High resolution structure, stability, and synaptotagmin binding of a truncated neuronal SNARE complex

The structure of a truncated SNARE complex has been solved to 1.4-Angstrom resolution revealing a stabilizing salt bridge, sites of hydration, and conformational variability of the ionic central layer that were not observed in a previously published structure at 2.4-Angstrom resolution (Sutton, R. B., Fasshauer, D., Jahn, R., and Brunger, A. T. (1998) Nature 395, 347-353). The truncated complex lacks residues involved in phospholipid binding and denatures at a lower temperature than longer complexes as assessed by SDS and circular dichroism thermal melts. The truncated SNARE complex is monomeric, and it retains binding to synaptotagmin I.