Lethal factor of anthrax toxin binds monomeric form of protective antigen

Biochem Biophys Res Commun. 2007 Aug 31;360(3):690-5. doi: 10.1016/j.bbrc.2007.06.124. Epub 2007 Jul 3.

Abstract

Anthrax toxin consists of three components: the enzymatic moieties edema factor (EF) and the lethal factor (LF) and the receptor-binding moiety protective antigen (PA). These toxin components are released from Bacillus anthracis as unassociated proteins and form complexes on the surface of host cells after proteolytic processing of PA into PA20 and PA63. The sequential order of PA heptamerization and ligand binding, as well as the exact mechanism of anthrax toxin entry into cells, are still unclear. In the present study, we provide direct evidence that PA63 monomers are sufficient for binding to the full length LF or its LF-N domain, though with lower affinity with the latter. Therefore, PA oligomerization is not a necessary condition for LF/PA complex formation. In addition, we demonstrated that the PA20 directly interacts with the LF-N domain. Our data points to an alternative process of self-assembly of anthrax toxin on the surface of host cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Bacterial / chemistry*
  • Antigens, Bacterial / genetics
  • Antigens, Bacterial / metabolism
  • Bacterial Toxins / chemistry*
  • Bacterial Toxins / genetics
  • Bacterial Toxins / metabolism
  • Dimerization
  • Electrophoresis, Polyacrylamide Gel
  • Mutagenesis, Site-Directed
  • Protein Binding / genetics
  • Protein Structure, Tertiary / genetics
  • Protein Structure, Tertiary / physiology

Substances

  • Antigens, Bacterial
  • Bacterial Toxins
  • anthrax toxin