http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
DNA replication restart is involved in trinucleotide repeat instability in E. coli
ABSTRACTS: The expansion of tribucleotide repeats causes many human hereditary neurological diseases. Previous observations showed that (CTG)·(CAG) repeats can stall the progression of replication forks. When replication forks are stalled by DNA damage, replication restart, which involves an interplay of replication, recombination, and repair, is employed to promote cell survival. Presumably, replication forks stalled at the repeats should also be rescued by replication restart, which may lead to repeat instability in E. coli. To examine this hypothesis, mutation rates for the deletions of (CAG)·(CTG) repeats were measured in several E. coli strains carrying mutations in genes involved in replication restart. In cells containing priA4, recG263, dnaC212, ruvAB, and rec0 mutations, deletion rates of the repeats were decreased relative to the rates in parental strains. Moreover, in a band-shift assay, purified PriA and RecG proteins bound to single-stranded, duplex and forked DNAs containing (CAG)n and/or (CTG)n loop-outs in various positions. Finally, functional PriA was required for the rescue of replication forks stalled at (CAG)·(CTG) repeats in living cells, as determined using two-dimensional agarose gel analyses. The results presented are consistent with an interpretation that the high rates of repeat instability observed in E. coli result from attempts to restart DNA replication when replication forks are stalled at the repeats.
"Submitted to the Graduate School of Biomedical Sciences of The Texas A&M University System Health Science Center in partial fulfillment for the requirements for the degree of Doctor of Philosophy August 2004."
Approved as to style and content by: Richard R. Sinden, Frederick S. Gimble, William A. Rosche, Robert D. Wells, Van G. Wilson, Richard H. Finnell.
Ph. D. Texas A&M University System Health Science Center 2004.
Includes bibliographical references (leaves 144-189).