Analysis of Direct-Repeat Mediated Deletions in Yeast Mitochondrial DNA

University Of Rochester, Rochester NY

Investigators

Abstract

Mitochondria are responsible for producing the bulk of cellular energy in the form of ATP in eukaryotic cells. Like nuclear DNA, the mitochondrial genome must be maintained with high fidelity to ensure normal cellular functions. Deletion of DNA sequences between identical or nearly identical repeats in the mitochondrial DNA are frequently observed in species as diverse as yeast, corn, and humans. Although several models have been proposed for the generation of direct-repeat-associated deletions, the mechanism by which they arise is not known. The aims of this project are directed at understanding the proteins involved in this process and their activities. In vertebrates, few molecular techniques are available for the study of mitochondrial DNA, making the identification and study of the proteins required for the deletions and rearrangement of mitochondrial DNA in these systems difficult. However, yeast mitochondria can be transformed with exogenous DNA, and this DNA can be integrated into the genome. These techniques have been used to generate genetic reporters that allow the measurement of direct-repeat mediated deletion events. These reporters will be used to identify the proteins required for recombination in the mitochondrial compartment, and to determine the molecular mechanisms by which these genome rearrangements take place. The molecular tools available for research in yeast have made it a powerful model system for the study of mitochondrial biology. Many of the proteins required for essential processes in the mitochondria remain unknown. Completion of this work will likely provide information on the broad area of mitochondrial DNA metabolism, including replication, recombination and repair. Most eukaryotic cells contain mitochondria, the membrane-bound organelles that produce energy for the cell. In addition to DNA found in the nucleus of the cell, DNA is also found in the mitochondria. The faithful maintenance of the mitochondrial DNA is essential to the normal function of cells. Deletions of large segments of the mitochondrial DNA are common mutations. Such deletions are also commonly observed in the mitochondrial DNA of baker's yeast. The long-term goal of this project is to understand the mechanism by which these deletions arise. This project will have a positive impact on the education of undergraduates in the biological sciences. In the past five years, Dr.Elaine Sia has mentored sixteen undergraduate students pursuing independent projects. This summer there are four students in the lab, one of whom qualifies for McNair funding. This award will allow the continued support of such students. In addition, the research represents a collaboration with Dr.Rey Sia at SUNY-Brockport, a primarily four-year institution that does not grant Ph.D. degrees. Over the past two years Dr.Rey Sia has supported the goal of the Department of Biological Sciences at Brockport to further undergraduate involvement in research. He has sponsored a total of nine students in a variety of independent studies and directed research projects; two of these students are CSTEP/McNair Scholars. This award will support future research opportunities for undergraduate biology majors at SUNY Brockport.