Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review
Mutant alpha-latrotoxin (LTXN4C) does not form pores and causes secretion by receptor stimulation : this action does not require neurexins. / Volynski, Kirill E; Capogna, Marco; Ashton, Anthony C et al.
In: The Journal of biological chemistry, Vol. 278, No. 33, 15.08.2003, p. 31058-66.Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review
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TY - JOUR
T1 - Mutant alpha-latrotoxin (LTXN4C) does not form pores and causes secretion by receptor stimulation
T2 - this action does not require neurexins
AU - Volynski, Kirill E
AU - Capogna, Marco
AU - Ashton, Anthony C
AU - Thomson, Derek
AU - Orlova, Elena V
AU - Manser, Catherine F
AU - Ribchester, Richard R
AU - Ushkaryov, Yuri A
PY - 2003/8/15
Y1 - 2003/8/15
N2 - Alpha-latrotoxin (LTX) causes massive release of neurotransmitters via a complex mechanism involving (i) activation of receptor(s) and (ii) toxin insertion into the plasma membrane with (iii) subsequent pore formation. Using cryo-electron microscopy, electrophysiological and biochemical methods, we demonstrate here that the recently described toxin mutant (LTXN4C) is unable to insert into membranes and form pores due to its inability to assemble into tetramers. However, this mutant still binds to major LTX receptors (latrophilin and neurexin) and causes strong transmitter exocytosis in synaptosomes, hippocampal slice cultures, neuromuscular junctions, and chromaffin cells. In the absence of mutant incorporation into the membrane, receptor activation must be the only mechanism by which LTXN4C triggers exocytosis. An interesting feature of this receptor-mediated transmitter release is its dependence on extracellular Ca2+. Because Ca2+ is also strictly required for LTX interaction with neurexin, the latter might be the only receptor mediating the LTXN4C action. To test this hypothesis, we used conditions (substitution of Ca2+ in the medium with Sr2+) under which LTXN4C does not bind to any member of the neurexin family but still interacts with latrophilin. We show that, in all the systems tested, Sr2+ fully replaces Ca2+ in supporting the stimulatory effect of LTXN4C. These results indicate that LTXN4C can cause neurotransmitter release just by stimulating a receptor and that neurexins are not critical for this receptor-mediated action.
AB - Alpha-latrotoxin (LTX) causes massive release of neurotransmitters via a complex mechanism involving (i) activation of receptor(s) and (ii) toxin insertion into the plasma membrane with (iii) subsequent pore formation. Using cryo-electron microscopy, electrophysiological and biochemical methods, we demonstrate here that the recently described toxin mutant (LTXN4C) is unable to insert into membranes and form pores due to its inability to assemble into tetramers. However, this mutant still binds to major LTX receptors (latrophilin and neurexin) and causes strong transmitter exocytosis in synaptosomes, hippocampal slice cultures, neuromuscular junctions, and chromaffin cells. In the absence of mutant incorporation into the membrane, receptor activation must be the only mechanism by which LTXN4C triggers exocytosis. An interesting feature of this receptor-mediated transmitter release is its dependence on extracellular Ca2+. Because Ca2+ is also strictly required for LTX interaction with neurexin, the latter might be the only receptor mediating the LTXN4C action. To test this hypothesis, we used conditions (substitution of Ca2+ in the medium with Sr2+) under which LTXN4C does not bind to any member of the neurexin family but still interacts with latrophilin. We show that, in all the systems tested, Sr2+ fully replaces Ca2+ in supporting the stimulatory effect of LTXN4C. These results indicate that LTXN4C can cause neurotransmitter release just by stimulating a receptor and that neurexins are not critical for this receptor-mediated action.
KW - Acetylcholine/metabolism
KW - Animals
KW - Black Widow Spider
KW - CHO Cells
KW - COS Cells
KW - Calcium/metabolism
KW - Carbon Radioisotopes
KW - Catecholamines/metabolism
KW - Cattle
KW - Cell Membrane/metabolism
KW - Chromaffin Cells/metabolism
KW - Cricetinae
KW - Exocytosis
KW - Glutamic Acid/pharmacokinetics
KW - Hippocampus/cytology
KW - Membrane Potentials/physiology
KW - Mice
KW - Mutation
KW - Neuromuscular Junction/metabolism
KW - Patch-Clamp Techniques
KW - Protein Structure, Quaternary
KW - Rats
KW - Receptors, Cell Surface/metabolism
KW - Spider Venoms/chemistry
KW - Strontium/pharmacology
KW - Synaptosomes/metabolism
U2 - 10.1074/jbc.M210395200
DO - 10.1074/jbc.M210395200
M3 - Journal article
C2 - 12782639
VL - 278
SP - 31058
EP - 31066
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 33
ER -