A conserved genetic interaction between Spt6 and Set2 regulates H3K36 methylation

Area of Science:

• Molecular Biology
• Epigenetics
• Gene Regulation

Background:

• Spt6 and Set2 are crucial for H3K36 methylation and transcriptional fidelity in yeast.
• The precise role of Spt6 in this process has been unclear.

Purpose of the Study:

• To elucidate the functional relationship between Spt6 and Set2 in H3K36 methylation.
• To identify the molecular mechanisms underlying Spt6's requirement for Set2 activity.

Main Methods:

• Isolation and characterization of dominant SET2 mutations (SET2sup) that suppress spt6 transcriptional defects.
• In vivo and in vitro biochemical assays to assess H3K36 methylation levels and Set2 enzymatic activity.
• Chromatin immunoprecipitation sequencing (ChIP-seq) to map Set2 recruitment and methylation sites.

Main Results:

• Dominant SET2sup mutations in the autoinhibitory domain suppress H3K36 methylation defects in spt6 mutants and others.
• SET2sup mutants exhibit increased H3K36 methylation in vivo and enhanced enzymatic activity in vitro.
• Suppression by SET2sup mutations occurs post-Set2 chromatin recruitment, indicating a conserved mechanism in yeast.

Conclusions:

• The autoinhibitory domain of Set2 plays a critical role in regulating H3K36 methylation.
• Spt6 likely facilitates Set2 interactions, ensuring methylation occurs specifically on actively transcribed chromatin.
• A conserved mechanism involving Set2 autoinhibition and interactions regulates H3K36 methylation across yeast species.