Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

CPF1 (<strong>c</strong>entromere <strong>p</strong>romoter <strong>f</strong>actor 1) of Saccharomyces cerevisiae is a multifunctional protein. This multifunctionality may be associated with the different forms of the protein. To date, no clear function has been attributed to this protein. The general roles currently attributed to CPF1 are: maintenance of proper chromosome segregation or centromere function; methionine prototrophy and chromatin modulation. A series of recent papers have suggested the possibility of CPF1 being involved in protein-protein interactions. This thesis shows that CPF1 has an additional protein-protein interaction domain which is a coiled-coil. A truncation of CPF1 coding for only the C-terminal dimerization motif was cloned into a 17 expression vector and the protein, Dd, was produced in and purified from E. coli. Characterisation of the conformation of the C-terminal dimerization domain of CPF1 show the presence of a leucine zipper in Dd and that Dd forms a dimer under physiological conditions. Sequence alignment analysis of CPF1 and other bHLHZIP proteins identified a conserved serine residue in the basic domain of CPF1 and a conserved asparagine residue in the leucine zipper. Point mutations were introduced separately mutating these residues into either alanine or glutamate. The mutant alleles were cloned into yeast expression vectors. The cloned alleles were used to transform YAG93, a cpf1 deletion strain. Characterisation of the transformants obtained indicate the possibility of CPF1 being involved in the spindle assembly checkpoint control, possibly as a tethering protein. Finally, attempts were made to identify interacting partners of CPF1 and a purification scheme was designed to purify a putative CPF1 complex. Initially, a GST-CPF1 chimera was used to screen radioactively labelled crude yeast extracts for interacting partners of CPF1. This strategy identified five or six potential proteins which might form a multiprotein complex with CPFl. Attempts were then made to purify this putative complex from S. cerevisiae. The partially purified extracts were tested for CDEI activity, indicative of the presence of CPF1 in the samples and. tjhen analysed for protein content. The samples were also tested in a Holiday junction binding assay and in a histone acetyltransferase activity assay. In conclusion, CPF1 is a bHLHZIP protein that has a role in nutrient signalling and checkpoint control, possibly by acting as an intermediary protein that recruits essential factors to gene promoters or the centromere by protein-protein interactions.

Thesis (Ph.D.)--University of Melbourne, Howard Florey Institute of Experimental Physiology and Medicine and Dept. of Anatomy and Cell Biology, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 108-130).

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Les oscillations en composition et taille des grains peuvent parfois être générées dans les intrusions magmatiques, produisant des motifs caractéristiques à l’échelle du centimètre au mètre sous forme de couches cycliques. Il est essentiel de comprendre l’origine de ces motifs afin d’établir les circonstances géologiques de formation de ces corps. Nous travaillons avec l’hypothèse que ces motifs sont le résultat d’un processus d’auto- organisation non linéaire selon lequel l’interaction entre la dynamique de cristallisation et la diffusion cause la ségrégation des minéraux selon leur nature et leur taille. Ce mécanisme est semblable à celui à l’origine des bandes de Liesegang et mène à des caractéristiques comparables, telles qu’une progression géométrique de la position des bandes. Dans le but d’obtenir une description plus complète du processus de formation des motifs périodiques dans le contexte d’un système magmatique eutectique binaire en contact avec une roche- mère plus froide, nous présentons un modèle numérique en une dimension de nucléation et croissance qui généralise les modèles précédents. Notre modèle inclut une correction tenant compte de l’effet de la porosité sur la tortuosité, ainsi que le mûrissement d’Ostwald, facul- tativement. La solidification est contrôlée par des paramètres clés déterminant l’émergence du motif. De plus, en utilisant une géométrie sphériquement symétrique, notre modèle peut être appliqué à la formation de granites orbiculaires.

Focal adhesion kinase (FAK) controls the assembly of focal adhesion sites and transduces signals from several membrane receptors. Controlled activation and localization of FAK functionally links cell adhesion, migration and survival. FAK is overexpressed in many cancer types, promoting tumor invasiveness and metastasis. The molecular mechanisms allowing FAK to fulfil numerous different functions and act as versatile ‘nanomachines’ are poorly understood. We have previously revealed that ligand-induced dimerization along with intramolecular interactions control FAK activation and localization where the C-terminal focal adhesion targeting (FAT) domain is strictly involved. In this study, we combine NMR with X-ray crystallography, as well as biophysical and computational methods to understand the molecular mechanisms that link the large-scale dynamics and intramolecular and intermolecular interactions of FAT into FAK’s capacity to integrate various stimuli into a site-specific function. Our results reveal FAT-mediated dynamical interplays between binding of known and newly discovered FAT ligands, and multimerization and autoactivation of FAK. Additionally, we investigate the impact of neuronal alternative splicing on FAT dynamics and interactions. Collectively, our results elucidate FAT’s role in allosterically controlling various FAK functions, and might inspire allosteric protein-protein interaction inhibitors against FAK-dependent cancer cell proliferation.

Christian motifs in the poetry of Jan Zahradnicek Abstract The goal of this thesis is to capture development and change of religious motifs in poems of Jan Zahradnicek and reflect on them the phenomenon of faith in poet's life with respect to the life events that shaped it. The thesis tries to define basic spiritual thelogical starting points of Zahradnicek's poetry and to point out the relationship between literature and theology. The aim of this work is to find and examine the constant features and development of Zahradnicek's Christological reflection: biblical basis, christological images, incarnation, mystery of Jesus' life, theology of the cross and soteriology. Keywords Jan Zahradníček, Christology, Soteriology, Systematic theology, Theology and art

C. Scott Littleton and Ann C. Thomas' assertion that the core of the Arthurian legends is ultimately rooted in a Sarmatian heroic tradition is challenged. It is argued that, at best, the Arthurian legends contain several names and motifs of possible Sarmatian origin that have been borrowed into what Arthurian scholars have long recognized as an inherently Celtic tradition. Several agencies for their introduction into the Arthurian cycle are considered. It is proposed that two names and at least one of the motifs were introduced by Iazyge cataphractarii stationed along Hadrian's Wall in 175 AD. The other motifs, however, are thought to have been introduced at a much later date --possibly by returning members of the crusader population in the East during the twelfth century. / Thesis / Master of Arts (MA)