title: A non-classical assembly pathway of Escherichia coli pore-forming toxin cytolysin A.
abstract: Cytolysin A (ClyA) is an α-pore forming toxin from pathogenic Escherichia coli (E. coli) and Salmonella enterica. Here, we report that E. coli ClyA assembles into an oligomeric structure in solution in the absence of either bilayer membranes or detergents at physiological temperature. These oligomers can rearrange to create transmembrane pores when in contact with detergents or biological membranes. Intrinsic fluorescence measurements revealed that oligomers adopted an intermediate state found during the transition between monomer and transmembrane pore. These results indicate that the water-soluble oligomer represents a prepore intermediate state. Furthermore, we show that ClyA does not form transmembrane pores on E. coli lipid membranes. Because ClyA is delivered to the target host cell in an oligomeric conformation within outer membrane vesicles (OMVs), our findings suggest ClyA forms a prepore oligomeric structure independently of the lipid membrane within the OMV. The proposed model for ClyA represents a non-classical pathway to attack eukaryotic host cells.
authors.affiliation: From the Departments of Chemistry and.
authors.forename: Monifa
authors.initials: M
authors.lastname: Fahie
authors.forename: Fabian B
authors.initials: FB
authors.lastname: Romano
authors.forename: Christina
authors.initials: C
authors.lastname: Chisholm
authors.forename: Alejandro P
authors.initials: AP
authors.lastname: Heuck
authors.forename: Mark
authors.initials: M
authors.lastname: Zbinden
authors.forename: Min
authors.initials: M
authors.lastname: Chen
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D048168:Escherichia coli K12 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D008956:Models, Chemical; D055503:Protein Multimerization / Q000502:physiology*; D019779:Salmonella enterica / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; D008563:Membrane Lipids; C119944:hlyE protein, E coli
keywords: Bacterial Pathogenesis; Bacterial Toxins; ClyA; Electrophysiology; Escherichia coli; Membrane Proteins; Outer Membrane Vesicle; Pore-forming Toxin; Protein Assembly
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