Sandbox WWC6
From Proteopedia
Hemolysins [1] are a lipid or protein toxins secreted by pathogens that lyse erythrocyte and some bacterial cell membranes. These toxins belong to a family of microbial exotoxins called cytolysins, which act on a broad number of cells[2]. The primary function of peptide hemolysins is pore formation at the cell membranes creating acytolytic effect, and is achieved by the release of cytosolic ions and small molecules through the hydrophilic, transmembrane portion of the beta-barrel pore[3].
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Function
Hemolysins are most commonly proteins found in red blood cells that allow for the rapid release of small molecules and ions across the membrane. [1] or lipid biosurfactants that disrupt membrane composition resulting in cell lysis. Hemolysins act through disruption of the cell membrane. [2] Pore formation[3] is the olgomerization of the pore sunbunits within the membrane. The pore is quickly filled with water, ions, and small molecules that rapidly exit the cell, dissipating ionic gradients and membrane potential. Osmotic pressure causes a rapid swelling of the cell, leading to total rupture of the membrane [4]
Structure
Hemolysins have three structural variations: alpha, beta, and gamma. These hemolysin types are comprised of di-, hepta- or octomeric subunits.
- Alpha-hemolysin
Alpha hemolysin causes a partial lysis of red blood cells. The heptameric pore assembles from water-soluble subunits. The alpha subunit, depicted right, consists seven identical monomeric units that exhibit rotational symmetry in oligomerized form. Each distinct subunit is differently colored for easy identification. The beta-barrel transmembrane domain is 50 Å in length. [5]
