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1tzq
From Proteopedia
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Crystal structure of the equinatoxin II 8-69 double cysteine mutant
Overview
Actinoporins are eukaryotic pore-forming proteins that create 2-nm pores, in natural and model lipid membranes by the self-association of four, monomers. The regions that undergo conformational change and form part of, the transmembrane pore are currently being defined. It was shown recently, that the N-terminal region (residues 10-28) of equinatoxin, an actinoporin, from Actinia equina, participates in building of the final pore wall., Assuming that the pore is formed solely by a polypeptide chain, other, parts of the toxin should constitute the conductive channel and here we, searched for these regions by disulfide scanning mutagenesis. Only double, cysteine mutants where the N-terminal segment 1-30 was attached to the, beta-sandwich exhibited reduced hemolytic activity upon disulfide, formation, showing that other parts of equinatoxin, particularly the, beta-sandwich and importantly the C-terminal alpha-helix, do not undergo, large conformational rearrangements during the pore formation. The role of, the beta-sandwich stability was independently assessed via destabilization, of a part of its hydrophobic core by mutations of the buried Trp117. These, mutants were considerably less stable than the wild-type but exhibited, similar or slightly lower permeabilizing activity. Collectively these, results show that a flexible N-terminal region and stable beta-sandwich, are pre-requisite for proper pore formation by the actinoporin family.
About this Structure
1TZQ is a Single protein structure of sequence from Actinia equina. Full crystallographic information is available from OCA.
Reference
Pore formation by equinatoxin, a eukaryotic pore-forming toxin, requires a flexible N-terminal region and a stable beta-sandwich., Kristan K, Podlesek Z, Hojnik V, Gutierrez-Aguirre I, Guncar G, Turk D, Gonzalez-Manas JM, Lakey JH, Macek P, Anderluh G, J Biol Chem. 2004 Nov 5;279(45):46509-17. Epub 2004 Aug 20. PMID:15322132
Page seeded by OCA on Wed Nov 21 03:43:46 2007
