"Lunar Landers"

This is my single-frame movie of the heat-labile enterotoxin (LT) from E. coli attacking a gut cell. The two lunar lander modules are each a single hexameric protein assembly as seen in the crystal structure of the LT AB5 holotoxin. The lunar surface is the outer membrane of an intestinal epithelial cell. Just visible protruding from the membrane surface under the toxin which has landed are five copies of the saccharide moitie of ganglioside GM1, to which the toxin binds. GM1 is a normal membrane component which the toxin coopts as a receptor. The toxin:GM1 association is modeled from the crystal structure of CTB:saccharide complex reported in Merritt et al (1994) Protein Science 3: 166-175.

More information (and pictures) from crystallographic study of bacterial toxins is also available via the web.

The picture was generated using the program Raster3D, which you can find elsewhere on this web site.

You can click on the small picture above to retrieve a much larger JPEG version of the same image.

Ethan A Merritt / merritt@u.washington.edu