Fig. 1: Disruption of the Munc13C trimer interface. | Nature Communications

Fig. 1: Disruption of the Munc13C trimer interface.

From: Two successive oligomeric Munc13 assemblies scaffold vesicle docking and SNARE assembly to support neurotransmitter release

Fig. 1: Disruption of the Munc13C trimer interface.The alternative text for this image may have been generated using AI.

A Surface representation of the Munc13C trimer (PDB: 7T7R). Domain color code: C1 (pink), C2B (blue), MUN (orange), and C2C (cyan). B Top view of the trimer interface. Green dashed lines show the proposed interaction between acidic (red) and alkaline (blue) residues within the MUN-D region of three Munc13C molecules. Putative residues involved in trimer formation are D1358 and D1369 (helix H12 of MUN domain) and K1494, K1495, and K1500 (helix H15 of MUN domain). C Sequence alignments for MUN H12 and H15 helices for a select group of metazoa with identical and similar residues highlighted in blue and red, respectively. The residues mutated in the trimer variants are highlighted in yellow. Protein sequences used for alignment: hydra = H. vulgaris (XP012567200), worm = C. elegans (NP001021874), human = H. sapiens (NP001073890), rat = R. rattus (XP032775345), fly = D. melanogaster (NP651949), aplysia = A. californica (XP035824675). D Top view of representative sections from cryo-electron tomograms showing the effect of mutations on crystal formation by Munc13C between lipid bilayers. Wild-type Munc13C (top left) forms a continuous hexagonal lattice (blue), whereas reversing polarity of K1494/K1495/K1500 (3xD top right), D1358/D1369 (2xR lower left) and K1495/K1500 (2xD lower right) disrupted the lattice. Isolated hexagons (red circles) are visible without forming the characteristic honeycomb pattern of wild-type Munc13C. Scale bars are 50 nm. Ten or more tomograms were collected for each variant using three separate sample preparations (see Methods for cryo-electron tomography details).

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