Characterisation of the ATP-dependent ligase, Lig E: An investigation into its significance in Neisseria gonorrhoeae
type: CreativeWork
description: The rapid rise in multidrug-resistant Neisseria gonorrhoeae isolates has caused major public concern for the treatment of its sexually transmitted disease, gonorrhoea. Previously easily treatable, gonorrhoea is now spreading at alarming rates due to the bacterium’s ability to take up DNA from its environment without regulation. With approximately 106 million new cases annually, thorough investigations into novel gonococcal pathways that can be targeted to limit its survival and spread are crucial. One possible target is the disruption of its DNA repair systems, which include ligases that seal breaks in DNA, and would greatly discourage bacterial growth. Interestingly, in addition to its replicative ligase, N. gonorrhoeae expresses a minimal ATP-dependent ligase, Ligase E (Lig E), which contains a signal peptide that indicates a likely periplasmic location as opposed to the cytosolic location of genomic DNA. Hence, I hypothesise that Lig E is working on repairing fragmented extracellular DNA which has a role in both biofilm formation and bacterial competence, both of which would be greatly beneficial for the persistence and acquisition of antibiotic resistance genes in N. gonorrhoeae. In this thesis, I focussed on characterising Lig E from N. gonorrhoeae (Ngo-Lig E) to determine its contribution to gonococcal phenotype, as well as its structure, function and cellular location. To analyse its biological role, several ngo-lig E mutants were created in vivo and their growth, stress response, biofilm formation as well as infection and adhesion to a human cell line were studied. I showed that Ngo-Lig E is not essential for normal planktonic N. gonorrhoeae growth and survival; however, it is important for its biofilm formation and subsequent adhesion onto human cells. Following this, I further investigated the potential role of Ngo-Lig E on biofilm formation by looking at its morphology via scanning electron microscopy and confocal laser scanning microscopy after growing t…
abstract: The rapid rise in multidrug-resistant Neisseria gonorrhoeae isolates has caused major public concern for the treatment of its sexually transmitted disease, gonorrhoea. Previously easily treatable, gonorrhoea is now spreading at alarming rates due to the bacterium’s ability to take up DNA from its environment without regulation. With approximately 106 million new cases annually, thorough investigations into novel gonococcal pathways that can be targeted to limit its survival and spread are crucial. One possible target is the disruption of its DNA repair systems, which include ligases that seal breaks in DNA, and would greatly discourage bacterial growth. Interestingly, in addition to its replicative ligase, N. gonorrhoeae expresses a minimal ATP-dependent ligase, Ligase E (Lig E), which contains a signal peptide that indicates a likely periplasmic location as opposed to the cytosolic location of genomic DNA. Hence, I hypothesise that Lig E is working on repairing fragmented extracellular DNA which has a role in both biofilm formation and bacterial competence, both of which would be greatly beneficial for the persistence and acquisition of antibiotic resistance genes in N. gonorrhoeae. In this thesis, I focussed on characterising Lig E from N. gonorrhoeae (Ngo-Lig E) to determine its contribution to gonococcal phenotype, as well as its structure, function and cellular location. To analyse its biological role, several ngo-lig E mutants were created in vivo and their growth, stress response, biofilm formation as well as infection and adhesion to a human cell line were studied. I showed that Ngo-Lig E is not essential for normal planktonic N. gonorrhoeae growth and survival; however, it is important for its biofilm formation and subsequent adhesion onto human cells. Following this, I further investigated the potential role of Ngo-Lig E on biofilm formation by looking at its morphology via scanning electron microscopy and confocal laser scanning microscopy after growing t…
author: Pan, Jolyn
license: https://researchcommons.waikato.ac.nz/bitstreams/438cc707-15a1-4d16-bb44-1f870269b09d/download
date published: 2025
date modified: 2026-07-24T05:57:30Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato