%0 Journal Article
%A Alegre Cebollada, Jorge
%A Cunietti, Michela
%A Herrero Galán, Elías
%A Gavilanes, José G.
%A Martínez Del Pozo, Álvaro
%T Calorimetric scrutiny of lipid binding by sticholysinII toxin mutants
%D 2008
%@ 0022-2836
%U https://hdl.handle.net/20.500.14352/52956
%X The mechanisms by which pore-forming toxins are able to insert into lipidmembranes are a subject of the highest interest in the field of lipid–proteininteraction. Eight mutants affecting different regions of sticholysin II, amember of the pore-forming actinoporin family, have been produced, andtheir hemolytic and lipid-binding properties were compared to those of thewild-type protein. A thermodynamic approach to the mechanism of poreformation is also presented. Isothermal titration calorimetry experimentsshow that pore formation by sticholysin II is an enthalpy-driven processthat occurs with a high affinity constant (1.7×108 M−1). Results suggest thatconformational flexibility at the N-terminus of the protein does not providehigher affinity for the membrane, although it is necessary for correct poreformation. Membrane binding is achieved through two separate mechanisms,that is, recognition of the lipid–water interface by a cluster of aromaticresidues and additional specific interactions that include a phosphocholinebindingsite. Thermodynamic parameters derived from titration experimentsare discussed in terms of a putative model for pore formation.
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