The VanS sensor histidine kinase from type-B vancomycin-resistant enterococci recognizes vancomycin directly.

Vancomycin-resistant enterococci (VRE) are high-priority targets for new therapeutic development. In VRE, expression of the resistance phenotype is controlled by the VanRS two-component system, which senses the presence of the antibiotic and responds by initiating transcription of resistance genes. VanS is a transmembrane sensor histidine kinase that is known to detect the antibiotic and then transduce this signal to the VanR transcription factor; however, fundamental questions remain about how exactly VanS senses vancomycin. Here, we focus on a purified VanRS system from one of the most clinically prevalent forms of VRE, type B. We show that in a native-like membrane environment, vancomycin strongly stimulates the autokinase activity of type-B VanS. We additionally demonstrate that this effect is mediated by a direct physical interaction between the antibiotic and the VanS periplasmic domain. This represents the first time that a direct sensing mechanism has been confirmed for any VanS protein from a human pathogen.