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    Probing sequence plasticity of Ung inhibitors via synthetic and structural biology

    Muselmani, Wael (2022) Probing sequence plasticity of Ung inhibitors via synthetic and structural biology. PhD thesis, Birkbeck, University of London.

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    The uracil-DNA glycosylases constitute a superfamily of DNA repair enzymes. Family 1 enzymes are referred to as Ung or UNG and this branch of the superfamily are also restriction factors, acting against cellular pathogens. UngIn is a global term of reference for anti-restriction proteins inhibiting Ung, which to date are known to be encoded by viruses and the SCCmec transposon pathogenicity islands of MRSA bacteria. UngIns belong to discrete protein fold classes (3 are currently known) that nevertheless share a universal mechanism of Ung inhibition. UngIn folds arise from unrelated sequence families, and within any family extreme sequence plasticity is characteristic. Consequently, the effectiveness of conventional sequence-based identification of UngIns is limited. The study aims were to develop and assess methods for the identification of UngIns in genomes that have a biological need to encode them, but for which no UngIn sequence has yet been identified. We modelled known mutations in UngIns and, via library mutagenesis, generated an expanded repertoire of synthetic UngIns by utilising a novel bacterial conditional lethal assay developed in this study. We also determined newly identified UngIn structures by X-ray crystallography. The insights from these studies permitted us to develop a computational heuristic approach to scan genomes that should encode biologically essential UngIns not yet identified. This approach has enriched our search for incidences of biologically essential UngIns and suggests alternative hypotheses for Ung activity modulation mechanisms.


    Item Type: Thesis
    Copyright Holders: The copyright of this thesis rests with the author, who asserts his/her right to be known as such according to the Copyright Designs and Patents Act 1988. No dealing with the thesis contrary to the copyright or moral rights of the author is permitted.
    Depositing User: Acquisitions And Metadata
    Date Deposited: 18 Nov 2022 10:55
    Last Modified: 01 Nov 2023 15:52


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