Identification of DraRS in , a Two-Component Regulatory System That Responds to Lipid II-Interacting Antibiotics

is a Gram-positive opportunistic pathogen that results in 220,000 infections, 12,000 deaths, and upwards of $1 billion in medical costs in the United States each year. is highly resistant to a variety of antibiotics, but we have a poor understanding of how senses and responds to antibiotic stress and how such sensory systems affect clinical outcomes. We have identified a spontaneous mutant that displays increased daptomycin resistance. We performed whole-genome sequencing and found a nonsense mutation, S605*, in , which encodes a putative sensor histidine kinase of a two-component system (TCS). The * mutant has an ~4- to 8-fold increase in the daptomycin MIC compared to the wild type (WT). We found that the expression of constitutively active DraR in the WT increases daptomycin resistance 8- to 16-fold and increases bacitracin resistance ~4-fold. We found that a selection of lipid II-inhibiting compounds leads to the increased activity of the luciferase-based reporter P, including vancomycin, bacitracin, ramoplanin, and daptomycin. Using RNA sequencing (RNA-seq), we identified the DraRS regulon. Interestingly, we found that DraRS can induce the expression of the previously identified locus required for the synthesis of a novel glycolipid produced in . Our data suggest that the induction of the locus by DraR explains some, but not all, of the DraR-induced daptomycin and bacitracin resistance. is a major cause of hospital-acquired diarrhea and represents an urgent concern due to the prevalence of antibiotic resistance and the rate of recurrent infections. encodes ~50 annotated two-component systems (TCSs); however, only a few have been studied. The function of these unstudied TCSs is not known. Here, we show that the TCS DraRS plays a role in responding to a subset of lipid II-inhibiting antibiotics and mediates resistance to daptomycin and bacitracin in part by inducing the expression of the recently identified locus, which encodes enzymes required for the production of a novel glycolipid in .