1
|
Nickens DG, Feng Z, Shen J, Gray SJ, Simmons R, Niu H, Bochman M. Cdc13 exhibits dynamic DNA strand exchange in the presence of telomeric DNA. Nucleic Acids Res 2024; 52:6317-6332. [PMID: 38613387 PMCID: PMC11194072 DOI: 10.1093/nar/gkae265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/22/2024] [Accepted: 04/01/2024] [Indexed: 04/14/2024] Open
Abstract
Telomerase is the enzyme that lengthens telomeres and is tightly regulated by a variety of means to maintain genome integrity. Several DNA helicases function at telomeres, and we previously found that the Saccharomyces cerevisiae helicases Hrq1 and Pif1 directly regulate telomerase. To extend these findings, we are investigating the interplay between helicases, single-stranded DNA (ssDNA) binding proteins (ssBPs), and telomerase. The yeast ssBPs Cdc13 and RPA differentially affect Hrq1 and Pif1 helicase activity, and experiments to measure helicase disruption of Cdc13/ssDNA complexes instead revealed that Cdc13 can exchange between substrates. Although other ssBPs display dynamic binding, this was unexpected with Cdc13 due to the reported in vitro stability of the Cdc13/telomeric ssDNA complex. We found that the DNA exchange by Cdc13 occurs rapidly at physiological temperatures, requires telomeric repeat sequence DNA, and is affected by ssDNA length. Cdc13 truncations revealed that the low-affinity binding site (OB1), which is distal from the high-affinity binding site (OB3), is required for this intermolecular dynamic DNA exchange (DDE). We hypothesize that DDE by Cdc13 is the basis for how Cdc13 'moves' at telomeres to alternate between modes where it regulates telomerase activity and assists in telomere replication.
Collapse
Affiliation(s)
- David G Nickens
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Zhitong Feng
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Jiangchuan Shen
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Spencer J Gray
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Robert H Simmons
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Hengyao Niu
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Matthew L Bochman
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| |
Collapse
|
2
|
Rivosecchi J, Jurikova K, Cusanelli E. Telomere-specific regulation of TERRA and its impact on telomere stability. Semin Cell Dev Biol 2024; 157:3-23. [PMID: 38088000 DOI: 10.1016/j.semcdb.2023.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 11/02/2023] [Indexed: 01/08/2024]
Abstract
TERRA is a class of telomeric repeat-containing RNAs that are expressed from telomeres in multiple organisms. TERRA transcripts play key roles in telomere maintenance and their physiological levels are essential to maintain the integrity of telomeric DNA. Indeed, deregulated TERRA expression or its altered localization can impact telomere stability by multiple mechanisms including fueling transcription-replication conflicts, promoting resection of chromosome ends, altering the telomeric chromatin, and supporting homologous recombination. Therefore, a fine-tuned control of TERRA is important to maintain the integrity of the genome. Several studies have reported that different cell lines express substantially different levels of TERRA. Most importantly, TERRA levels markedly vary among telomeres of a given cell type, indicating the existence of telomere-specific regulatory mechanisms which may help coordinate TERRA functions. TERRA molecules contain distinct subtelomeric sequences, depending on their telomere of origin, which may instruct specific post-transcriptional modifications or mediate distinct functions. In addition, all TERRA transcripts share a repetitive G-rich sequence at their 3' end which can form DNA:RNA hybrids and fold into G-quadruplex structures. Both structures are involved in TERRA functions and can critically affect telomere stability. In this review, we examine the mechanisms controlling TERRA levels and the impact of their telomere-specific regulation on telomere stability. We compare evidence obtained in different model organisms, discussing recent advances as well as controversies in the field. Furthermore, we discuss the importance of DNA:RNA hybrids and G-quadruplex structures in the context of TERRA biology and telomere maintenance.
