Molecular mechanism for pore-formation in lipid membranes by the hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata.
The pore-forming activity of CEL-III, a Gal/GalNAc specific lectin from the Holothuroidea Cucumaria echinata, was examined using artificial lipid membranes as a model system of erythrocyte membrane. The carboxyfluorescein (CF)-leakage studies clearly indicated that CEL-III induced the formation of pores in the dipalmitoyl phosphatidyl choline (DPPC)-lactosyl ceramide (LacCer) liposomes effectively but not in the DPPC-glucosyl ceramide (GlcCer) liposomes or DPPC liposomes. Such a leakage of CF was strongly inhibited by lactose, a potent inhibitor of CEL-III, suggesting that the leakage is mediated through the specific binding of CEL-III to the carbohydrate chains on the surface of the liposomes. The leakage of CF from the DPPC-lactosyl ceramide liposomes was pH-dependent, and it increased with increasing pH. The immunoblotting analysis and circular dichroism data indicated that upon interaction with liposomes, CEL-III associated to form an oligomer concomitantly with a marked conformational change. Furthermore, channel measurements showed that CEL-III has an ability to form small ion channels in the planar lipid bilayers consisting of diphytanoylphosphatidylcholine and human globoside (Gb4Cer)/LacCer.
Kouriki-Nagatomo
H
H
Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Hatakeyama
T
T
Jelokhani-Niaraki
M
M
Kondo
M
M
Ehara
T
T
Yamasaki
N
N
D000818:Animals; D015139:Blotting, Southern; D002942:Circular Dichroism; D005452:Fluoresceins / Q000737:chemistry; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D037102:Lectins / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes; D008970:Molecular Weight; D018408:Patch-Clamp Techniques; D016062:Porosity; D012616:Sea Cucumbers / Q000737:chemistry*
D005452:Fluoresceins; D037102:Lectins; D008051:Lipid Bilayers; D008081:Liposomes; C024098:6-carboxyfluorescein