This proposal focuses on the steps of DNA replication that are important in maintaining the stability of long tracts of CAG trinucleotide repeats. Long CAG repeat tracts are found in some human genes and are the mutational cause of over a dozen inherited neurological disorders. Using yeast mutants that are defective in DNA replication, we have defined the replication steps that are most likely to lead to tract expansions and to those that give rise to tract contractions. The studies described in this proposal further elaborate the mechanisms of tract expansion and tract contraction. An initial study examines whether Okazaki fragments containing CAG repeats are the same length as fragments containing unique sequence DNA. By detailed studies on mutations of the DNA helicase, DNA polymerase, DNA ligase, flap endonuclease and proliferating cell nuclear antigen (PCNA) we will define the mechanism by which flaps of DNA give rise to tract expansions. Additional studies look at whether tract contractions are limited by the extent to which the replication fork opens and by the presence of topoisomerases. Finally, we will examine whether chromosomes bearing CAG repeat tracts are lost as a result of replication stalling.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS041283-04
Application #
6791326
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Sutherland, Margaret L
Project Start
2001-09-30
Project End
2008-07-31
Budget Start
2004-08-01
Budget End
2008-07-31
Support Year
4
Fiscal Year
2004
Total Cost
$255,954
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Biochemistry
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455