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Lee HT, Sanford S, Paul T, Choe J, Bose A, Opresko PL, Myong S. Position-Dependent Effect of Guanine Base Damage and Mutations on Telomeric G-Quadruplex and Telomerase Extension. Biochemistry 2020; 59:2627-2639. [PMID: 32578995 DOI: 10.1021/acs.biochem.0c00434] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Telomeres are hot spots for mutagenic oxidative and methylation base damage due to their high guanine content. We used single-molecule fluorescence resonance energy transfer detection and biochemical assays to determine how different positions and types of guanine damage and mutations alter telomeric G-quadruplex structure and telomerase activity. We compared 15 modifications, including 8-oxoguanine (8oxoG), O-6-methylguanine (O6mG), and all three possible point mutations (G to A, T, and C) at the 3' three terminal guanine positions of a telomeric G-quadruplex, which is the critical access point for telomerase. We found that G-quadruplex structural instability was induced in the order C < T < A ≤ 8oxoG < O6mG, with the perturbation caused by O6mG far exceeding the perturbation caused by other base alterations. For all base modifications, the central G position was the most destabilizing among the three terminal guanines. While the structural disruption by 8oxoG and O6mG led to concomitant increases in telomerase binding and extension activity, the structural perturbation by point mutations (A, T, and C) did not, due to disrupted annealing between the telomeric overhang and the telomerase RNA template. Repositioning the same mutations away from the terminal guanines caused both G-quadruplex structural instability and elevated telomerase activity. Our findings demonstrate how a single-base modification drives structural alterations and telomere lengthening in a position-dependent manner. Furthermore, our results suggest a long-term and inheritable effect of telomeric DNA damage that can lead to telomere lengthening, which potentially contributes to oncogenesis.
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Affiliation(s)
- Hui-Ting Lee
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Samantha Sanford
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania 15261, United States
| | - Tapas Paul
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Joshua Choe
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Arindam Bose
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania 15261, United States
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health and University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania 15261, United States
| | - Sua Myong
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, United States
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Frelih T, Wang B, Plavec J, Šket P. Pre-folded structures govern folding pathways of human telomeric G-quadruplexes. Nucleic Acids Res 2020; 48:2189-2197. [PMID: 31950178 PMCID: PMC7038944 DOI: 10.1093/nar/gkz1235] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/12/2019] [Accepted: 12/31/2019] [Indexed: 01/12/2023] Open
Abstract
Understanding the mechanism by which biological macromolecules fold into their functional native conformations represents a problem of fundamental interest. DNA oligonucleotides derived from human telomeric repeat d[TAGGG(TTAGGG)3] and d[TAGGG(TTAGGG)3TT] fold into G-quadruplexes through diverse steps. Varying the pH and temperature by the use of nuclear magnetic resonance and other methods enabled detection of pre-folded structures that exist in solution before completely formed G-quadruplexes upon addition of cations. Pre-folded structures are in general hard to detect, however their knowledge is crucial to set up folding pathways into final structure since they are believed to be a starting point. Unexpectedly well-defined pre-folded structures composed of base triples for both oligonucleotides were detected at certain pH and temperature. These kinds of structures were up to now only hypothesized as intermediates in the folding process. All revealed pre-folded structures irrespective of the pH and temperature exhibited one common structural feature that could govern folding process.
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Affiliation(s)
- Tjaša Frelih
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
| | - Baifan Wang
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
- EN-FIST Center of Excellence, Ljubljana 1000, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
- Correspondence may also be addressed to Janez Plavec. Tel: +386 1 476 0353; Fax: +386 1 476 0300;
| | - Primož Šket
- Slovenian NMR Center, National Institute of Chemistry, Ljubljana 1000, Slovenia
- To whom correspondence should be addressed. Tel: +386 1 476 0223; Fax: +386 1 476 0300;
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Wumaier M, Shi JJ, Yao TM, Hu XC, Gao RR, Shi S. G-quadruplex and duplex DNA binding studies of novel Ruthenium(II) complexes containing ascididemin ligands. J Inorg Biochem 2019; 196:110681. [DOI: 10.1016/j.jinorgbio.2019.03.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 03/22/2019] [Accepted: 03/27/2019] [Indexed: 11/29/2022]
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