Regulation of the histone H3K36 methyltransferase Set2 by the histone chaperone Spt6

Histone H3 lysine 36 (H3K36) trimethylation is a conserved post-translational modification critical for maintaining eukaryotic transcriptional fidelity and genomic stability. This modification is catalyzed in yeast by Set2, an ortholog of the mammalian H3K36 methyltransferase SETD2. Several studies have shown that Set2 activity in vivo requires the histone chaperone Spt6. Genetic studies in yeast suggested that Spt6 regulation occurs via controlling a Set2 autoinhibitory domain (AID) and recent structural studies of active Set2 demonstrated a direct physical interaction between Set2 and Spt6. These results suggested a model in which Spt6 directly interacts with Set2 to relieve autoinhibition of Set2 activity by the Set2 AID. However, there is little evidence of how Set2 autoinhibition functions. To address this, we have isolated and analyzed multiple classes of Spt6 and Set2 mutants that likely impair either Set2-Spt6 interactions or the Set2 intramolecular interactions underlying Set2 autoinhibition. The Set2 autoinhibition mutants contain mutations within the Set2 catalytic domain at a predicted interface with the Set2 AID, which is in support of the AlphaFold-predicted structure of inactive Set2. Biophysical and analytic approaches reveal that the wild-type Set2 catalytic domain and Set2 AID physically interact, and that the autoinhibition mutants reduce or abolish this interaction. Also, in support of the autoinhibition model, ChIP-seq and RNA-seq studies demonstrate that autoinhibition mutants that disrupt the physical interaction in vitro bypass the requirement of Spt6 for H3K36 methylation in vivo. Taken together, our results support the model that Set2 exists in an inactive, autoinhibited state in vivo through direct catalytic-AID interactions, and that binding to Spt6 is required to relieve Set2 autoinhibition.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Doctoral

Grantor

Harvard University Graduate School of Arts and Sciences

Year dc:date.issued

2026

Author dc:creator

• Elchert, Alexandra

Advisor dc:contributor.advisor

• Winston, Fred M.

• Genetics
• Biology
• Molecular biology

Language dc:language.iso

en

Dc Identifier Other

32701236

OAI identifier oai:identifier

oai:dash.harvard.edu:1/42744854