Boundary region between coexisting lipid phases as initial binding sites for Escherichia coli alpha-hemolysin: A real-time study

被引：26

作者：

Mate, Sabina M. ^{[1
]}

Vazquez, Romina F. ^{[1
]}

Herlax, Vanesa S. ^{[1
]}

Daza Millone, Maria A. ^{[2
]}

Fanani, Maria L. ^{[3
]}

Maggio, Bruno ^{[3
]}

Vela, Maria E. ^{[2
]}

Bakas, Laura S. ^{[1
,4
]}

机构：

[1] Univ Natl La Plata, Fac Ciencias Med, CONICET, Inst Invest Bioquim La Plata INIBIOLP,CCT La Plat, RA-1900 La Plata, Buenos Aires, Argentina

[2] Univ Natl La Plata CONICET, Inst Invest Fisicoquim Teor & Aplicadas INIFTA, RA-1900 La Plata, Buenos Aires, Argentina

[3] UNC, Fac Cs Quim, Dpto Quim Biol, Ctr Invest Quim Biol Cordoba CIQUIBIC,UNC CONICET, Cordoba, Argentina

[4] Univ Natl La Plata, Fac Ciencias Exactas, Dept Ciencias Biol, RA-1900 La Plata, Buenos Aires, Argentina

来源：

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES | 2014年 / 1838卷 / 07期

关键词：

Pore-forming toxin; Mono layer; Supported lipid bilayer; Liquid-ordered phase; Liquid-disordered phase; ATOMIC-FORCE MICROSCOPY; MODEL MEMBRANES; BILAYER-MEMBRANES; LYTIC ACTIVITY; LINE TENSION; SPHINGOMYELIN; MECHANISM; DOMAINS; AFM; CHOLESTEROL;

D O I：

10.1016/j.bbamem.2014.02.022

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

alpha-Hemolysin (HlyA) is a protein toxin, a member of the pore-forming Repeat in Toxin (RTX) family, secreted by some pathogenic strands of Escherichia coli. The mechanism of action of this toxin seems to involve three stages that ultimately lead to cell lysis: binding, insertion, and oligomerization of the toxin within the membrane. Since the influence of phase segregation on HlyA binding and insertion in lipid membranes is not clearly understood, we explored at the meso- and nanoscale-both in situ and in real-time the interaction of HlyA with lipid monolayers and bilayers. Our results demonstrate that HlyA could insert into monolayers of dioleoylphosphatidylcholine/sphingomyelin/cholesterol (DOPC/16:0SM/Cho) and DOPC/24:1SM/Cho. The time course for HlyA insertion was similar in both lipidic mixtures. HlyA insertion into DOPC/16:0SM/Cho monolayers, visualized by Brewster-angle microscopy (BAM), suggest an integration of the toxin into both the liquid-ordered and liquid-expanded phases. Atomic-force-microscopy, imaging reported that phase boundaries favor the initial binding of the toxin, whereas after a longer time period the HlyA becomes localized into the liquid-disordered (Ld) phases of supported planar bilayers composed of DOPC/16:0SM/Cho. Our AFM images, however, showed that the HlyA interaction does not appear to match the general strategy described for other invasive proteins. We discuss these results in terms of the mechanism of action of HlyA. (C) 2014 Elsevier B.V. All rights reserved.

引用

页码：1832 / 1841

页数：10