<i>Francisella tularensis</i> universal stress protein contributes to persistence during growth arrest and paraquat-induced superoxide stress

<i>Francisella tularensis</i> is classified as a Tier 1 select agent due to the low infectious dose, ease of transmission, and potential use as a bioweapon. To better understand the stress defense mechanisms that contribute to the ability of this highly virulent pathogen to persist, we evaluated the conserved <i>F. tularensis</i> <u>u</u>niversal <u>s</u>tress <u>p</u>rotein (Usp). We show that <i>F. tularensis</i> Usp is unusually stable and remains abundant, regardless of the stress conditions tested, differing from other bacterial Usp homologs. We also determined that <i>F. tularensis</i> Usp enhances the expression of several critical antioxidant defense genes and increases survival during paraquat exposure and growth arrest. Determining the factors that promote <i>F. tularensis</i> persistence in the environment is needed to prevent tularemia transmission.