Molecular analyses of YhcN/YlaJ and spore-associated proteins involved in germination of Bacillus cereus spores
University of Cambridge
Doctor of Philosophy (PhD)
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Mustafa, A. (2021). Molecular analyses of YhcN/YlaJ and spore-associated proteins involved in germination of Bacillus cereus spores (Doctoral thesis). https://doi.org/10.17863/CAM.79010
Bacterial spores formed by members of the Bacillales are notable for their properties of dormancy and resistance to a range of physicochemical and biological factors that would kill their vegetative cellular counterparts. Bacillus cereus is one such spore-forming organism, and is a significant vector in food-borne toxigenesis. The spore form of the organism is important in surviving food processing procedures, but germination and subsequent formation of a new vegetative cell is required for the production of toxins. Accordingly, there is much interest – both applied and intrinsic - in gaining a complete understanding of the spore germination process of this and other species. This project employed principally molecular genetic and fluorescence microscopy techniques to investigate various aspects of the germination apparatus of Bacillus cereus 10876 and 14579 spores. Significant findings include the observation that the YhcN protein appears to influence the precise location of SleB within spores and or possibly influence the properties of the inner membrane such that initiation of germination is extended considerably in DyhcN strains. Work associated with the early stages of germination revealed that Bacillus cereus germinant receptors cluster to form low numbers of germinosome-type structures in individual spores, as does the GerD protein. The delay in initiation of DyhcN spores is not, however, due to any obviously negative effect on germinosome formation. The most significant observations stemming from work associated with spore peptidoglycan depolymerisation concerns the function of hybrid cortex lytic enzymes. Mother-cell expressed SleB and forespore-expressed SleB-CwlJ hybrid proteins are capable of efficient cortex hydrolysis during germination and, additionally, can be activated by exogenous CaDPA. Activation of SleB by CaDPA has hitherto not been observed in spores. Collectively, outputs from the work permit refinement of models of Bacillus cereus spore germination, and indeed, germination more generally, and provide a basis for further work in this area.
Bacillus spores, Bacillus cereus, Endospores, Spore germination
Ministry of Higher Education Malaysia Scholarship, University of Malaysia Perlis Training Scheme.
This record's DOI: https://doi.org/10.17863/CAM.79010
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