title: Characterisation of the transcriptional regulator CysB in Neisseria gonorrhoeae

authors: Klaus, Hannah Rose

subjects: Neisseria gonorrhoeae

abstract: Neisseria gonorrhoeae is an obligate human pathogen and the causative agent of the sexually transmitted infection gonorrhoea. Rapid emergence of antibiotic resistant strains of N. gonorrhoeae has given rise to multi-drug resistant gonorrhoea. Combined with increasing incidence and the most recent resistance event in 2018, there is an urgent need for new antimicrobial treatments for gonorrhoeal infection. N. gonorrhoeae has a limited number of transcriptional regulators, one of which, CysB, is essential and regulates genes required for de novo cysteine biosynthesis. The cysteine biosynthetic pathway is a promising target for the development of novel antimicrobials. Cysteine plays an important role in protein folding and function, and is the precursor for many thiol-containing molecules within N. gonorrhoeae including effective oxidative stress defences such as glutathione. N. gonorrhoeae displays unique differences in assimilation of sulfur and cysteine biosynthesis, yet little is known about how this altered pathway is regulated in N. gonorrhoeae.
The cysteine regulon consists of the genes required for sulfur transport, assimilation and cysteine biosynthesis. The transcriptional regulator CysB regulates this regulon in other organisms and is essential in N. gonorrhoeae. Understanding how N. gonorrhoeae regulates gene expression will improve our understanding of the pathogenicity of N. gonorrhoeae. In order to understand how CysB mediates gene expression, we need to characterise DNA-binding activity and elucidate the three-dimensional structure. In this thesis, we determine the DNA-binding activity of CysB, its three-dimensional structure and investigate conformational changes of CysB. Our results indicate that CysB regulates genes in the altered cysteine regulon, but that CysB does not respond to the inducer N-acetylserine. The three-dimensional structure of CysB is the first reported full-length CysB structure and was solved to 2.73 Å. Analysis of this structure, coupled with small angle scattering data suggest that CysB from N. gonorrhoeae lacks the ability to undergo the hypothesised large scale conformational changes upon inducer binding. This indicates that CysB may have an alternate mechanism in N. gonorrhoeae.
Collectively, the data presented in this thesis represents key advances in our understanding of how N. gonorrhoeae regulates gene expression by characterisation of the transcriptional regulator CysB. Data presented here is the basis for future work to identify other targets within N. gonorrhoeae that may be investigated for the development of new antimicrobials for treatment of extensively drug resistant gonorrhoea.

text: Characterisation of the transcriptional regulator CysB in Neisseria gonorrhoeae Neisseria gonorrhoeae is an obligate human pathogen and the causative agent of the sexually transmitted infection gonorrhoea. Rapid emergence of antibiotic resistant strains of N. gonorrhoeae has given rise to multi-drug resistant gonorrhoea. Combined with increasing incidence and the most recent resistance event in 2018, there is an urgent need for new antimicrobial treatments for gonorrhoeal infection. N. gonorrhoeae has a limited number of transcriptional regulators, one of which, CysB, is essential and regulates genes required for de novo cysteine biosynthesis. The cysteine biosynthetic pathway is a promising target for the development of novel antimicrobials. Cysteine plays an important role in protein folding and function, and is the precursor for many thiol-containing molecules within N. gonorrhoeae including effective oxidative stress defences such as glutathione. N. gonorrhoeae displays unique differences in assimilation of sulfur and cysteine biosynthesis, yet little is known about how this altered pathway is regulated in N. gonorrhoeae.
The cysteine regulon consists of the genes required for sulfur transport, assimilation and cysteine biosynthesis. The transcriptional regulator CysB regulates this regulon in other organisms and is essential in N. gonorrhoeae. Understanding how N. gonorrhoeae regulates gene expression will improve our understanding of the pathogenicity of N. gonorrhoeae. In order to understand how CysB mediates gene expression, we need to characterise DNA-binding activity and elucidate the three-dimensional structure. In this thesis, we determine the DNA-binding activity of CysB, its three-dimensional structure and investigate conformational changes of CysB. Our results indicate that CysB regulates genes in the altered cysteine regulon, but that CysB does not respond to the inducer N-acetylserine. The three-dimensional structure of CysB is the first reported full-length CysB structure and was solved to 2.73 Å. Analysis of this structure, coupled with small angle scattering data suggest that CysB from N. gonorrhoeae lacks the ability to undergo the hypothesised large scale conformational changes upon inducer binding. This indicates that CysB may have an alternate mechanism in N. gonorrhoeae.
Collectively, the data presented in this thesis represents key advances in our understanding of how N. gonorrhoeae regulates gene expression by characterisation of the transcriptional regulator CysB. Data presented here is the basis for future work to identify other targets within N. gonorrhoeae that may be investigated for the development of new antimicrobials for treatment of extensively drug resistant gonorrhoea.

