Home
    • Login
    View Item 
    •   TDL DSpace Home
    • Federated Electronic Theses and Dissertations
    • Texas A&M University at College Station
    • View Item
    •   TDL DSpace Home
    • Federated Electronic Theses and Dissertations
    • Texas A&M University at College Station
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Inter-kingdom Recognition of Norepinephrine by E. Coli : Identification of the Receptors Involved in Chemotaxis

    Thumbnail
    Date
    2012-10-19
    Author
    Kim, Dae Nyun
    Metadata
    Show full item record
    Abstract
    There are approximately 10^14 bacteria belonging to nearly 1000 different species in the human gastrointestinal (GI) tract that co-exist with host cells. Within the GI tract, signaling molecules secreted by both eukaryotic and prokaryotic cells are abundant. Recent studies have shown that both bacteria and human cells recognize and respond to the signals from each other, presumably to gain a competitive advantage. The cross-recognition of signals is known as Inter-kingdom (IK) signaling and this phenomenon is considered to be important in the onset of infections in the GI tract. Of the eukaryotic signaling molecules present in the GI tract, the neuroendocrine hormone norepinephrine (NE) is considered to be important in the context of infections as NE is produced at very high concentration in the intestine under post traumatic stress, is known to increase bacterial virulence and infection, and has also been shown to be a potent chemoattractant for GI tract pathogens such as enterohemorrhagic E. coli (EHEC). The focus of this study is on elucidating the mechanisms underlying the recognition and chemotaxis of bacteria towards NE. While chemotaxis has been typically investigated in the context of bacteria moving towards a metabolizable source (e.g., amino acids), chemotaxis is potentially important in the onset of infections in the human GI tract. In this study we use a microfluidic plug assay to investigate the receptor and mechanism utilized by a model bacterium Escherichia coli in its chemotactic response to NE. A series mutant of E. coli RP437 strains of knockouts for four MCP-encoding genes was used in this study. The results from the microfluidic plug assay were then confirmed quantitatively by capillary assay. We have shown that Tsr receptor is necessary for chemotaxis of NE for E. coli RP437, and attraction of E. coli towards NE may require an additional receptor. Results from the priming experiments suggest that exposure to NE may result in the de novo expression of co-receptor(s) that are crucial to chemotaxis towards NE. The requirement for high cell density also suggests the possibility that NE per se may not be an attractant for E. coli, but could be a precursor that is modified into a chemoattractant by cells. These results are expected to further our understanding of bacterial chemotaxis and its role in bacterial colonization and infection of the human GI tract.
    URI
    http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11818
    Collections
    • Texas A&M University at College Station

    DSpace software copyright © 2002-2016  DuraSpace
    Contact Us | Send Feedback
    TDL
    Theme by @mire NV
     

     

    Browse

    All of DSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login

    DSpace software copyright © 2002-2016  DuraSpace
    Contact Us | Send Feedback
    TDL
    Theme by @mire NV