Collapse
Affiliation(s)
- Julieta Rivosecchi
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Katarina Jurikova
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy; Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovakia
| | - Emilio Cusanelli
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy.
| |
Collapse
|
3
|
Gajarsky M, Stadlbauer P, Sponer J, Cucchiarini A, Dobrovolna M, Brazda V, Mergny JL, Trantirek L, Lenarcic Zivkovic M. DNA Quadruplex Structure with a Unique Cation Dependency. Angew Chem Int Ed Engl 2024; 63:e202313226. [PMID: 38143239 DOI: 10.1002/anie.202313226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 12/11/2023] [Accepted: 12/22/2023] [Indexed: 12/26/2023]
Abstract
DNA quadruplex structures provide an additional layer of regulatory control in genome maintenance and gene expression and are widely used in nanotechnology. We report the discovery of an unprecedented tetrastranded structure formed from a native G-rich DNA sequence originating from the telomeric region of Caenorhabditis elegans. The structure is defined by multiple properties that distinguish it from all other known DNA quadruplexes. Most notably, the formation of a stable so-called KNa-quadruplex (KNaQ) requires concurrent coordination of K+ and Na+ ions at two distinct binding sites. This structure provides novel insight into G-rich DNA folding under ionic conditions relevant to eukaryotic cell physiology and the structural evolution of telomeric DNA. It highlights the differences between the structural organization of human and nematode telomeric DNA, which should be considered when using C. elegans as a model in telomere biology, particularly in drug screening applications. Additionally, the absence/presence of KNaQ motifs in the host/parasite introduces an intriguing possibility of exploiting the KNaQ fold as a plausible antiparasitic drug target. The structure's unique shape and ion dependency and the possibility of controlling its folding by using low-molecular-weight ligands can be used for the design or discovery of novel recognition DNA elements and sensors.
Collapse
Affiliation(s)
- Martin Gajarsky
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
- Current address: Center for Molecular Medicine Cologne, University of Cologne, 50931, Cologne, Germany
| | - Petr Stadlbauer
- Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 61265, Brno, Czech Republic
| | - Jiri Sponer
- Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 61265, Brno, Czech Republic
| | - Anne Cucchiarini
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120, Palaiseau, France
| | - Michaela Dobrovolna
- Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 61265, Brno, Czech Republic
- Faculty of Chemistry, Brno University of Technology, Purkynova 464, 61200, Brno, Czech Republic
| | - Vaclav Brazda
- Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 61265, Brno, Czech Republic
- Faculty of Chemistry, Brno University of Technology, Purkynova 464, 61200, Brno, Czech Republic
| | - Jean-Louis Mergny
- Institute of Biophysics, Czech Academy of Sciences, Kralovopolska 135, 61265, Brno, Czech Republic
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91120, Palaiseau, France
| | - Lukas Trantirek
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
| | - Martina Lenarcic Zivkovic
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 753/5, 62500, Brno, Czech Republic
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| |
Collapse
|
4
|
Iwata T, Kurahashi Y, Wijaya IMM, Kandori H. Spectroscopic Investigation of Na +-Dependent Conformational Changes of a Cyclobutane Pyrimidine Dimer-Repairing Deoxyribozyme. ACS OMEGA 2023; 8:37274-37281. [PMID: 37841180 PMCID: PMC10569015 DOI: 10.1021/acsomega.3c05083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 09/19/2023] [Indexed: 10/17/2023]
Abstract
UV1C is an enzymatically active DNA sequence (deoxyribozyme, DNAzyme) that functions as a cyclobutane pyrimidine dimer (CPD) photolyase. UV1C forms parallel guanine quadruplexes (G-quadruplexes) with a DNA substrate in the presence of 240 mM Na+, the structure of which is important for the enzymatic activity. To investigate the repair mechanism of CPD by UV1C, we designed light-induced Fourier transform infrared (FTIR) spectroscopy. Prior to FTIR measurements, circular dichroism (CD) spectroscopy was conducted to determine the Na+ concentration at which the most G-quadruplexes were formed. We found that UV1C also forms a hybrid G-quadruplex structure at over 500 mM Na+. By assuming a concentration equilibrium between G-quadruplexes and Na+, 1.3 and 1.8 Na+ were found to bind to parallel and hybrid G-quadruplexes, respectively. The hybrid G-quadruplex form of UV1C was also suggested to exhibit photolyase activity. Light-induced FTIR spectra recorded upon the photorepair of CPD by UV1C were compared for parallel G-quadruplex-rich and hybrid G-quadruplex-rich samples. Spectral variations were indicative of structural differences in parallel and hybrid G-quadruplexes before and after CPD cleavage. Differences were also observed when compared to the CPD repair spectrum by CPD photolyase. The spectral differences during CPD repair by either protein or DNAzyme suggest the local environment of the substrates, the surrounding protein, or the aqueous solution.
