Homologous recombination is a major mechanism for repair of double-strand breaks caused by exposure to chemical mutagens and radiation. Repair of these breaks is an evolutionary imperative and ensures proper transfer of information from generation to generation without information loss. General understanding of this process has come mostly from studies from the bacterial or eukaryotic branches of life. Very little is known about double-strand break repair in the third, archaeal branch. Archaea physically resemble bacteria, but use some cellular approaches to life that seem to be more eukaryotic. Key among these eukaryotic-like processes are methods of genome maintenance, including double-strand break repair. This provides a unique opportunity to study homologous recombination mechanisms in an evolutionarily distinct group of organisms. The overall objective of this project is to use the well established archaeal model Sulfolobus solfataricus to determine the mechanistic role of three proteins that are related by sequence to the strand-exchange protein, RadA. The research on these paralogues will involve graduate, undergraduate, and high school students using two complementary but independent approaches: 1) Biochemical activity of the proteins in vitro will be determined individually and in combination with other known recombination-related proteins, where their interactions and point of function in the repair pathway will be established; 2) Roles of the paralogues in vivo will be assessed through studies of protein persistence after radiation damage and measurement of chromosomal repair rates in both wild-type and mutant strain backgrounds.
This project focuses on a mechanism necessary for cellular survival following DNA damage in a member of the least well studied branch of life. In addition to understanding more about the way in which all cells repair their DNA, this work is expected to provide new overall insight into the regulation of homologous recombination and maintenance of genome stability. These studies are multidisciplinary, using biochemical, genetic, and cellular approaches that will provide a broad laboratory education for students at various educational stages. Specifically, this project provides laboratory training for one graduate and two undergraduate students, with a special emphasis on outreach recruiting of underrepresented minority students. Additionally, two high school students will be supported through summer internships, which will offer a valuable research experience to young scientists at early stages in their careers.
