Biochemistry, Biophysics, and Structural Biology Commons^™

An Examination Of The Inhibitory Effects Of Antibiotic Combinations On Ribosome Biosynthesis In Staphylococcus Aureus, Justin Beach

Electronic Theses and Dissertations

Bacteremia initiated by Staphylococcus aureus infections can be a serious medical problem. Although a number of different antibiotics are used to combat staphylococcal infections, resistance has continued to develop. Combination therapy for certain infections has been used to reduce the emergence of resistance when a single agent has become ineffective. We hypothesize that the use of rifampicin and ciprofloxacin in combination with azithromycin, known for its inhibitory effects on the bacterial ribosome, can create potential synergistic effects resulting from indirect effects on ribosomal subunit synthesis.

To determine this we measured the effects of single and multiple antibiotics on cell growth …

New Insights Into The Roles Of Human Dna Damage Checkpoint Protein Atr In The Regulation Of Nucleotide Excision Repair And Dna Damage-Induced Cell Death, Zhengke Li

Electronic Theses and Dissertations

Integrity of the human genome is frequently threatened by endogenous and exogenous DNA damaging reagents that may lead to genome instability and cancer. Cells have evolved multiple mechanisms to repair DNA damage or to eliminate the damaged cells beyond repair and to prevent diverse diseases. Among these are ataxia telangiectasia and Rad3-related (ATR)-mediated DNA damage checkpoint and nucleotide excision repair (NER) that are the major pathways by which cells handle ultraviolet C (UV-C)- or other exogenous genotoxin-induced bulky DNA damage. However, it is unclear how these 2 pathways may be coordinated. In this study we show that ATR physically interacts …

Mechanisms Of The Anti-Pneumococcal Function Of C-Reactive Protein, Toh B. Gang

Electronic Theses and Dissertations

Human C-reactive protein (CRP) increases survival of and decreases bacteremia in mice infected with Streptococcus pneumoniae. Such protection of mice against pneumococcal infection is seen only when CRP is administered into mice 6 hours before to 2 hours after the injection of pneumococci, but not when CRP is given to mice at a later time. Our first aim was to define the mechanism of CRP-mediated initial protection of mice against infection. It was proposed that CRP binds to phosphocholine (PCh) moieties present in the cell wall and activates the complement system on the pneumococcal surface that kills the pathogen. …

Bioengineering The Expression Of Active Recombinant Human Cathepsin G, Enteropeptidase, Neutrophil Elastase, And C-Reactive Protein In Yeast, Eliot T. Smith

Electronic Theses and Dissertations

The yeasts Pichia pastoris and Kluyveromyces lactis were used to express several recombinant human proteins for further biochemical characterization. Two substitution variants of recombinant human enteropeptidase light chain (rhEPL) were engineered to modify the extended substrate specificity of this serine protease. Both were secreted as active enzymes in excess of 1.7 mg/L in P. pastoris fermentation broth. The substitution variant rhEPL R96Q showed significantly reduced specificities for the preferred substrate sequences DDDDK and DDDDR; however, the rhEPL Y174R variant displayed improved specificities for these substrate sequences relative to all other reported variants of this enzyme. The neutrophil serine proteases human …

Novel Roles Of Replication Protein A Phosphorylation In Cellular Response To Dna Damage, Moises A. Serrano

Electronic Theses and Dissertations

Human replication protein A (RPA) is an eukaryotic single-stranded DNA binding protein directly involved in a variety of DNA metabolic pathways including replication, recombination, DNA damage checkpoints and signaling, as well as all DNA repair pathways. This project presents 2 novel roles of RPA in the cellular response to DNA damage. The first elucidates the regulation of RPA and p53 interaction by DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) in homologous recombination (HR). HR and nonhomologous end joining (NHEJ) are 2 distinct DNA double-stranded break (DSB) repair pathways. Here, we report that DNA-PK, the …