Physiological and Regulatory Characterization of KatA and KatY inYersinia pestis

The catalase or catalase-peroxidase activity commonly exists in many pathogens and plays an important role in resisting the oxidative burst of phagocytes helping the pathogen persistently colonize in the host. Yersinia pestis is a facultative pathogen and the causative agent of plague. KatY has been identified as a thermosensing antigen with modest catalase activity in this pathogen. Here Y. pestis KatA and KatY were experimentally confirmed as a monofunctional catalase and bifunctional catalase-peroxidase, respectively. Their expression induced by H2O2 was proven to be mediated by the oxidative regulator, OxyR. Expression of KatA changed with growth phases and was crucial to its traditional physiological role in protecting Y. pestis cells against toxicity of exogenous H2O2. KatY was regulated by temperature and H2O2, two major elements of phagolysosomal microenvironments. Consistent with the above results, gene expression of katY increased significantly during intracellular growth of Y. pestis compared with that in vitro growth. However, a DeltakatY mutant was fully virulent to mice, suggesting that KatY is not required for Y. pestis virulence.