Structure and function analysis of the natural product plantazolicin, a bacillus anthracis-specific antibiotic

Bacteria are a fruitful source of metabolites, many of which have been the scaffolds for the majority of approved antibiotic compounds. In this dissertation, I present the discovery and characterization of a bacterial natural product from Bacillus methylotrophicus FZB42, a Gram-positive, rod-shaped bacterium that stimulates plant growth. A prolific producer of secondary metabolites, FZB42 excretes a compound bearing the molecular mass of 1335 Daltons called plantazolicin (PZN). I describe the genetic locus responsible for the biosynthesis of PZN, which is ribosomally synthesized via an amino acid precursor peptide and post-translationally modified to contain thiazoles and (methyl)oxazoles. This group of compounds, known as thiazole/oxazole-modified microcins (TOMMs), exhibit disparate biological activities and complex chemical structures. Using high-resolution mass spectrometry, chemoselective modification, genetic interruptions, and various spectroscopic tools, I report the molecular structure of PZN. PZN contains two conjugated polyazole moieties and an Nα,Nα-dimethylarginine on the amino terminus. By altering oxygenation levels during fermentation, PZN analogs were produced that bear variability in their heterocycle content, which yielded insight into the order of biosynthetic events. Extensive tailoring of PZN endows it with not only a rigid, polyheterocyclic structure, but also antibacterial activity. After screening numerous microorganisms, PZN exhibited highly selective antibiotic activity against Bacillus anthracis. This remarkably discriminatory activity rivals a previously-described B. anthracis-specific gamma (γ) phage lysis assay in distinguishing B. anthracis from other members of the Bacillus cereus group. I evaluate this unusually selective activity by measuring the RNA expression profile of PZN-treated B. anthracis, which revealed significant upregulation of genes within the cell envelope stress response. Using fluorescence microscopy, PZN localizes to distinct ~200 nm wide foci within the envelope; furthermore, like other cell envelope-acting compounds, PZN depolarizes the B. anthracis membrane. Upon selection and whole-genome sequencing of PZN-resistant mutants of B. anthracis, I implicate a relationship between the action of PZN and the phospholipid cardiolipin within the membrane. Exogenous cardiolipin increases the potency of PZN in wild type B. anthracis and promotes the incorporation of fluorescently tagged PZN in the cell envelope. I propose that PZN localizes to and exacerbates structurally compromised regions of the bacterial membrane, which ultimately results in cell lysis

Small Islands, Big Heart: Reproducing the Marquesas Islands Through The Body

Through the analysis of a Marquesan family in a touristic setting in Tahiti, this thesis explores the notion of the Polynesian body as a site of struggle between the gaze of cosmopolitan French tourists on the exotic other, and the resistance and self-interiorizing of the body by Marquesans. Many contemporary Marquesans choose to migrate to the more urbanized, popular tourist destination of Tahiti, for work, schooling, and medical procedures. Removed from their native land, Marquesans build upon traditional cultural practices and worldviews, while simultaneously actively creating innovative aspects of their experience in the new setting, on and within the body. Based on data gathered through ethnographic research, participant observation and interviews in August, 2014, Pape’ete, Tahiti, I analyze how tourist performances, food preparation, consumption and distribution, as well as tattooing create and affirm Marquesan culture in the diaspora

Induced shear stress measurement in overtopped floodwalls

The scour generated by water overtopping floodwalls results in tilting and sometimes failure of floodwalls. The water free fall induces shear stress, which is difficult to measure, at the levee surface and if it exceeds the critical shear stress, scouring initiates. It is perceived that once a pool of water is generated at the levee crest due to scour, the induced stresses on soil surface at the pool bottom will decrease. The scour progress is stopped once the induced shear stresses at the pool bottom are less than critical shear stress; however, due to the low values of critical shear stress, the scour most likely continues for a long time. A methodology was developed in this study to measure the induced shear stresses. Based on the tests conducted in this study, the generated pool will decrease the induced shear stress until constant erosion rate is achieved. This shear stress is defined as ‘equilibrium’ shear stress herein

The Total Synthesis of the Bioactive Natural Product Plantazolicin A and Its Biosynthetic Precursor Plantazolicin B.

Herein, we describe our full investigations into the synthesis of the peptide-derived natural product plantazolicin A, a compound that demonstrates promising selective activity against the causative agent of anthrax toxicity, and its biosynthetic precursor plantazolicin B. This report particularly focuses on the challenging preparation of the arginine containing thiazole fragment, including the development of a robust, high yielding procedure that avoids the use of sulfurating agents. Extensive studies on the design of a coherent protecting group strategy and the establishment of a step-efficient dicyclization/oxidation approach allowed high levels of convergence for the construction of the oxazole fragments. This has led to a unified, highly convergent synthesis for both plantazolicin A and B.German Academic Exchange Service DAAD, Royal Society (Newton International Fellowship), Engineering and Physical Sciences Research Council (grants EP/ K009494/1 and EP/K039520/1

Total syntheses of linear polythiazole/oxazole plantazolicin A and its biosynthetic precursor plantazolicin B.

