Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 137-159).

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (MS)--University of Montana, 2007. / Contents viewed on March 26, 2010. Title from author supplied metadata. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Case Western Reserve University, 2007. / [School of Medicine] Department of Genetics. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Thesis (Ph. D.)--Case Western Reserve University, 2007. / [School of Medicine] Department of Environmental Health Science. Includes bibliographical references. Available online via OhioLINK's ETD Center.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Metnase is a novel bifunctional protein that contains a SET domain and a transposase domain. Metnase contains sequence-specific DNA binding activity and sequence non-specific DNA cleavage activity, as well as enhances genomic integration of exogenous DNA. Although Metnase can bind specifically to DNA sequences containing a core Terminal Inverted Repeat sequence, this does not explain how the protein could function at sites of DNA damage. Through immunoprecipitation and gel shift assays, I have identified the Pso4 protein as a binding partner of Metnase both in vitro and in vivo. Pso4 is essential for cell survival in yeast, and cells containing a mutation in Pso4 show increased sensitivity to DNA cross-linking agents. In addition, the protein has sequence-independent DNA binding activity, favoring double-stranded DNA over single-stranded DNA. I demonstrated that the two proteins form a 1:1 stochiometric complex, and once formed, Metnase can localize to DNA damage foci as shown by knockdown of Pso4 protein using in vivo immunofluorescence. In conclusion, this shows that Metnase plays an indispensable role in DNA end joining, possibly through its cleavage activity and association with DNA Ligase IV.

Indiana University-Purdue University Indianapolis (IUPUI) / Toxoplasma gondii is an obligate intracellular parasite of the phylum Apicomplexa. Toxoplasma infection is a serious threat to immunocompromised individuals such as AIDS patients and organ transplant recipients. Side effects associated with current drug treatment calls for identification of new drug targets. DNA repair is essential for cell viability and proliferation. In addition to reactive oxygen species produced as a byproduct of their own metabolism, intracellular parasites also have to manage oxidative stress generated as a defense mechanism by the host immune response. Most of the oxidative DNA damage is repaired through the base excision repair (BER) pathway, of which, the apurinic /apyrimidinic (AP) endonucleases are the rate limiting enzymes. Toxoplasma possesses two different AP endonucleases. The first, TgAPE, is a magnesium-dependent homologue of the human APE1 (hAPE1), but considerably divergent from hAPE1. The second, TgAPN, is a magnesium-independent homologue of yeast (Saccharomyces cerevisiae) APN1 and is not present in mammals. We have expressed and purified recombinant versions of TgAPE and TgAPN in E. coli and shown AP endonuclease activity. Our data shows that TgAPN is the more abundant AP endonuclease and confers protection against a DNA damaging agent when over-expressed in Toxoplasma tachyzoites. We also generated TgAPN knockdown Toxoplasma tachyzoites to establish that TgAPN is important for parasite protection against DNA damage. We have also identified pharmacological inhibitors of TgAPN in a high-throughput screen. The lead compound inhibits Toxoplasma replication at concentrations that do not have overt toxicity to the host cells. The importance of TgAPN in parasite physiology and the fact that humans lack APN1 makes TgAPN a promising candidate for drug development to treat toxoplasmosis.

No description available.