Clostridial neurotoxins, deadly toxins that also can heal -How do these large proteins bind to, and then cross the membrane?

We propose to study the clostridial neurotoxins, a family of protein toxins that include the closely related tetanus and botulinum neurotoxins, which are the most toxic substances known. Even though these toxins can be deadly, the botulinum neurotoxins are extensively used therapeutically.

The clostridial neurotoxins perform all of their key functions at or in the membrane. In spite of this, the membrane itself has generally been neglected in studies. We will generate the first structural insights on how the clostridial toxins function on the membrane and in the membrane.We will study:How the soluble translocation domain is transformed into a transmembrane pore, capable of moving entire proteins across the membraneHow binding to cell surface receptors at the membrane occursThe total binding avidity of the clostridial neurotoxins to intact neuronal cells, and how distinct interactions contribute to the total avidityThe structures, receptors, substrates, lipid interactions of recently identified, novel toxinsWe will employ recent method developments and advances which include:Single-particle cryo-EMQuartz crystal microbalance biosensorsThe structure and mechanism of the enigmatic translocation of the clostridial neurotoxins across the membrane and receptor binding at the membrane surface are complex, high risk/high gain questions. We will decipher how the soluble toxins are transformed into transmembrane channels capable of translocating entire proteins across the lipid bilayer.