Disruption of putative regulatory loci in XXXX demonstrates a significant role for Fur and PerR in virulence.

@entity19 @entity3642 @entity5125 @entity281 @entity273 @entity68
The ability to adapt to adverse environmental conditions encountered in food and during host @entity281 is a sine qua non for a successful @entity5125 @entity281 . This ability is likely to depend on complex regulatory pathways controlled by a number of key regulators. We utilized the pORI19 plasmid integration system to analyze the role of six putative regulatory loci in growth under suboptimal environmental conditions and during @entity19 @entity281 . Disruption of loci encoding a topoisomerase III (lmo2756), a putative methyltransferase (lmo0581), and a regulator of the MarR family (lmo1618) revealed roles for the methyltransferase and the MarR regulator in growth under environmental stress conditions. However, plasmid integration into these loci had no impact on virulence potential in the @entity19 model of @entity281 . Disruption of the alternative sigma factor Sigma-H resulted in a mutant that demonstrated reduced growth potential in minimal medium. @entity19 studies indicated a minor role for this sigma factor in the infectious process. Strikingly, disruption of both perR and fur loci resulted in mutants that are significantly affected in virulence for @entity19 , with the fur mutant demonstrating the greatest reduction in virulence potential. Both perR and fur mutants demonstrated increased resistance to @entity273 and the fur mutant was sensitive to low- @entity68 conditions. The virulence defect of both fur and perR mutants could be rescued by @entity68 -overload after @entity3642 treatment of @entity19 , suggesting that the in vivo role of these gene products is to procure @entity68 for bacterial growth.
