Figure 1. . Schematic for the DosRST signaling pathway, with examples of where small molecules and peptides interfere with DosRST signaling.

Artemisinin and HC106A target DosST heme to inhibit the sensing domain. Peptides A-ext and D, and small molecules HC102A and HC103A inhibit histidine kinase autophosphorylation. Peptide DevR_N inhibits phosphotransfer from DosS to DosR. Phenylcoumarin compound 10 and HC104A inhibit DosR DNA-binding. These compounds inhibit expression of DosR-regulated genes and inhibit survival during hypoxia, with the exception of HC104A. Compounds HC101A–HC106 were identified using a reporter strain where the DosR-regulated promoter, hspX, was cloned upstream of green fluorescent protein (GFP). Whole cell screening of a library of >540,000 compounds for inhibitors of hypoxia-inducible GFP fluorescence was conducted to discover DosRST inhibitors.

CO: Carbon monoxide; GFP: Green fluorescent protein; NO: Nitric oxide; TAG: Triacylglycerol.