Tyrosine Phosphorylation Modulates the Activity of Clostridial Neurotoxins

• Published in: The Journal of biological chemistry Vol. 271; no. 31; pp. 18322 - 18325
• Main Authors: Ferrer-Montiel, Antonio V., Canaves, Jaume M., DasGupta, Bibhuti R., Wilson, Michael C., Montal, Mauricio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.08.1996; American Society for Biochemistry and Molecular Biology
• Subjects: ACTIVIDAD CATALITICA; ACTIVITE CATALYTIQUE; Animals; Botulinum Toxins - metabolism; Botulinum Toxins - pharmacology; BOTULISM; BOTULISME; BOTULISMO; CALOR; CATALYTIC ACTIVITY; CHALEUR; CLOSTRIDIUM BOTULINUM; CLOSTRIDIUM TETANI; Focal Adhesion Kinase 2; FOSFORILACION; HEAT; HEAT STABILITY; In Vitro Techniques; KINASES; Kinetics; Membrane Proteins; Metalloendopeptidases - metabolism; Mice; Nerve Tissue Proteins - metabolism; NERVOUS SYSTEM; Neurotoxins - metabolism; Neurotoxins - pharmacology; PC12 Cells; PHOSPHORYLATION; PROTEIN DEPHOSPHORYLATION; PROTEIN PHOSPHORYLATION; Protein-Tyrosine Kinases - metabolism; PROTEOLISIS; PROTEOLYSE; PROTEOLYSIS; Rats; RESISTANCE A LA TEMPERATURE; RESISTENCIA A LA TEMPERATURA; SEROTIPOS; SEROTYPE; SEROTYPES; Signal Transduction; SISTEMA NERVIOSO; src-Family Kinases - metabolism; Substrate Specificity; Synaptic Transmission - drug effects; Synaptic Vesicles - drug effects; Synaptosomal-Associated Protein 25; SYSTEME NERVEUX; TEMPERATURE RESISTANCE; TETANO; TETANOS; TETANUS; TIROSINA; TOXINAS; TOXINE; TOXINS; TRANSFERASAS; TRANSFERASE; TRANSFERASES; TYROSINE; Tyrosine - metabolism; TYROSINE KINASES
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.31.18322

Clostridial neurotoxins' metalloprotease domain selectively cleaves proteins implicated in the process of synaptic vesicle fusion with the plasma membrane and, accordingly, blocks neurotransmitter release into the synaptic cleft. Here we investigate the potential modulation of these neurotoxins by intracellular cascades triggered by environmental signals, which in turn may alter its activity on target substrates. We report that the nonreceptor tyrosine kinase Src phosphorylates botulinum neurotoxins A, B, and E and tetanus neurotoxin. Protein tyrosine phosphorylation of serotypes A and E dramatically increases both their catalytic activity and thermal stability, while dephosphorylation reverses the effect. This suggests that the biologically significant form of the neurotoxins inside neurons is phosphorylated. Indeed, in PC12 cells in which tyrosine kinases such as Src and PYK2 are highly abundant, stimulation by membrane depolarization in presence of extracellular calcium induces rapid and selective tyrosine phosphorylation of internalized light chain, the metalloprotease domain, of botulinum toxin A. These findings provide a conceptual framework to connect intracellular signaling pathways involving tyrosine kinases, G-proteins, phosphoinositides, and calcium with the action of botulinum neurotoxins in abrogating vesicle fusion and neurosecretion.