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Sterol and pH interdependence in the binding, oligomerization, and pore formation of listeriolysin O

Lookup NU author(s): Professor Jeremy Lakey

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Abstract

Listeriolysin O (LLO) is the most important virulence factor of the intracellular pathogen Listeria monocytogenes. Its main task is to enable escape of bacteria from the phagosomal vacuole into the cytoplasm. LLO belongs to the cholesterol-dependent cytolysin (CDC) family but differs from other members, as it exhibits optimal activity at low pH. Its pore forming ability at higher pH values has been largely disregarded in Listeria pathogenesis. Here we show that high cholesterol concentrations in the membrane restore the low activity of LLO at high pH values. LLO binds to lipid membranes, at physiological or even slightly basic pH values, in a cholesterol-dependent fashion. Binding, insertion into lipid monolayers, and permeabilization of calcein-loaded liposomes are maximal above approximately 35 mol % cholesterol, a concentration range typically found in lipid rafts. The narrow transition region of cholesterol concentration separating low and high activity indicates that cholesterol not only allows the binding of LLO to membranes but also affects other steps in pore formation. We were able to detect some of these by surface plasmon resonance-based assays. In particular, we show that LLO recognition of cholesterol is determined by the most exposed 3β-hydroxy group of cholesterol. In addition, LLO binds and permeabilizes J774 cells and human erythrocytes in a cholesterol-dependent fashion at physiological or slightly basic pH values. The results clearly show that LLO activity at physiological pH cannot be neglected and that its action at sites distal to cell entry may have important physiological consequences for Listeria pathogenesis. © 2007 American Chemical Society.


Publication metadata

Author(s): Bavdek A, Gekara NO, Priselac D, Aguirre IG, Darji A, Chakraborty T, Macek P, Lakey JH, Weisse S, Anderluh G

Publication type: Article

Publication status: Published

Journal: Biochemistry

Year: 2007

Volume: 46

Issue: 14

Pages: 4425-4437

ISSN (print): 0006-2960

ISSN (electronic): 1520-4995

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/bi602497g

DOI: 10.1021/bi602497g

PubMed id: 17358050


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