Collapse
Affiliation(s)
- Tatsuya Iwata
- Department
of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan
| | - Yuhi Kurahashi
- Department
of Life Science and Applied Chemistry, Nagoya
Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - I Made Mahaputra Wijaya
- Department
of Life Science and Applied Chemistry, Nagoya
Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department
of Life Science and Applied Chemistry, Nagoya
Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology
Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| |
Collapse
|
5
|
Pires VB, Lohner N, Wagner T, Wagner CB, Wilkens M, Hajikazemi M, Paeschke K, Butter F, Luke B. RNA-DNA hybrids prevent resection at dysfunctional telomeres. Cell Rep 2023; 42:112077. [PMID: 36729832 DOI: 10.1016/j.celrep.2023.112077] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 12/19/2022] [Accepted: 01/23/2023] [Indexed: 02/03/2023] Open
Abstract
At critically short telomeres, stabilized TERRA RNA-DNA hybrids drive homology-directed repair (HDR) to delay replicative senescence. However, even at long- and intermediate-length telomeres, not subject to HDR, transient TERRA RNA-DNA hybrids form, suggestive of additional roles. We report that telomeric RNA-DNA hybrids prevent Exo1-mediated resection when telomeres become non-functional. We used the well-characterized cdc13-1 allele, where telomere resection can be induced in a temperature-dependent manner, to demonstrate that ssDNA generation at telomeres is either prevented or augmented when RNA-DNA hybrids are stabilized or destabilized, respectively. The viability of cdc13-1 cells is affected by the presence or absence of hybrids accordingly. Telomeric hybrids do not affect the shortening rate of bulk telomeres. We suggest that TERRA hybrids require dynamic regulation to drive HDR at short telomeres; hybrid presence may initiate HDR through replication stress, whereby their removal allows strand resection.
Collapse
Affiliation(s)
- Vanessa Borges Pires
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal; Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Nina Lohner
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany; Faculty of Biology, Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Tina Wagner
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Carolin B Wagner
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Maya Wilkens
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Mona Hajikazemi
- Clinic of Internal Medicine III, Oncology, Haematology, Rheumatology and Clinical Immunology, University Hospital Bonn, 53127 Bonn, Germany
| | - Katrin Paeschke
- Clinic of Internal Medicine III, Oncology, Haematology, Rheumatology and Clinical Immunology, University Hospital Bonn, 53127 Bonn, Germany
| | - Falk Butter
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Brian Luke
- Institute of Molecular Biology gGmbH, Ackermannweg 4, 55128 Mainz, Germany; Faculty of Biology, Institute of Developmental Biology and Neurobiology, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany.
| |
Collapse
|
6
|
Choi BE, Lee HT. DNA-RNA hybrid G-quadruplex tends to form near the 3' end of telomere overhang. Biophys J 2022; 121:2962-2980. [PMID: 35769005 PMCID: PMC9388385 DOI: 10.1016/j.bpj.2022.06.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/14/2022] [Accepted: 06/24/2022] [Indexed: 11/25/2022] Open
Abstract
Telomeric repeat-containing RNA (TERRA) has been suggested to participate in telomere maintenance. TERRA consisting of UUAGGG repeats is capable of forming an intermolecular G-quadruplex (GQ) with single-stranded TTAGGG-repeat DNA in the telomere 3' overhang. To explore the structural features and potential functions of this DNA-RNA hybrid GQ (HGQ), we used single-molecule FRET to study the folding patterns of DNA with four to seven telomeric tandem repeats annealed with a short RNA consisting of two or five telomeric repeats. Our data highlight that RNA prefers to form DNA-RNA HGQ near the 3' end of telomeric DNA. Furthermore, the unfolding of secondary structures by a complementary C-rich sequence was observed for DNA GQ but not for DNA-RNA HGQ, which demonstrated the enhanced stability of the telomere 3' end via hybridization with RNA. These conformational and physical properties of telomeric DNA-RNA HGQ suggest that TERRA might limit access to the 3' end of the telomeric DNA overhang, which is known to be critical for the interaction with telomerase and other telomere-associated proteins.
