Pore forming toxin, α-hemolysin

The α-hemolysin oligomer

α-hemolysin (7ahl) is from Staphylococcus aureus.

Each chain in the oligomeric complex is ; the other monomers are translucent to emphasize one of the seven monomers. Note the seven-fold rotational symmetry. .

Seven monomers come together in a ring, with

. .

α-hemolysin interaction with the membrane

, α-hemolysin's stalk is perfectly designed to span the plasma membrane of eukaryotic cells (ca. 2.5 nm or 25 Å). A fancier version of this scene is below.

[Note: the following view generates a substantial surface which may take several minutes to calculate. Use the one above as an alternative unless you are willing to spend the time.], α-hemolysin's stalk is perfectly designed to span the plasma membrane of eukaryotic cells (ca. 2.5 nm or 25 Å).

Unlike the polar surface of more typical proteins, , and is instead lipophilic or preferring to be in a lipid environment.

which is largely polar since it would sit outside the cell.
KEY: Polar Hydrophobic

To help give a better idea of how α-hemolysin interacts with the membrane lipid bilayer, as calculated by the Orientations of Proteins in Membranes database(University of Michigan, USA) is shown with the red patch of spheres indicating the boundary of the hydrophobic core closet to the outside of the cell and the blue patch of spheres indicating the boundary closest to the inside of the cell.

The α-hemolysin pore

[Note: the following view generates a substantial surface which may take several minutes to calculate. Be patient.] Displaying the surface illustrates clearly that there is , which is the structural basis for why these are toxins. Such pores are expectedly detrimental to the cell, allowing exodus of critical molecules, destroying the established membrane potential and ionic gradients, and contributing to osmotic swelling. .