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J Biol Chem. 2017 Oct 13;292(41):17037-17045. doi: 10.1074/jbc.M117.808600. Epub 2017 Aug 16.

A screen for kinase inhibitors identifies antimicrobial imidazopyridine aminofurazans as specific inhibitors of the Listeria monocytogenes PASTA kinase PrkA.

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From the Departments of Medical Microbiology and Immunology and.
Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706.
the Structural Genomics Consortium-University of North Carolina at Chapel Hill (SGC-UNC), University of North Carolina at Chapel Hill Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
the School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, and.
the Department of Molecular and Cell Biology, W. S. Middleton Memorial Veteran's Hospital, Madison, Wisconsin 53705.
From the Departments of Medical Microbiology and Immunology and


Bacterial signaling systems such as protein kinases and quorum sensing have become increasingly attractive targets for the development of novel antimicrobial agents in a time of rising antibiotic resistance. The family of bacterial Penicillin-binding-protein And Serine/Threonine kinase-Associated (PASTA) kinases is of particular interest due to the role of these kinases in regulating resistance to β-lactam antibiotics. As such, small-molecule kinase inhibitors that target PASTA kinases may prove beneficial as treatments adjunctive to β-lactam therapy. Despite this interest, only limited progress has been made in identifying functional inhibitors of the PASTA kinases that have both activity against the intact microbe and high kinase specificity. Here, we report the results of a small-molecule screen that identified GSK690693, an imidazopyridine aminofurazan-type kinase inhibitor that increases the sensitivity of the intracellular pathogen Listeria monocytogenes to various β-lactams by inhibiting the PASTA kinase PrkA. GSK690693 potently inhibited PrkA kinase activity biochemically and exhibited significant selectivity for PrkA relative to the Staphylococcus aureus PASTA kinase Stk1. Furthermore, other imidazopyridine aminofurazans could effectively inhibit PrkA and potentiate β-lactam antibiotic activity to varying degrees. The presence of the 2-methyl-3-butyn-2-ol (alkynol) moiety was important for both biochemical and antimicrobial activity. Finally, mutagenesis studies demonstrated residues in the back pocket of the active site are important for GSK690693 selectivity. These data suggest that targeted screens can successfully identify PASTA kinase inhibitors with both biochemical and antimicrobial specificity. Moreover, the imidazopyridine aminofurazans represent a family of PASTA kinase inhibitors that have the potential to be optimized for selective PASTA kinase inhibition.


Listeria monocytogenes; PASTA Kinase; aminofurazans; antibiotics; bacterial protein kinase; bacterial signal transduction; drug discovery; drug screening; β-lactams

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