Molecular basis for the recognition of adenomatous polyposis coli by the Discs Large 1 protein

Area of Science:

• Molecular Biology
• Structural Biology
• Cancer Research

Background:

• The Discs Large 1 (DLG1) protein interacts with the Adenomatous Polyposis Coli (APC) tumor suppressor protein.
• The DLG1/APC complex plays roles in cell cycle regulation, epithelial cell migration, and microtubule cytoskeleton polarization.
• The precise molecular mechanism of DLG1 recognition of APC remains unclear.

Purpose of the Study:

• To investigate the molecular details of the interaction between DLG1 PDZ domains and the APC C-terminal peptide.
• To elucidate the structural basis of DLG1-APC complex formation.

Main Methods:

• Biochemical and biophysical assays were employed to study DLG1-APC interactions.
• Crystal structures of DLG1 PDZ1 and PDZ2 domains complexed with the APC C-terminal peptide were determined.

Main Results:

• Structural and biochemical data identified crucial residues and structural elements in DLG1 PDZ domains and APC for their interaction.
• The β2/β3 loops of DLG1 PDZ1 and PDZ2 domains were found to be critical for binding affinity.
• These loops interact with residues upstream of the canonical S/T-X-V motif in APC.

Conclusions:

• The study provides detailed structural insights into how DLG1 PDZ domains recognize a specific C-terminal segment of APC.
• The findings reveal the significant contribution of the β2/β3 loops in mediating DLG1-APC binding.
• This work enhances understanding of the molecular mechanisms underlying DLG1-APC complex function.