Abo1 is required for the H3K9me2 to H3K9me3 transition in heterochromatin

Wenbo Dong,Karl Ekwall,Mickaël Durand-Dubief,J Peter Svensson,Andreas Lennartsson,Punit Prasad,Eriko Oya,Yasaman Zahedi

doi:10.1038/s41598-020-63209-y

Wenbo Dong, Karl Ekwall + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-63209-y

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Abstract

Heterochromatin regulation is critical for genomic stability. Different H3K9 methylation states have been discovered, with distinct roles in heterochromatin formation and silencing. However, how the transition from H3K9me2 to H3K9me3 is controlled is still unclear. Here, we investigate the role of the conserved bromodomain AAA-ATPase, Abo1, involved in maintaining global nucleosome organisation in fission yeast. We identified several key factors involved in heterochromatin silencing that interact genetically with Abo1: histone deacetylase Clr3, H3K9 methyltransferase Clr4, and HP1 homolog Swi6. Cells lacking Abo1 cultivated at 30 °C exhibit an imbalance of H3K9me2 and H3K9me3 in heterochromatin. In abo1∆ cells, the centromeric constitutive heterochromatin has increased H3K9me2 but decreased H3K9me3 levels compared to wild-type. In contrast, facultative heterochromatin regions exhibit reduced H3K9me2 and H3K9me3 levels in abo1∆. Genome-wide analysis showed that abo1∆ cells have silencing defects in both the centromeres and subtelomeres, but not in a subset of heterochromatin islands in our condition. Thus, our work uncovers a role of Abo1 in stabilising directly or indirectly Clr4 recruitment to allow the H3K9me2 to H3K9me3 transition in heterochromatin.

Highlights

Heterochromatin regulation is critical for genomic stability
Among 711 investigated genes, the strongest negative genetic interactions were recorded with genes encoding proteins involved in heterochromatin assembly: histone deacetylase Clr[3], H3K9 methyltransferase Clr[4], and chromodomain heterochromatin protein 1 (HP1) homologue Swi[6] (Supplementary Table S1)
These results show that Abo[1] is required for the establishment of heterochromatin and contributes to the transition of H3K9me[2] to me[3] at determinant of selective removal” (DSR) islands

Summary

Introduction

Heterochromatin regulation is critical for genomic stability. Different H3K9 methylation states have been discovered, with distinct roles in heterochromatin formation and silencing. The effects of these mutations on H3K9me[2] levels in the different heterochromatin regions were compared to the H3K9me[2] levels in cells lacking Abo[1] In the otr1R region, H3K9me[2] levels were increased but H3K9me[3] levels were reduced compared to wild-type in both abo1∆ and clr4W31G mutant cells (Supplementary Fig. S2, middle panel; Supplementary Fig. S6, top panel)[43], which suggested that abo[1] deletion may disrupt the transition of H3K9me[2] to H3K9me[3] as clr4W31G mutation.

Results

Conclusion