Rabphilin 3A binds the N-peptide of SNAP-25 to promote SNARE complex assembly in exocytosis.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36173100.
- Also identified by DOI 10.7554/eLife.79926 and PMC identifier 9522249.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Exocytosis of secretory vesicles requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and small GTPase Rabs. As a Rab3/Rab27 effector protein on secretory vesicles, Rabphilin 3A was implicated to interact with SNAP-25 to regulate vesicle exocytosis in neurons and neuroendocrine cells, yet the underlying mechanism remains unclear. In this study, we have characterized the physiologically relevant binding sites between Rabphilin 3A and SNAP-25. We found that an intramolecular interplay between the N-terminal Rab-binding domain and C-terminal C<sub>2</sub>AB domain enables Rabphilin 3A to strongly bind the SNAP-25 N-peptide region via its C<sub>2</sub>B bottom α-helix. Disruption of this interaction significantly impaired docking and fusion of vesicles with the plasma membrane in rat PC12 cells. In addition, we found that this interaction allows Rabphilin 3A to accelerate SNARE complex assembly. Furthermore, we revealed that this interaction accelerates SNARE complex assembly via inducing a conformational switch from random coils to α-helical structure in the SNAP-25 SNARE motif. Altogether, our data suggest that the promotion of SNARE complex assembly by binding the C<sub>2</sub>B bottom α-helix of Rabphilin 3A to the N-peptide of SNAP-25 underlies a pre-fusion function of Rabphilin 3A in vesicle exocytosis.
Medical subject headings
- Adaptor Proteins, Signal Transducing
- Exocytosis
- Membrane Fusion
- Nerve Tissue Proteins
- Synaptosomal-Associated Protein 25
- Vesicular Transport Proteins