title: Novel evidence for the specific interaction between cholesterol and α-haemolysin of Escherichia coli.
abstract: Several toxins that act on animal cells present different, but specific, interactions with cholesterol or sphingomyelin. In the present study we demonstrate that HlyA (α-haemolysin) of Escherichia coli interacts directly with cholesterol. We have recently reported that HlyA became associated with detergent-resistant membranes enriched in cholesterol and sphingomyelin; moreover, toxin oligomerization, and hence haemolytic activity, diminishes in cholesterol-depleted erythrocytes. Considering these results, we studied the insertion process, an essential step in the lytic mechanism, by the monolayer technique, finding that HlyA insertion is favoured in cholesterol- and sphingomyelin-containing membranes. On the basis of this result, we studied the direct interaction with either of the lipids by lipid dot blotting, lysis inhibition and SPR (surface plasmon resonance) assays. The results of the present study demonstrated that an interaction between cholesterol and HlyA exists that seems to favour a conformational state of the protein that allows its correct insertion into the membrane and its further oligomerization to form pores.
authors.affiliation: *Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, (1900) La Plata, Argentina.
authors.forename: Romina F
authors.initials: RF
authors.lastname: Vazquez
authors.affiliation: *Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, (1900) La Plata, Argentina.
authors.forename: Sabina M
authors.initials: SM
authors.lastname: Maté
authors.forename: Laura S
authors.initials: LS
authors.lastname: Bakás
authors.affiliation: ‡Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni, CONICET, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 4to P, (1113) Buenos Aires, Argentina.
authors.forename: Marisa M
authors.initials: MM
authors.lastname: Fernández
authors.affiliation: ‡Cátedra de Inmunología and Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni, CONICET, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 4to P, (1113) Buenos Aires, Argentina.
authors.forename: Emilio L
authors.initials: EL
authors.lastname: Malchiodi
authors.affiliation: *Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, (1900) La Plata, Argentina.
authors.forename: Vanesa S
authors.initials: VS
authors.lastname: Herlax
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000737:chemistry / Q000378:metabolism*; D006461:Hemolysis; D066298:In Vitro Techniques; D012756:Sheep; D013109:Sphingomyelins / Q000737:chemistry / Q000378:metabolism; D020349:Surface Plasmon Resonance; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D013109:Sphingomyelins; D053835:Unilamellar Liposomes; D002784:Cholesterol