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PMID:22934938

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Citation

Paul, K and Chattopadhyay, K (2012) Single point mutation in Vibrio cholerae cytolysin compromises the membrane pore-formation mechanism of the toxin. FEBS J. 279:4039-51

Abstract

Vibrio cholerae cytolysin (VCC) belongs to the family of β-barrel pore-forming protein toxins. VCC is secreted by the bacteria as water-soluble monomers, which upon binding to target eukaryotic cells form transmembrane heptameric β-barrel channels. High-resolution 3D structures are described both for the water-soluble monomeric form and the transmembrane oligomeric pore; albeit that our understanding of the mechanistic details of the membrane pore-formation process remains incomplete. Here, we report the characterization of a nonfunctional VCC variant harboring a single point mutation of Ala425Val positioned within a potential membrane-interacting loop in the VCC structure. The mutation appears to affect interaction of the toxin with erythrocytes as well as cholesterol-containing liposome membrane, without affecting the oligomerization ability of the membrane-bound toxin molecules. The membrane-bound oligomers formed by this VCC mutant do not appear to represent the functional pore assembly of the toxin; rather, such assembly could be considered as being trapped in an abortive, nonfunctional oligomeric state. Our results suggest that the Ala425Val mutation in VCC critically compromises its cholesterol-dependent membrane-interaction mechanism and also abrogates the process of functional membrane pore formation by the toxin.

Links

PubMed Online version:10.1111/j.1742-4658.2012.08809.x

Keywords

Blotting, Western; Cholesterol/metabolism; Cytotoxins/pharmacology; Enzyme-Linked Immunosorbent Assay; Erythrocyte Membrane/drug effects; Erythrocyte Membrane/metabolism; Flow Cytometry; Hemolysis/drug effects; Humans; Liposomes; Perforin/chemistry; Perforin/genetics; Perforin/pharmacology; Phosphatidylcholines/metabolism; Point Mutation/genetics; Protein Conformation; Protein Multimerization; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Vibrio cholerae/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

VIBCH:HLYA

enables

GO:0042802: identical protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:P09545

F

Seeded From UniProt

complete

Notes

See also

References

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