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Pkd1 unusual DNA conformations are recognized by nucleotide excision repair
A Bacolla1, A Jaworski, T D Connors
1Institute of Biosciences and Technology, Center for Genome Research, Texas A & M University System Health Science Center, Texas Medical Center, Houston, Texas 77030-3303, USA.
The Journal of Biological Chemistry
|March 30, 2001
Summary
The poly(R.Y) tract in the PKD1 gene causes cell death and slows growth by triggering DNA repair mechanisms. This suggests the tract contributes to high PKD1 mutation rates.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- The polycystic kidney disease 1 (PKD1) gene exhibits a high mutation frequency.
- A 2.5-kilobase pair poly(purine.pyrimidine) (poly(R.Y)) tract in intron 21 of PKD1 is hypothesized to contribute to this mutation rate.
Purpose of the Study:
- To investigate the role of the PKD1 poly(R.Y) tract in gene mutation frequency.
- To evaluate the impact of this tract on cell viability and DNA repair pathways.
Main Methods:
- Investigated growth rates of 11 Escherichia coli strains with mutations in DNA repair and topoisomerase genes.
- Utilized plasmids containing the full-length poly(R.Y) tract, 5'-truncations, and a control plasmid.
- Modulated DNA supercoiling using strain genotypes and specific drugs.
Main Results:
- The full-length poly(R.Y) tract significantly reduced cell viability and prolonged doubling times, especially in strains with an inducible SOS response.
- Cell loss correlated with the length of the poly(R.Y) tract and levels of negative supercoiling.
- The tract induced the SOS response and was recognized and cleaved by the nucleotide excision repair system.
Conclusions:
- Unusual DNA conformations of the PKD1 poly(R.Y) tract, influenced by negative supercoiling, activate the SOS response pathway.
- This activation leads to DNA cleavage by the nucleotide excision repair system, causing cell division delays and plasmid loss.
- These findings support a role for the poly(R.Y) tract in PKD1 gene mutation by stimulating repair and recombination functions.