• Login
    View Item 
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Molecular mechanism of export of alginate in Pseudomonas aeruginosa : a thesis presented in partial fulfilment of the requirements for [the] degree of Doctor of Philosophy in Microbiology at Massey University, New Zealand

    Icon
    View/Open Full Text
    02_whole.pdf (3.151Mb)
    01_front.pdf (144.4Kb)
    Export to EndNote
    Abstract
    Pseudomonas aeruginosa is an opportunistic pathogen; infecting insects, plants and humans. It is of particular relevance to cystic fibrosis (CF) patients where it causes pulmonary infection and the leading cause of morbidity and mortality. The CF lung environment selects for a variant of P. aeruginosa characterised by the overproduction of an exopolysaccharide called alginate. It has been hypothesized that outer membrane protein AlgE forms a channel through which alginate is secreted into the extracellular environment. Furthermore, studies have suggested that proteins involved in the polymerisation, modification and export of alginate form a multiprotein complex that span the bacterial envelope. The aim of this thesis was to investigate the role of AlgE in polymerisation and secretion of alginate. For this purpose algE knockout mutant was created in PDO300. Results showed that AlgE does not have a role in alginate polymerisation however it has a role in secretion of alginate and stability of the alginate biosynthesis machinery. By performing FLAG epitope insertion mutagenesis the topology of AlgE was verified and site-directed mutagenesis further showed that the positive electrostatic field inside the AlgE lumen is required for efficient secretion of negatively charged alginate. By employing mutual stability analysis, evidence was provided for the existence of trans-envelope multiprotein complex required for alginate biosynthesis. Co-immuniprecipitaion assay suggest that AlgE interacts with periplasmic located AlgK and, most probably, this interaction is mediated by the peripasmic turn 4 of AlgE. Pull-down assays further showed that AlgK interacts with another periplasmic protein AlgX which in turn interacts with the inner membrane protein Alg44. Based on mutual stability analysis it was proposed that Alg44 interacts with Alg8 which might interacts with AlgG as well. Our results also support the existence of internal promoters for AlgE and AlgG.
    Date
    2013
    Author
    Rehman, Zahid ur
    Rights
    The Author
    Publisher
    Massey University
    Description
    Chapter 2 has been published as: Hay, I.D., Rehman, Z.U., Ghafoor, A., & Rehm, B.H.A. (2010). Bacterial biosynthesis of alginates. Journal of Chemical Technology and Biotechnology, 85(6), 752-759. The definitive version is available at www3.interscience.wiley.com
    URI
    http://hdl.handle.net/10179/4322
    Collections
    • Theses and Dissertations
    Metadata
    Show full item record

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1-beta1
     

     

    Tweets by @Massey_Research
    Information PagesContent PolicyDepositing content to MROCopyright and Access InformationDeposit LicenseDeposit License SummaryTheses FAQFile FormatsDoctoral Thesis Deposit

    Browse

    All of MROCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2020.1-beta1