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Zou X, Zhao Y, Lai C, Liang Y, Lin W. A non-peptide probe for detecting chymotrypsin activity based on protection-deprotection strategy in living systems. J Mater Chem B 2021; 9:8417-8423. [PMID: 34545893 DOI: 10.1039/d1tb01509e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chymotrypsin (CHT) plays a vital role in the metabolism of organisms and affects cell proliferation and apoptosis. Abnormal levels of CHT will lead to a variety of diseases, such as inflammatory arthritis, diabetes, pharyngitis, indigestion, and pancreatic cancer. Therefore, it is significant to design an effective method for the detection of CHT in living systems. Here, we synthesized a specific deep-red non-peptide probe DT by effectively combining isophorone and p-hydroxybenzaldehyde for the detection of CHT using 3-phenylpropionate chloride as the recognition group based on a protection-deprotection strategy. The DT probe exhibited an emission range of 525-700 nm and showed excellent photostability, high sensitivity (LOD = 0.071 U mL-1), and selectivity for CHT detection. The cellular experiments demonstrated that DT could sensitively recognize CHT activity in three cell lines and the content of CHT was much higher in P815 cells than in MCF-7 and 3T3 cells. Also, DT was successfully used to visualize the endogenous CHT in zebrafish. Notably, the DT probe provided an intuitive way to visualize endogenous CHT in mouse pancreas for the first time, demonstrating the potential for application in the future clinical diagnosis of pancreatic diseases. Therefore, the small-molecule probe DT is expected to be a useful molecular tool for CHT-related disease diagnosis and drug discovery.
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Affiliation(s)
- Xiang Zou
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, P. R. China.
| | - Yuping Zhao
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, P. R. China.
| | - Chaofeng Lai
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, P. R. China.
| | - Yun Liang
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, P. R. China.
| | - Weiying Lin
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, P. R. China.
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52
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Bohálová N, Mergny JL, Brázda V. Novel G-quadruplex prone sequences emerge in the complete assembly of the human X chromosome. Biochimie 2021; 191:87-90. [PMID: 34508825 DOI: 10.1016/j.biochi.2021.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/01/2021] [Accepted: 09/05/2021] [Indexed: 12/13/2022]
Abstract
G-quadruplexes are non-B secondary structures with regulatory functions and therapeutic potential. Improvements in sequencing methods recently allowed the completion of the first human chromosome which is now available as a gapless, end-to-end assembly, with the previously remaining spaces filled and newly identified regions added. We compared the presence of G-quadruplex forming sequences in the current human reference genome (GRCh38) and in the new end-to-end assembly of the X chromosome constructed by high-coverage ultra-long-read nanopore sequencing. This comparison revealed that, even though the corrected length of the chromosome X assembly is surprisingly 1.14% shorter than expected, the number of G-quadruplex forming sequences found in this gapless chromosome is significantly higher, with 493 new motifs having G4Hunter scores above 1.4 and 23 new sequences with G4Hunter scores above 3.5. This observation reflects an improved precision of the new sequencing approaches and points to an underestimation of G-quadruplex propensity in the previous, widely used version of the human genome assembly, especially for motifs with a high G4Hunter score, expected to be very stable. These G-quadruplex forming sequences probably remained undiscovered in earlier genome datasets due to previously unsolved G-rich and repetitive genomic regions. These observations allow a precise targeting of these important regulatory regions.
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Affiliation(s)
- Natália Bohálová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic; Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Jean-Louis Mergny
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic; Laboratoire d'Optique & Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, Palaiseau, France
| | - Václav Brázda
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65, Brno, Czech Republic.
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53
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Xie L, Li R, Zheng B, Xie Z, Fang X, Wang Y, Cuny GD, Li Z, Lin B, Chen X, Hu M. Development of Rofecoxib-Based Fluorescent Probes and Investigations on Their Solvatochromism, AIE Activity, Mechanochromism, and COX-2-Targeted Bioimaging. Anal Chem 2021; 93:11991-12000. [PMID: 34424685 DOI: 10.1021/acs.analchem.1c01978] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cyclooxygenase-2 (COX-2) fluorescent probes are promising tools for early diagnosis of cancer. Traditionally, COX-2 probes were designed by connecting two parts, a fluorophore and a COX-2 binding unit, via a flexible linker. Herein, a new class of COX-2-specific fluorescent probes have been developed via one-step modification from rofecoxib by an integrative approach to combine the binding unit and the fluorophore into one. Among them, several new rofecoxib analogues not only exhibited still potent COX-2 binding ability but also exhibited attractive fluorescence properties, such as tunable blue-red emission, solvatochromism, aggression-induced emission behavior, and mechanochromism. Notably, the emission of 2a16 can be switched between green-yellow in the crystalline state and red-orange in the amorphous state by grinding and fuming treatments. Furthermore, the highly fluorescent compound 2a16 (Φf = 0.94 in powder) displayed a much stronger fluorescence imaging of COX-2 in HeLa cancer cells overexpressing COX-2 than RAW264.7 normal cells with a minimal expression of COX-2. Most importantly, 2a16 can light up human cancer tissues from adjacent normal tissues with a much brighter fluorescence by targeting the COX-2 enzyme. These results demonstrated the potential of 2a16 as a new red fluorescent probe for human cancer imaging in clinical applications.
