Sandbox WWC6

HemolysinHemolysin

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].

spinqualitylabelsall models Stapholococcal alpha-hemolysin Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

FunctionFunction

Hemolysins are most commonly proteins found in red blood cells that selectively allow for the diffusion of potassium ions across the membrane. or lipid biosurfactants that disrupt membrane composition resulting in cell lysis. Hemolysins act through disruption of the cell membrane. Pore formation 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

StructureStructure

Hemolysins have three structural variations: alpha, beta, and gamma. These hemolysin types are comprised of di-, hepta- or octomeric subunits. The alpha subunit, depicted right, consists of four repeating structures, named I through IV and shown in different colors .

Alpha-hemolysinAlpha-hemolysin

Alpha hemolysins cause a partial lysis of red blood cells. The heptameric pore assembles from water-soluble subunits The transmembrane domain of this water-filled pore is primarily comprised of an anti-parallel beta-barrel

Beta-hemolysinBeta-hemolysin

Beta-hemolysins cause a total lysis of red blood cells.

Gamma-hemolysinGamma-hemolysin

Gamma-hemolysin is both hemolytic and leukotoxic.

Pathogenic MicroorganismsPathogenic Microorganisms

Pore-forming toxins have been shown to closely relate to the pathogenicity of the toxin-producing organism

Role in infectionRole in infection

Hemolysin lysis of red blood cells is a marker for many kinds of pathogenic infection characterized by...

OncologyOncology

This disease causes seizures, fainting or sudden death from cardiac arrhythmias and is caused my a mutation in the SCN5A gene, or the gene that encodes the NaV1.5 alpha subunit. It was found that this deletion includes residues 1505-1507 (KPQ). These residues occur in the cytoplasmic linker between domain III and domain IV.

Hemolytic anemiaHemolytic anemia

Hyperkalemic period paralysis is caused by the mutations T704M, S906T, A1156T, M1360V, A1448C and/or M1592V. These mutations cause periodic or permanent weakness. Physiologically, this is a gain of function mutation. During rest after exercise, or after eating foods rich in K⁺, the extracellular K⁺ increases, which mildly depolarizes the membrane. This causes abnormal Na⁺ channels to open, and they are unable to inactivate. This sustained depolarization of the membrane causes even more abnormal Na⁺ channels to open and ultimately this leads to loss of excitability and weakness. This symptom usually appears within the first decade of life and can be aggravated by exercise, cold, potassium loading, fasting or pregnancy. Attacks are usually brief and do not need treatment.

Marker for fungi exposureMarker for fungi exposure

Many indoor fungi have been shown to produse both alpha and beta-hemolysins. The treatment of blood samples with