Date of Award
Master of Science
Biochemistry, Biophysics and Molecular Biology
Richard B. Honzatko
Forty percent of the population worldwide is at risk of malarial infections. Approximately 200 million cases of malaria occur annually, resulting in over 400,000 deaths in 2015, the most heavily impacted demographic being children under the age of five. Plasmodium falciparum, responsible for 99% of deaths, has an organelle called the apicoplast, not found in mammals and most other eukaryotic organisms. The apicoplast must reproduce (and duplicate its own genome) in order for Plasmodium to sustain infections. Efforts in the discovery of new anti-malarial drugs target the duplication of the apicoplast genome, specifically an apicoplast-specific DNA polymerase (hereafter apPOL), which exhibits low sequence identity to other know polymerases, including those found in humans and bacteria. Inhibition of DNA polymerases has led to effective treatments of viral infections (HIV, herpes simplex virus, hepatitis B virus, and cytomegalovirus), indicating an inhibitor of apPOL might be useful in the treatment of malaria. Structures of crystalline complexes of apPOL could facilitate the development of potent inhibitors; however, in order to provide structural information, suitable crystals must be available in quantity. Reported here are conditions that support the growth of large single crystals of apPOL. Crystal structures reveal binding sites for hydrated lithium cations and sulfate anions, and suggest mechanisms by which these ligands support the growth of large single crystals. Sulfate anions map to the polymerase active site and editing site; however, well-define sulfate anions also map to sites without a known function. 2-Methyl-2,4-pentandiol could stabilize crystals, whereas dimethyl sulfoxide disrupts polymerase conformation and stability.
Chen, Ai, "Optimization of a Crystallographic Protocol for Screening Inhibitors of the DNA Polymerase from the Apicoplast of Plasmodium falciparum" (2017). Graduate Theses and Dissertations. 15279.