Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Effects of lipid composition on membrane permeabilization by sticholysin Iand II, two cytolysins of the sea anemone Stichodactyla helianthus
Autore:
Valcarcel, CA; Dalla Serra, M; Potrich, C; Bernhart, I; Tejuca, M; Martinez, D; Pazos, F; Lanio, ME; Menestrina, G;
Indirizzi:
CNR, Ctr Fis Stati Aggregati, ITC, I-38050 Povo, TN, Italy CNR Povo TN Italy I-38050 s Stati Aggregati, ITC, I-38050 Povo, TN, Italy Univ La Habana, Fac Biol, Dept Bioquim, La Habana, Cuba Univ La Habana LaHabana Cuba , Fac Biol, Dept Bioquim, La Habana, Cuba
Titolo Testata:
BIOPHYSICAL JOURNAL
fascicolo: 6, volume: 80, anno: 2001,
pagine: 2761 - 2774
SICI:
0006-3495(200106)80:6<2761:EOLCOM>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
PORE-FORMING TOXIN; ACTINIA-EQUINA L; STOICHACTIS-HELIANTHUS; ERYTHROCYTE-MEMBRANE; SECONDARY STRUCTURE; HEMOLYTIC-ACTIVITY; PHOSPHATIDIC-ACID; BILAYER-MEMBRANES; DELTA-ENDOTOXIN; MODEL MEMBRANES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
65
Recensione:
Indirizzi per estratti:
Indirizzo: Menestrina, G CNR, Ctr Fis Stati Aggregati, ITC, Via Sommar 18, I-38050 Povo, TN, Italy CNR Via Sommar 18 Povo TN Italy I-38050 8050 Povo, TN, Italy
Citazione:
C.A. Valcarcel et al., "Effects of lipid composition on membrane permeabilization by sticholysin Iand II, two cytolysins of the sea anemone Stichodactyla helianthus", BIOPHYS J, 80(6), 2001, pp. 2761-2774

Abstract

Sticholysin I and II (St I and St II), two basic cytolysins purified from the Caribbean sea anemone Stichodactyla helianthus, efficiently permeabilize lipid Vesicles by forming pores in their membranes. A general characteristic of these toxins is their preference for membranes containing sphingomyelin (SM). As a consequence, vesicles formed by equimolar mixtures of SM with phosphatidylcholine (PC) are very good targets for St I and II. To bettercharacterize the lipid dependence of the cytolysin-membrane interaction, we have now evaluated the effect of including different lipids in the composition of the vesicles. We observed that at low doses of either St I or St II vesicles composed of SM and phosphatidic acid (PA) were permeabilized faster and to a higher extent than vesicles of PC and SM. As in the case of PC/SM mixtures, permeabilization was optimal when the molar ratio of PA/SM was similar to1. The preference for membranes containing PA was confirmed by inhibition experiments in which the hemolytic activity of St I was diminished by pre-incubation with vesicles of different composition. The inclusion of even small proportions of PA into PC/SM LUVs led to a marked increase incalcein release caused by both St I and St II, reaching maximal effect at similar to5 mol % of PA. Inclusion of other negatively charged lipids (phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidylinositol (PI), or cardiolipin (CL)), all at 5 mol %, also elicited an increase in calcein release, the potency being in the order CL approximate to PA much greater than PG approximate to PI approximate to PS. However, some boosting effect was also obtained, including the zwitterionic lipid phosphatidylethanolamine(PE) or even, albeit to a lesser extent, the positively charged lipid stearylamine (SA). This indicated that the effect was not mediated by electrostatic interactions between the cytolysin and the negative surface of the vesicles. In fact, increasing the ionic strength of the medium had only a small inhibitory effect on the interaction, but this was actually larger with uncharged vesicles than with negatively charged vesicles. A study of the fluidity of the different vesicles, probed by the environment-sensitive fluorescent dye diphenylhexatriene (DPH), showed that toxin activity was also notcorrelated to the average membrane fluidity. It is suggested that the insertion of the toxin channel could imply the formation in the bilayer of a nonlamellar structure, a toroidal lipid pore. In this case, the presence of lipids favoring a nonlamellar phase, in particular PA and CL, strong inducers of negative curvature in the bilayer, could help in the formation of the pore. This possibility is confirmed by the fact that the formation of toxinpores strongly promotes the rate of transbilayer movement of lipid molecules, which indicates local disruption of the lameliar structure.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/01/20 alle ore 12:22:36