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Department of Biological Sciences

Rey Antonio L. Sia, Ph.D.


Research Interests

The current research in my lab focuses on DNA repair. Using modern molecular and genetic techniques, the lab is currently addressing questions that focus on the regulation of DNA repair and the proteins that carry out the regulation process. There are two lines of research currently ongoing in the lab. The first involves determining proteins that regulate stability of the mitochondrial genome. The second explores the role of sumoylation as a regulatory process in DNA repair. The lab uses the budding yeast, Saccharomyces cerevisiae, as the model organism in these studies.

Mitochondria are essential organelles found in all higher eukaryotes. These organelles are required for cellular respiration and the generation of most of the cellular ATP. Mitochondria and the production of cellular energy are essential in higher eukaryotes for their viability. The mitochondria have their own DNA that is organized, replicated, segregated, mutated, repaired, and recombined independent of the nuclear DNA

The lab is focused on identifying genes involved in the organization, repair, and recombination of mitochondrial DNA. The work in the lab will lead to the understanding of the regulatory pathways utilized in these processes. The lab found that the dual function protein, Ilv5p, plays an important role in regulating the maintenance of mitochondrial DNA. The research employs the use of a yeast two-hybrid assay with Ilv5p as the bait protein. The lab will identify novel proteins that interact with Ilv5p. These interactors will then be characterized for their role in mitochondrial DNA repair, recombination, and organization using several types of reporter assays.

Sumoylation is the biological process by which a small protein molecule called SUMO (small ubiquitin related modifier) is attached to a target protein. SUMO modification on a variety of target proteins has been shown to regulate target protein function by increasing or decreasing its activity, altering its subcellular localization, regulating DNA binding, altering protein-protein interaction, as well as several other biological processes.

Our preliminary genetic data has indicated that a physical interaction exists between the SUMO protein and the nuclear DNA repair enzyme, Pol eta/Rad30p. Our hypothesis is that Pol eta/Rad30p is sumoylated and that this modification regulates its activity or function. This research topic has a dual focus. First, the lab will determine whether the Pol eta/Rad30p protein is modified through a process called sumoylation and whether sumoylation affects Pol eta/Rad30p activity or function. Second, the lab will use the yeast two-hybrid assay to identify other nuclear or mitochondrial DNA repair proteins that are sumoylated. Regulation by sumoylation of these proteins will then be further investigated.