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Title

Characterization of the Yersinia Autotransporter Proteins (Yaps) and Their Roles in the Pathogenesis of Y. pestis

Date of Award

Summer 8-15-2012

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Molecular Microbiology & Microbial Pathogenesis)

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Yersinia pestis CO92 has 12 open reading frames encoding putative conventional autotransporters (yaps), nine of which appear to produce functional proteins. This work provides evidence supporting the annotation of these genes as autotransporters by demonstrating that the Yaps localize to the cell surface in both E. coli and Y. pestis, and that a subset is processed by bacterial omptin proteases and released into the supernatant. Using mouse models of plague, we determined that all nine yap genes are transcribed in the lymph nodes during bubonic infection and in the lungs during pneumonic infection, suggesting a role for the Yaps during infection. Autotransporters have been implicated in the pathogenesis of numerous Gram–negative bacteria. We therefore evaluated the contribution of several yaps to the virulence of Y. pestis in mouse models of plague and found three that are important for Y. pestis virulence. The yapE gene is unique in that it is found not only in Y. pestis, but also in the related gastrointestinal pathogens Y. pseudotuberculosis and Y. enterocolitica. Deletion of yapE from Y. pestis results in decreased efficiency in lymph node colonization and disseminated spread during bubonic infection. YapE appears to function as an adhesin, as it facilitates adhesion to eukaryotic cells and bacterial auto–aggregation. yapK and yapJ are found in Y. pestis and share high sequence identity, but only yapK is found in Y. pseudotuberculosis, along with two homologs not found in Y. pestis (YPTB3285 and YPTB3286). Phylogenetic analysis indicates that members of this family cluster as either YapK–like (YapK, YPTB0365, YPTB3285) or YapJ–like (YapJ, YPTB3286), while sharing >96% amino acid identity in their C–termini and 58-72% in their N–termini. Deletion of all yapJ/yapK, homologous in Y. pseudotuberculosis does not seem to impact virulence in orogastric or systemic infection models, but yapK and yapJ make non–redundant contributions to systemic Y. pestis infection. Further work aims to elucidate the specific functions of the Yaps and clarify the contributions of these proteins to Y. pestis pathogenesis.

Language

English (en)

Chair and Committee

Virginia L Miller

Committee Members

Michael G Caparon, David A Hunstad, Gregory D Longmore, Mark J Miller

Comments

Permanent URL: https://doi.org/10.7936/K7445JDR

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