Abstract - Werner

The SNAP-25a (isoform 2) protein is a part of the SNARE complex, a four-helix bundle composed of SNAP-25a and the two other SNARE proteins synaptobrevin-2 and syntaxin-1a. SNAREs are responsible for the transport of vesicles and membrane fusion to exocytosis. SNAP-25a contributes with two α-helices, while synaptobrevin-2 and syntaxin-1a contribute with one helix each to a four-helix bundle. In its monomeric pre-fusion form, SNAP-25a is disordered, except for two α-helices at the N-terminus and displays a high flexibility1. SNAP-25a lacks a transmembrane region but hasfour palmitoylation sites that anchor the protein to the cell membrane. We aim for deeper insights into the structural dynamics and long-range interaction of the pre-fusion SNAP- 25a monomer in the presence and absence of a lipid bilayer. Our current focus is a possible interaction between the N- and C-terminus of SNAP-25a and the palmitoylation site. NMR spectroscopy is used as the primary technique supported by further biophysical methods. Paramagnetic relaxation enhancement (PRE) data are recorded to obtain long-rangedistance information relative to a paramagnetic spin-label (MTSL). High-purity protein samples for a diamagnetic wildtype and a cysteine mutant were obtained, and the paramagnetic spin label was introduced successfully. Both yielded well-resolved NMR spectra. 1HT2 relaxation data are currently recorded for the PREs and will be presented at the conference.

Sophia Werner (HHU), Tobias Stief (HHU,FZJ), Katharina Vormann (HHU,FZJ), Selcuk Er (HHU)