Plantazolicin A, a linear decacyclic natural product, exhibits desirable selective activity against the causative agent of anthrax toxicity. The total synthesis of plantazolicin A and its biosynthetic precursor plantazolicin B was successfully achieved by an efficient, unified, and highly convergent route featuring dicyclizations to form 2,4-concatenated oxazoles and the mild synthesis of thiazoles from natural amino acids. This report represents the first synthesis of plantazolicin B and includes the first complete characterization data for both natural products.We gratefully acknowledge Prof. D. A. Mitchell (University of Illinois at Urbana-Champaign) for providing an authentic sample of plantazolicin A and advice on purification, Peter Grice and Duncan Howe for assistance with NMR spectroscopy, and generous funding from the Royal Society (Newton International Fellowship—Z.E.W.), the German Academic Exchange Service DAAD (S.F.), and the Engineering and Physical Sciences Research Council.This is the final version. It was first published by Wiley at http://onlinelibrary.wiley.com/doi/10.1002/anie.201410063/abstrac

Kidron Road and Other Stories

Kidron Road and Other Stories is a collection of fiction that ranges from the soberly tragic to the magically real. The characters in each selection are molded by their choices, the choices of others, and the cruel whims of fate. I am fascinated by the way fatalism and free will intersect in the human experience. Therefore, my work often explores the paradoxical way lives are molded by past decisions while, at the same time, those decisions seem determined by outside forces

The Body as a Battlefield of Resistance: Cracking the Skulls of the System in a Polynesian Performance

Through the analysis of a Marquesan haka performance in a touristic setting in Tahiti, this paper explores the notion of the Polynesian body as a site of struggle between the gaze and premonitions of cosmopolitan French tourists of the exotic other, and the resistance and self-interiorizing of the body by Marquesans. Many contemporary Marquesans choose to migrate to the more urbanized, popular tourist destination of Tahiti, for work, schooling, and medical procedures. Removed from their native land, Marquesans still build upon traditional cultural practices and worldviews, while simultaneously actively creating innovative aspects of their experience in the new setting. My analysis is based on stories of how tourist performances create and affirm Marquesan culture, gathered through ethnographic research, participant observation, and interviews in August, 2014, in Pape’ete, Tahiti. How does the body, prone to commoditizing processes within the tourist system, also emerge as a site of moral economy, community empowerment, and generalized reciprocity

Hva er effekten av bistand på økonomisk utvikling i subsahariske Afrika?

Denne oppgaven tar for seg effektene av økonomisk bistand fra donorland til utviklingsland i subsaharisk Afrika, for å se om bistand har en virkning på økonomisk utvikling. Siden avkoloniseringsbølgen som startet i Afrika rundt 1960-tallet har det vært et økende fokus fra primært den vestlige verden å øke bistand og utviklingslån til de fattige, utviklende økonomiene i subsaharisk Afrika. Det er et omstridt tema om slik bistand har en effekt på økonomisk utvikling, også om at det kan ha en negativ effekt. Vi skal se på argumenter og teorier fra hver «fløy» av disse synspunktene, og se på forskjellige former for bistand – transformativ og marginal bistand. I vår analyse har vi samlet opp relevant tall om HDI (som vi bruker som en basis på økonomisk utvikling), Humankapital, Polity-4, Kapitalintensitet, samt økonomisk bistand. Tidsperioden vi har tatt for oss er satt til 1990-2010. Det er flere grunner til dette. Hovedsakelig er det da flere land som vi har inkludert i analysen som ikke har relevante tall før 1990. Deretter har vi ført tallene inn i statistikkprogrammet Stata for å utføre regresjoner og se på signifikans og koeffisient på variablene for å se om de har en sammenheng, og i hvilken grad. Resultatet av vår analyse antyder at økonomisk bistand faktisk har en signifikant positiv effekt på den økonomiske utvikling til de subsahariske landene i perioden 1990-2010. Et slikt resultat er interessant da det støtter opp den fløyen som er tilhengere av økonomist bistand, og i retning av transformativ bistand, som bl.a. Jeffrey Sachs. Dermed kan vi antyde at det vil ha en positiv effekt å øke bistandsbudsjetter rettet mot subsaharisk Afrika for å akselerere den økonomiske utviklingen, og dermed få landene inn på en selvstendig vekstspiral