Biophysical characterization of gossypium synaptotagmin-1 C2B domain

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Synaptotagmins constitute a family of membrane-trafficking proteins that are characterized by an N-terminal transmembrane region a variable linker, and two C-terminal C2-domains. In humans, neurotransmitter release is a process highly regulated by intracellular Ca2+ levels in association with SNARE complex assembly and SYT-1 protein. In plants SYT-1 is the first synaptotagmin protein identified to participate in Ca2+ dependent repair of membranes, thus playing an important role in stress tolerance. Our long term goal is to tune the response of Gossipium SYT-1 to abiotic stress. Understanding the quaternary structure of SYT-1 C2 in plants as well as how it interacts with its cations and phospholipid is essential to further our understanding of how it exhibits its unique properties. So far, we have been successful in;

  1. Developing purification protocols for Gossipium SYT-1 C2B domain, WW and AA mutants.
  2. We have circular dichroism (CD) data that shows that it predominantly contains β-sheets.
  3. We have probably obtained crystals in several different conditions.
  4. We have confirmed the mutants through Mass Spectrometric analysis.
  5. We have shown the affinity of Gossypium SYT-1 C2B WT to cations as well as to phospholipids.
  6. The effect of mutations in the Ca2+ binding loop of Gossypium SYT-1 C2B was also studied.