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Dynamics of protein folding and subunit interactions in assembly of the yeast mediator complexShaikhibrahim, Zaki January 2009 (has links)
The Mediator complex was originally discovered in the yeast Saccharomyces cerevisiae and has since then been shown to be required for transcriptional regulation both in vitro and in vivo. The Mediator complex also stimulates basal, unregulated transcription and serves as a bridge by conveying signals from promoter-bound transcriptional regulatory proteins such as activators and repressors to the RNA Polymerase II general transcriptional machinery. The Mediator consists of 21 subunits and can be divided into three distinct modules head, middle and tail. Despite the tremendous progress that has been achieved so far in characterizing the Mediator complex both functionally and structurally, many aspects of the complex are not yet well understood. The objective of this work is to achieve further understanding of the Mediator complex by studying the folding of different protein subunits, their interactions and how that affects assembly of the Mediator complex. In our first study we made a temperature-sensitive med21 mutant and used it to identify genes that can suppress the mutation when present in high copy number. Among the 10 genes that we identified, the strongest suppressors were Med7 and Med10, which encode Mediator subunits, and Ash1, which encodes a repressor of the HO gene. We also used 2-hybrid experiments and immunoprecipitation to study protein-protein interactions between Med21 and the Med4, Med7 and Med10 proteins which are all essential for viability and located within the middle domain of the Mediator complex. We found that the N-terminal 2-8 amino acids of Med21 are required for interactions with Med7 and Med10. These results led us to propose a model in which the N-terminal part of Med21 functions as a molecular switchboard where competing signals from various activators, repressors and mediator subunits are integrated prior to reaching the general transcription machinery. In our second study, we extended our studies of protein-protein interactions to another part of the mediator complex by studying the folding and the assembly processes of the mediator head domain subunits Med8, Med18 and Med20. Using purified proteins and a combination of several different methods such as immunoprecipitation, far-UV circular dichroism and fluorescence, we demonstrated that the Med8, Med18 and Med20 subunits are interdependent on each other for proper folding and complex formation.
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The Best There Is? : An Inquiry into Best Execution RulesOrdeberg, Thomas January 2013 (has links)
Best execution obligations weigh on brokers when they execute orders to trade in shares for clients. These obligations have been seen as an outflow of general agency duties, and have been complemented by regulatory requirements related to best execution, dissemination of trading data, the handling of client orders and – in the United States – an obligation to execute at the best publicly available price or better (price protection). Here, different sets of real-world rules are analyzed with regard to transactional efficiency. Economic analyses are used to compare the effects of different rules, and are underpinned by a detailed analysis of relevant rules in the United States, the European Union, France, Sweden and England & Wales. Several normative conclusions can be drawn. Best execution rules that impose an agency duty on brokers do not seem to contribute in a discernible way to increased transactional efficiency. In contrast, disclosure rules that require both brokers and trading venues to provide ex post information about execution quality, and about how client orders have been routed, may contribute to mitigating the information asymmetry between brokers and clients. The compliance costs associated with such rules are outweighed by the positive effects on transactional efficiency. Lastly, a solution such as the US National Market System, which entails consolidated collection and dissemination of market data as well as price protection, can deliver significant efficiency gains through the virtual consolidation of trading venues. It also allows for more detailed regulations on different aspects of order execution, allow order execution regulations to function better, and is conducive to deeper integration of trading. However, creating such a system entails large initial investments. In the end, the choice whether to create a tightly-knit market system or not has wide-ranging implications for market structure, the design of regulatory rules and market integration.
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Strategic Control of Private Security by Canadian Extraction IndustriesAtchison, Scott 20 December 2012 (has links)
In the absence of Canadian legislation this thesis conducts an exploratory study of the regulations Canadian extraction companies (mining and oil and gas) have implemented to control private security in developing countries. It focuses on discerning what private security policies extraction companies have in place and whether companies have adopted voluntary regulations such as the Voluntary Principles on Security and Human Rights. For this study a survey was conducted of almost all extraction companies listed on the TSX and TSX Venture Exchange. Publically available documents, such as company websites, codes of conduct, annual reports, and corporate presentations, were analyzed to determine what regulations companies have in place. The data indicates that regulation of private security is mainly limited to Canada’s largest extraction companies and that private security is usually a small portion of a company’s overall corporate social responsibility policy. This research also reviews incidents of human rights abuses committed by private security personnel working for Canadian extraction companies over the last ten years. Incidents are drawn from media outlets, NGOs, and academic articles. These cases help illustrate the challenges Canadian companies face employing private security personnel on the ground.