Collapse
Affiliation(s)
- Bok-Eum Choi
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama
| | - Hui-Ting Lee
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama.
| |
Collapse
|
7
|
Marquevielle J, De Rache A, Vialet B, Morvan E, Mergny JL, Amrane S. G-quadruplex structure of the C. elegans telomeric repeat: a two tetrads basket type conformation stabilized by a non-canonical C-T base-pair. Nucleic Acids Res 2022; 50:7134-7146. [PMID: 35736226 PMCID: PMC9262591 DOI: 10.1093/nar/gkac523] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 05/07/2022] [Accepted: 06/01/2022] [Indexed: 12/24/2022] Open
Abstract
The Caenorhabditis elegans model has greatly contributed to the understanding of the role of G-quadruplexes in genomic instability. The GGCTTA repeats of the C. elegans telomeres resemble the GGGTTA repeats of the human telomeres. However, the comparison of telomeric sequences (Homo sapiens, Tetrahymena, Oxytricha, Bombyx mori and Giardia) revealed that small changes in these repeats can drastically change the topology of the folded G-quadruplex. In the present work we determined the structure adopted by the C. elegans telomeric sequence d[GG(CTTAGG)3]. The investigated C. elegans telomeric sequence is shown to fold into an intramolecular two G-tetrads basket type G-quadruplex structure that includes a C-T base pair in the diagonal loop. This work sheds light on the telomeric structure of the widely used C. elegans animal model.
Collapse
Affiliation(s)
| | | | - Brune Vialet
- Univ. Bordeaux, Inserm U1212, CNRS UMR 5320, ARNA laboratory, 146 rue Léo Saignat F-33000 Bordeaux, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UMS 3033 US001, CNRS-Université de Bordeaux, 2 rue Robert Escarpit, F-33600 Pessac, France
| | - Jean-Louis Mergny
- Correspondence may also be addressed to Jean-Louis Mergny. Tel: + 33 1 69 33 50 01;
| | - Samir Amrane
- To whom correspondence should be addressed. Tel: +33 5 40 00 22 24;
| |
Collapse
|
8
|
Paul T, Opresko PL, Ha T, Myong S. Vectorial folding of telomere overhang promotes higher accessibility. Nucleic Acids Res 2022; 50:6271-6283. [PMID: 35687089 PMCID: PMC9226509 DOI: 10.1093/nar/gkac401] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/20/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Human telomere overhang composed of tandem repeats of TTAGGG folds into G-quadruplex (G4). Unlike in an experimental setting in the test tube in which the entire length is allowed to fold at once, inside the cell, the overhang is expected to fold as it is synthesized directionally (5' to 3') and released segmentally by a specialized enzyme, the telomerase. To mimic such vectorial G4 folding process, we employed a superhelicase, Rep-X which can unwind DNA to release the TTAGGG repeats in 5' to 3' direction. We demonstrate that the folded conformation achieved by the refolding of full sequence is significantly different from that of the vectorial folding for two to eight TTAGGG repeats. Strikingly, the vectorially folded state leads to a remarkably higher accessibility to complementary C-rich strand and the telomere binding protein POT1, reflecting a less stably folded state resulting from the vectorial folding. Importantly, our study points to an inherent difference between the co-polymerizing and post-polymerized folding of telomere overhang that can impact telomere architecture and downstream processes.
