Exploiting a Cryptic Pocket in DsbA Through Structure-Guided Parallel Synthesis and Direct-to-Biology Screening

Antibacterial resistance is a major global health problem, causing an increasing number of deaths worldwide. DsbA, a bacterial oxidoreductase enzyme, is pivotal for the correct folding and activity of virulence factors in bacteria. Inhibiting DsbA presents a promising avenue for developing antivirulence compounds and combating bacterial resistance. The enzyme's structure features two ligand-binding sites: a hydrophobic groove that is the binding site for natural peptide substrates, and a "cryptic pocket" enclosed within the protein, which has recently been identified as a target for ligand design. In this study, we report the elaboration of a fragment from within the enclosed cryptic pocket into the hydrophobic groove of Escherichia coli DsbA, using X-ray crystallography-guided structure-based design and parallel synthesis coupled with crude reaction mixture screening (direct-to-biology). This effort yielded the most potent small molecule EcDsbA inhibitors reported to date and exemplifies a productive strategy for exploiting a cryptic pocket for drug development.