scholarly journals Supramolecular Polymorphism of (G4C2)n Repeats Associated with ALS and FTD

2021 ◽  
Vol 22 (9) ◽  
pp. 4532
Author(s):  
Melani Potrč ◽  
Nerea Sebastián ◽  
Miha Škarabot ◽  
Irena Drevenšek-Olenik ◽  
Lea Spindler
Keyword(s):  
Dna Sequences ◽  
Vital Role ◽  
Surface Films ◽  
Structural Polymorphism ◽  
Afm Imaging ◽  
G Quadruplex ◽  
Dna Quadruplexes ◽  
Supramolecular Aggregates ◽  
Regular Medium ◽  
Lateral Sclerosis

Guanine-rich DNA sequences self-assemble into highly stable fourfold structures known as DNA-quadruplexes (or G-quadruplexes). G-quadruplexes have furthermore the tendency to associate into one-dimensional supramolecular aggregates termed G-wires. We studied the formation of G-wires in solutions of the sequences d(G4C2)n with n = 1, 2, and 4. The d(G4C2)n repeats, which are associated with some fatal neurological disorders, especially amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), represent a challenging research topic due to their extensive structural polymorphism. We used dynamic light scattering (DLS) to measure translational diffusion coefficients and consequently resolve the length of the larger aggregates formed in solution. We found that all three sequences assemble into longer structures than previously reported. The d(G4C2) formed extremely long G-wires with lengths beyond 80 nm. The d(G4C2)2 formed a relatively short stacked dimeric quadruplex, while d(G4C2)4 formed multimers corresponding to seven stacked intramolecular quadruplexes. Profound differences between the multimerization properties of the investigated sequences were also confirmed by the AFM imaging of surface films. We propose that π-π stacking of the basic G-quadruplex units plays a vital role in the multimerization mechanism, which might be relevant for transformation from the regular medium-length to disease-related long d(G4C2)n repeats.

scholarly journals ATRX promotes heterochromatin formation to protect cells from G-quadruplex DNA-mediated stress

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yu-Ching Teng ◽  
Aishwarya Sundaresan ◽  
Ryan O’Hara ◽  
Vincent U. Gant ◽  
Minhua Li ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Genome Stability ◽  
Helicase Domain ◽  
Quadruplex Dna ◽  
Heterochromatin Formation ◽  
Replicative Stress ◽  
G4 Dna ◽  
Mutation Burden ◽  
G Quadruplex ◽  
Dna Replication Stress

AbstractATRX is a tumor suppressor that has been associated with protection from DNA replication stress, purportedly through resolution of difficult-to-replicate G-quadruplex (G4) DNA structures. While several studies demonstrate that loss of ATRX sensitizes cells to chemical stabilizers of G4 structures, the molecular function of ATRX at G4 regions during replication remains unknown. Here, we demonstrate that ATRX associates with a number of the MCM replication complex subunits and that loss of ATRX leads to G4 structure accumulation at newly synthesized DNA. We show that both the helicase domain of ATRX and its H3.3 chaperone function are required to protect cells from G4-induced replicative stress. Furthermore, these activities are upstream of heterochromatin formation mediated by the histone methyltransferase, ESET, which is the critical molecular event that protects cells from G4-mediated stress. In support, tumors carrying mutations in either ATRX or ESET show increased mutation burden at G4-enriched DNA sequences. Overall, our study provides new insights into mechanisms by which ATRX promotes genome stability with important implications for understanding impacts of its loss on human disease.

Research Progress in the Typical Structure of Human Telomeric G-Quadruplex

2014 ◽  
Vol 955-959 ◽  
pp. 419-422
Author(s):  
Gui Lin Liu ◽  
Yan Ping Ding ◽  
Yan Ling Wu ◽  
Wen Zhang
Keyword(s):  
Cell Cycle ◽  
Dna Sequences ◽  
Research Progress ◽  
Human Chromosomes ◽  
Telomeric Dna ◽  
Typical Structure ◽  
Special Sequence ◽  
Physiological Processes ◽  
G Quadruplex ◽  
Small Molecule Ligands

Telomeric DNA of human chromosomes plays a significant role in physiological processes such as cell cycle, aging, cancer and genetic stability due to its special sequence and structure. The research on small molecule ligands targeting G-quadruplex formed by such special sequence has attracted considerable attention, and has achieved great breakthrough. In this paper, we summarize the DNA sequences and structures of three kinds of typical human telomeric G-quadruplex, providing an important reference for further research.

scholarly journals Voltammetry and molecular assembly of G-quadruplex DNAzyme on single-crystal Au(111)-electrode surfaces – hemin as an electrochemical intercalator

2016 ◽  
Vol 193 ◽  
pp. 99-112 ◽  
Author(s):  
Ling Zhang ◽  
Jens Ulstrup ◽  
Jingdong Zhang
Keyword(s):  
Single Crystal ◽  
Single Molecule ◽  
Electrode Surface ◽  
Molecular Assembly ◽  
Electrode Surfaces ◽  
Potential Control ◽  
G Quadruplex ◽  
Tunnelling Microscopy ◽  
Dna Quadruplexes

DNA quadruplexes (qs) are a class of “non-canonical” oligonucleotides (OGNs) composed of stacked guanine (G) quartets stabilized by specific cations. Metal porphyrins selectively bind to G-qs complexes to form what is known as DNAzyme, which can exhibit peroxidase and other catalytic activity similar to heme group metalloenzymes. In the present study we investigate the electrochemical properties and the structure of DNAzyme monolayers on single-crystal Au(111)-electrode surfaces using cyclic voltammetry and scanning tunnelling microscopy under electrochemical potential control (in situ STM). The target DNAzyme is formed from a single-strand OGN with 12 guanines and iron(iii) porphyrin IX (hemin), and assembles on Au(111) through a mercapto alkyl linker. The DNAzyme monolayers exhibit a strong pair of redox peaks at 0.0 V (NHE) at pH 7 in acetate buffer, shifted positively by about 50 mV compared to free hemin weakly physisorbed on the Au(111)-electrode surface. The voltammetric hemin signal of DNAzyme is enhanced 15 times compared with that of hemin adsorbed directly on the Au(111)-electrode surface. This is indicative of both the formation of a close to dense DNAzyme monolayer and that hemin is strongly bound to the immobilized 12G-qs in well-defined orientation favorable for interfacial ET with a rate constant of 6.0 ± 0.4 s−1. This is supported by in situ STM which discloses single-molecule G-quartet structures with a size of 1.6 ± 0.2 nm.

scholarly journals Evaluating the Influence of a G-Quadruplex Prone Sequence on the Transactivation Potential by Wild-Type and/or Mutant P53 Family Proteins through a Yeast-Based Functional Assay

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 277
Author(s):  
Paola Monti ◽  
Vaclav Brazda ◽  
Natália Bohálová ◽  
Otília Porubiaková ◽  
Paola Menichini ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Relative Activity ◽  
Gene Organization ◽  
Functional Assay ◽  
Wild Type ◽  
P53 Family ◽  
Transactivation Potential ◽  
G Quadruplex

P53, P63, and P73 proteins belong to the P53 family of transcription factors, sharing a common gene organization that, from the P1 and P2 promoters, produces two groups of mRNAs encoding proteins with different N-terminal regions; moreover, alternative splicing events at C-terminus further contribute to the generation of multiple isoforms. P53 family proteins can influence a plethora of cellular pathways mainly through the direct binding to specific DNA sequences known as response elements (REs), and the transactivation of the corresponding target genes. However, the transcriptional activation by P53 family members can be regulated at multiple levels, including the DNA topology at responsive promoters. Here, by using a yeast-based functional assay, we evaluated the influence that a G-quadruplex (G4) prone sequence adjacent to the p53 RE derived from the apoptotic PUMA target gene can exert on the transactivation potential of full-length and N-terminal truncated P53 family α isoforms (wild-type and mutant). Our results show that the presence of a G4 prone sequence upstream or downstream of the P53 RE leads to significant changes in the relative activity of P53 family proteins, emphasizing the potential role of structural DNA features as modifiers of P53 family functions at target promoter sites.