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Affiliation(s)
- Lijun Xie
- Fujian Provincial Key Laboratory of Screening for Novel Microbial Products, Fujian Institute of Microbiology, Fuzhou, Fujian 350007, P.R. China.,Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, United States
| | - Renfu Li
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P.R. China
| | - Biyun Zheng
- Department of Gastroenterology, Fujian Medical University Union Hospital, Fuzhou, Fujian 350007, P.R. China
| | - Zuoxu Xie
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, United States
| | - Xuefen Fang
- Department of Gastroenterology, Fujian Medical University Union Hospital, Fuzhou, Fujian 350007, P.R. China
| | - Yanqi Wang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P.R. China
| | - Gregory D Cuny
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, United States
| | - Zhenli Li
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P.R. China
| | - Bin Lin
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P.R. China
| | - Xueyuan Chen
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P.R. China
| | - Ming Hu
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, United States
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54
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Libera V, Andreeva EA, Martel A, Thureau A, Longo M, Petrillo C, Paciaroni A, Schirò G, Comez L. Porphyrin Binding and Irradiation Promote G-Quadruplex DNA Dimeric Structure. J Phys Chem Lett 2021; 12:8096-8102. [PMID: 34406777 DOI: 10.1021/acs.jpclett.1c01840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nucleic acid sequences rich in guanines can organize into noncanonical DNA G-quadruplexes (G4s) of variable size. The design of small molecules stabilizing the structure of G4s is a rapidly growing area for the development of novel anticancer therapeutic strategies and bottom-up nanotechnologies. Among a multitude of binders, porphyrins are very attractive due to their light activation that can make them valuable conformational regulators of G4s. Here, a structure-based strategy, integrating complementary probes, is employed to study the interaction between TMPyP4 porphyrin and a 22-base human telomeric sequence (Tel22) before and after irradiation with blue light. Porphyrin binding is discovered to promote Tel22 dimerization, while light irradiation of the Tel22-TMPyP4 complex controls dimer fraction. Such a change in quaternary structure is found to be strictly correlated with modifications at the secondary structure level, thus providing an unprecedented link between the degree of dimerization and the underlying conformational changes in G4s.
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Affiliation(s)
- Valeria Libera
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Elena A Andreeva
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Anne Martel
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Aurelien Thureau
- Swing Beamline, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - Marialucia Longo
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Caterina Petrillo
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Alessandro Paciaroni
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Giorgio Schirò
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Lucia Comez
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
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55
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Chen J, Gill AD, Hickey BL, Gao Z, Cui X, Hooley RJ, Zhong W. Machine Learning Aids Classification and Discrimination of Noncanonical DNA Folding Motifs by an Arrayed Host:Guest Sensing System. J Am Chem Soc 2021; 143:12791-12799. [PMID: 34346209 DOI: 10.1021/jacs.1c06031] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
An arrayed host:guest fluorescence sensor system can discriminate among and classify multiple different noncanonical DNA structures by exploiting selective molecular recognition. The sensor is highly selective and can discriminate between folds as similar as native G-quadruplexes and those with bulges or vacancies. The host and guest can form heteroternary complexes with DNA strands, with the host acting as mediator between the DNA and dye, modulating the emission. By applying machine learning algorithms to the sensing data, prediction of the folding state of unknown DNA strands is possible with high fidelity.
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56
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Manoli F, Doria F, Colombo G, Zambelli B, Freccero M, Manet I. The Binding Pocket at the Interface of Multimeric Telomere G-quadruplexes: Myth or Reality? Chemistry 2021; 27:11707-11720. [PMID: 34152657 PMCID: PMC8456957 DOI: 10.1002/chem.202101486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Indexed: 01/23/2023]
Abstract
Human telomeric DNA with hundreds of repeats of the 5'-TTAGGG-3' motif plays a crucial role in several biological processes. It folds into G-quadruplex (G4) structures and features a pocket at the interface of two contiguous G4 blocks. Up to now no structural NMR and crystallographic data are available for ligands interacting with contiguous G4s. Naphthalene diimide monomers and dyads were investigated as ligands of a dimeric G4 of human telomeric DNA comparing the results with those of the model monomeric G4. Time-resolved fluorescence, circular dichroism, isothermal titration calorimetry and molecular modeling were used to elucidate binding features. Ligand fluorescence lifetime and induced circular dichroism unveiled occupancy of the binding site at the interface. Thermodynamic parameters confirmed the hypothesis as they remarkably change for the dyad complexes of the monomeric and dimeric telomeric G4. The bi-functional ligand structure of the dyads is a fundamental requisite for binding at the G4 interface as only the dyads engage in complexes with 1 : 1 stoichiometry, lodging in the pocket at the interface and establishing multiple interactions with the DNA skeleton. In the absence of NMR and crystallographic data, our study affords important proofs of binding at the interface pocket and clues on the role played by the ligand structure.
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Affiliation(s)
- Francesco Manoli
- Institute for Organic Synthesis and Photoreactivity (ISOF)National Research Council (CNR)Via P. Gobetti 10140129BolognaItaly
| | - Filippo Doria
- Department of ChemistryUniversity of PaviaV. le Taramelli 1027100PaviaItaly
| | - Giorgio Colombo
- Department of ChemistryUniversity of PaviaV. le Taramelli 1027100PaviaItaly
| | - Barbara Zambelli
- Department of Pharmacy and BiotechnologyUniversity of BolognaV. le Fanin 4040127BolognaItaly
| | - Mauro Freccero
- Department of ChemistryUniversity of PaviaV. le Taramelli 1027100PaviaItaly
| | - Ilse Manet
- Institute for Organic Synthesis and Photoreactivity (ISOF)National Research Council (CNR)Via P. Gobetti 10140129BolognaItaly
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57
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Sheet SK, Rabha M, Sen B, Patra SK, Aguan K, Khatua S. Ruthenium(II) Complex-Based G-quadruplex DNA Selective Luminescent 'Light-up' Probe for RNase H Activity Detection. Chembiochem 2021; 22:2880-2887. [PMID: 34314094 DOI: 10.1002/cbic.202100229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/03/2021] [Indexed: 12/14/2022]
Abstract
A bis-heteroleptic ruthenium(II) complex, 1[PF6 ]2 of benzothiazole amide substituted 2,2'-bipyridine ligand (bmbbipy) has been synthesized for the selective detection of G-quadruplex (GQ) DNA and luminescence-assay-based RNase H activity monitoring. Compound 1[PF6 ]2 exhibited aggregation-caused quenching (ACQ) in water. Aggregate formation was supported by DLS, UV-vis, and 1 H NMR spectroscopy results, and the morphology of aggregated particles was witnessed by SEM and TEM. 1[PF6 ]2 acted as an efficient GQ DNA-selective luminescent light-up probe over single-stranded and double-stranded DNA. The competency of 1[PF6 ]2 for selective GQ structure detection was established by PL and CD spectroscopy. For 1[PF6 ]2 , the PL light-up is exclusively due to the rigidification of the benzothiazole amide side arm in the presence of GQ-DNA. The interaction between the probe and GQ-DNA was analyzed by molecular docking analysis. The GQ structure detection capability of 1[PF6 ]2 was further applied in the luminescent 'off-on' RNase H activity detection. The assay utilized an RNA:DNA hybrid, obtained from 22AG2-RNA and 22AG2-DNA sequences. RNase H solely hydrolyzed the RNA of the RNA:DNA duplex and released G-rich 22AG2-DNA, which was detected via the PL enhancement of 1[PF6 ]2 . The selectivity of RNase H activity detection over various other restriction enzymes was also demonstrated.
