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The role of structural domains in RIP II toxin model membrane binding
Author(s) -
Agapov Igor I,
Tonevitsky Alexander G,
Shamshiev Abdijapar T,
Pohl Elena,
Pohl Peter,
Palmer Rex A,
Kirpichnikov Michail P
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01452-4
Subject(s) - ricin , liposome , lectin , chemistry , toxin , biochemistry , phospholipid , lipid bilayer fusion , protein subunit , membrane , biophysics , biology , gene
The interaction of plant toxin ricin and MLI binding subunits to liposomes containing monosialoganglioside (GM1), bearing a terminal galactose residue, has been examined as a possible receptor model. For the first time we demonstrate that ricin B‐chain but not ricin provokes liposome aggregation at 10 M% GM1 concentration, whereas in the presence of either ricin A‐chain or galactose the aggregation is inhibited. The B‐subunit of plant toxin MLI from Viscum album has similar lectin specificity and activity but cannot aggregate GM1 liposomes. The ability of the B‐chain to aggregate liposomes adds a new crucial step in the toxin transmembrane penetration mechanism. We demonstrate here possible ricin B‐chain interactions with membranes proceeding via two sites, namely (a) a galactose‐binding domain and (b) a hydrophobic interchain domain. In close contact with two phospholipid bilayers, ricin B‐chain may determine the geometry of the fusion site. These events can provoke A‐chain translocation which follows membrane fusion.