Collapse
Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, PA15213, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA.,Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
| |
Collapse
|
9
|
Abstract
The gene encoding the Pif1 helicase was first discovered in a Saccharomyces cerevisiae genetic screen as a mutant that reduces recombination between mitochondrial respiratory mutants and was subsequently rediscovered in a screen for genes affecting the telomere length in the nucleus. It is now known that Pif1 is involved in numerous aspects of DNA metabolism. All known functions of Pif1 rely on binding to DNA substrates followed by ATP hydrolysis, coupling the energy released to translocation along DNA to unwind duplex DNA or alternative DNA secondary structures. The interaction of Pif1 with higher-order DNA structures, like G-quadruplex DNA, as well as the length of single-stranded (ss)DNA necessary for Pif1 loading have been widely studied. Here, to test the effects of ssDNA length, sequence, and structure on Pif1's biochemical activities in vitro, we used a suite of oligonucleotide-based substrates to perform a basic characterization of Pif1 ssDNA binding, ATPase activity, and helicase activity. Using recombinant, untagged S. cerevisiae Pif1, we found that Pif1 preferentially binds to structured G-rich ssDNA, but the preferred binding substrates failed to maximally stimulate ATPase activity. In helicase assays, significant DNA unwinding activity was detected at Pif1 concentrations as low as 250 pM. Helicase assays also demonstrated that Pif1 most efficiently unwinds DNA fork substrates with unstructured ssDNA tails. As the chemical step size of Pif1 has been determined to be 1 ATP per translocation or unwinding event, this implies that the highly structured DNA inhibits conformational changes in Pif1 that couple ATP hydrolysis to DNA translocation and unwinding.
Collapse
Affiliation(s)
- David G Nickens
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, Indiana 47405, United States
| | - Matthew L Bochman
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, Indiana 47405, United States
| |
Collapse
|
10
|
Peska V, Fajkus P, Bubeník M, Brázda V, Bohálová N, Dvořáček V, Fajkus J, Garcia S. Extraordinary diversity of telomeres, telomerase RNAs and their template regions in Saccharomycetaceae. Sci Rep 2021; 11:12784. [PMID: 34140564 PMCID: PMC8211666 DOI: 10.1038/s41598-021-92126-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/03/2021] [Indexed: 01/08/2023] Open
Abstract
Telomerase RNA (TR) carries the template for synthesis of telomere DNA and provides a scaffold for telomerase assembly. Fungal TRs are long and have been compared to higher eukaryotes, where they show considerable diversity within phylogenetically close groups. TRs of several Saccharomycetaceae were recently identified, however, many of these remained uncharacterised in the template region. Here we show that this is mainly due to high variability in telomere sequence. We predicted the telomere sequences using Tandem Repeats Finder and then we identified corresponding putative template regions in TR candidates. Remarkably long telomere units and the corresponding putative TRs were found in Tetrapisispora species. Notably, variable lengths of the annealing sequence of the template region (1–10 nt) were found. Consequently, species with the same telomere sequence may not harbour identical TR templates. Thus, TR sequence alone can be used to predict a template region and telomere sequence, but not to determine these exactly. A conserved feature of telomere sequences, tracts of adjacent Gs, led us to test the propensity of individual telomere sequences to form G4. The results show highly diverse values of G4-propensity, indicating the lack of ubiquitous conservation of this feature across Saccharomycetaceae.
Collapse
Affiliation(s)
- Vratislav Peska
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic.
| | - Petr Fajkus
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic.,Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, 62500, Czech Republic
| | - Michal Bubeník
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic.,Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, 62500, Czech Republic
| | - Václav Brázda
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic
| | - Natália Bohálová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, 62500, Czech Republic
| | - Vojtěch Dvořáček
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic
| | - Jiří Fajkus
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, 61265, Czech Republic.,Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, 62500, Czech Republic
| | - Sònia Garcia
- Institut Botànic de Barcelona (IBB-CSIC, Ajuntament de Barcelona), Passeig del Migdia s/n, 08038, Barcelona, Catalonia, Spain.
