Abstract
Recent research indicates that hundreds of thousands of G-rich sequences within the human genome have the potential to form secondary structures known as G-quadruplexes. Telomeric regions, consisting of long arrays of TTAGGG/AATCCC repeats, are among the most likely areas in which these structures might form. Since G-quadruplexes assemble from certain G-rich single-stranded sequences, they might arise when duplex DNA is unwound such as during replication. Coincidentally, these bulky structures when present in the DNA template might also hinder the action of DNA polymerases. In this study, single-stranded telomeric templates with the potential to form G-quadruplexes were examined for their effects on a variety of replicative and translesion DNA polymerases from humans and lower organisms. Our results demonstrate that single-stranded templates containing four telomeric GGG runs fold into intramolecular G-quadruplex structures. These intramolecular G quadruplexes are somewhat dynamic in nature and stabilized by increasing KCl concentrations and decreasing temperatures. Furthermore, the presence of these intramolecular G-quadruplexes in the template dramatically inhibits DNA synthesis by various DNA polymerases, including the human polymerase δ employed during lagging strand replication of G-rich telomeric strands and several human translesion DNA polymerases potentially recruited to sites of replication blockage. Notably, misincorporation of nucleotides is observed when certain translesion polymerases are employed on substrates containing intramolecular G-quadruplexes, as is extension of the resulting mismatched base pairs upon dynamic unfolding of this secondary structure. These findings reveal the potential for blockage of DNA replication and genetic changes related to sequences capable of forming intramolecular G-quadruplexes.
Document Type
Article
Publication Date
1-14-2014
Digital Object Identifier (DOI)
http://dx.doi.org/10.1371/journal.pone.0080664
Repository Citation
Edwards, Deanna N.; Machwe, Amrita; Wang, Zhigang; and Orren, David K., "Intramolecular Telomeric G-Quadruplexes Dramatically Inhibit DNA Synthesis by Replicative and Translesion Polymerases, Revealing their Potential to Lead to Genetic Change" (2014). Toxicology and Cancer Biology Faculty Publications. 19.
https://uknowledge.uky.edu/toxicology_facpub/19
Table S1
Table_S2.pdf (55 kB)
Table S2
Table_S3.pdf (59 kB)
Table S3
Table_S4.pdf (42 kB)
Table S4
Table_S5.pdf (42 kB)
Table S5
Figure_S1.pdf (39 kB)
Figure S1
Figure_S2.pdf (54 kB)
Figure S2
Figure_S3.pdf (30 kB)
Figure S3
Figure_S4.pdf (37 kB)
Figure S4
Figure_S5.pdf (56 kB)
Figure S5
Notes/Citation Information
Published in PLoS ONE, v. 9, issue 1, no. e80664.
© 2014 Edwards et al.
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.