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Title: Structural studies of pathogenicity-related proteins in Clostridium difficile
Author: Crawshaw, Adam Daniel
ISNI:       0000 0004 6499 6038
Awarding Body: Newcastle University
Current Institution: University of Newcastle upon Tyne
Date of Award: 2017
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Clostridium difficile is a Gram-positive obligate anaerobic pathogen that causes debilitating infections which can ultimately be fatal. The life cycle of C. difficile from gut colonisation in vegetative cell form, to survival in the aerobic environment as spores is not fully understood. Sporulation is a cell-cycle stress response that produces a daughter cell by asymmetric division. This forespore is engulfed by the mother-cell and matured before release into the environment. The SpoIIQ-SpoIIIAH complex has been proposed to enable communication between the two cells during this process. The aim of this work was to characterise the inter-sporangial domains of the complex in C. difficile. Localised to the forespore membrane, SpoIIQ was shown to bind a Zn2+ within a conserved LytM endopeptidase domain. Furthermore, it was demonstrated that Zn2+ is essential to form a stable interaction with SpoIIIAH, located in the mother cell membrane, a role not previously observed in homologous SpoIIQ-SpoIIIAH complexes. Cell-surface adhesion is an important factor in gut colonisation. Type IV pili (TFP) form filamentous protein appendages that extended from the cell wall into the environment and have recently been recognised in Gram-positive bacteria. In C. difficile, TFP enable twitching-motility. This work aimed to determine the structures of major and minor pilins in TFP filaments in C. difficile. The crystal structures of the major pilin, PilA1, were determined from two strains of C. difficile. These exhibit similarities to pseudo-pilins from Gram-negative bacteria. Although crystals of a minor pilin, PilK, were obtained, structure determination was so far unachievable. Investigations of potential interactions between major and minor pilins were performed suggesting they may interact, presumably to form the complete pilus. This work contributes to the understanding of proteins involved in sporulation and colonisation, two key mechanisms in C. difficile pathogenicity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available