Evidence for Reverse Hoogsteen Hairpin Intermediates in the Photocrosslinking of Human Telomeric DNA Sequences
| Autor: | Chen Lu, Jillian E. Smith-Carpenter, John-Stephen Taylor |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Stereochemistry Base pair Reactive intermediate Pyrimidine dimer Lithium G-quadruplex Biochemistry Article 03 medical and health sciences chemistry.chemical_compound Humans Physical and Theoretical Chemistry Base Pairing Polyacrylamide gel electrophoresis Base Sequence Sodium Temperature DNA General Medicine Telomere Photochemical Processes G-Quadruplexes Native Polyacrylamide Gel Electrophoresis Kinetics Cross-Linking Reagents 030104 developmental biology chemistry Pyrimidine Dimers Regulatory sequence Potassium Nucleic Acid Conformation Electrophoresis Polyacrylamide Gel |
| Zdroj: | Photochemistry and Photobiology. 94:685-697 |
| ISSN: | 0031-8655 |
| DOI: | 10.1111/php.12898 |
| Popis: | UVB irradiation of human telomeric d(GGGTTA)3 GGG sequences in potassium ion solution crosslinks the first and third TTA segments through anti cyclobutane pyrimidine dimer (CPD) formation. The photocrosslinking reaction was first proposed to occur through a form 3 two-tetrad G-quadruplex in which the lateral four-nucleotide GTTA loop can interact with an adjacent TTA loop. Curiously, the reaction does not occur with sodium ion, which was explained by the formation of a basket structure which only has three-nucleotide TTA loops that cannot interact. Sequences known or expected to favor the two-tetrad basket did not show enhanced photocrosslinking, suggesting that some other structure was the reactive intermediate. Herein, we report that anti CPDs form in human telomeric DNA sequences with lithium ion that is known to disfavor G-quadruplex formation, as well as with potassium ion when the bases are modified to interfere with G-quartet formation. We also show that anti CPDs form in sequences containing A's in place of G's that cannot form Hoogsteen hairpins, but can form reverse Hoogsteen hairpins. These results suggest that reverse Hoogsteen hairpins may play a hitherto unrecognized role in the biology and photoreactivity of DNA in telomeres, and possibly in other purine-rich sequences found in regulatory regions. |
| Databáze: | OpenAIRE |
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