Author/Editor     Bavdek, Andrej; Gekara, Nelson O; Priselac, Dragan; Gutierrez-Aguirre, Ion; Darji, Ayub; Chakraborty, Trinad; Maček, Peter; Lakey, Jeremy H; Weiss, Siegfried; Anderluh, Gregor
Title     Sterol and pH interdependence in the binding, oligomerization, and pore formation of listeriolysin O
Type     članek
Source     Biochemistry
Vol. and No.     Letnik 46, št. 14
Publication year     2007
Volume     str. 4425-37
Language     eng
Abstract     Listeriolysin O (LLO) is the most important virulence factor of the intracellular pathogen Listeria monocytogerzes. Its main task is to enable escape of bacteria from the phagosomal vacuole into the cytoplasm. LLO belongs to the cholesterol-dependent cytolysis (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 3% beta-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. Tle 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.
Descriptors     LISTERIA MONOCYTOGENES
VIRULENCE
PORINS
BACTERIAL TOXINS
HYDROGEN-ION CONCENTRATION
MEMBRANE FLUIDITY
LIPOSOMES
CHOLESTEROL
FLOW CYTOMETRY