Toxin studies using an integrated biophysical and structural biology approach.

Technical Report · Tue Mar 01 04:00:00 EST 2005

DOI:https://doi.org/10.2172/922768· OSTI ID:922768

Last, Julie A; Schroeder, Anne E; Slade, Andrea Lynn; Sasaki, Darryl Yoshio; Yip, Christopher M ^[1]; Schoeniger, Joseph S ^[2]

---

1. University of Toronto, Toronto, Ontario, Canada
2. Sandia National Laboratories, Livermore, CA

Clostridial neurotoxins, such as botulinum and tetanus, are generally thought to invade neural cells through a process of high affinity binding mediated by gangliosides, internalization via endosome formation, and subsequent membrane penetration of the catalytic domain activated by a pH drop in the endosome. This surface recognition and internalization process is still not well understood with regard to what specific membrane features the toxins target, the intermolecular interactions between bound toxins, and the molecular conformational changes that occur as a result of pH lowering. In an effort to elucidate the mechanism of tetanus toxin binding and permeation through the membrane a simple yet representative model was developed that consisted of the ganglioside G{sub tlb} incorporated in a bilayer of cholesterol and DPPC (dipalmitoylphosphatidyl choline). The bilayers were stable over time yet sensitive towards the binding and activity of whole toxin. A liposome leakage study at constant pH as well as with a pH gradient, to mimic the processes of the endosome, was used to elucidate the effect of pH on the toxin's membrane binding and permeation capability. Topographic imaging of the membrane surface, via in situ tapping mode AFM, provided nanoscale characterization of the toxin's binding location and pore formation activity.

• Research Organization: Sandia National Laboratories
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 922768
• Report Number(s): SAND2005-1700
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AFFINITY
BIOLOGY
Biology.
CHOLESTEROL
CHOLINE
CONFORMATIONAL CHANGES
GANGLIOSIDES
LIPOSOMES
MEMBRANES
Molecular biology-Methodology.
TETANUS
TOXINS
Toxins.