year: 2022

title: Abrupt millennial-scale changes in intensity of Southern Hemisphere westerly winds during marine isotope stages 2–4

authors: Whittaker, Thomas Edward

subjects: chemistry

abstract: The strength of mid-southern latitude westerly atmospheric circulation plays an important role in global climate. Due to a lack of long, continuous, high-resolution paleoclimate archives from mid-southern latitudes, it remains unclear what factors control changes in its intensity and how past changes affected the climates of landmasses in their path. Here we show growth rate and stable isotope (18O, 13C) profiles from a South Island, New Zealand, stalagmite (HW3) that permit centennial-scale investigation of Southern Hemisphere westerly paleointensity between 73 and 11 ka. Correlation between HW3 growth rate and isotope profiles suggests sensitivity to changes in annual precipitation, a factor controlled by westerly intensity. Low growth rates and relatively enriched isotope ratios define long-term trends in HW3, supporting existing evidence that weaker westerlies predominated during the last glacial period. Abrupt millennial-scale events occur frequently, such that the HW3 record resembles Greenland ice core stable isotope profiles. Furthermore, nearly synchronous timing of nine prominent wet and cool intervals with Heinrich events supports studies showing that increased westerly intensity is closely linked to North Atlantic cooling. As well as Heinrich events, the HW3 profiles also show an Antarctic Cold Reversal–like event during deglaciation, advocating for a bipolar seesaw of global climate at that time.

text: Abrupt millennial-scale changes in intensity of Southern Hemisphere westerly winds during marine isotope stages 2–4 The strength of mid-southern latitude westerly atmospheric circulation plays an important role in global climate. Due to a lack of long, continuous, high-resolution paleoclimate archives from mid-southern latitudes, it remains unclear what factors control changes in its intensity and how past changes affected the climates of landmasses in their path. Here we show growth rate and stable isotope (18O, 13C) profiles from a South Island, New Zealand, stalagmite (HW3) that permit centennial-scale investigation of Southern Hemisphere westerly paleointensity between 73 and 11 ka. Correlation between HW3 growth rate and isotope profiles suggests sensitivity to changes in annual precipitation, a factor controlled by westerly intensity. Low growth rates and relatively enriched isotope ratios define long-term trends in HW3, supporting existing evidence that weaker westerlies predominated during the last glacial period. Abrupt millennial-scale events occur frequently, such that the HW3 record resembles Greenland ice core stable isotope profiles. Furthermore, nearly synchronous timing of nine prominent wet and cool intervals with Heinrich events supports studies showing that increased westerly intensity is closely linked to North Atlantic cooling. As well as Heinrich events, the HW3 profiles also show an Antarctic Cold Reversal–like event during deglaciation, advocating for a bipolar seesaw of global climate at that time.

year: 2011

title: Representations of diversity in the revised New Zealand PictureBook Collection

authors: Daly, Nicola

subjects: picturebooks

abstract: Collections of children’s literature are used for a range of reasons including preservation, record keeping, and more recently the encouragement of intercultural understanding. Both the signifi- cance of learning about other cultures and the importance of children seeing themselves reflected in the books that they read have been discussed extensively. In 2010, the New Zealand PictureBook Collection (NZPBC) was developed in order to create a resource that reflected New Zealand national identity. In 2015 the NZPBC was revised and this article presents a visual and textual analysis of the diversity present in the sixty books nomi- nated through the lens of critical multicultural analysis, using four variables. Findings indicate considerable diversity is present in the collection in terms of representations of ethnicity and family; less so for representations of disability and languages.

text: Representations of diversity in the revised New Zealand PictureBook Collection Collections of children’s literature are used for a range of reasons including preservation, record keeping, and more recently the encouragement of intercultural understanding. Both the signifi- cance of learning about other cultures and the importance of children seeing themselves reflected in the books that they read have been discussed extensively. In 2010, the New Zealand PictureBook Collection (NZPBC) was developed in order to create a resource that reflected New Zealand national identity. In 2015 the NZPBC was revised and this article presents a visual and textual analysis of the diversity present in the sixty books nomi- nated through the lens of critical multicultural analysis, using four variables. Findings indicate considerable diversity is present in the collection in terms of representations of ethnicity and family; less so for representations of disability and languages.

year: 2017