Restriction of Retrotransposon Mobilization in Schizosaccharomyces pombe by Transcriptional Silencing and Higher-Order Chromatin Organization.

Uncontrolled propagation of retrotransposons is potentially detrimental to host genome integrity. Therefore, cells have evolved surveillance mechanisms to restrict the mobility of these elements. In Schizosaccharomyces pombe the Tf2 LTR retrotransposons are transcriptionally silenced and are also clustered in the nucleus into structures termed Tf bodies.

Heterochromatin assembly and transcriptome repression by Set1 in coordination with a class II histone deacetylase.

Histone modifiers play essential roles in controlling transcription and organizing eukaryotic genomes into functional domains. Here, we show that Set1, the catalytic subunit of the highly conserved Set1C/COMPASS complex responsible for histone H3K4 methylation (H3K4me), behaves as a repressor of the transcriptome largely independent of Set1C and H3K4me in the fission yeast Schizosaccharomyces pombe. Intriguingly, while Set1 is enriched at highly expressed and repressed loci, Set1 binding levels do not generally correlate with the levels of transcription.

Multifaceted genome control by Set1 Dependent and Independent of H3K4 methylation and the Set1C/COMPASS complex.

Histone modifiers are critical regulators of chromatin-based processes in eukaryotes. The histone methyltransferase Set1, a component of the Set1C/COMPASS complex, catalyzes the methylation at lysine 4 of histone H3 (H3K4me), a hallmark of euchromatin. Here, we show that the fission yeast Schizosaccharomyces pombe Set1 utilizes distinct domain modules to regulate disparate classes of repetitive elements associated with euchromatin and heterochromatin via H3K4me-dependent and -independent pathways.