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Involvement of domain II in toxicity of anthrax lethal factor

Xudong Liang1, John J Young, Sherrie A Boone

  • 1Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.

The Journal of Biological Chemistry
|October 7, 2004
PubMed

Insights

Anthrax lethal factor (LF) mutations outside its active site reduce toxicity by impairing MEK binding. These findings reveal domain II

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Toxicology

Background:

  • Anthrax lethal factor (LF) is a toxic metalloprotease.
  • LF cleaves and inactivates mitogen-activated protein kinase kinases (MEKs).
  • Understanding LF's mechanism is crucial for developing countermeasures.

Purpose of the Study:

  • To identify residues in LF domain II critical for MEK cleavage.
  • To investigate the role of these residues in LF's cellular activity and toxicity.

Main Methods:

  • Site-directed mutagenesis of specific LF residues (Leu293, Lys294, Leu514, Asn516, Arg491).
  • Assessment of LF toxicity in cell-based assays.
  • Measurement of MEK2 cleavage and B-Raf phosphorylation inhibition in vitro.

Main Results:

  • Mutations outside the LF active site, particularly in domain II, significantly reduced LF toxicity (10-50 fold).
  • Specific pairwise mutations abrogated LF toxicity, while others showed partial reduction.
  • Mutations impaired LF-mediated MEK2 cleavage and B-Raf phosphorylation inhibition but not LF binding or translocation.

Conclusions:

  • Residues in LF domain II, outside the active site, are essential for productive interaction with MEKs.
  • These domain II elements are involved in LF's association with MEKs, impacting cellular activity.
  • The findings provide insights into LF's mechanism of action and potential therapeutic targets.

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