Clathrin coat controls synaptic vesicle acidification by blocking vacuolar ATPase activity.

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Newly-formed synaptic vesicles (SVs) require acidification by vacuolar adenosine triphosphatases (vATPases) to establish a proton gradient for neurotransmitter uptake.
• The precise timing of SV acidification and refilling following clathrin-mediated endocytosis remains unclear at the synapse.

Purpose of the Study:

• To investigate the acidification capacity of clathrin-coated vesicles (CCVs) directly.
• To determine the role of the clathrin coat in regulating vATPase activity during SV recycling.

Main Methods:

• Isolation of clathrin-coated vesicles (CCVs) from mouse brain tissue.
• Direct measurement of ATP-dependent acidification at the single vesicle level.

Main Results:

• Clathrin-coated vesicles (CCVs) exhibited significantly reduced ATP-induced acidification compared to synaptic vesicles (SVs).
• Removal of the clathrin coat restored ATP-dependent acidification in CCVs, indicating the presence of functional vATPases.
• The clathrin coat directly inhibits the activity of the vATPase.

Conclusions:

• The clathrin coat acts as a functional inhibitor of the vATPase on newly formed vesicles.
• This coat-mediated inhibition is proposed to regulate the timing of vATPase activity and subsequent SV refilling at the synapse.