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Affiliation(s)
- Sanjoy Kumar Sheet
- Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
| | - Monosh Rabha
- Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
| | - Bhaskar Sen
- Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
| | - Sumit Kumar Patra
- Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
| | - Kripamoy Aguan
- Department of Biotechnology and Bioinformatics, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
| | - Snehadrinarayan Khatua
- Centre for Advanced Studies, Department of Chemistry, North-Eastern Hill University, 793022, Shillong, Meghalaya, India
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58
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Laouer K, Schmid M, Wien F, Changenet P, Hache F. Folding Dynamics of DNA G-Quadruplexes Probed by Millisecond Temperature Jump Circular Dichroism. J Phys Chem B 2021; 125:8088-8098. [PMID: 34279936 DOI: 10.1021/acs.jpcb.1c01993] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G-quadruplexes play important roles in cellular regulatory functions, but despite significant experimental and theoretical efforts, their folding mechanisms remain poorly understood. In this context, we developed a T-jump experiment to access the thermal denaturation and renaturation dynamics of short intramolecular G-quadruplexes in vitro, on the time scale of a few hundred milliseconds. With this new setup, we compared the thermal denaturation and renaturation kinetics of three antiparallel topologies made of the human telomeric sequences d[(5'-GGG(TTAGGG)3-3']/Na+ and d[5'-AGGG(TTAGGG)3-3']/Na+ and the thrombin-binding aptamer sequence d[5'-GGTTGGTGTGGTTGG-3']/K+, with those of the parallel topology made of the human CEB25 minisatellite d[5'-AAGGGTGGGTGTAAGTGTGGGTGGGT-3']/Na+. In all cases, exponential kinetics of the order of several hundred milliseconds were observed. Measurements performed for different initial temperatures revealed distinct denaturation and renaturation dynamics, ruling out a simple two-state mechanism. The parallel topology, in which all guanines adopt an anti conformation, displays much slower dynamics than antiparallel topologies associated with very low activation barriers. This behavior can be explained by the constrained conformational space due to the presence of the single-base propeller loops that likely hinders the movement of the coiled DNA strand and reduces the contribution of the entropy during the renaturation process at high temperatures.
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Affiliation(s)
- K Laouer
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - M Schmid
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Wien
- L'orme des merisiers, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - P Changenet
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
| | - F Hache
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS -INSERM, Institut Polytechnique de Paris, 91128 Cedex Palaiseau, France
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59
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Carloni LE, Wechselberger R, De Vijlder T. Characterization of In Vitro G-Quadruplex Formation of Imetelstat Telomerase Inhibitor. Nucleic Acid Ther 2021; 31:341-350. [PMID: 34018844 DOI: 10.1089/nat.2020.0918] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Imetelstat (GRN163L) is a potent and specific telomerase inhibitor currently in clinical development for the treatment of hematological malignancies such as myelofibrosis and myelodysplastic syndrome. It is a 13-mer N3'-P5' thio-phosphoramidate oligonucleotide covalently functionalized at the 5'-end with a palmitoyl lipid moiety through an aminoglycerol linker. As a competitive inhibitor of human telomerase, imetelstat directly binds to the telomerase RNA component sequence (hTR) in the catalytic site of the enzyme and acts as a direct competitor of human telomere binding. Administration of imetelstat causes progressive shortening of the telomeres, thereby inhibiting malignant cells' proliferation. We report here the ability of imetelstat to form stable, parallel, intermolecular G-quadruplex structures in vitro. The impact of the ionic environment on the formation and stability of imetelstat higher-order structure was investigated through circular dichroism spectroscopy, thermal denaturation analysis, and size-exclusion chromatography. We demonstrated that different structural elements, such as the 5'-palmitoyl linker and the thio-phosphoramidate backbone, critically contribute to G-quadruplex stability. Experiments further showed that G-quadruplex formation does not hamper binding to the hTR oligonucleotide sequence in vitro.
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Affiliation(s)
- Laure-Elie Carloni
- Small Molecule Pharmaceutical Development, Janssen Research & Development, Beerse, Belgium
| | - Rainer Wechselberger
- Small Molecule Pharmaceutical Development, Janssen Research & Development, Beerse, Belgium
| | - Thomas De Vijlder
- Small Molecule Pharmaceutical Development, Janssen Research & Development, Beerse, Belgium
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60
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Structures of telomerase at several steps of telomere repeat synthesis. Nature 2021; 593:454-459. [PMID: 33981033 DOI: 10.1038/s41586-021-03529-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/09/2021] [Indexed: 12/14/2022]
Abstract
Telomerase is unique among the reverse transcriptases in containing a noncoding RNA (known as telomerase RNA (TER)) that includes a short template that is used for the processive synthesis of G-rich telomeric DNA repeats at the 3' ends of most eukaryotic chromosomes1. Telomerase maintains genomic integrity, and its activity or dysregulation are critical determinants of human longevity, stem cell renewal and cancer progression2,3. Previous cryo-electron microscopy structures have established the general architecture, protein components and stoichiometries of Tetrahymena and human telomerase, but our understandings of the details of DNA-protein and RNA-protein interactions and of the mechanisms and recruitment involved remain limited4-6. Here we report cryo-electron microscopy structures of active Tetrahymena telomerase with telomeric DNA at different steps of nucleotide addition. Interactions between telomerase reverse transcriptase (TERT), TER and DNA reveal the structural basis of the determination of the 5' and 3' template boundaries, handling of the template-DNA duplex and separation of the product strand during nucleotide addition. The structure and binding interface between TERT and telomerase protein p50 (a homologue of human TPP17,8) define conserved interactions that are required for telomerase activation and recruitment to telomeres. Telomerase La-related protein p65 remodels several regions of TER, bridging the 5' and 3' ends and the conserved pseudoknot to facilitate assembly of the TERT-TER catalytic core.
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61
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Cagirici HB, Budak H, Sen TZ. Genome-wide discovery of G-quadruplexes in barley. Sci Rep 2021; 11:7876. [PMID: 33846409 PMCID: PMC8041835 DOI: 10.1038/s41598-021-86838-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 03/19/2021] [Indexed: 12/04/2022] Open
Abstract
G-quadruplexes (G4s) are four-stranded nucleic acid structures with closely spaced guanine bases forming square planar G-quartets. Aberrant formation of G4 structures has been associated with genomic instability. However, most plant species are lacking comprehensive studies of G4 motifs. In this study, genome-wide identification of G4 motifs in barley was performed, followed by a comparison of genomic distribution and molecular functions to other monocot species, such as wheat, maize, and rice. Similar to the reports on human and some plants like wheat, G4 motifs peaked around the 5′ untranslated region (5′ UTR), the first coding domain sequence, and the first intron start sites on antisense strands. Our comparative analyses in human, Arabidopsis, maize, rice, and sorghum demonstrated that the peak points could be erroneously merged into a single peak when large window sizes are used. We also showed that the G4 distributions around genic regions are relatively similar in the species studied, except in the case of Arabidopsis. G4 containing genes in monocots showed conserved molecular functions for transcription initiation and hydrolase activity. Additionally, we provided examples of imperfect G4 motifs.
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Affiliation(s)
- H Busra Cagirici
- Crop Improvement and Genetics Research Unit, Western Regional Research Center, U.S. Department of Agriculture - Agricultural Research Service, 800 Buchanan St, Albany, CA, 94710, USA
| | - Hikmet Budak
- Montana BioAg Inc., Missoula, MT, USA.,Agrogen, LLC., Omaha, NE, USA
| | - Taner Z Sen
- Crop Improvement and Genetics Research Unit, Western Regional Research Center, U.S. Department of Agriculture - Agricultural Research Service, 800 Buchanan St, Albany, CA, 94710, USA.
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62
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POT1 stability and binding measured by fluorescence thermal shift assays. PLoS One 2021; 16:e0245675. [PMID: 33784306 PMCID: PMC8009405 DOI: 10.1371/journal.pone.0245675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/03/2021] [Indexed: 11/19/2022] Open
Abstract
The protein POT1 (Protection of Telomeres 1) is an integral part of the shelterin complex that protects the ends of human chromosomes from degradation or end fusions. It is the only component of shelterin that binds single-stranded DNA. We describe here the application of two separate fluorescent thermal shift assays (FTSA) that provide quantitative biophysical characterization of POT1 stability and its interactions. The first assay uses Sypro Orange™ and monitors the thermal stability of POT1 and its binding under a variety of conditions. This assay is useful for the quality control of POT1 preparations, for biophysical characterization of its DNA binding and, potentially, as an efficient screening tool for binding of small molecule drug candidates. The second assay uses a FRET-labeled human telomeric G-quadruplex structure that reveals the effects of POT1 binding on thermal stability from the DNA frame of reference. These complementary assays provide efficient biophysical approaches for the quantitative characterization of multiple aspects of POT1 structure and function. The results from these assays provide thermodynamics details of POT1 folding, the sequence selectivity of its DNA binding and the thermodynamic profile for its binding to its preferred DNA binding sequence. Most significantly, results from these assays elucidate two mechanisms for the inhibition of POT1 -DNA interactions. The first is by competitive inhibition at the POT1 DNA binding site. The second is indirect and is by stabilization of G-quadruplex formation within the normal POT1 single-stranded DNA sequence to prevent POT1 binding.
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63
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The Long Linker Region of Telomere-Binding Protein TRF2 Is Responsible for Interactions with Lamins. Int J Mol Sci 2021; 22:ijms22073293. [PMID: 33804854 PMCID: PMC8036907 DOI: 10.3390/ijms22073293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 12/15/2022] Open
Abstract
Telomere-binding factor 2 (TRF2) is part of the shelterin protein complex found at chromosome ends. Lamin A/C interacts with TRF2 and influences telomere position. TRF2 has an intrinsically disordered region between the ordered dimerization and DNA-binding domains. This domain is referred to as the long linker region of TRF2, or udTRF2. We suggest that udTRF2 might be involved in the interaction between TRF2 and lamins. The recombinant protein corresponding to the udTRF2 region along with polyclonal antibodies against this region were used in co-immunoprecipitation with purified lamina and nuclear extracts. Co-immunoprecipitation followed by Western blots and mass spectrometry indicated that udTRF2 interacts with lamins, preferably lamins A/C. The interaction did not involve any lamin-associated proteins, was not dependent on the post-translation modification of lamins, nor did it require their higher-order assembly. Besides lamins, a number of other udTRF2-interacting proteins were identified by mass spectrometry, including several heterogeneous nuclear ribonucleoproteins (hnRNP A2/B1, hnRNPA1, hnRNP A3, hnRNP K, hnRNP L, hnRNP M), splicing factors (SFPQ, NONO, SRSF1, and others), helicases (DDX5, DHX9, and Eif4a3l1), topoisomerase I, and heat shock protein 71, amongst others. Some of the identified interactors are known to be involved in telomere biology; the roles of the others remain to be investigated. Thus, the long linker region of TRF2 (udTRF2) is a regulatory domain responsible for the association between TRF2 and lamins and is involved in interactions with other proteins.
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64
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Lim CJ, Cech TR. Shaping human telomeres: from shelterin and CST complexes to telomeric chromatin organization. Nat Rev Mol Cell Biol 2021; 22:283-298. [PMID: 33564154 DOI: 10.1038/s41580-021-00328-y] [Citation(s) in RCA: 115] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2021] [Indexed: 01/14/2023]
Abstract
The regulation of telomere length in mammals is crucial for chromosome end-capping and thus for maintaining genome stability and cellular lifespan. This process requires coordination between telomeric protein complexes and the ribonucleoprotein telomerase, which extends the telomeric DNA. Telomeric proteins modulate telomere architecture, recruit telomerase to accessible telomeres and orchestrate the conversion of the newly synthesized telomeric single-stranded DNA tail into double-stranded DNA. Dysfunctional telomere maintenance leads to telomere shortening, which causes human diseases including bone marrow failure, premature ageing and cancer. Recent studies provide new insights into telomerase-related interactions (the 'telomere replisome') and reveal new challenges for future telomere structural biology endeavours owing to the dynamic nature of telomere architecture and the great number of structures that telomeres form. In this Review, we discuss recently determined structures of the shelterin and CTC1-STN1-TEN1 (CST) complexes, how they may participate in the regulation of telomere replication and chromosome end-capping, and how disease-causing mutations in their encoding genes may affect specific functions. Major outstanding questions in the field include how all of the telomere components assemble relative to each other and how the switching between different telomere structures is achieved.
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Affiliation(s)
- Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA. .,Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA. .,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.
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65
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Savva L, Georgiades SN. Recent Developments in Small-Molecule Ligands of Medicinal Relevance for Harnessing the Anticancer Potential of G-Quadruplexes. Molecules 2021; 26:molecules26040841. [PMID: 33562720 PMCID: PMC7914483 DOI: 10.3390/molecules26040841] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
G-quadruplexes, a family of tetraplex helical nucleic acid topologies, have emerged in recent years as novel targets, with untapped potential for anticancer research. Their potential stems from the fact that G-quadruplexes occur in functionally-important regions of the human genome, such as the telomere tandem sequences, several proto-oncogene promoters, other regulatory regions and sequences of DNA (e.g., rDNA), as well as in mRNAs encoding for proteins with roles in tumorigenesis. Modulation of G-quadruplexes, via interaction with high-affinity ligands, leads to their stabilization, with numerous observed anticancer effects. Despite the fact that only a few lead compounds for G-quadruplex modulation have progressed to clinical trials so far, recent advancements in the field now create conditions that foster further development of drug candidates. This review highlights biological processes through which G-quadruplexes can exert their anticancer effects and describes, via selected case studies, progress of the last few years on the development of efficient and drug-like G-quadruplex-targeted ligands, intended to harness the anticancer potential offered by G-quadruplexes. The review finally provides a critical discussion of perceived challenges and limitations that have previously hampered the progression of G-quadruplex-targeted lead compounds to clinical trials, concluding with an optimistic future outlook.
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66
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Active and Passive Destabilization of G-Quadruplex DNA by the Telomere POT1-TPP1 Complex. J Mol Biol 2021; 433:166846. [PMID: 33549587 DOI: 10.1016/j.jmb.2021.166846] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/05/2021] [Accepted: 01/22/2021] [Indexed: 11/23/2022]
Abstract
Chromosome ends are protected by guanosine-rich telomere DNA that forms stable G-quadruplex (G4) structures. The heterodimeric POT1-TPP1 complex interacts specifically with telomere DNA to shield it from illicit DNA damage repair and to resolve secondary structure that impedes telomere extension. The mechanism by which POT1-TPP1 accomplishes these tasks is poorly understood. Here, we establish the kinetic framework for POT1-TPP1 binding and unfolding of telomere G4 DNA. Our data identify two modes of POT1-TPP1 destabilization of G4 DNA that are governed by protein concentration. At low concentrations, POT1-TPP1 passively captures transiently unfolded G4s. At higher concentrations, POT1-TPP1 proteins bind to G4s to actively destabilize the DNA structures. Cancer-associated POT1-TPP1 mutations impair multiple reaction steps in this process, resulting in less efficient destabilization of G4 structures. The mechanistic insight highlights the importance of cell cycle dependent expression and localization of the POT1-TPP1 complex and distinguishes diverse functions of this complex in telomere maintenance.
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Palka C, Forino NM, Hentschel J, Das R, Stone MD. Folding heterogeneity in the essential human telomerase RNA three-way junction. RNA (NEW YORK, N.Y.) 2020; 26:1787-1800. [PMID: 32817241 PMCID: PMC7668248 DOI: 10.1261/rna.077255.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Telomeres safeguard the genome by suppressing illicit DNA damage responses at chromosome termini. To compensate for incomplete DNA replication at telomeres, most continually dividing cells, including many cancers, express the telomerase ribonucleoprotein (RNP) complex. Telomerase maintains telomere length by catalyzing de novo synthesis of short DNA repeats using an internal telomerase RNA (TR) template. TRs from diverse species harbor structurally conserved domains that contribute to RNP biogenesis and function. In vertebrate TRs, the conserved regions 4 and 5 (CR4/5) fold into a three-way junction (TWJ) that binds directly to the telomerase catalytic protein subunit and is required for telomerase function. We have analyzed the structural properties of the human TR (hTR) CR4/5 domain using a combination of in vitro chemical mapping, secondary structural modeling, and single-molecule structural analysis. Our data suggest the essential P6.1 stem-loop within CR4/5 is not stably folded in the absence of the telomerase reverse transcriptase in vitro. Rather, the hTR CR4/5 domain adopts a heterogeneous ensemble of conformations. Finally, single-molecule FRET measurements of CR4/5 and a mutant designed to stabilize the P6.1 stem demonstrate that TERT binding selects for a structural conformation of CR4/5 that is not the dominant state of the TERT-free in vitro RNA ensemble.
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Affiliation(s)
- Christina Palka
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
| | - Nicholas M Forino
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Jendrik Hentschel
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
| | - Rhiju Das
- Biophysics Program, Stanford University, Stanford, California 94305, USA
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Michael D Stone
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
- Center for Molecular Biology of RNA, University of California, Santa Cruz, California 95064, USA
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68
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Zhang R, Xiao K, Gu Y, Liu H, Sun X. Whole Genome Identification of Potential G-Quadruplexes and Analysis of the G-Quadruplex Binding Domain for SARS-CoV-2. Front Genet 2020; 11:587829. [PMID: 33329730 PMCID: PMC7728997 DOI: 10.3389/fgene.2020.587829] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/22/2020] [Indexed: 01/08/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has become a global public health emergency. G-quadruplex, one of the non-canonical secondary structures, has shown potential antiviral values. However, little is known about the G-quadruplexes of the emerging SARS-CoV-2. Herein, we characterized the potential G-quadruplexes in both positive and negative-sense viral strands. The identified potential G-quadruplexes exhibited similar features to the G-quadruplexes detected in the human transcriptome. Within some bat- and pangolin-related betacoronaviruses, the G-tracts rather than the loops were under heightened selective constraints. We also found that the amino acid sequence similar to SUD (SARS-unique domain) was retained in SARS-CoV-2 but depleted in some other coronaviruses that can infect humans. Further analysis revealed that the amino acid residues related to the binding affinity of G-quadruplexes were conserved among 16,466 SARS-CoV-2 samples. Moreover, the dimer of the SUD-homology structure in SARS-CoV-2 displayed similar electrostatic potential patterns to the SUD dimer from SARS. Considering the potential value of G-quadruplexes to serve as targets in antiviral strategy, our fundamental research could provide new insights for the SARS-CoV-2 drug discovery.
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Affiliation(s)
- Rongxin Zhang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Ke Xiao
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Yu Gu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Hongde Liu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Xiao Sun
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
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69
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Pandey S, Li Y, Young MD, Mandal S, Lu L, Shelley JT, Mao H. Cooperative Heteroligand Interaction with G-Quadruplexes Shows Evidence of Allosteric Binding. Biochemistry 2020; 59:3438-3446. [PMID: 32833433 PMCID: PMC7511437 DOI: 10.1021/acs.biochem.0c00351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although allosteric binding of small molecules is commonplace in protein structures, it is rather rare in DNA species such as G-quadruplexes. By using CD melting, here, we found binding of the small-molecule ligands PDS and L2H2-6OTD to the telomeric DNA G-quadruplex was cooperative. Mass spectrometry indicated a 1:1:1 ratio in the ternary binding complex of the telomeric G-quadruplex, PDS, and L2H2-6OTD. Compared to the binding of each individual ligand to the G-quadruplex, single-molecule mechanical unfolding assays revealed a significantly decreased dissociation constant when one ligand is evaluated in the presence of another. This demonstrates that cooperative binding of PDS and L2H2-6OTD to the G-quadruplex is allosteric, which is also supported by the mass spectra data that indicated the ejection of coordinated sodium ions upon binding of the heteroligands to the G-quadruplex. The unprecedented observation of the allosteric ligand binding to higher-ordered structures of DNA may help to design more effective ligands to target non-B DNA species involved in many critical cellular processes.
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Affiliation(s)
- Shankar Pandey
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio, 44242, USA
| | - Yuanyuan Li
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio, 44242, USA
- Department of Pharmacy, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Montwaun D. Young
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Shankar Mandal
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio, 44242, USA
| | - Laichun Lu
- National Institute for Drug Clinical Trial, Beijing Tongren Hospital, Capital Medical University, 1 Dongjiaominxiang Road, Beijing, 100730, China
| | - Jacob T. Shelley
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Hanbin Mao
- Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio, 44242, USA
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70
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Bryan TM. G-Quadruplexes at Telomeres: Friend or Foe? Molecules 2020; 25:molecules25163686. [PMID: 32823549 PMCID: PMC7464828 DOI: 10.3390/molecules25163686] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/28/2022] Open
Abstract
Telomeres are DNA-protein complexes that cap and protect the ends of linear chromosomes. In almost all species, telomeric DNA has a G/C strand bias, and the short tandem repeats of the G-rich strand have the capacity to form into secondary structures in vitro, such as four-stranded G-quadruplexes. This has long prompted speculation that G-quadruplexes play a positive role in telomere biology, resulting in selection for G-rich tandem telomere repeats during evolution. There is some evidence that G-quadruplexes at telomeres may play a protective capping role, at least in yeast, and that they may positively affect telomere maintenance by either the enzyme telomerase or by recombination-based mechanisms. On the other hand, G-quadruplex formation in telomeric DNA, as elsewhere in the genome, can form an impediment to DNA replication and a source of genome instability. This review summarizes recent evidence for the in vivo existence of G-quadruplexes at telomeres, with a focus on human telomeres, and highlights some of the many unanswered questions regarding the location, form, and functions of these structures.
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Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
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71
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Varshney D, Spiegel J, Zyner K, Tannahill D, Balasubramanian S. The regulation and functions of DNA and RNA G-quadruplexes. Nat Rev Mol Cell Biol 2020; 21:459-474. [PMID: 32313204 PMCID: PMC7115845 DOI: 10.1038/s41580-020-0236-x] [Citation(s) in RCA: 583] [Impact Index Per Article: 145.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2020] [Indexed: 02/06/2023]
Abstract
DNA and RNA can adopt various secondary structures. Four-stranded G-quadruplex (G4) structures form through self-recognition of guanines into stacked tetrads, and considerable biophysical and structural evidence exists for G4 formation in vitro. Computational studies and sequencing methods have revealed the prevalence of G4 sequence motifs at gene regulatory regions in various genomes, including in humans. Experiments using chemical, molecular and cell biology methods have demonstrated that G4s exist in chromatin DNA and in RNA, and have linked G4 formation with key biological processes ranging from transcription and translation to genome instability and cancer. In this Review, we first discuss the identification of G4s and evidence for their formation in cells using chemical biology, imaging and genomic technologies. We then discuss possible functions of DNA G4s and their interacting proteins, particularly in transcription, telomere biology and genome instability. Roles of RNA G4s in RNA biology, especially in translation, are also discussed. Furthermore, we consider the emerging relationships of G4s with chromatin and with RNA modifications. Finally, we discuss the connection between G4 formation and synthetic lethality in cancer cells, and recent progress towards considering G4s as therapeutic targets in human diseases.
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Affiliation(s)
- Dhaval Varshney
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Jochen Spiegel
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Katherine Zyner
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - David Tannahill
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK
| | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, UK.
- Department of Chemistry, University of Cambridge, Cambridge, UK.
- School of Clinical Medicine, University of Cambridge, Cambridge, UK.
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72
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Paudel BP, Moye AL, Abou Assi H, El-Khoury R, Cohen SB, Holien JK, Birrento ML, Samosorn S, Intharapichai K, Tomlinson CG, Teulade-Fichou MP, González C, Beck JL, Damha MJ, van Oijen AM, Bryan TM. A mechanism for the extension and unfolding of parallel telomeric G-quadruplexes by human telomerase at single-molecule resolution. eLife 2020; 9:56428. [PMID: 32723475 PMCID: PMC7426096 DOI: 10.7554/elife.56428] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/28/2020] [Indexed: 02/07/2023] Open
Abstract
Telomeric G-quadruplexes (G4) were long believed to form a protective structure at telomeres, preventing their extension by the ribonucleoprotein telomerase. Contrary to this belief, we have previously demonstrated that parallel-stranded conformations of telomeric G4 can be extended by human and ciliate telomerase. However, a mechanistic understanding of the interaction of telomerase with structured DNA remained elusive. Here, we use single-molecule fluorescence resonance energy transfer (smFRET) microscopy and bulk-phase enzymology to propose a mechanism for the resolution and extension of parallel G4 by telomerase. Binding is initiated by the RNA template of telomerase interacting with the G-quadruplex; nucleotide addition then proceeds to the end of the RNA template. It is only through the large conformational change of translocation following synthesis that the G-quadruplex structure is completely unfolded to a linear product. Surprisingly, parallel G4 stabilization with either small molecule ligands or by chemical modification does not always inhibit G4 unfolding and extension by telomerase. These data reveal that telomerase is a parallel G-quadruplex resolvase.
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Affiliation(s)
- Bishnu P Paudel
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Aaron Lavel Moye
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
| | - Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, Canada
| | | | - Scott B Cohen
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
| | - Jessica K Holien
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, Australia
| | - Monica L Birrento
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Siritron Samosorn
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok, Thailand
| | - Kamthorn Intharapichai
- Department of Biobased Materials Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan
| | | | - Marie-Paule Teulade-Fichou
- Institut Curie, PSL Research University, Orsay, France.,Université Paris Sud, Université Paris-Saclay, Orsay, France
| | - Carlos González
- Instituto de Química Física 'Rocasolano', CSIC, Madrid, Spain
| | - Jennifer L Beck
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Canada
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawara Health and Medical Research Institute, Wollongong, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, Australia
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73
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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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74
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Genome-Wide Discovery of G-Quadruplexes in Wheat: Distribution and Putative Functional Roles. G3-GENES GENOMES GENETICS 2020; 10:2021-2032. [PMID: 32295768 PMCID: PMC7263691 DOI: 10.1534/g3.120.401288] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
G-quadruplexes are nucleic acid secondary structures formed by a stack of square planar G-quartets. G-quadruplexes were implicated in many biological functions including telomere maintenance, replication, transcription, and translation, in many species including humans and plants. For wheat, however, though it is one of the world's most important staple food, no G-quadruplex studies have been reported to date. Here, we computationally identify putative G4 structures (G4s) in wheat genome for the first time and compare its distribution across the genome against five other genomes (human, maize, Arabidopsis, rice, and sorghum). We identified close to 1 million G4 motifs with a density of 76 G4s/Mb across the whole genome and 93 G4s/Mb over genic regions. Remarkably, G4s were enriched around three regions, two located on the antisense and one on the sense strand at the following positions: 1) the transcription start site (TSS) (antisense), 2) the first coding domain sequence (CDS) (antisense), and 3) the start codon (sense). Functional enrichment analysis revealed that the gene models containing G4 motifs within these peaks were associated with specific gene ontology (GO) terms, such as developmental process, localization, and cellular component organization or biogenesis. We investigated genes encoding MADS-box transcription factors and showed examples of G4 motifs within critical regulatory regions in the VRN-1 genes in wheat. Furthermore, comparison with other plants showed that monocots share a similar distribution of G4s, but Arabidopsis shows a unique G4 distribution. Our study shows for the first time the prevalence and possible functional roles of G4s in wheat.
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75
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Mitra J, Ha T. Streamlining effects of extra telomeric repeat on telomeric DNA folding revealed by fluorescence-force spectroscopy. Nucleic Acids Res 2020; 47:11044-11056. [PMID: 31617570 PMCID: PMC6868435 DOI: 10.1093/nar/gkz906] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/29/2019] [Accepted: 10/02/2019] [Indexed: 01/26/2023] Open
Abstract
A human telomere ends in a single-stranded 3′ tail, composed of repeats of T2AG3. G-quadruplexes (GQs) formed from four consecutive repeats have been shown to possess high-structural and mechanical diversity. In principle, a GQ can form from any four repeats that are not necessarily consecutive. To understand the dynamics of GQs with positional multiplicity, we studied five and six repeats human telomeric sequence using a combination of single molecule FRET and optical tweezers. Our results suggest preferential formation of GQs at the 3′ end both in K+ and Na+ solutions, with minor populations of 5′-GQ or long-loop GQs. A vectorial folding assay which mimics the directional nature of telomere extension showed that the 3′ preference holds even when folding is allowed to begin from the 5′ side. In 100 mM K+, the unassociated T2AG3 segment has a streamlining effect in that one or two mechanically distinct species was observed at a single position instead of six or more observed without an unassociated repeat. We did not observe such streamlining effect in 100 mM Na+. Location of GQ and reduction in conformational diversity in the presence of extra repeats have implications in telomerase inhibition, T-loop formation and telomere end protection.
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Affiliation(s)
- Jaba Mitra
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana IL 61801, USA.,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.,Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, MD 21218, USA
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76
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Baldassarri EJ, Ortore MG, Spinozzi F, Round A, Ferrero C, Mariani P. K vs. Na Effects on the Self-Assembly of Guanosine 5'-Monophosphate: A Solution SAXS Structural Study +. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E629. [PMID: 32231081 PMCID: PMC7221663 DOI: 10.3390/nano10040629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/18/2020] [Accepted: 03/20/2020] [Indexed: 12/18/2022]
Abstract
The hierarchical process of guanosine (G) self-assembly, leading in aqueous solution and in the presence of metal cations to the formation of G-quadruplexes, represents an intriguing topic both for the biological correlation with telomerase activity and for the nano-technological applications, as demonstrated by the current measured in a quadruplex wire 100 nm long. Similar to G-rich DNA sequences and G-oligonucleotides, the guanosine 5'-monophosphate (GMP) self-aggregates in water to form quadruplexes. However, due to the absence of a covalent axial backbone, this system can be very useful to understand the chemical-physical conditions that govern the guanosine supramolecular aggregation. We have then investigated by in-solution Synchrotron Small Angle X-ray Scattering technique the role of different cations in promoting the quadruplex formation as a function of concentration and temperature. Results show how potassium, with its peculiar biological traits, favours the G-quadruplex elongation process in respect to other cations (Na + , but also NH 4 + and Li + ), determining the longest particles in solution. Moreover, the formation and the elongation of G-quadruplexes have been demonstrated to be controlled by both GMP concentration and excess cation content, even if they specifically contribute to these processes in different ways. The occurrence of condensed liquid crystalline phases was also detected, proving that excess cations play also unspecific effects on the effective charges on the G-quadruplex surface.
