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Unusual DNA Conformations From Intron 21 of the PKD1 Gene Cause Mutagenesis

Published

Author(s)

A Bacolla, A Jaworski, A Larson, J P. Jakupciak, C D. O'Connell, R D. Wells

Abstract

Intron 21 of the polycystic kidney disease 1 (PKD1) gene contains a 2.5 kbp of purine-pyrimidine asymmetry [poly(R-Y)] predicted to adopt unusual DNA structures (slipped, triplexes, tetraplexes)and proposed to cause mutations in the gene. The poly (R-Y) tract and a shorter fragment of 1 kbp were cloned downstream of a reporter green fluorescent protein (GFP) gene in plasmids; frequencies of loss of fluorescent were determined for several E. coli strains and stable mutant clones were sequenced. The proportion of large deletion events affecting the GFP gene increased from 1.5 in the absence of tract to 6.3x10e-5 in the presence of the 2.5 kbp poly (R-Y) tract. DNA sequencing (16 clones) indicated that most breakpoints, including those in the vector, occurred at sites predicted to adopt unusual DNA structures. Five additional deleted clones selected by their growth advantage also indicated the presence of alternative DNA structures at breakpoints. The 2.5 kbp poly(R-Y), but not the shorter tract, increased the frequency of fluorescence loss caused by plasmid loss, plasmid multimerization, and other uncharacterized mutations in a transcription-dependent manner. These effects were much more severe in wild-types, RecA, UvrB, Polll, PollV, and PolV strains than in MutL. A limited analysis of DNA sequences flanking breakpoints in human diseases also predicted the formation of unusual DNA structures. We conclude that non-canonical DNA structures are mutagenic, and genetic instabilities likely occur by the enzymatic activities associated with the transcription-coupled repair pathway. These effects were much more severe in wild-types, RecA, UvrB, Polll, PollV, and PolV strains than in MutL. A limited analysis of DNA sequences flanking breakpoints in human diseases also predicted and PolV strains than in MutL. A limited analysis of DNA sequences flanking breakpoints in human diseases also predicted the formation of unusual DNA structures. We conclude that non-canonical DNA structures are mutagenic, and genetic instabilities likely occur by the enzymatic activities associated with the transcription-coupled repair pathway.
Citation
Science

Keywords

kidney disease, mutation, recombination-repair

Citation

Bacolla, A. , Jaworski, A. , Larson, A. , Jakupciak, J. , O'Connell, C. and Wells, R. (2021), Unusual DNA Conformations From Intron 21 of the PKD1 Gene Cause Mutagenesis, Science (Accessed April 14, 2024)
Created October 12, 2021