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Assessing the impact of demographic, experiential, and attitudinal factors on support for the criminalization of HIV transmissionPerkins, Michael 01 December 2012 (has links)
Over the years criminal prosecutions regarding HIV transmission have increased in
Canada. There is ongoing debate within the academic and legal community regarding whether
reactive, criminal justice measures or preventative, harm reduction measures are best suited to
address HIV transmission. Using an on-line survey and multiple logistical regression analyses on
six vignettes on 316 undergraduate students from mostly 18-26 years of age, this research
assessed student attitudes towards the criminal law as a response to HIV transmission against
demographic, experiential and attitudinal predictors. The findings indicated that the majority of
participants were in favour of the criminalization of HIV transmission. The policy implications
that come from this study imply that there is a need to educate young people about HIV related
issues and the harm criminal justice responses cause to HIV prevention efforts. / UOIT
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The Role of BERP in Mammalian SystemsCheung, Carol Chui-San 17 January 2012 (has links)
p53 functions as an important tumour suppressor through its ability to regulate a number of important cellular processes such as cell cycle arrest, apoptosis, DNA repair, senescence, and angiogenesis. An in vivo genetic modifier screen performed using Drosophila melanogaster resulted in the identification of D. melanogaster brain tumour (brat) as a putative modifier of of the p53 small eye phenotype. Mammalian homologs of brat are members of the tripartite motif family that contain a c-terminal NHL domain. We focus on elucidating the in vivo role of one such homolog, BERP, through the generation and characterization of a classical gene-deletion mouse mutant. We report that BERP-deficient mice exhibit enhanced learning/memory, increased fear, impaired motor coordination, and increased resistance to PTZ -induced seizures. Electrophysiological and biochemical studies show a decrease in mIPSC amplitude along with a decrease in cell surface expression of gamma2 subunit-containing GABA A receptors in the brains of BERP-deficient mice. In addition, no effect of genotype is apparent when examining BERP mRNA levels in the brain. This suggests that the decreased cell surface expression of gamma2 subunit-containing GABA A receptors is likely a posttranscriptional phenomenon and supports the possibility that BERP may be involved in the intracellular trafficking of GABA A receptors. In investigating the possible relationship between BERP and p53, we identify the presence of a transcriptionally competent p53 response element within the first intron of the human BERP genomic locus and demonstrate that the BERP expression is up regulated in a p53-dependent manner both in vitro and in vivo. These results support the interpretation that BERP is a novel p53-regulated gene and suggest a new role for p53 in the regulation of GABA A receptor trafficking and epileptogenesis.
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Cloning, expression, and purification of the <i>Drosophila melanogaster</i> dosage compensation complex chromodomains and their <i>Homo sapiens</i> orthologuesWelham, Andrew James 25 February 2009
Sexual differentiation is a fundamental characteristic of all eukaryotes, dictating sex-specific morphology, physiology and behavior. Diploid organisms with heteromorphic sex chromosomes (XX or XY) require regulatory compensation of the X chromosome to maintain correct levels of genetic expression between the sexes, a process termed sex-specific dosage compensation (SSDC). The fruit fly, <i>Drosophila melanogaster</i> dosage compensates by upregulating transcription of most X-linked genes two-fold. Associated with this two-fold up regulation is the male-specific lethal (MSL) complex, a RNA-protein complex comprised of at least five known proteins; MSL1, MSL2, MSL3, males absent on the first (MOF), and maleless (MLE) and two non-translated RNA molecules; roX1 (RNA on the X chromosome) and roX2. The complex modulates the chromatin structure of the male X chromosome via acetylation of H4K16. MOF and MSL3 both exhibit an N-terminal chromodomain, whose function is unclear. The MSL3 chromodomain has been suggested to bind H3K36Me3. Chromodomains are a paradigm of how a single structural fold has evolved in diverse proteins to bind distinct targets. Chromodomains are common to nuclear regulators, and bind diverse targets including histones, DNA, and RNA. They function as recognition motifs of histone post-translational modifications and facilitate the translation of the histone code into a distinct local chromatin structure via recruiting the appropriate chromatin modulating machinery.<p>
The goal of this research is to determine the structure of the <i>D. melanogaster</i> MOF and MSL3 chromodomains by X-ray crystallographic and/or nuclear magnetic resonance techniques, to advance our understanding of the structural characteristics of these diverse domains. Here we report the cloning and reproducible expression and purification of the <i>D. melanogaster</i> MOF and MSL3 chromodomains and their Homo sapiens orthologues. The <i>D. melanogaster</i> MOF chromodomain, whose NMR structure was published during this research, has been crystallized. Attempts to solve the crystal structure by molecular replacement, multiple-wavelength anomalous dispersion, and single-wavelength isomorphous replacement are reported.
