The enzyme adenosine triphosphate phosphoribosyltransferase (ATP-PRT) catalyses the first reaction of the histidine biosynthetic pathway. ATP-PRT also represents a metabolic control point, directing the flux of metabolites through this energetically expensive pathway. Two distinctly different forms of ATP-PRT exist, the long form and the short form, which differ in the presence of a C-terminal regulatory domain. In the short form, where this domain is absent, it is functionally replaced by a regulatory protein, called HisZ. ATP-PRT activity is modulated by two layers of regulation: active site inhibition by adenosine monophosphate, which reflects cellular energy levels, and pathway end product feedback inhibition by histidine. In the long form ATP-PRT histidine binds to the allosteric site at the regulatory domain, but the exact nature of the inhibitory mechanism is still debated. This thesis characterises a new member of the ATP-PRT long form from Campylobacter jejuni (CjeATP-PRT) and investigates the molecular mechanisms involved in the feed back inhibition by histidine. Chapter 2 describes the characterisation of the CjeATP-PRT including a detailed description of its crystal structure. The C. jejuni enzyme is similar to the previously described enzymes of the ATP-PRT long form, but exists only as hexameric species under experimental conditions, which contradicts previous assumptions that the hexamer is exclusively inactive. Chapter 3 investigates the catalytic apparatus of CjeATP-PRT by separating the catalytic and regulatory domains of the enzyme for individual study. The isolated catalytic portion of the enzyme, the CjeATP-PRT Core mutant, forms a dimeric species with very limited catalytic capabilities but high substrate and product affnities. The CjeATP-PRT Core characteristics suggest that it exists in a permanently inhibited conformation, highlighting the requirement of the regulatory domain not only for feedback regulation but also for enzyme function. Additionally this supports the evolutionary need for the recruitment of a regulatory apparatus. In chapter 4 a potential intramolecular communication pathway from the allosteric to the active site is probed by the generation of several single site mutations. One of these, CjeATP-PRT R216A, is completely insensitive to histidine inhibition, although this ligand is still able to bind at the allosteric site, which is consistent with the involvement of R216 in the allosteric signal communication. The catalytic abilities of CjeATP-PRT R216A are largely impaired, leading to the assumption that this mutation causes a permanent inhibitory response. In summary this thesis supports the existence of a simple physical regulatorymechanism for the feedback inhibition of the ATP-PRT long form, the change between two different hexamer conformations depending on the presence of the allosteric effector.

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published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

This dissertation explores the impact of nongovernmental organizations (NGOs) and state-civil society relations on national development. In doing so, it advances the development literature by keeping pace with the institutional changes brought about by decades of neoliberal policy. The NGO sector has expanded rapidly in recent years, becoming a major component of developing countries' civil societies and key actors in the development process at all levels, from the local to the global. NGOs now participate in everything from service delivery to policy design and advocacy. States, on the other hand, have seen aspects of their capacity weakened and their involvement in development transformed. At the same time, they are exposed to new demands and pressures by both domestic and international groups, including the NGO sector. Drawing on the insights of state, world society, and social capital theories, this dissertation addresses this new institutional reality of national development by examining the relationship between the state and NGO sector. The dissertation proceeds in two parts. Part I uses cross-national quantitative methods to assess the effect of global society embeddedness on national economic and social development, particularly through the promotion of more responsive and effective governance. As such, the analyses expand on and contribute empirically to the literature on the developmental state. Part II focuses on the state-NGO sector relationship more directly, using Qualitative Comparative Analysis and case study methods to identify types of state-civil society regimes, as well as the conditions associated with complementary state-NGO sector relations.

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No description available.

No description available.

The cell's nucleus contains DNA in the form of chromosomes, which are the hereditary content of the organism. The proper transmission of DNA from one generation to the next is critical. Along with this crucial process, cells will also need to transcribe the DNA, silence certain genes (or whole chromosomes) during development and regulate other chromosome dynamics that are still being identified. The molecular components responsible for these processes are starting to be identified. However, the regulation of these components and how they interact with each other is not well understood.The condensin complex is one component that has been identified to play a role in chromosome dynamics. Activity of the complex has been studied in vitro but in vivo activity has been difficult to measure. Similarly, understanding the regulation of the complex has been difficult given the lack of assays and that the complex is essential for cell survival. In this dissertation, I have identified and characterized a regulator of condensin II function using Drosophila melanogaster. The chromo-domain protein Mrg15 interacts with condensin II to inhibit homologous chromosome interactions.Lastly, I look at the role of condensin II in female meiosis. Meiosis involves pairing and subsequent segregation of homologous chromosomes. The process of the initial pairing has remained elusive but specialized structures have evolved to maintain this pairing. Condensin II can antagonize a basal level of homologous pairing and also removes the specialized structure that pair meiotic chromosomes. This dissertation will add to the growing knowledge of the regulation of the condensin II complex and its role in female meiosis.