Repurposing Hsp90 inhibitors as antibiotics targeting histidine kinases

Abstract

To address the growing need for new antimicrobial agents, we explored whether inhibition of bacterial signaling machinery could inhibit bacterial growth. Because bacteria rely on two-component signaling systems to respond to environmental changes, and because these systems are both highly conserved and mediated by histidine kinases, inhibiting histidine kinases may provide broad spectrum antimicrobial activity. The histidine kinase ATP binding domain is conserved with the ATPase domain of eukaryotic Hsp90 molecular chaperones. To find a chemical scaffold for compounds that target histidine kinases, we leveraged this conservation. We screened ATP competitive Hsp90 inhibitors against CckA, an essential histidine kinase in Caulobacter crescentus that controls cell growth, and showed that the diaryl pyrazole is a promising scaffold for histidine kinase inhibition. We synthesized a panel of derivatives and found that they inhibit the histidine kinases C. crescentus CckA and Salmonella PhoQ but not C. crescentus DivJ; and they inhibit bacterial growth in both Gram-negative and Gram-positive bacterial strains.

Integration of cell cycle signals by multi-PAS domain kinases

“…The bifunctional histidine kinase/phosphatase CckA controls the phosphorylation state of CtrA (6–9). CckA uses sensory PAS domains to change its activity depending upon its subcellular location and the progression of the cell cycle (10, 11).…”

Evaluation of small molecule kinase inhibitors as novel antimicrobial and antibiofilm agents

“…After identifying radicicol (7, Figure 2) as a putative binder, they used crystallography to confirm the interaction and determine that the aromatic ring of radicicol binds in similar orientations in Hsp90 and PhoQ, further supporting their initial hypothesis. A similar study was conducted by Vo et al (2017) using purified C-terminal domain of CckA from Caulobacter crescentus in a differential scanning fluorimetry assay In a screen of six commercially available Hsp90 inhibitors, NVP-AUY922 (8, Figure 2) and CCT018159 (9, Figure 2) were found to increase the melting temperature of CckA greater than 1.5°C relative to the control, indicating that they were able to tightly bind the C-terminal domain of CckA. Further studies revealed that these structurally similar inhibitors were also capable of inhibiting CckA activity in vitro.…”

“…CckA (Vo et al, 2017) Signal transduction to control proteolysis regulation 8 (Vo et al, 2017), 9 (Vo et al, 2017) CheA (Stock et al, 1988) Chemotaxis 20 (Goswami et al, 2018), 21 (Goswami et al, 2018) DevS DosS (Converse et al, 2009;Gautam et al, 2015;Leistikow et al, 2010;Zheng et al, 2017) Oxygen sensing and surviving hypoxia 34 (Zheng et al, 2017), 35 (Zheng et al, 2017) EnvZ (Gilmour et al, 2005) Responding to changes in osmolarity; necessary for survival in macrophages 6 (Gilmour et al, 2005) KinA (LeDeaux et al, 1995) Regulates sporulation 1 (Barrett et al, 1998), 2 (Macielag et al, 1998) NblS (Waasbergen et al, 2002) Controls photosynthesis and photobleaching 14 (Velikova et al, 2016), 15 (Velikova et al, 2016) PhoR Phosphorus acquisition 16-18 (Velikova et al, 2016) YycG/WalK (Dubrac et al, 2007(Dubrac et al, , 2008Gilmour et al, 2005;Hancock & Perego, 2002;Lange et al, 1999;Martin et al, 1999;Okada et al, 2010;Watanabe et al, 2012) Signal transduction in cell wall signaling 6 (Gilmour et al, 2005), 10 (Okada et al, 2010, 11 (Watanabe et al, 2012), 12 (Igarashi et al, 2013), 13 (Huang et al, 2012;Qin et al, 2006Qin et al, , 2007, 14-17 (Velikova et al, 2016)…”

Design of a Histidine Kinase FRET Sensor to Detect Complex Signal Integration within Living Bacteria

“…Cells with CckA FRET sensor expressed were incubated with the compound for 3 h. DMSO and Kanamycin were used as controls that should not impact the CckA FRET sensor. CCT018159 (IC 50 30 μM), CDV008 (IC 50 17.5 μM), and CDV009 (IC 50 12.5 μM) were previously shown to bind CckA in vitro …”