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Structural and Functional Insights on Regulation by Phenolic CompoundsShahinas, Dea 26 February 2009 (has links)
The shikimate pathway is a primary metabolic pathway involved in the synthesis
of aromatic compounds in plants, fungi, apicomplexan parasites and microbes.
The absence of this pathway in animals makes it ideal for the synthesis of
antimicrobial compounds and herbicides. Additionally, its branching into indole
hormone synthesis and phenylpropanoid secondary metabolism makes this
pathway attractive for metabolic engineering. Here, the focus is on the first step
of the shikimate pathway catalyzed by DAHP synthase. This step consists of the
condensation of phosphoenol pyruvate and erythrose-4-phosphate to make
DAHP, which undergoes another six catalytic steps to synthesize chorismate, the
precursor of the aromatic amino acids. Arabidopsis thaliana contains three DAHP
synthase isozymes, which are known to indirectly regulate downstream pathways
in response to wounding and pathogen stress. The model presented here
proposes that DAHP synthase isozymes are regulated by the end products
tyrosine, tryptophan and phenylalanine.
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Protein-protein Interaction Between Two Key Regulators of One-carbon Metabolism in Saccaharomyces cerevisiae.Khan, Aftab 27 July 2010 (has links)
One-carbon metabolism is an essential process that is conserved from yeast to humans. Glycine stimulates the expression of genes in one-carbon metabolism, whereas its withdrawal causes repression of these genes. The transcription factor Bas1p and the metabolic enzyme Shm2p have been implicated in this regulation. I have shown that Bas1p physically interacts with Shm2p through co-immunoprecipitation. Using chromatin immunoprecipitation (ChIP), I have also shown that the interaction between Bas1p and Shm2p occurs at the promoter of two genes in the one-carbon metabolism regulon and that the binding of Shm2p requires Bas1p. Using a yeast-two hybrid system, I have systematically truncated Bas1p from the C-terminal end to find a region responsible for the interaction with Shm2p. My data suggest that Shm2p is directly bound to Bas1p at the promoters of glycine regulated genes where it regulates the transcriptional activity of Bas1p in response to changes in glycine levels.
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How Regulatory Arbitrage Contributed To The Financial Crisis Of 2007-2009; And How We Can Prevent Regulatory Avoidance In The Financial Services Sector Going ForwardHochberg, Michael 01 January 2011 (has links)
This paper will consider how regulatory arbitrage contributed to the 2007-2009 financial crisis (the “financial crisis”). In particular, the paper will establish how the avoidance of regulatory capital requirements by large and complex financial institutions (“LC financial institutions”) severely worsened the financial crisis, necessitating a massive rent extraction from U.S. taxpayers. In doing to, the paper will examine the regulatory arbitrage perpetrated by American International Group and the subsequent U.S. taxpayer bailout of that firm.
Because of the enormous amount of sovereign credit that had to be substituted for private capital during the financial crisis the paper assumes that the net negative nature of regulatory avoidance by LC financial institutions is axiomatic. Therefore, the paper advances several possible reform measures that could eventually be implemented into a new legal framework to confront the problems that are posed by the avoidance of financial services regulations.
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The Directive on Alternative Investment Fund Managers: Comparative Analysis of Certain Aspects of the Regulatory Regimes of Europe, Canada and the United States of AmericaHernandez, Miguel A. 21 March 2012 (has links)
The Alternative Investment Fund Managers Directive ("AIFMD"), adopted by the European Union on 11 November 2010, has introduced a harmonized set of rules for alternative investment funds (“AIFs”) in Europe.
This thesis discusses potential financial risks for the AIFs industry arising from the European regulatory reform, which started before the current financial crisis, and compares relevant European, Canadian and US rules governing AIFs. This comparative analysis is based on four main criteria: i) registration and authorization requirements, ii) general financial transparency requirements, iii) capital requirements, and iv) remuneration restrictions.
The analysis of AIFs regulatory reform in Europe leads to three main conclusions. First, the AIFMD requirements are much stricter than analogue regimes in Canada and the United States. Second, as a consequence of this regulation, European AIFs may be in disadvantage. Third, the complexity of the present European institutional framework is not able to fully implement the European regulatory reform.
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