Identification of inhibitors of the E. coli chaperone SurA using in silico and in vitro techniques. Issue 22 (1st December 2018)

• Record Type: Journal Article
• Authors: Bell, Eric W.; Zheng, Erica J.; Ryno, Lisa M.
• Is Part Of: Bioorganic & medicinal chemistry letters. Volume 28:Issue 22(2018)
• Page Start: 3540
• Page End: 3548
• Publication Date: 2018-12-01
• Subjects: E. coli -- SurA -- Chaperones -- Virtual screening -- Fluorescence anisotropy; Bioorganic chemistry -- Periodicals; Pharmaceutical chemistry -- Periodicals; 572
• DOI: 10.1016/j.bmcl.2018.09.034
• Languages: English
• ISSNs: 0960-894X

Abstract

Graphical abstract: Schematic of how the results from the ZINC12 Drugs Now library were processed. Abstract: SurA is a gram-negative, periplasmic chaperone protein involved in the proper folding of outer membrane porins (OMPs), which protect bacteria against toxins in the extracellular environment by selectively regulating the passage of nutrients into the cell. Previous studies demonstrated that deletion of SurA renders bacteria more sensitive to toxins that compromise the integrity of the outer membrane. Inhibitors of SurA will perturb the folding of OMPs, leading to disruption of the outer membrane barrier and making the cell more vulnerable to toxic insults. The discovery of novel SurA inhibitors is therefore of great importance for developing alternative strategies to overcome antibiotic resistance. Our laboratory has screened over 10, 000, 000 compounds in silico by computationally docking these compounds onto the crystal structure of SurA. Through this screen and a screen of fragment compounds (molecular weight less than 250 g/mol), we found twelve commercially readily available candidate compounds that bind to the putative client binding site of SurA. We confirmed binding to SurA by developing and employing a competitive fluorescence anisotropy-based binding assay. Our results show that one of these compounds, Fmoc-β-(2-quinolyl)-d -alanine, binds the client binding site with high micromolar affinity. Using this compound as a lead, we also discovered that Fmoc-l -tryptophan and Fmoc-l -phenylalanine, but not Fmoc-l -tyrosine, bind SurA with similar micromolar affinity. To our knowledge, this is the first report of a competitive fluorescence anisotropy assay developed for the identification of inhibitors of the chaperone SurA, and the identification of three small molecules that bind SurA at its client binding site.