Calorimetric scrutiny of lipid binding by sticholysin II toxin mutants



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Alegre Cebollada, Jorge and Cunietti, Michela and Herrero Galán, Elías and Gavilanes, José G. and Martínez del Pozo, Álvaro (2008) Calorimetric scrutiny of lipid binding by sticholysin II toxin mutants. Journal of Molecular Biology, 382 . pp. 920-930. ISSN 0022-2836

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The mechanisms by which pore-forming toxins are able to insert into lipid
membranes are a subject of the highest interest in the field of lipid–protein
interaction. Eight mutants affecting different regions of sticholysin II, a
member of the pore-forming actinoporin family, have been produced, and
their hemolytic and lipid-binding properties were compared to those of the
wild-type protein. A thermodynamic approach to the mechanism of pore
formation is also presented. Isothermal titration calorimetry experiments
show that pore formation by sticholysin II is an enthalpy-driven process
that occurs with a high affinity constant (1.7×108 M−1). Results suggest that
conformational flexibility at the N-terminus of the protein does not provide
higher affinity for the membrane, although it is necessary for correct pore
formation. Membrane binding is achieved through two separate mechanisms,
that is, recognition of the lipid–water interface by a cluster of aromatic
residues and additional specific interactions that include a phosphocholinebinding
site. Thermodynamic parameters derived from titration experiments
are discussed in terms of a putative model for pore formation.

Item Type:Article
Uncontrolled Keywords:Actinoporin, Equinatoxin, Hemolytic toxin, ITC, Lipid binding
Subjects:Sciences > Chemistry > Chemistry, Physical and theoretical
Sciences > Chemistry > Biochemistry
Medical sciences > Biology > Biotechnology
Medical sciences > Biology > Molecular biology
ID Code:8092
Deposited On:03 Oct 2008 11:03
Last Modified:06 Feb 2014 07:59

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