In Axel Brunger's laboratory I performed structural and a modicum of biochemical studies on N-ethylmaleimide sensitive factor , a eukaryotic protein involved in membrane fusion. It seems to act not as an actual fusion protein, but by making membranes competent for fusion. A group of proteins known as SNAREs are found on membranes and, during the fusion process, form huge four-member helical bundles (a structure which was recently solved by our lab and collaborators). Current simple models propose that after one round of fusion, NSF and an adaptor protein, a SNAP protein, bind to and disrupt this stable SNARE complex, making the SNARE components competent to fuse. NSF, an ATPase, appears to drive this disruption with energy from ATP hydroppears to drive this disruption with energy from ATP hydrolysis.
We solved two domains of this three domain protein. First, we solved the structure of the oligomerization domain ("D2" or "NSF-D2") of this protein (jpeg ribbon diagram, PDB coordinates). We found some interesting details about how ATP binding contributes to the stability of NSF oligomerization. Currently, Axel's lab (in addition to other labs, I'm sure) is working on getting the whole NSF shebang, all by its lonesome and complexed with the SNAP/SNARE ultra-mega-complex, which would shed some light on not only the immediate question of how ATP hydrolysis is linked to complex disruption, but also provide unique high-resolution structural information on the so-called AAA superfamily of proteins.
We also determined the structure of the N-terminal domain ("N" or "NSF-N") of NSF (jpeg ribbon diagram, PDB coordinates here). In light of the structure (by Luke Rice) of Sec17, the yeast homologue of alpha-SNAP solved right around the time NSF-N was, we proposed a binding model, consistent with existing biochemical data, that has a large, positive groove on the surface of N interacting with the negatively charged, C-terminal helical region of alpha-SNAP.
One of these days I'll get my thesis online.
[Back]Last updated 01.2002.
