Widespread colocalization of the Drosophila histone acetyltransferase homolog MYST5 with DREF and insulator proteins at active genes.

MYST family histone acetyltransferases play important roles in gene regulation. Here, we have characterized the Drosophila MYST histone acetyltransferase (HAT) encoded by cg1894, whose closest homolog is Drosophila MOF, and which we have termed MYST5. We found it localized to a large number of interbands as well as to the telomeres of polytene chromosomes, and it showed strong colocalization with the interband protein Z4/Putzig and RNA polymerase II. Accordingly, genome-wide location analysis by ChIP-seq showed co-occurrence of MYST5 with the Z4-interacting partner Chriz/Chromator. Interestingly, MYST5 bound to the promoter of actively transcribed genes, and about half of MYST5 sites colocalized with the transcription factor DNA replication-related element-binding factor (DREF), indicating a role for MYST5 in gene expression. Moreover, we observed substantial overlap of MYST5 binding with that of the insulator proteins CP190, dCTCF, and BEAF-32, which mediate the organization of the genome into functionally distinct topological domains. Altogether, our data suggest a broad role for MYST5 both in gene-specific transcriptional regulation and in the organization of the genome into chromatin domains, with the two roles possibly being functionally interconnected.