The role of structural domains in RIP II toxin model membrane binding

FEBS Letters

Pohl, Elena³  Tonevitsky, Alexander G⁴  Pohl, Peter³  Kirpichnikov, Michail P¹  Shamshiev, Abdijapar T⁴  Palmer, Rex A²  Agapov, Igor I⁴ 

[1] Institute of Molecular Biology, Russian Academy of Science, Vavilov st. 32, 117984 Moscow, Russian Federation;Crystallography Department, Birkbeck College, University of London, Malet Street, London WCIE 7HX, UK;Department of Medical Physics and Biophysics, Martin Luther University, Str. OdF 6, 06097 Halle, Germany;State Scientific Center for Genetics and Selection of Microorganisms, GosNIIGENETIKA, 1st Dorozhny pr. 1, Moscow 113545, Russian Federation

关键词: Ricin;    Ricin B-chain;    Mistletoe lectin I;    Liposome aggregation;    RTB;    ricin B-chain;    RTA;    ricin A-chain;    MLI;    mistletoe lectin I;    MLIB;    mistletoe lectin I B-chain;    PBS;    phosphate-buffered saline;    BSA;    bovine serum albumin;    DMPC;    dimyristoylphosphatidylcholine;    IC50;    toxin concentration causing 50% inhibition of [3H]thymidine incorporation into cells;   

DOI  :  10.1016/S0014-5793(96)01452-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown