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Wang KB, Dickerhoff J, Yang D. Solution Structure of Ternary Complex of Berberine Bound to a dGMP-Fill-In Vacancy G-Quadruplex Formed in the PDGFR-β Promoter. J Am Chem Soc 2021; 143:16549-16555. [PMID: 34586799 PMCID: PMC8626096 DOI: 10.1021/jacs.1c06200] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The G-quadruplexes (G4s) formed in the PDGFR-β gene promoter are transcriptional modulators and amenable to small-molecule targeting. Berberine (BER), a clinically important natural isoquinoline alkaloid, has gained increasing attention due to its potential as anticancer drug. We previously showed that the PDGFR-β gene promoter forms a unique vacancy G4 (vG4) that can be filled in and stabilized by guanine metabolites, such as dGMP. Herein, we report the high-resolution NMR structure of a ternary complex of berberine bound to the dGMP-fill-in PDGFR-β vG4 in potassium solution. This is the first small-molecule complex structure of a fill-in vG4. This ternary complex has a 2:1:1 binding stoichiometry with a berberine molecule bound at each the 5'- and 3'-end of the 5'-dGMP-fill-in PDGFR-β vG4. Each berberine recruits the adjacent adenine residue from the 5'- or 3'-flanking sequence to form a "quasi-triad plane" that covers the external G-tetrad of the fill-in vG4, respectively. Significantly, berberine covers and stabilizes the fill-in dGMP. The binding of berberine involves both π-stacking and electrostatic interactions, and the fill-in dGMP is covered and well-protected by berberine. The NMR structure can guide rational design of berberine analogues that target the PDGFR-β vG4 or dGMP-fill-in vG4. Moreover, our structure provides a molecular basis for designing small-molecule guanine conjugates to target vG4s.
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Wang KB, Dickerhoff J, Wu G, Yang D. PDGFR-β Promoter Forms a Vacancy G-Quadruplex that Can Be Filled in by dGMP: Solution Structure and Molecular Recognition of Guanine Metabolites and Drugs. J Am Chem Soc 2020; 142:5204-5211. [PMID: 32101424 DOI: 10.1021/jacs.9b12770] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aberrant expression of PDGFR-β is associated with a number of diseases. The G-quadruplexes (G4s) formed in PDGFR-β gene promoter are transcriptional modulators and amenable to small molecule targeting. The major G4 formed in the PDGFR-β gene promoter was previously shown to have a broken G-strand. Herein, we report that the PDGFR-β gene promoter sequence forms a vacancy G-quadruplex (vG4) which can be filled in and stabilized by physiologically relevant guanine metabolites, such as dGMP, GMP, and cGMP, as well as guanine-derivative drugs. We determined the NMR structure of the dGMP-fill-in PDGFR-β vG4 in K+ solution. This is the first structure of a guanine-metabolite-fill-in vG4 based on a human gene promoter sequence. Our structure and systematic analysis elucidate the contributions of Hoogsten hydrogen bonds, sugar, and phosphate moieties to the specific G-vacancy fill-in. Intriguingly, an equilibrium of 3'- and 5'-end vG4s is present in the PDGFR-β promoter sequence, and dGMP favors the 5'-end fill-in. Guanine metabolites and drugs were tested and showed a conserved selectivity for the 5'-vacancy, except for cGMP. cGMP binds both the 3'- and 5'-end vG4s and forms two fill-in G4s with similar population. Significantly, guanine metabolites are involved in many physiological and pathological processes in human cells; thus, our results provide a structural basis to understand their potential regulatory functions by interaction with promoter vG4s. Moreover, the NMR structure can guide rational design of ligands that target the PDGFR-β vG4.
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Li Y, Liu B, Huang Z, Liu J. Engineering base-excised aptamers for highly specific recognition of adenosine. Chem Sci 2020; 11:2735-2743. [PMID: 34084332 PMCID: PMC8157715 DOI: 10.1039/d0sc00086h] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The DNA aptamer for adenosine and ATP has been used as a model system for developing analytical biosensors. For practical reasons, it is important to distinguish adenosine from ATP, although this has yet to be achieved despite extensive efforts made on selection of new aptamers. We herein report a strategy of excising an adenine nucleotide from the backbone of a one-site adenosine aptamer, and the adenine-excised aptamer allowed highly specific binding of adenosine. Cognate analytes including AMP, ATP, guanosine, cytidine, uridine, and theophylline all failed to bind to the engineered aptamer according to the SYBR Green I (SGI) fluorescence spectroscopy and isothermal titration calorimetry (ITC) results. Our A-excised aptamer has two binding sites: the original aptamer binding site in the loop and the newly created one due to base excision from the DNA backbone. ITC demonstrated that the A-excised aptamer strand can bind to two adenosine molecules, with a Kd of 14.8 ± 2.1 μM at 10 °C and entropy-driven binding. Since the wild-type aptamer cannot discriminate adenosine from AMP and ATP, we attributed this improved specificity to the excised site. Further study showed that these two sites worked cooperatively. Finally, the A-excised aptamer was tested in diluted fetal bovine serum and showed a limit of detection of 46.7 μM adenosine. This work provides a facile, cost-effective, and non-SELEX method to engineer existing aptamers for new features and better applications. The DNA aptamer for adenosine and ATP has been used as a model system for developing analytical biosensors.![]()
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Affiliation(s)
- Yuqing Li
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo Waterloo Ontario N2L 3G1 Canada
| | - Biwu Liu
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo Waterloo Ontario N2L 3G1 Canada
| | - Zhicheng Huang
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo Waterloo Ontario N2L 3G1 Canada
| | - Juewen Liu
- Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo Waterloo Ontario N2L 3G1 Canada
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Sagi J. In What Ways Do Synthetic Nucleotides and Natural Base Lesions Alter the Structural Stability of G-Quadruplex Nucleic Acids? J Nucleic Acids 2017; 2017:1641845. [PMID: 29181193 PMCID: PMC5664352 DOI: 10.1155/2017/1641845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/15/2017] [Indexed: 01/03/2023] Open
Abstract
Synthetic analogs of natural nucleotides have long been utilized for structural studies of canonical and noncanonical nucleic acids, including the extensively investigated polymorphic G-quadruplexes (GQs). Dependence on the sequence and nucleotide modifications of the folding landscape of GQs has been reviewed by several recent studies. Here, an overview is compiled on the thermodynamic stability of the modified GQ folds and on how the stereochemical preferences of more than 70 synthetic and natural derivatives of nucleotides substituting for natural ones determine the stability as well as the conformation. Groups of nucleotide analogs only stabilize or only destabilize the GQ, while the majority of analogs alter the GQ stability in both ways. This depends on the preferred syn or anti N-glycosidic linkage of the modified building blocks, the position of substitution, and the folding architecture of the native GQ. Natural base lesions and epigenetic modifications of GQs explored so far also stabilize or destabilize the GQ assemblies. Learning the effect of synthetic nucleotide analogs on the stability of GQs can assist in engineering a required stable GQ topology, and exploring the in vitro action of the single and clustered natural base damage on GQ architectures may provide indications for the cellular events.
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Affiliation(s)
- Janos Sagi
- Rimstone Laboratory, RLI, Carlsbad, CA 92010, USA
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Wang Y, Liu C, Hong T, Wu F, Yu S, He Z, Mao W, Zhou X. Application of Ammonium Persulfate for Selective Oxidation of Guanines for Nucleic Acid Sequencing. Molecules 2017; 22:molecules22071222. [PMID: 28753999 PMCID: PMC6152272 DOI: 10.3390/molecules22071222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/14/2017] [Accepted: 07/17/2017] [Indexed: 12/20/2022] Open
Abstract
Nucleic acids can be sequenced by a chemical procedure that partially damages the nucleotide positions at their base repetition. Many methods have been reported for the selective recognition of guanine. The accurate identification of guanine in both single and double regions of DNA and RNA remains a challenging task. Herein, we present a new, non-toxic and simple method for the selective recognition of guanine in both DNA and RNA sequences via ammonium persulfate modification. This strategy can be further successfully applied to the detection of 5-methylcytosine by using PCR.
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Affiliation(s)
- Yafen Wang
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Chaoxing Liu
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Tingting Hong
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Fan Wu
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Shuyi Yu
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Zhiyong He
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
| | - Wuxiang Mao
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan 430062, Hubei, China.
| | - Xiang Zhou
- Key Laboratory of Biomedical Polymers of Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, China.
- The Institute for Advanced Studies, Wuhan University, Wuhan 430072, Hubei, China.
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