced binding of JIL-1 to hypoacetylated chromatin.