Examining virulence plasmid loss in Yersinia pseudotuberculosis

Dunlop, Jake (2021) Examining virulence plasmid loss in Yersinia pseudotuberculosis. MRes thesis, University of Nottingham.

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Abstract

The genus Yersinia is composed of eleven species, three of which (Y. pseudotuberculosis, Y. enterolitica, and Y. pestis) are human pathogens. It is believed that Y. pseudotuberculosis is the predecessor of Y. pestis, which causes plague, and as a result there is a close genetic link between the two species. Each of the pathogenic species possess an approx. 70 kb plasmid known as pYV, (pCD1 in Y. pestis and pYVe in Y. enterocolitica) which is essential for virulence. The plasmid codes for a Type III Secretion system (T3SS) composed of structural proteins which form an injectisome (analogous to a hypodermic needle) and effectors which when combined disarm host immune cells through disruption of processes such as actin polymerisation as well as inducing cellular apoptosis. Expression of these proteins, usually referred to as Yops, are known to be regulated by both the environment (through temperature and calcium concentration) and the bacterial cell-to-cell signalling system known as Quorum Sensing (QS).

The QS system plays an important role in the maintenance of the pYV plasmid within the population. Previous work has shown that transcriptional regulators and signal synthase mutants in the QS system are unable to secrete Yops, and virulence plasmid levels in a population fall rapidly in these mutants when compared to the parent. It is hypothesised that QS plays a key role in the maintenance of the pYV plasmid.

This study aims to investigate the link between QS and plasmid maintenance through the targeting of the copA/copB promoters. copA and copB both control the plasmid replication initiation protein RepA through repression of the repA gene. They play a key role in plasmid replication and therefore plasmid maintenance. lux-based reporter fusion technology was used, which contains a luxCDABE cassette, and copA/copB promoters. When gene expression occurs, light is emitted from the cell, which can be measured to indicate the level of this expression. The promoters of copA and copB will be used as a marker for plasmid maintenance by examining expression in the parent and QS mutant backgrounds. These fusions were successfully created, however further data was not possible to obtain given the situation regarding the 2019-Novel-Coronavirus pandemic.

Item Type: Thesis (University of Nottingham only) (MRes)
Supervisors: Atkinson, Steve
Williams, Paul
Keywords: Virulence plasmid loss, Yersinia pseudotuberculosis
Subjects: Q Science > QR Microbiology > QR 75 Bacteria. Cyanobacteria
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
UK Campuses > Faculty of Science > School of Biosciences
Item ID: 65478
Depositing User: Dunlop, Jake
Date Deposited: 04 Aug 2021 04:42
Last Modified: 04 Aug 2021 04:42
URI: http://eprints.nottingham.ac.uk/id/eprint/65478

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