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Full-Text Articles in Medical Sciences

Structure-Function Analysis Of Udp-Sugar: Polyisoprenyl Phosphate Sugar-1-Phosphate Transferases, Sarah E. Furlong Sep 2013

Structure-Function Analysis Of Udp-Sugar: Polyisoprenyl Phosphate Sugar-1-Phosphate Transferases, Sarah E. Furlong

Electronic Thesis and Dissertation Repository

The synthesis of lipid-linked glycans is a conserved process in eukaryotes and prokaryotes that is initiated by two major enzyme families: the polyisoprenyl-phosphate hexose-1-phosphate transferases (PHPTs) and the polyisoprenyl-phosphate N-acetylaminosugar-1-phosphate transferases (PNPTs). These enzymes contain multiple membrane domains and transfer a sugar-1-phosphate from a nucleotide sugar precursor to a lipid carrier. The prototypic PNPT member used in this study is the E. coli WecA, which initiates the synthesis of O antigen and enterobacterial common antigen in Enterobacteriaceae by transferring N-acetylglucosamine-1-P to undecaprenyl phosphate (Und-P). We investigated the topology and function of the highly conserved VFMGD motif. Our results revealed that …


Evaluating The Co-Commensal Lifestyles Of Staphylococcus Aureus And Staphylococcus Epidermidis, Piraveina Gnanasuntharam Aug 2013

Evaluating The Co-Commensal Lifestyles Of Staphylococcus Aureus And Staphylococcus Epidermidis, Piraveina Gnanasuntharam

Electronic Thesis and Dissertation Repository

Staphylococcus epidermidis is a ubiquitous skin commensal, and produces a serine protease Esp that can eradicate nasal carriage of the opportunistic pathogen, Staphylococcus aureus. We evaluated the ability of S. epidermidis and S. aureus to express serine protease and compete with one another in response to acidic pH and unsaturated free fatty acids; conditions encountered on human skin. The hypervirulent USA300 strain of S. aureus was more competitive in co-culture conditions of acidic pH or 25 µM palmitoleic acid alone, but could not compete with S. epidermidis when these conditions were combined. Conversely, in pure culture, these conditions promoted …


Systematic Assessment Of The Contribution Of Superantigens To Nasopharyngeal Colonization In A Mouse Model Of Streptococcal Infection, Katherine J. Kasper Jan 2013

Systematic Assessment Of The Contribution Of Superantigens To Nasopharyngeal Colonization In A Mouse Model Of Streptococcal Infection, Katherine J. Kasper

Electronic Thesis and Dissertation Repository

Streptococcus pyogenes is adapted for persistence in humans. It typically colonizes the tonsils and skin, and humans are the only known reservoir. S. pyogenes can cause a wide range of mild to serious infections. Most streptococci-related deaths are due to complications of rheumatic fever and invasive infections. S. pyogenes produces virulence factors that contribute to the pathogen’s ability to colonize and cause disease, including streptococcal superantigens (SAgs), also known as streptococcal pyrogenic exotoxins (Spes). SAgs function by cross-linking T cells and antigen presenting cells (APC) which may cause a massive inflammatory response, and as such have been found to contribute …