Identification of small molecule inhibitors of anthrax lethal factor

Area of Science:

• Biochemistry
• Microbiology
• Pharmacology

Background:

• Bacillus anthracis secretes anthrax toxin, comprising protective antigen (PA), lethal factor (LF), and edema factor (EF).
• Lethal factor (LF) is a zinc-dependent metalloprotease that targets and inactivates crucial signaling molecules like mitogen-activated protein kinase kinases (MAPKK), leading to cell death.
• Developing inhibitors against LF is critical for combating anthrax toxicity.

Purpose of the Study:

• To identify and characterize small molecule (nonpeptidic) inhibitors of Bacillus anthracis lethal factor (LF).
• To explore potential therapeutic strategies against anthrax by targeting LF.

Main Methods:

• A two-stage screening assay was employed to evaluate the inhibitory activity of 19 compounds against LF.
• X-ray crystallographic data, molecular docking, and 3D database mining of the NCI chemical repository were used to establish pharmacophoric relationships.
• Inhibition constants (K(i)) and inhibition type were determined for promising compounds.

Main Results:

• Six small molecule inhibitors of LF were identified.
• Three of these inhibitors demonstrated competitive inhibition with K(i) values in the 0.5-5 microM range.
• The identified compounds share a common pharmacophoric relationship.

Conclusions:

• Small molecule scaffolds targeting LF have been identified.
• These inhibitors represent a promising starting point for the development of novel, therapeutically viable treatments for anthrax.
• Further development of these molecular scaffolds could lead to effective anti-anthrax therapeutics.