IgA protease from Neisseria gonorrhoeae inhibits exocytosis in bovine chromaffin cells like tetanus toxin.

When tetanus toxin from Clostridium tetani or IgA protease from Neisseria gonorrhoeae is translocated artificially into the cytosol of chromaffin cells, both enzymes inhibit calcium-induced exocytosis, which can be measured by changes in membrane capacitance. The block of exocytosis caused by both proteases cannot be reversed by enforced stimulation with increased calcium concentration. This effect differs from the botulinum A neurotoxin-induced block of exocytosis that can be overcome by elevation of the intracellular calcium concentration.

Specific antibodies against the Zn(2+)-binding domain of clostridial neurotoxins restore exocytosis in chromaffin cells treated with tetanus or botulinum A neurotoxin.

Although tetanus and botulinum A neurotoxins are ineffective in cultured chromaffin cells, they will inhibit carbachol-induced release of noradrenaline provided they gain access to the cytosol either through artificial pores generated in the plasma membrane or by binding to incorporated exogenous gangliosides. The block of exocytosis persists for weeks followed by a slow recovery of cell function. When specific anti-botulinum A toxin antibodies are introduced into cells through pores after manifestation of the block by botulinum A neurotoxin, restoration of exocytotic function is accelerated and fully reestablished within 4 days.