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Articles 1 - 4 of 4

Full-Text Articles in Molecular Biology

Novel Cell Surface Anchoring Mechanism Of Prokaryotic Secreted Protein, Mohd Farid Abdul Halim Jan 2017

Novel Cell Surface Anchoring Mechanism Of Prokaryotic Secreted Protein, Mohd Farid Abdul Halim

Publicly Accessible Penn Dissertations

The microbial cell surface is decorated with a variety of protein structures that play important roles in key cellular processes such as providing cell stability, facilitating interactions between cells, and interacting with the environment. One important feature of the biosynthesis of these structures is the proper anchoring of proteins to the cell surface. In silico work recently predicted a novel protein anchoring mechanism for a subset of surface proteins that contain a conserved C-terminal tripartite architecture, which consists of a conserved motif, followed by a hydrophobic (H) domain, and positively charged amino acids. Using the well-studied model archaeon Haloferax volcanii ...


Rumen Microbial Ecology And Rumen-Derived Fatty Acids: Determinants Of And Relationship To Dairy Cow Production Performance, Laura Marie Cersosimo Jan 2017

Rumen Microbial Ecology And Rumen-Derived Fatty Acids: Determinants Of And Relationship To Dairy Cow Production Performance, Laura Marie Cersosimo

Graduate College Dissertations and Theses

Rumen microbiota enable dairy cattle to breakdown fiber into useable energy for milk production. Rumen bacteria, protozoa, and fungi ferment feedstuff into volatile fatty acids (VFA), the main energy source, while methanogens utilize fermentation by-products to produce methane. Milk fat contains several bioactive rumen-derived fatty acids (FA), including odd-chain FA (OCFA) and branched-chain FA (BCFA), important for maintenance of human health. The overarching dissertation goal was to determine which factors affect rumen methanogen and protozoal community structures and their metabolism products, while defining relationships between rumen microbiota and animal performance. Results presented contribute to the goals of providing new knowledge ...


Oxidative Stress Response In Archaea: Elucidation Of Oxidant Sensing And Tolerance Mechanisms In Methanosarcina Acetivorans, Matthew Edward Jennings May 2016

Oxidative Stress Response In Archaea: Elucidation Of Oxidant Sensing And Tolerance Mechanisms In Methanosarcina Acetivorans, Matthew Edward Jennings

Theses and Dissertations

Methanogens are archaea possessing a conserved metabolic pathway which produces methane. Many of the enzymes in the methanogenesis pathway are Fe-S proteins, meaning methanogens are sensitive to conditions which disrupt Fe-S clusters. Molecular oxygen is capable of disrupting Fe-S clusters through oxidation of the iron atoms. Furthermore, reduced iron can facilitate the production of reactive oxygen species (ROS), meaning methanogens must possess antioxidant mechanisms. Detection and eradication of ROS is important for all cells, due to the potentially fatal consequences of unchecked oxidation. This dissertation presents two separate projects investigating mechanisms the model methanogen Methanosarcina acetivorans possess for dealing with ...


Haloferax Volcanii Strategies To Regulate Type Iv Pilus Dependent Adhesion And Microcolony Formation, Rianne Nicole Esquivel Jan 2016

Haloferax Volcanii Strategies To Regulate Type Iv Pilus Dependent Adhesion And Microcolony Formation, Rianne Nicole Esquivel

Publicly Accessible Penn Dissertations

Microorganisms can utilize type IV pili to initiate and maintain biofilms - microbial communities that provide protection against stressful conditions. Because environmental conditions change suddenly, microorganisms have evolved multiple mechanisms to rapidly transition from a planktonic to sessile cell state. Despite the presence of archaea alongside bacteria throughout the environment, including the human microbiome, little is known about how these organisms form and maintain biofilms. Here we use genetic, microscopic and biochemical techniques to investigate multiple strategies the model archaeon Haloferax volcanii employs to permit effective adhesion and microcolony formation, early steps in biofilm formation and maturation, as well as eventual ...