Fig 6. Set2 primarily functions in DSB repair in the context of a transcribing unit.

(A) Linearized (SmaI) or circularized pRS316 plasmids were transformed, in parallel, into the indicated strains and colony numbers were counted after 2-3 days on Sc-Ura plates. Religation frequency was calculated as the ratio of the number of colonies obtained from linearized plasmid to the number colonies obtained from circularized plasmid, with the value for WT strain normalized to 1.0. yku70Δ is the positive control for the assay. (B) Linearized (SmaI) or circularized pGV255-live plasmids were transformed, in parallel, into indicated strains and number of colonies were counted after 2-3 days on Sc-Ura plates. Religation frequency was calculated as above. (** represents p< 0.02; error bars represent standard deviation from 3 different independent transformation experiments). (C) A simplified model depicting a function of Set2 and H3K36me in regulating DNA damage response and repair. Immediately after DSB (shown as ‘lightning bolt’), Set2-dependent H3K36me3 becomes enriched around the DSB. Increased H3K36me3 ensures a de-acetylated chromatin structure to prevent inappropriate DNA transactions especially in the context of a transcription unit, which we propose is important for maintaining the genomic integrity of transcribing units. Consistent with this model, loss of Set2/H3K36me leads to abrogated DNA damage signaling activation, altered chromatin structure, and inappropriate repair.