Bacterial chromosomes and plasmids are usually circular. Borrelia burgdorferi, the Lyme disease agent, has linear chromosomes and harbor linear as well as circular plasmids. These linear replicons have closed hairpin ends (one DNA strand turns around and continues but becomes the complementary strand to form a linear duplex without free ends). In the temperate lambda-like phages N15 of E. coli and KO2 of Klebsiella oxytoca, upon lysogeny the prophage DNA's are not integrated into the circular bacterial chromosome, but exist as linear plasmids with closed hairpin ends. Occurrences of this type of DNA ends, though not common, have recently been recognized in different branches of the bacterial kingdom. The goal of this research is to study the mechanism with which these closed hairpin ends are generated using both genetic and molecular biological approaches. Both the phage encoded as well as the Borrelia bacterial encoded systems will be investigated. An integrase/recombinase-like protein called protelomerase has been identified as the enzyme that acts in a sequence-specific manner via a cleavage-rejoining mechanism to generate the closed hairpin ends. The specific interaction between the protein and the target site, as well as the pathway of hairpin end generation will be investigated in detail. A saturation mutagenesis will be conducted to identify critical amino acids needed for function. This project can also lead to the design of new linear cloning vehicles especially for cloning lethal genes. The study of linear hairpin-ended replicons will provide new insight into chromosome maintenance. Since all pathogenic Borrelias have linear chromosomes with hairpin ends, this research will also contribute to the understanding of the biology of Borrelia diseases.

Agency
National Science Foundation (NSF)
Institute
Division of Molecular and Cellular Biosciences (MCB)
Application #
0213124
Program Officer
Patrick P. Dennis
Project Start
Project End
Budget Start
2002-07-01
Budget End
2007-06-30
Support Year
Fiscal Year
2002
Total Cost
$362,999
Indirect Cost
Name
University of Utah
Department
Type
DUNS #
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112