Discovery of small molecule inhibitors of Immunoglobulin A1 proteases
Abstract: Antibiotic-resistant bacteria are a major threat to global health, and will be for the foreseeable future. Inhibition of bacterial virulence factors is a promising alternative approach to treating bacterial infections, including infections caused by antibiotic resistant bacteria. Immunoglobulin A1 protease (IgA1P) is a virulence factor of a diverse group of Gram-negative and Gram-positive ... read morebacteria, including H. influenzae, N. meningitidis, N. gonorrhoeae, and S. pneumoniae. IgA1 proteases selectively cleave IgA1, which is the primary immunoglobulin on mucosal surfaces. This activity of IgA1P aids in immune suppression and evasion by the bacteria. Recent studies show that IgA1P also cleaves other host proteins, including Tumor necrosis factor receptor-II and Lysosome-associated membrane protein-1. These additional activities are likely involved in disabling host defenses, including extrinsic apoptosis and lysosomal trafficking. Since their discovery forty years ago, research into IgA1 proteases has been severely limited due to lack of synthetic IgA1P substrates and inhibitors. New probes and inhibitors would permit exploration of the roles that IgA1 proteases play in adherence, colonization and infection of human epithelial cells by the human pathogens mentioned above. If the roles of IgA1 proteases are critical for virulence, then IgA1Ps would emerge as novel antivirulence drug targets. To identify synthetic substrates for IgA1Ps, we screened peptide libraries and peptides derived from native autoproteolysis sites. Newly discovered substrates were modified into Förster energy resonance transfer (FRET) probes, which were then utilized to develop sensitive IgA1P activity assays. High-throughput screening assays were developed using the FRET probes, and these assays are being implemented for the discovery of small-molecule inhibitors of IgA1Ps. Despite 40 years of interest in IgA1 proteases, these probes, high throughput screening assays and small molecule inhibitors are the first of their kind.
Thesis (Ph.D.)--Tufts University, 2018.
Submitted to the Dept. of Chemistry.
Advisor: Joshua Kritzer.
Committee: Krishna Kumar, Clay Bennett, and Daniel DeOliveira.
Keywords: Chemistry, and Biochemistry.read less