Intrinsic Thermal Sensing Controls Proteolysis of Yersinia Virulence Regulator RovA

Abstract

Pathogens, which alternate between environmental reservoirs and a mammalian host, frequently use thermal sensing devices to adjust virulence gene expression. Here, we identify the Yersinia virulence regulator RovA as a protein thermometer. Thermal shifts encountered upon host entry lead to a reversible conformational change of the autoactivator, which reduces its DNA-binding functions and renders it more susceptible for proteolysis. Cooperative binding of RovA to its target promoters is significantly reduced at 37°C, indicating that temperature control of rovA transcription is primarily based on the autoregulatory loop. Thermally induced reduction of DNA-binding is accompanied by an enhanced degradation of RovA, primarily by the Lon protease. This process is also subject to growth phase control. Studies with modified/chimeric RovA proteins indicate that amino acid residues in the vicinity of the central DNA-binding domain are important for proteolytic susceptibility. Our results establish RovA as an intrinsic temperature-sensing protein in which thermally induced conformational changes interfere with DNA-binding capacity, and secondarily render RovA susceptible to proteolytic degradation.

Temperature-responsive in vitro RNA structurome of Yersinia pseudotuberculosis

“…Y. pseudotuberculosis is a foodborne pathogen closely related to Y. pestis and causes enteritis, diarrhea, and mesenteric lymphadenitis in animals and humans. Its metabolism and virulence are strictly temperature controlled by various posttranscriptional mechanisms (6,26). An intercistronic RNAT is present upstream of low calcium response gene F (lcrF) coding for the master regulator of Yersinia virulence (6).…”

Unique Virulence Properties of Yersinia enterocolitica O:3

“…Moreover, significantly higher amounts of RovA were identified in YeO:3 strains at 25°C and 37°C. This result was unexpected, as it was recently shown that RovA synthesis of Y. pseudotuberculosis is positively autoregulated and subjected to temperature regulation on the post-transcriptional level (Herbst et al, 2009). RovA acts as an intrinsic thermometer.…”

“…upon uptake by the human host) induces reversible conformational changes. These alterations reduce the DNA-binding capacity of RovA and render the regulator more susceptible to proteolysis by the Lon protease (Herbst et al, 2009). As a consequence, RovA of Y. pseudotuberculosis is rapidly degraded at 37°C and less able to induce its own transcription due to a lower DNA binding ability.…”

RNA Regulators: Formidable Modulators of Yersinia Virulence

“…Temperature represents a major stimulus for Yersinia to adjust metabolism and virulence gene expression, indicating that besides proteineaceous thermosensors such as the virulence regulator RovA [41], RNATs also represent reasonable players in this process. Surprisingly, so far only one RNAT has been identified and characterized in Y. pseudotuberculosis, the lcrF RNAT located in the intergenic region of the yscWlcrF operon [42] [44].…”