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Affiliation(s)
- Enrico Junior Baldassarri
- Marche Structural Biology Center, Department of Life and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona, Italy
| | - Maria Grazia Ortore
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona, Italy
| | - Francesco Spinozzi
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona, Italy
| | - Adam Round
- European XFEL, SPB/SFX Instrument, 22869 Schenefeld, Germany
| | - Claudio Ferrero
- European Synchrotron Radiation Facility-E.S.R.F., 38043 Grenoble, France
| | - Paolo Mariani
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, 60131 Ancona, Italy
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77
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Patrick EM, Slivka JD, Payne B, Comstock MJ, Schmidt JC. Observation of processive telomerase catalysis using high-resolution optical tweezers. Nat Chem Biol 2020; 16:801-809. [PMID: 32066968 PMCID: PMC7311264 DOI: 10.1038/s41589-020-0478-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/14/2020] [Indexed: 02/07/2023]
Abstract
Telomere maintenance by telomerase is essential for continuous proliferation of human cells and is vital for the survival of stem cells and 90% of cancer cells. To compensate for telomeric DNA lost during DNA replication, telomerase processively adds GGTTAG repeats to chromosome ends by copying the template region within its RNA subunit. Between repeat additions, the RNA template must be recycled. How telomerase remains associated with substrate DNA during this critical translocation step remains unknown. Using a newly developed single-molecule telomerase activity assay utilizing high-resolution optical tweezers, we demonstrate that stable substrate DNA binding at an anchor site within telomerase facilitates the processive synthesis of telomeric repeats. The product DNA synthesized by telomerase can be recaptured by the anchor site or fold into G-quadruplex structures. Our results provide detailed mechanistic insights into telomerase catalysis, a process of critical importance in aging and cancer.
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Affiliation(s)
- Eric M Patrick
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Joseph D Slivka
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
| | - Bramyn Payne
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA
| | - Matthew J Comstock
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA.
| | - Jens C Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA. .,Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA.
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78
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Golenkina EA, Viryasova GM, Dolinnaya NG, Bannikova VA, Gaponova TV, Romanova YM, Sud’ina GF. The Potential of Telomeric G-quadruplexes Containing Modified Oligoguanosine Overhangs in Activation of Bacterial Phagocytosis and Leukotriene Synthesis in Human Neutrophils. Biomolecules 2020; 10:E249. [PMID: 32041263 PMCID: PMC7072695 DOI: 10.3390/biom10020249] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/28/2020] [Accepted: 02/04/2020] [Indexed: 12/14/2022] Open
Abstract
Human neutrophils are the first line of defense against bacterial and viral infections. They eliminate pathogens through phagocytosis, which activate the 5-lipoxygenase (5-LOX) pathway resulting in synthesis of leukotrienes. Using HPLC analysis, flow cytometry, and other biochemical methods, we studied the effect of synthetic oligodeoxyribonucleotides (ODNs) able to fold into G-quadruplex structures on the main functions of neutrophils. Designed ODNs contained four human telomere TTAGGG repeats (G4) including those with phosphorothioate oligoguanosines attached to the end(s) of G-quadruplex core. Just modified analogues of G4 was shown to more actively than parent ODN penetrate into cells, improve phagocytosis of Salmonella typhimurium bacteria, affect 5-LOX activation, the cytosol calcium ion level, and the oxidative status of neutrophils. As evident from CD and UV spectroscopy data, the presence of oligoguanosines flanking G4 sequence leads to dramatic changes in G-quadruplex topology. While G4 folds into a single antiparallel structure, two main folded forms have been identified in solutions of modified ODNs: antiparallel and dominant, more stable parallel. Thus, both the secondary structure of ODNs and their ability to penetrate into the cytoplasm of cells are important for the activation of neutrophil cellular effects. Our results offer new clues for understanding the role of G-quadruplex ligands in regulation of integral cellular processes and for creating the antimicrobial agents of a new generation.
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Affiliation(s)
- Ekaterina A. Golenkina
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow 119234, Russia; (E.A.G.); (G.M.V.)
| | - Galina M. Viryasova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow 119234, Russia; (E.A.G.); (G.M.V.)
| | - Nina G. Dolinnaya
- Lomonosov Moscow State University, Department of Chemistry, Moscow 119234, Russia; (N.G.D.); (V.A.B.)
| | - Valeria A. Bannikova
- Lomonosov Moscow State University, Department of Chemistry, Moscow 119234, Russia; (N.G.D.); (V.A.B.)
| | - Tatjana V. Gaponova
- National Research Center for Hematology, Russia Federation Ministry of Public Health, Moscow 125167, Russia;
| | - Yulia M. Romanova
- Gamaleya National Research Centre of Epidemiology and Microbiology, Moscow 123098, Russia;
| | - Galina F. Sud’ina
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow 119234, Russia; (E.A.G.); (G.M.V.)
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79
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Wang S, Liang L, Tang J, Cai Y, Zhao C, Fang S, Wang H, Weng T, Wang L, Wang D. Label-free single-molecule identification of telomere G-quadruplexes with a solid-state nanopore sensor. RSC Adv 2020; 10:27215-27224. [PMID: 35515777 PMCID: PMC9055465 DOI: 10.1039/d0ra05083k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022] Open
Abstract
Telomere sequences can spontaneously form G-quadruplexes (G4) in the presence of some cations. In view of their relevance to genetic processes and potential as therapeutic-targets, hitherto, a wealth of conventional techniques have been reported for interrogation of G4 conformation diversity and corresponding folding kinetics, most of which are limited in precision and sensitivity. This work introduces a label-free solid-state nanopore (SSN) approach for the determination of inter-, intra- and tandem molecular G4 with distinct base permutation in various cation buffers with a tailored aperture and meanwhile captures the single-molecule G4 folding process. SSN translocation properties elucidated that both inter- and intramolecular G4 generated higher current blockage with longer duration than flexible homopolymer nucleotide, and intramolecular G4 are structurally more stable with higher event frequency and longer blockage time than intermolecular ones; base arrangement played weak role in translocation behaviors; the same sequences with one, two and three G4 skeletons displayed an increase in current blockage and a gradual extension in dwell time with the increase of molecule size recorded in the same nanopore. We observed the conformation change of single-molecule G4 which indicated the existence of folding/unfolding equilibration in nanopore, and real-time test suggested a gradual formation of G4 with time. Our results could provide a continued and improved understanding of the underlying relevance of structural stability and G4 folding process by utilizing SSN platform which exhibits strategic potential advances over the other methods with high spatial and temporal resolution. Nanopore detection of single-molecule G-quadruplexes.![]()
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