[Molecular model of anthrax toxin translocation into target-cells]

Bioorg Khim. 2014 Jul-Aug;40(4):399-404. doi: 10.1134/s1068162014040098.
[Article in Russian]

Abstract

Anthrax toxin is formed from three components: protective antigen (PA), lethal (LF) and edema (EF) factors. PA83 is cleaved by cell surface protease furin to produce a 63-kDa fragment (PA63). PA63 and LF/EF molecules are assembled to anthrax toxin complexes: oligomer PA63 x 7 + LF/EF x 3. Assembly is occurred during of binding with cellular receptor or near surface of target-cell. This toxin complex forms pore and induces receptor-mediated endocytosis. Formed endosome consists extracellular liquid with LF/EF and membrane-associated ferments (H+ and K+/Na+-ATPases) and proteins (receptors and others). H+ concentration is increased into endosome as result of K/Na-ATPase-dependent- activity of H+-ATPase. Difference of potentials (between endosome and intracellular liquid) is increased and LF/EF molecules are moved to pore and bound with PA63-oligomer to PA63 x 7 + LF/EF x 7 and full block pore (ion-selective channel). Endosome is increased in volume and induces increasing of PA63-oligomer pore to.size of effector complex: LF/EF x 7 + PAl7 x 7 = 750 kDa. Effector complex is translocated from endosome to cytosol by means high difference of potentials (H+) and dissociates from PA47 x 7 complex after cleavage of FFD315-sait by intracellular chymotrypsin-like proteases in all 7 molecules PA63. PA47 x 7 complex (strongly fixed in membrane with debris of hydrophobic loops) return into endosome and pore is destroyed. Endosome pH is decreased rapidly and PA47 x 7 complex is destroyed by endosomal/lysosomal proteases. Receptor-mediated endocytosis is ended by endosome recycling in cell-membrane.

Publication types

  • English Abstract
  • Review

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / metabolism
  • Anthrax / microbiology
  • Anthrax / pathology*
  • Antigens, Bacterial / chemistry
  • Antigens, Bacterial / toxicity*
  • Bacillus anthracis / chemistry
  • Bacillus anthracis / pathogenicity
  • Bacterial Toxins / chemistry
  • Bacterial Toxins / toxicity*
  • Endocytosis*
  • Endosomes / chemistry
  • Endosomes / pathology
  • Humans
  • Models, Molecular

Substances

  • Antigens, Bacterial
  • Bacterial Toxins
  • anthrax toxin
  • Adenosine Triphosphatases