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  • Functional interaction of Rpb1 and Spt5 C-terminal domains in co-transcriptional histone modification.

Functional interaction of Rpb1 and Spt5 C-terminal domains in co-transcriptional histone modification.

Nucleic acids research (2015-08-16)
Jean Mbogning, Viviane Pagé, Jillian Burston, Emily Schwenger, Robert P Fisher, Beate Schwer, Stewart Shuman, Jason C Tanny
ABSTRACT

Transcription by RNA polymerase II (RNAPII) is accompanied by a conserved pattern of histone modifications that plays important roles in regulating gene expression. The establishment of this pattern requires phosphorylation of both Rpb1 (the largest RNAPII subunit) and the elongation factor Spt5 on their respective C-terminal domains (CTDs). Here we interrogated the roles of individual Rpb1 and Spt5 CTD phospho-sites in directing co-transcriptional histone modifications in the fission yeast Schizosaccharomyces pombe. Steady-state levels of methylation at histone H3 lysines 4 (H3K4me) and 36 (H3K36me) were sensitive to multiple mutations of the Rpb1 CTD repeat motif (Y1S2P3T4S5P6S7). Ablation of the Spt5 CTD phospho-site Thr1 reduced H3K4me levels but had minimal effects on H3K36me. Nonetheless, Spt5 CTD mutations potentiated the effects of Rpb1 CTD mutations on H3K36me, suggesting overlapping functions. Phosphorylation of Rpb1 Ser2 by the Cdk12 orthologue Lsk1 positively regulated H3K36me but negatively regulated H3K4me. H3K36me and histone H2B monoubiquitylation required Rpb1 Ser5 but were maintained upon inactivation of Mcs6/Cdk7, the major kinase for Rpb1 Ser5 in vivo, implicating another Ser5 kinase in these regulatory pathways. Our results elaborate the CTD 'code' for co-transcriptional histone modifications.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-RNA polymerase II subunit B1 (phospho CTD Ser-2) Antibody, clone 3E10, clone 3E10, from rat
Sigma-Aldrich
Anti-RNA polymerase II subunit B1 (phospho-CTD Ser-5) Antibody, clone 3E8, clone 3E8, from rat