Transduction of the scorpion toxin maurocalcine into cells. Evidence that the toxin crosses the plasma membrane.
Maurocalcine (MCa) is a 33-amino-acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. External application of MCa to cultured myotubes is known to produce Ca2+ release from intracellular stores. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long lasting channel openings in a mode of smaller conductance. Here we investigated the way MCa proceeds to cross biological membranes to reach its target. A biotinylated derivative of MCa was produced (MCa(b)) and complexed with a fluorescent indicator (streptavidine-cyanine 3) to follow the cell penetration of the toxin. The toxin complex efficiently penetrated into various cell types without requiring metabolic energy (low temperature) or implicating an endocytosis mechanism. MCa appeared to share the same features as the so-called cell-penetrating peptides. Our results provide evidence that MCa has the ability to act as a molecular carrier and to cross cell membranes in a rapid manner (1-2 min), making this toxin the first demonstrated example of a scorpion toxin that translocates into cells.
Estève
Eric
E
INSERM U607, Canaux Calciques, Fonctions et Pathologies, Département Réponse et Dynamique Cellulaire, Commissariat à l'Energie Atomique Grenoble, 17 Rue des Martyrs, 38054 Grenoble Cedex 09, France.
Mabrouk
Kamel
K
Dupuis
Alain
A
Smida-Rezgui
Sophia
S
Altafaj
Xavier
X
Grunwald
Didier
D
Platel
Jean-Claude
JC
Andreotti
Nicolas
N
Marty
Isabelle
I
Sabatier
Jean-Marc
JM
Ronjat
Michel
M
De Waard
Michel
M
D000595:Amino Acid Sequence; D001692:Biological Transport; D019921:Biotinylation; D002118:Calcium / Q000737:chemistry; D002352:Carrier Proteins / Q000737:chemistry; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D004705:Endocytosis; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015696:Gene Products, tat / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D020033:Protein Isoforms; D021381:Protein Transport; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D012604:Scorpion Venoms / Q000378:metabolism* / Q000493:pharmacokinetics; D015398:Signal Transduction; D013696:Temperature; D013997:Time Factors
D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D015696:Gene Products, tat; D010455:Peptides; D020033:Protein Isoforms; D019837:Ryanodine Receptor Calcium Release Channel; D012604:Scorpion Venoms; C406406:maurocalcine; D012433:Ryanodine; C414409:penetratin; D002118:Calcium