DNA repair during bacterial competence? A potential role for the periplasmic ligase, Lig E

Pan, Jolyn Tyn Tyn

DNA repair during bacterial competence? A potential role for the periplasmic ligase, Lig E

dc.contributor.advisor	Williamson, Adele
dc.contributor.advisor	Hicks, Joanna
dc.contributor.author	Pan, Jolyn Tyn Tyn
dc.date.accessioned	2021-08-30T21:56:13Z
dc.date.available	2021-08-30T21:56:13Z
dc.date.issued	2021
dc.date.updated	2021-08-30T01:40:35Z
dc.description.abstract	The rapid rise in antibiotic resistance among pathogenic bacteria calls for better understanding of drivers of resistance and pathways by which it occurs. Identification of such mechanisms could identify novel pathways that can be targeted for therapeutic interventions. In particular, disruption of the DNA repair system, which includes ligases that seal breaks in DNA, would greatly discourage bacterial growth. Recently, an enigmatic ATP-dependent DNA ligase, Lig E, has been discovered in many species of antibiotic-resistant Gram-negative bacteria. This enzyme is not only minimal and compact, but also contains an N (amino)-terminal signal peptide that indicates a likely periplasmic location, as opposed to the cytoplasm, the location of genomic DNA. It is thus hypothesised that Lig E has a potential role in bacterial competence and aids in repairing breaks in damaged DNA obtained from the environment, a role which may enhance the acquisition of antibiotic resistance genes under DNA damaging conditions. In recent years, there has been growing public concern about the human pathogen Neisseria gonorrhoeae, which causes the sexually transmitted disease, gonorrhoea. Previously easily treatable, this disease is now spreading at alarming rates due to the bacterium’s rapid acquisition of antibiotic resistance genes, attributable to its ability to take up pieces of DNA without regulation. It is in relation to this natural competence that Lig E is hypothesised to function, not only by accelerating the uptake process, but also by increasing the uptake efficiency. Thus, the aim of this thesis was to identify the cellular location and biological function of Lig E in N. gonorrhoeae (Ngo-Lig) by generating in vivo mutants, the effects of which were characterised both in vivo (growth experiment) and in vitro (ligation assays). Steps were also made towards developing an in vivo assay to test the role of Ngo-Lig in DNA uptake by optimisation of uptake reporter constructs. Results obtained over the course of this thesis showed that disruption of Lig E in N. gonorrhoeae leads to a decrease in the rates of gonococcal growth. From this, the hypothesis of the role of Lig E evolved to also consider its potential role in biofilm formation, which is important for the bacterium’s attachment and infection. Although further research into the biological role of Lig E are necessary, the results collected demonstrated potentially novel pathways involving Lig E that may be targeted by future drug developments to tackle this emerging threat in our community.
dc.format.mimetype	application/pdf
dc.identifier.citation	Pan, J. T. T. (2021). DNA repair during bacterial competence? A potential role for the periplasmic ligase, Lig E. (Thesis, Master of Science (Research) (MSc(Research))). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/14546	en
dc.identifier.uri	https://hdl.handle.net/10289/14546
dc.language.iso	en
dc.publisher	The University of Waikato
dc.rights	All items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subject.lcsh	DNA ligases
dc.subject.lcsh	Ligases
dc.subject.lcsh	Neisseria gonorrhoeae -- Treatment
dc.subject.lcsh	Bacterial genetics
dc.subject.lcsh	Neisseria gonorrhoeae -- Molecular aspects
dc.title	DNA repair during bacterial competence? A potential role for the periplasmic ligase, Lig E
dc.type	Thesis
pubs.place-of-publication	Hamilton, New Zealand	en_NZ
thesis.degree.grantor	The University of Waikato
thesis.degree.level	Masters
thesis.degree.name	Master of Science (Research) (MSc(Research))