IGA PROTEASE FROM NEISSERIA-GONORRHOEAE INHIBITS EXOCYTOSIS IN BOVINECHROMAFFIN CELLS LIKE TETANUS TOXIN

When tetanus toxin from Clostridium tetani or IgA protease from Neisse ria gonorrhoeae is translocated artificially into the cytosol of chrom affin cells, both enzymes inhibit calcium-induced exocytosis, which ca n be measured by changes in membrane capacitance. The block of exocyto sis caused by both proteases cannot be reversed by enforced stimulatio n with increased calcium concentration. This effect differs from the b otulinum A neurotoxin-induced block of exocytosis that can be overcome by elevation of the intracellular calcium concentration. Tetanus toxi n is about 50-fold more potent than IgA protease in cells stimulated b y carbachol. In this case, the release of [H-3]noradrenaline was deter mined. Trypsin and endoprotease Glu-C are hardly effective and only at concentrations that disturb the integrity of the cells. Like tetanus toxin, IgA protease also splits synaptobrevin II, though at a differen t site of the molecule. However, unlike tetanus toxin, it does not cle ave cellubrevin. It is concluded that the membranes of chromaffin vesi cles contain synaptobrevin II, which, as in neurons, appears to play a crucial part in exocytosis.