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Fis Is Essential for Yersinia pseudotuberculosis Virulence and Protects against Reactive Oxygen Species Produced by Phagocytic Cells during Infection.

ABSTRACT: All three pathogenic Yersinia species share a conserved virulence plasmid that encodes a Type 3 Secretion System (T3SS) and its associated effector proteins. During mammalian infection, these effectors are injected into innate immune cells, where they block many bactericidal functions, including the production of reactive oxygen species (ROS). However, Y. pseudotuberculosis (Yptb) lacking the T3SS retains the ability to colonize host organs, demonstrating that chromosome-encoded factors are sufficient for growth within mammalian tissue sites. Previously we uncovered more than 30 chromosomal factors that contribute to growth of T3SS-deficient Yptb in livers. Here, a deep sequencing-based approach was used to validate and characterize the phenotype of 18 of these genes during infection by both WT and plasmid-deficient Yptb. Additionally, the fitness of these mutants was evaluated in immunocompromised mice to determine whether any genes contributed to defense against phagocytic cell restriction. Mutants containing deletions of the dusB-fis operon, which encodes the nucleoid associated protein Fis, were markedly attenuated in immunocompetent mice, but were restored for growth in mice lacking neutrophils and inflammatory monocytes, two of the major cell types responsible for restricting Yersinia infection. We determined that Fis was dispensable for secretion of T3SS effectors, but was essential for resisting ROS and regulated the transcription of several ROS-responsive genes. Strikingly, this protection was critical for virulence, as growth of ?dusB-fis was restored in mice unable to produce ROS. These data support a model in which ROS generated by neutrophils and inflammatory monocytes that have not been translocated with T3SS effectors enter bacterial cells during infection, where their bactericidal effects are resisted in a Fis-dependent manner. This is the first report of the requirement for Fis during Yersinia infection and also highlights a novel mechanism by which Yptb defends against ROS in mammalian tissues.

SUBMITTER: Green ER

PROVIDER: S-EPMC5045184 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Fis Is Essential for Yersinia pseudotuberculosis Virulence and Protects against Reactive Oxygen Species Produced by Phagocytic Cells during Infection.

Green Erin R ER Clark Stacie S Crimmins Gregory T GT Mack Matthias M Kumamoto Carol A CA Mecsas Joan J

PLoS pathogens 20160930 9

All three pathogenic Yersinia species share a conserved virulence plasmid that encodes a Type 3 Secretion System (T3SS) and its associated effector proteins. During mammalian infection, these effectors are injected into innate immune cells, where they block many bactericidal functions, including the production of reactive oxygen species (ROS). However, Y. pseudotuberculosis (Yptb) lacking the T3SS retains the ability to colonize host organs, demonstrating that chromosome-encoded factors are suff ...[more]

PMID: 27689357

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Project description:Although bacterial peptidases are known to be produced by various microorganisms, including pathogenic bacteria, their role in bacterial physiology is not fully understood. In particular, oligopeptidases are thought to be mainly involved in degradation of short peptides e.g. leader peptides released during classical protein secretion pathways. The aim of this study was to investigate effects of inactivation of an oligopeptidase encoding gene opdA gene of Yersinia pseudotuberculosis on bacterial properties in vivo and in vitro, and to test dependence of the enzymatic activity of the respective purified enzyme on the presence of different divalent cations.In this study we found that oligopeptidase OpdA of Yersinia pseudotuberculosis is required for bacterial virulence, whilst knocking out the respective gene did not have any effect on bacterial viability or growth rate in vitro. In addition, we studied enzymatic properties of this enzyme after expression and purification from E. coli. Using an enzyme depleted of contaminant divalent cations and different types of fluorescently labelled substrates, we found strong dependence of its activity on the presence of particular cations. Unexpectedly, Zn2+ showed stimulatory activity only at low concentrations, but inhibited the enzyme at higher concentrations. In contrast, Co2+, Ca2+ and Mn2+ stimulated activity at all concentrations tested, whilst Mg2+ revealed no effect on the enzyme activity at all concentrations used.The results of this study provide valuable contribution to the investigation of bacterial peptidases in general, and that of metallo-oligopeptidases in particular. This is the first study demonstrating that opdA in Yersinia pseudotuberculsosis is required for pathogenicity. The data reported are important for better understanding of the role of OpdA-like enzymes in pathogenesis in bacterial infections. Characterisation of this protein may serve as a basis for the development of novel antibacterials based on specific inhibition of this peptidase activity.

Dataset Information

Fis Is Essential for Yersinia pseudotuberculosis Virulence and Protects against Reactive Oxygen Species Produced by Phagocytic Cells during Infection.

Publications

Fis Is Essential for Yersinia pseudotuberculosis Virulence and Protects against Reactive Oxygen Species Produced by Phagocytic Cells during Infection.

Similar Datasets

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