| |
Collapse
|
11
|
Douglas ME, Diffley JFX. Budding yeast Rap1, but not telomeric DNA, is inhibitory for multiple stages of DNA replication in vitro. Nucleic Acids Res 2021; 49:5671-5683. [PMID: 34048583 PMCID: PMC8191780 DOI: 10.1093/nar/gkab416] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/27/2021] [Accepted: 05/26/2021] [Indexed: 12/26/2022] Open
Abstract
Telomeres are copied and reassembled each cell division cycle through a multistep process called telomere replication. Most telomeric DNA is duplicated semiconservatively during this process, but replication forks frequently pause or stall at telomeres in yeast, mouse and human cells, potentially causing chronic telomere shortening or loss in a single cell cycle. We have investigated the cause of this effect by examining the replication of telomeric templates in vitro. Using a reconstituted assay for eukaryotic DNA replication in which a complete eukaryotic replisome is assembled and activated with purified proteins, we show that budding yeast telomeric DNA is efficiently duplicated in vitro unless the telomere binding protein Rap1 is present. Rap1 acts as a roadblock that prevents replisome progression and leading strand synthesis, but also potently inhibits lagging strand telomere replication behind the fork. Both defects can be mitigated by the Pif1 helicase. Our results suggest that GC-rich sequences do not inhibit DNA replication per se, and that in the absence of accessory factors, telomere binding proteins can inhibit multiple, distinct steps in the replication process.
Collapse
Affiliation(s)
- Max E Douglas
- Telomere Biology Laboratory, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - John F X Diffley
- Chromosome Replication Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| |
Collapse
|
12
|
Bonnell E, Pasquier E, Wellinger RJ. Telomere Replication: Solving Multiple End Replication Problems. Front Cell Dev Biol 2021; 9:668171. [PMID: 33869233 PMCID: PMC8047117 DOI: 10.3389/fcell.2021.668171] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic genomes are highly complex and divided into linear chromosomes that require end protection from unwarranted fusions, recombination, and degradation in order to maintain genomic stability. This is accomplished through the conserved specialized nucleoprotein structure of telomeres. Due to the repetitive nature of telomeric DNA, and the unusual terminal structure, namely a protruding single stranded 3′ DNA end, completing telomeric DNA replication in a timely and efficient manner is a challenge. For example, the end replication problem causes a progressive shortening of telomeric DNA at each round of DNA replication, thus telomeres eventually lose their protective capacity. This phenomenon is counteracted by the recruitment and the activation at telomeres of the specialized reverse transcriptase telomerase. Despite the importance of telomerase in providing a mechanism for complete replication of telomeric ends, the majority of telomere replication is in fact carried out by the conventional DNA replication machinery. There is significant evidence demonstrating that progression of replication forks is hampered at chromosomal ends due to telomeric sequences prone to form secondary structures, tightly DNA-bound proteins, and the heterochromatic nature of telomeres. The telomeric loop (t-loop) formed by invasion of the 3′-end into telomeric duplex sequences may also impede the passage of replication fork. Replication fork stalling can lead to fork collapse and DNA breaks, a major cause of genomic instability triggered notably by unwanted repair events. Moreover, at chromosomal ends, unreplicated DNA distal to a stalled fork cannot be rescued by a fork coming from the opposite direction. This highlights the importance of the multiple mechanisms involved in overcoming fork progression obstacles at telomeres. Consequently, numerous factors participate in efficient telomeric DNA duplication by preventing replication fork stalling or promoting the restart of a stalled replication fork at telomeres. In this review, we will discuss difficulties associated with the passage of the replication fork through telomeres in both fission and budding yeasts as well as mammals, highlighting conserved mechanisms implicated in maintaining telomere integrity during replication, thus preserving a stable genome.
