1TZQ

Crystal structure of the equinatoxin II 8-69 double cysteine mutant

Summary for 1TZQ

• Entry DOI: 10.2210/pdb1tzq/pdb
• Related: 1IAZ
• Descriptor: Equinatoxin II (2 entities in total)
• Functional Keywords: beta-sandwich, toxin
• Biological source: Actinia equina
• Cellular location: Secreted: P61914
• Total number of polymer chains: 1
• Total formula weight: 19451.03

Authors

Kristan, K.,Podlesek, Z.,Hojnik, V.,Gutirrez-Aguirre, I.,Guncar, G.,Turk, D.A.,Gonzalez-Maas, J.M.,Lakey, J.H.,Anderluh, G. (deposition date: 2004-07-11, release date: 2004-09-28, Last modification date: 2024-11-20)

Primary citation

Kristan, K.,Podlesek, Z.,Hojnik, V.,Gutierrez-Aguirre, I.,Guncar, G.,Turk, D.A.,Gonzalez-Manas, J.M.,Lakey, J.H.,Macek, P.,Anderluh, G.
Pore formation by equinatoxin, a eukaryotic pore-forming toxin, requires a flexible N-terminal region and a stable beta-sandwich
J.Biol.Chem., 279:46509-46517, 2004

PubMed Abstract: 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.

PubMed: 15322132
DOI: 10.1074/jbc.M406193200

Experimental method

X-RAY DIFFRACTION (2.3 Å)