A conserved clathrin assembly motif essential for synaptic vesicle endocytosis

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Clathrin assembly by adaptor proteins (APs) is vital for synaptic vesicle recycling.
• The precise molecular mechanisms by which APs facilitate clathrin assembly remain largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanism of clathrin assembly mediated by adaptor proteins.
• To identify the specific motif responsible for clathrin binding and assembly.

Main Methods:

• Sequence analysis to identify conserved motifs in clathrin APs.
• In vitro clathrin assembly assays with modified AP180.
• Inhibition studies using peptides containing the identified motif.
• Microinjection into squid giant presynaptic terminals to assess in vivo effects.

Main Results:

• AP180, similar to AP-2 and AP-3, binds the N-terminal domain of clathrin.
• A conserved DLL motif within APs was identified as critical for clathrin assembly.
• Deletion of DLL motifs reduced AP180's clathrin assembly ability in vitro.
• Peptides with the DLL motif inhibited clathrin assembly and synaptic vesicle endocytosis in vivo.

Conclusions:

• The DLL motif confers clathrin assembly properties to AP180 and AP-2.
• APs likely cross-link clathrin triskelia via multivalent interactions involving DLL motifs.
• This study reveals the structural basis of clathrin assembly and its role in synaptic vesicle endocytosis.