title: Versatile substrates and probes for IgA1 protease activity.
abstract: Bacterial meningitis is a severe infectious disease with high mortality. Gram-positive and Gram-negative bacteria that cause meningitis secrete immunoglobulin A1 (IgA1) proteases to assist in mucosal colonization, invasion, and immune evasion. IgA1 proteases have unique selectivity, with few reported substrates other than IgA1 from human tissue. Here we describe the design, characterization, and application of peptide substrates for diverse IgA1 proteases from Neisseria, Haemophilus, and Streptococcus bacteria. IgA1 proteases from diverse strains showed unexpected selectivity profiles among peptide substrates derived from autoproteolytic sites. A fluorescence probe derived from one of these peptides was used to quantitate IgA1 protease activity in buffer and in human cerebrospinal fluid; it was able to detect recombinant Haemophilus influenzae type 1 IgA1 protease at less than 1 μg mL(-1) . We also used the probe to establish the first high-throughput screen for IgA1 protease inhibitors. This work provides tools that will help investigate the roles of IgA1 proteases in bacterial colonization, immune evasion, and infection.
authors.affiliation: Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford MA 02155 (USA).
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Choudary
authors.forename: Jiazhou
authors.initials: J
authors.lastname: Qiu
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Plaut
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Kritzer
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology; D001665:Binding Sites; D004353:Drug Evaluation, Preclinical; D057075:Enzyme Assays / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry; D057166:High-Throughput Screening Assays; D006801:Humans; D007070:Immunoglobulin A / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D059748:Proteolysis
chemical_list: D005456:Fluorescent Dyes; D007070:Immunoglobulin A; D010455:Peptides; D010447:Peptide Hydrolases
keywords: bacterial meningitis; high-throughput screening; immunoglobulins; peptides; proteases