Puroindoline-a and alpha1-purothionin form ion channels in giant liposomes but exert different toxic actions on murine cells.
Puroindoline-a (PIN-a) and alpha1-purothionin (alpha1-PTH), isolated from wheat endosperm of Triticum aestivum sp., have been suggested to play a role in plant defence mechanisms against phytopathogenic organisms. We investigated their ability to form pores when incorporated into giant liposomes using the patch-clamp technique. PIN-a formed cationic channels (approximately 15 pS) with the following selectivity K(+) > Na(+) >> Cl(-). Also, alpha1-PTH formed channels of approximately 46 pS and 125 pS at +100 mV, the selectivity of which was Ca(2+) > Na(+) approximately K(+) >> Cl(-) and Cl(-) >> Na(+), respectively. In isolated mouse neuromuscular preparations, alpha1-PTH induced muscle membrane depolarization, leading to blockade of synaptic transmission and directly elicited muscle twitches. Also, alpha1-PTH caused swelling of differentiated neuroblastoma NG108-15 cells, membrane bleb formation, and disorganization of F-actin. In contrast, similar concentrations of PIN-a had no detectable effects. The cytotoxic actions of alpha1-PTH on mammalian cells may be explained by its ability to induce cationic-selective channels.
Llanos
Paola
P
Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago.
Henriquez
Mauricio
M
Minic
Jasmina
J
Elmorjani
Khalil
K
Marion
Didier
D
Riquelme
Gloria
G
Molgó
Jordi
J
Benoit
Evelyne
E
D000199:Actins / Q000378:metabolism; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D002412:Cations / Q000378:metabolism*; D002454:Cell Differentiation; D002462:Cell Membrane / Q000187:drug effects; D003964:Diaphragm / Q000187:drug effects* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D007473:Ion Channels / Q000378:metabolism*; D008081:Liposomes; D051379:Mice; D018613:Microscopy, Confocal; D009447:Neuroblastoma / Q000188:drug therapy / Q000473:pathology; D018408:Patch-Clamp Techniques; D010791:Phrenic Nerve / Q000187:drug effects* / Q000378:metabolism; D010940:Plant Proteins / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D014908:Triticum / Q000737:chemistry; D014407:Tumor Cells, Cultured
D000199:Actins; D023181:Antimicrobial Cationic Peptides; D002412:Cations; D007473:Ion Channels; D008081:Liposomes; D010940:Plant Proteins; C082942:puroindoline protein, Triticum aestivum; C063948:alpha1-purothionin protein, wheat