INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
artículos
Título:
Paradoxical lipid dependence of pores formed by the Escherichia coli alpha hemolysin in planar phospholipid bilayer membranes.
Autor/es:
LAURA BAKÁS; ALEXANDR CHANTURIYA; VANESA HERLAX; JOSHUA ZIMMERBERG
Revista:
BIOPHYSICAL JOURNAL
Referencias:
Año: 2006 vol. 91 p. 3748 - 3755
ISSN:
0006-3495
Resumen:
a-Hemolysin (HlyA) is an extracellular protein toxin (117 kDa) secreted by Escherichia coli that targets the plasma
membranes of eukaryotic cells. We studied the interaction of this toxin with membranes using planar phospholipid bilayers. For
all lipid mixtures tested, addition of nanomolar concentrations of toxin resulted in an increase of membrane conductance and
a decrease in membrane stability. HlyA decreased membrane lifetime up to three orders of magnitude in a voltage-dependent
manner. Using a theory for lipidic pore formation, we analyzed these data to quantify how HlyA diminished the line tension of the
membrane (i.e., the energy required to form the edge of a new pore). However, in contrast to the expectation that adding the
positive curvature agent lysophosphatidylcholine would synergistically lower line tension, its addition signi.cantly stabilized
HlyA-treated membranes. HlyA also appeared to thicken bilayers to which it was added. We discuss these results in terms of
models for proteolipidic pores.
membranes of eukaryotic cells. We studied the interaction of this toxin with membranes using planar phospholipid bilayers. For
all lipid mixtures tested, addition of nanomolar concentrations of toxin resulted in an increase of membrane conductance and
a decrease in membrane stability. HlyA decreased membrane lifetime up to three orders of magnitude in a voltage-dependent
manner. Using a theory for lipidic pore formation, we analyzed these data to quantify how HlyA diminished the line tension of the
membrane (i.e., the energy required to form the edge of a new pore). However, in contrast to the expectation that adding the
positive curvature agent lysophosphatidylcholine would synergistically lower line tension, its addition signi.cantly stabilized
HlyA-treated membranes. HlyA also appeared to thicken bilayers to which it was added. We discuss these results in terms of
models for proteolipidic pores.
membranes of eukaryotic cells. We studied the interaction of this toxin with membranes using planar phospholipid bilayers. For
all lipid mixtures tested, addition of nanomolar concentrations of toxin resulted in an increase of membrane conductance and
a decrease in membrane stability. HlyA decreased membrane lifetime up to three orders of magnitude in a voltage-dependent
manner. Using a theory for lipidic pore formation, we analyzed these data to quantify how HlyA diminished the line tension of the
membrane (i.e., the energy required to form the edge of a new pore). However, in contrast to the expectation that adding the
positive curvature agent lysophosphatidylcholine would synergistically lower line tension, its addition signi.cantly stabilized
HlyA-treated membranes. HlyA also appeared to thicken bilayers to which it was added. We discuss these results in terms of
models for proteolipidic pores.
-Hemolysin (HlyA) is an extracellular protein toxin (117 kDa) secreted by Escherichia coli that targets the plasma
membranes of eukaryotic cells. We studied the interaction of this toxin with membranes using planar phospholipid bilayers. For
all lipid mixtures tested, addition of nanomolar concentrations of toxin resulted in an increase of membrane conductance and
a decrease in membrane stability. HlyA decreased membrane lifetime up to three orders of magnitude in a voltage-dependent
manner. Using a theory for lipidic pore formation, we analyzed these data to quantify how HlyA diminished the line tension of the
membrane (i.e., the energy required to form the edge of a new pore). However, in contrast to the expectation that adding the
positive curvature agent lysophosphatidylcholine would synergistically lower line tension, its addition signi.cantly stabilized
HlyA-treated membranes. HlyA also appeared to thicken bilayers to which it was added. We discuss these results in terms of
models for proteolipidic pores.