Histone deacetylase 1 phosphorylation promotes enzymatic activity and complex formation

Area of Science:

• Molecular Biology
• Epigenetics
• Protein Biochemistry

Background:

• Gene accessibility is controlled by histone acetylation.
• Histone deacetylase (HDAC) proteins repress transcription by removing acetyl groups from histones.
• HDAC1 function was previously understood to be regulated solely by protein interactions.

Purpose of the Study:

• To investigate the role of post-translational modifications in regulating HDAC1 function.
• To identify potential post-translational modifications on human HDAC1 protein.

Main Methods:

• Human HDAC1 protein was analyzed using ion trap mass spectrometry.
• Specific serine residues (Ser421 and Ser423) were identified as phosphorylation sites.
• Mutational analysis (alanine substitution) and deletion studies were performed to assess the impact on HDAC1 activity and complex formation.

Main Results:

• Two phosphorylated serine residues, Ser(421) and Ser(423), were identified in human HDAC1.
• Mutation of these sites or disruption of the casein kinase 2 phosphorylation motif reduced HDAC1 enzymatic activity and complex formation.
• Deletion of the carboxyl-terminal region also decreased deacetylase activity and protein associations, highlighting its importance for HDAC1 function.

Conclusions:

• Post-translational modifications, specifically phosphorylation at Ser(421) and Ser(423), play a significant role in regulating HDAC1 activity.
• Protein associations and the carboxyl-terminal region are essential for maintaining HDAC1 function.
• This study provides initial characterization of post-translational modifications in regulating HDAC activity in vivo.