The PHD finger, a nuclear protein-interaction domain.

Area of Science:

• Molecular Biology
• Structural Biology
• Genomics

Background:

• PHD fingers are ubiquitous Zn(2+)-binding domains in eukaryotic genomes.
• They share structural similarity with RING domains, known for mediating protein ubiquitination.
• The specific functions and commonalities among PHD fingers remain largely undefined.

Purpose of the Study:

• To investigate the potential common functions of PHD fingers.
• To explore the substrate specificity of PHD fingers, particularly in the nuclear context.
• To determine if PHD fingers interact with chromatin or nucleosomes.

Main Methods:

• Bioinformatic analysis of PHD finger distribution and conservation.
• Structural comparison of PHD fingers and RING domains.
• Experimental investigation of PHD finger-protein and PHD finger-nucleosome interactions (implied).

Main Results:

• PHD fingers are predominantly found in nuclear proteins.
• Many PHD fingers interact with nuclear proteins via a surface similar to that used by RING domains for E2 ligase binding.
• Emerging data indicate PHD finger binding to nucleosomes, suggesting chromatin as a potential common ligand.

Conclusions:

• PHD fingers may share a common functional role related to chromatin.
• The interaction surface for nuclear partners is conserved between PHD and RING domains.
• Chromatin is a likely common nuclear ligand for PHD fingers, highlighting their role in nuclear processes.