Collapse
Affiliation(s)
- Erin Bonnell
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Cancer Research Pavilion, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Emeline Pasquier
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Cancer Research Pavilion, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Cancer Research Pavilion, Université de Sherbrooke, Sherbrooke, QC, Canada
| |
Collapse
|
13
|
Živković ML, Gajarský M, Beková K, Stadlbauer P, Vicherek L, Petrová M, Fiala R, Rosenberg I, Šponer J, Plavec J, Trantírek L. Insight into formation propensity of pseudocircular DNA G-hairpins. Nucleic Acids Res 2021; 49:2317-2332. [PMID: 33524154 PMCID: PMC7913771 DOI: 10.1093/nar/gkab029] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 12/21/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
We recently showed that Saccharomyces cerevisiae telomeric DNA can fold into an unprecedented pseudocircular G-hairpin (PGH) structure. However, the formation of PGHs in the context of extended sequences, which is a prerequisite for their function in vivo and their applications in biotechnology, has not been elucidated. Here, we show that despite its ‘circular’ nature, PGHs tolerate single-stranded (ss) protrusions. High-resolution NMR structure of a novel member of PGH family reveals the atomistic details on a junction between ssDNA and PGH unit. Identification of new sequences capable of folding into one of the two forms of PGH helped in defining minimal sequence requirements for their formation. Our time-resolved NMR data indicate a possibility that PGHs fold via a complex kinetic partitioning mechanism and suggests the existence of K+ ion-dependent PGH folding intermediates. The data not only provide an explanation of cation-type-dependent formation of PGHs, but also explain the unusually large hysteresis between PGH melting and annealing noted in our previous study. Our findings have important implications for DNA biology and nanotechnology. Overrepresentation of sequences able to form PGHs in the evolutionary-conserved regions of the human genome implies their functionally important biological role(s).
Collapse
Affiliation(s)
- Martina Lenarčič Živković
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,Slovenian NMR Centre, National Institute of Chemistry, Ljubljana SI-1000, Slovenia
| | - Martin Gajarský
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
| | - Kateřina Beková
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,National Centre for Biomolecular Research, Masaryk University, Brno 62500, Czech Republic
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Lukáš Vicherek
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
| | - Magdalena Petrová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Radovan Fiala
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
| | - Ivan Rosenberg
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiří Šponer
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic.,Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, Ljubljana SI-1000, Slovenia.,EN-FIST Centre of Excellence, Ljubljana SI-1001, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana SI-1000, Slovenia
| | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, Brno 62500, Czech Republic
| |
Collapse
|
14
|
Schult P, Paeschke K. The DEAH helicase DHX36 and its role in G-quadruplex-dependent processes. Biol Chem 2020; 402:581-591. [PMID: 33021960 DOI: 10.1515/hsz-2020-0292] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023]
Abstract
DHX36 is a member of the DExD/H box helicase family, which comprises a large number of proteins involved in various cellular functions. Recently, the function of DHX36 in the regulation of G-quadruplexes (G4s) was demonstrated. G4s are alternative nucleic acid structures, which influence many cellular pathways on a transcriptional and post-transcriptional level. In this review we provide an overview of the current knowledge about DHX36 structure, substrate specificity, and mechanism of action based on the available models and crystal structures. Moreover, we outline its multiple functions in cellular homeostasis, immunity, and disease. Finally, we discuss the open questions and provide potential directions for future research.
Collapse
Affiliation(s)
- Philipp Schult
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, D-53127Bonn, Germany
| | - Katrin Paeschke
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, D-53127Bonn, Germany
| |
Collapse
|
15
|
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.
Collapse
Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| |
Collapse
|
16
|
Abstract
Several decades elapsed between the first descriptions of G-quadruplex nucleic acid structures (G4s) assembled in vitro and the emergence of experimental findings indicating that such structures can form and function in living systems. A large body of evidence now supports roles for G4s in many aspects of nucleic acid biology, spanning processes from transcription and chromatin structure, mRNA processing, protein translation, DNA replication and genome stability, and telomere and mitochondrial function. Nonetheless, it must be acknowledged that some of this evidence is tentative, which is not surprising given the technical challenges associated with demonstrating G4s in biology. Here I provide an overview of evidence for G4 biology, focusing particularly on the many potential pitfalls that can be encountered in its investigation, and briefly discuss some of broader biological processes that may be impacted by G4s including cancer.
Collapse
Affiliation(s)
- F. Brad Johnson
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| |
Collapse
|