Transcription factor Sp3 is regulated by acetylation

Area of Science:

• Molecular Biology
• Gene Regulation
• Protein Function

Background:

• Sp3 is a transcription factor structurally similar to Sp1.
• Sp3 exhibits reduced transcriptional activity compared to Sp1 in certain contexts.
• An inhibitory domain in Sp3 was previously identified.

Purpose of the Study:

• To investigate the transcriptional properties of Sp3.
• To elucidate the mechanisms regulating Sp3 activity in vivo.
• To identify specific residues or modifications affecting Sp3 function.

Main Methods:

• Expression and purification of recombinant Sp3 and Sp1.
• In vitro transcription assays using depleted nuclear extracts.
• Transfection experiments and mutational analysis in cultured cells.
• Analysis of protein acetylation in vivo.

Main Results:

• Recombinant Sp3 functions as a potent activator in vitro, similar to Sp1.
• Sp3 shows significantly lower activity when transfected into cells.
• A single lysine residue was identified as crucial for Sp3's low in vivo activity.
• Sp3, but not a mutant lacking this lysine, is highly acetylated in vivo.

Conclusions:

• Sp3's transcriptional activity is regulated by post-translational modification.
• Acetylation of Sp3, linked to a specific lysine residue, modulates its in vivo function.
• This suggests acetylation is a key regulatory mechanism for Sp3 activity.