title: Disarming bacterial virulence through chemical inhibition of the DNA binding domain of an AraC-like transcriptional activator protein.
abstract: The misuse of antibiotics during past decades has led to pervasive antibiotic resistance in bacteria. Hence, there is an urgent need for the development of new and alternative approaches to combat bacterial infections. In most bacterial pathogens the expression of virulence is tightly regulated at the transcriptional level. Therefore, targeting pathogens with drugs that interfere with virulence gene expression offers an effective alternative to conventional antimicrobial chemotherapy. Many Gram-negative intestinal pathogens produce AraC-like proteins that control the expression of genes required for infection. In this study we investigated the prototypical AraC-like virulence regulator, RegA, from the mouse attaching and effacing pathogen, Citrobacter rodentium, as a potential drug target. By screening a small molecule chemical library and chemical optimization, we identified two compounds that specifically inhibited the ability of RegA to activate its target promoters and thus reduced expression of a number of proteins required for virulence. Biophysical, biochemical, genetic, and computational analyses indicated that the more potent of these two compounds, which we named regacin, disrupts the DNA binding capacity of RegA by interacting with amino acid residues within a conserved region of the DNA binding domain. Oral administration of regacin to mice, commencing 15 min before or 12 h after oral inoculation with C. rodentium, caused highly significant attenuation of intestinal colonization by the mouse pathogen comparable to that of an isogenic regA-deletion mutant. These findings demonstrate that chemical inhibition of the DNA binding domains of transcriptional regulators is a viable strategy for the development of antimicrobial agents that target bacterial pathogens.
authors.affiliation: From the Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010.
authors.forename: Ji
authors.initials: J
authors.lastname: Yang
authors.forename: Dianna M
authors.initials: DM
authors.lastname: Hocking
authors.forename: Catherine
authors.initials: C
authors.lastname: Cheng
authors.forename: Con
authors.initials: C
authors.lastname: Dogovski
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Perugini
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Holien
authors.forename: Michael W
authors.initials: MW
authors.lastname: Parker
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Hartland
authors.forename: Marija
authors.initials: M
authors.lastname: Tauschek
authors.forename: Roy M
authors.initials: RM
authors.lastname: Robins-Browne
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D051777:AraC Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D044082:Citrobacter rodentium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007422:Intestines / Q000382:microbiology / Q000473:pathology; D051379:Mice; D017434:Protein Structure, Tertiary; D037521:Virulence Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D051777:AraC Transcription Factor; D037521:Virulence Factors
keywords: Antibiotics; AraC-like Regulator; Bacterial Infection; Bacterial Pathogenesis; Enteric Pathogen; Gene Regulation; Infectious Diseases; Small Molecule Inhibitors; Small Molecules; Virulence Gene Regulation
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