The conserved C2 phospholipid-binding domain in Delta contributes to robust Notch signalling

Area of Science:

• Developmental Biology
• Cell Signaling
• Structural Biology

Background:

• Notch signaling is essential for development and homeostasis.
• Notch ligand-receptor interactions are finely tuned, impacting signaling outcomes.
• A conserved C2 domain in human Notch ligands binds phospholipids in vitro.

Purpose of the Study:

• To investigate the structure and function of the C2 domain in Drosophila Notch ligands (Delta and Serrate).
• To determine the in vivo role of C2 domain phospholipid binding in Notch signaling.

Main Methods:

• Structural analysis of Drosophila Delta and Serrate C2 domains.
• In vitro phospholipid binding assays with mutated Delta C2 domains.
• In vivo functional analysis of endogenous Delta with a deleted β1-2 loop.

Main Results:

• Drosophila Delta and Serrate possess C2 domains similar to human ligands, with variations in phospholipid-binding loops.
• Mutations in the Delta C2 domain's β1-2 loop impaired in vitro phospholipid binding but retained Notch binding.
• Deletion of five residues in the endogenous Delta β1-2 loop compromised ligand function in vivo, affecting Notch signaling phenotypes.

Conclusions:

• C2 domain phospholipid binding is essential for robust Notch ligand function in vivo.
• This interaction fine-tunes the balance between trans and cis ligand-receptor interactions.
• The findings reveal a conserved mechanism for Notch signaling regulation across species.