Trachynilysin, a Neurosecretory Protein Isolated from Stonefish
(Synanceia trachynis) Venom, Forms Nonselective Pores in
the Membrane of NG108-15 Cells*
Gilles
Ouanounou
§,
Michel
Malo§,
Jacques
Stinnakre,
Arnold S.
Kreger¶, and
Jordi
Molgó
From the Laboratoire de Neurobiologie Cellulaire et
Moléculaire, UPR 9040 CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France and the ¶ Department of Epidemiology
and Preventive Medicine, University of Maryland School of Medicine,
Baltimore, Maryland 21201-1595
Trachynilysin, a protein toxin isolated from the
venom of the stonefish Synanceia trachynis, has been
reported to elicit massive acetylcholine release from motor nerve
endings of isolated neuromuscular preparations and to increase both
cytosolic Ca2+ and catecholamine release from chromaffin
cells. In the present study, we used the patch clamp technique to
investigate the effect of trachynilysin on the cytoplasmic membrane of
differentiated NG108-15 cells in culture. Trachynilysin increased
membrane conductance the most when the negativity of the cell holding
membrane potential was reduced. The trachynilysin-induced current was
carried by cations and reversed at about 
3 mV in standard
physiological solutions, which led to strong membrane depolarization
and Ca2+ influx. La3+ blocked the trachynilysin
current in a dose-, voltage-, and time-dependent manner,
and antibodies raised against the toxin antagonized its effect on the
cell membrane. The inside-out configuration of the patch clamp
technique allowed the recording of single channel activity from which
various multiples of 22 pS elementary conductance were resolved.
These results indicate that trachynilysin forms pores in the NG108-15
cell membrane, and they advance our understanding of the toxin's mode
of action on motor nerve endings and neurosecretory cells.
*
This work was supported in part by the CNRS, by a grant from
the Direction des Systèmes de Forces et de la Prospective (to J. M.), and by National Institutes of Health Public Health Service Grant GM-43728 (to A. S. K.).The costs of publication of this article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. Section
1734 solely to indicate this fact.
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