Christiane Leprince

Functional Roles of Domains of Clostridial Neurotoxins: The Contribution from Studies on Aplysia

In recent years there has been increasing interest in the study of the mode of action of botulinum neurotoxin (BoNT) and tetanus toxin (TeTx) at the cellular level (for recent reviews see Simpson, 1986, 1989; Habermann and Dreyer, 1986; Niemann, 1991; Poulain and Molgo, 1992; Wellhoner, 1992, Dolly, 1992, and this volume). This is mainly due to the unique ability of these toxins to effectively block neurotransmitter release in all types of nerve terminals once they gain access inside the nerve endings; BoNTs and TeTx are, thus, useful research tools to study transmitter release mechanisms and tools in medicine. Deciphering their intracellular modes of action still remains a challenge for future research; however, during the last decade continuous progress has been made in the identification of the functional domains of BoNTs and TeTx implicated in the multiple facets of the intoxication. Using neuronal preparations from Aplysra, an identification of the functional role of different protein domains of BoNTs and TeTx has been made which contrasts somewhat with those proposed for vertebrates. Thus the aim of the present paper is to review data in Aplysra and, also, to stress the similarities and differences into observations made in the various models.