Sequence-specific assignment of methyl groups from the neuronal SNARE complex using lanthanide-induced pseudocontact...

Area of Science:

• Structural Biology
• Neuroscience
• Biochemistry

Background:

• Neurotransmitter release relies on the neuronal SNARE complex (syntaxin-1, SNAP-25, synaptobrevin) and associated proteins.
• The precise assembly and membrane fusion mechanism of the SNARE complex remain incompletely understood despite available component structures.
• Methyl TROSY NMR is a valuable technique for studying protein complexes, but SNARE complex solubility issues hinder methyl group assignment.

Purpose of the Study:

• To assign the methyl groups of syntaxin-1, SNAP-25, and synaptobrevin within the neuronal SNARE complex.
• To overcome challenges posed by limited solubility for structural studies of the SNARE complex.
• To demonstrate a novel approach for protein resonance assignment using lanthanide-induced pseudocontact shifts.

Main Methods:

• Utilized Methyl TROSY Nuclear Magnetic Resonance (NMR) spectroscopy.
• Employed lanthanide-induced pseudocontact shifts (PCS) for resonance assignment.
• Focused on isoleucine, leucine, methionine, and valine methyl groups within the four SNARE motifs.

Main Results:

• Successfully assigned the methyl groups of syntaxin-1, SNAP-25, and synaptobrevin within the assembled SNARE complex.
• Achieved assignment solely through PCS measurements, bypassing the need for triple resonance experiments.
• Demonstrated the efficacy of PCS-based NMR for studying challenging, low-solubility protein complexes.

Conclusions:

• The PCS-based NMR approach provides an effective method for assigning protein resonances in low-solubility systems like the SNARE complex.
• This assignment is crucial for future structural investigations of SNARE complex interactions with other release machinery components.
• The findings facilitate a deeper understanding of the molecular mechanisms underlying fast, calcium-dependent neurotransmitter release.