Molecular Mechanism of LEDGF/p75 Dimerization

Area of Science:

• Molecular Biology
• Epigenetics
• Protein Structure

Background:

• Dimerization is crucial for many eukaryotic transcription factors.
• Lens epithelium-derived growth factor/p75 (LEDGF/p75) requires dimerization to facilitate transcription elongation.
• Dimeric features of LEDGF/p75 binding partners highlight the importance of its dimerization.

Purpose of the Study:

• To identify the minimal dimerization region of LEDGF/p75.
• To elucidate the molecular contacts stabilizing the LEDGF/p75 dimer structure.
• To investigate the functional consequences of LEDGF/p75 dimerization.

Main Methods:

• Paramagnetic NMR spectroscopy to determine dimer structure.
• Structure-inspired mutagenesis to create dimerization-defective variants.
• Chemical crosslinking coupled with mass spectrometry for validation.

Main Results:

• The minimal dimerization region was mapped to the C-terminal part of LEDGF/p75.
• Dimerization is stabilized by domain swapping in the integrase binding domain and electrostatic interactions in the C-terminal α helix.
• Dimerization-defective variants confirmed the proposed stabilization mechanism.

Conclusions:

• LEDGF/p75 dimerization is a key regulatory mechanism.
• The identified structural features provide insights into LEDGF/p75 function.
• Dimerization significantly influences the LEDGF/p75 interactome.