A high-throughput screening approach to anthrax lethal factor inhibition

Abstract

A high-throughput screening approach was used to identify new inhibitors of the metallo-protease lethal factor from Bacillus anthracis. A library of approximately 14,000 compounds was screened using a fluorescence-based in vitro assay and hits were further characterized enzymatically via measurements of IC50 and Ki values against a small panel of metallo-proteases. This study led to the identification of new scaffolds that inhibit LF and the Botulinum Neurotoxin Type A in the low micromolar range, while sparing the human metallo-proteases MMP-2 and MMP-9. Therefore, these scaffolds could be further exploited for the development of potent and selective anti-toxin agents.

Figure 1

Lineweaver-Burk analysis of compound 6 at various concentrations of compound (square, no compound; triangle down, 5 μM; triangle up, 10 μM). Substrate concentration is expressed in μM units.

Figure 2

Molecular models of compounds 5 and 6 docked into the catalytic site of the enzyme, LF. A) and B), surface representation colored according to cavity depth: blue, shallow; yellow, deep. The metal ion is shown in magenta. C) and D), stick model displaying the catalytic Zn ion (magenta) and coordinating side chains. Hydrogen bonding interactions are depicted in yellow dashed lines (A and B) while coordination with the metal ion is represented by white dashed lines.