Subsite specificity of anthrax lethal factor and its implications for inhibitor development

Area of Science:

• Biochemistry
• Microbiology
• Molecular Biology

Background:

• Bacillus anthracis lethal factor (LF) is a critical virulence factor responsible for anthrax lethality.
• LF functions as a metalloprotease within the host cell cytosol, contributing to disease pathogenesis.

Purpose of the Study:

• To elucidate the substrate specificity of Bacillus anthracis lethal factor.
• To identify preferred amino acid residues at six subsites (P3 to P3') of the LF active site.
• To leverage specificity data for designing improved substrates and potent inhibitors.

Main Methods:

• Determination of relative k(cat)/K(m) values (specificity constants) for 19 amino acids across six subsites.
• Analysis of residue preferences to characterize LF's enzymatic specificity.
• Molecular modeling of preferred residues within the LF active site.

Main Results:

• Lethal factor demonstrates broad substrate specificity, favoring hydrophobic residues.
• Charged and branched residues are disfavored.
• The most preferred residues at subsites P1 to P3' are Trp, Leu, Met, Tyr, Pro, and Leu, respectively.

Conclusions:

• The characterized residue preferences provide a foundation for rational drug design against anthrax.
• New substrates with enhanced hydrolytic properties can be designed based on these findings.
• Insights into active site interactions guide the development of highly potent LF inhibitors.