Structural Polymorphism of d(GA · TC)n DNA Sequences

1993 ◽  
Vol 233 (4) ◽  
pp. 671-681 ◽  
Author(s):  
J.M. Casasnovas ◽  
D. Huertas ◽  
M. Ortiz-Lombardı́a ◽  
J. Kypr ◽  
F. Azorı́n
Keyword(s):  
Dna Sequences ◽  
Structural Polymorphism

scholarly journals Intra-locked G-quadruplex structures formed by irregular DNA G-rich motifs

2020 ◽  
Vol 48 (6) ◽  
pp. 3315-3327 ◽  
Author(s):  
Arijit Maity ◽  
Fernaldo Richtia Winnerdy ◽  
Weili Denyse Chang ◽  
Gang Chen ◽  
Anh Tuân Phan
Keyword(s):  
Human Genome ◽  
Dna Sequences ◽  
Structural Features ◽  
Nmr Structure ◽  
Solution Nmr ◽  
Structural Studies ◽  
High Propensity ◽  
G Quadruplex ◽  
High Prevalence

Abstract G-rich DNA sequences with tracts of three or more continuous guanines (G≥3) are known to have high propensity to adopt stable G-quadruplex (G4) structures. Bioinformatic analyses suggest high prevalence of G-rich sequences with short G-tracts (G≤2) in the human genome. However, due to limited structural studies, the folding principles of such sequences remain largely unexplored and hence poorly understood. Here, we present the solution NMR structure of a sequence named AT26 consisting of irregularly spaced G2 tracts and two isolated single guanines. The structure is a four-layered G4 featuring two bi-layered blocks, locked between themselves in an unprecedented fashion making it a stable scaffold. In addition to edgewise and propeller-type loops, AT26 also harbors two V-shaped loops: a 2-nt V-shaped loop spanning two G-tetrad layers and a 0-nt V-shaped loop spanning three G-tetrad layers, which are named as VS- and VR-loop respectively, based on their distinct structural features. The intra-lock motif can be a basis for extending the G-tetrad core and a very stable intra-locked G4 can be formed by a sequence with G-tracts of various lengths including several G2 tracts. Findings from this study will aid in understanding the folding of G4 topologies from sequences containing irregularly spaced multiple short G-tracts.

Targeting multiple G-quadruplex–forming DNA sequences: Design, biophysical and biological evaluations of indolo-naphthyridine scaffold derivatives

2019 ◽  
Vol 182 ◽  
pp. 111627 ◽  
Author(s):  
Raffaella Catalano ◽  
Federica Moraca ◽  
Jussara Amato ◽  
Camilla Cristofari ◽  
Riccardo Rigo ◽  
...  
Keyword(s):  
Dna Sequences ◽  
G Quadruplex

scholarly journals G-rich telomeric and ribosomal DNA sequences from the fission yeast genome form stable G-quadruplex DNA structuresin vitroand are unwound by the Pfh1 DNA helicase

2016 ◽  
Vol 44 (13) ◽  
pp. 6213-6231 ◽  
Author(s):  
Marcus Wallgren ◽  
Jani B. Mohammad ◽  
Kok-Phen Yan ◽  
Parham Pourbozorgi-Langroudi ◽  
Mahsa Ebrahimi ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Ribosomal Dna ◽  
Dna Sequences ◽  
Dna Helicase ◽  
Yeast Genome ◽  
Quadruplex Dna ◽  
G Quadruplex

scholarly journals G4Killer web application: a tool to design G-quadruplex mutations

2020 ◽  
Vol 36 (10) ◽  
pp. 3246-3247
Author(s):  
Vaclav Brazda ◽  
Jan Kolomaznik ◽  
Jean-Louis Mergny ◽  
Jiri Stastny
Keyword(s):  
Dna Sequences ◽  
Web Application ◽  
Rational Design ◽  
Therapeutic Potential ◽  
Supplementary Information ◽  
Web Tool ◽  
Web Based ◽  
Dna Structures ◽  
G Quadruplex ◽  
User Friendly

Abstract Motivation G-quadruplexes (G4) are important regulatory non-B DNA structures with therapeutic potential. A tool for rational design of mutations leading to decreased propensity for G4 formation should be useful in studying G4 functions. Although tools exist for G4 prediction, no easily accessible tool for the rational design of G4 mutations has been available. Results We developed a web-based tool termed G4Killer that is based on the G4Hunter algorithm. This new tool is a platform-independent and user-friendly application to design mutations crippling G4 propensity in a parsimonious way (i.e., keeping the primary sequence as close as possible to the original one). The tool is integrated into our DNA analyzer server and allows for generating mutated DNA sequences having the desired lowered G4Hunter score with minimal mutation steps. Availability and implementation The G4Killer web tool can be accessed at: http://bioinformatics.ibp.cz. Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals Evidences for Piperine inhibiting cancer by targeting human G-quadruplex DNA sequences

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Arpita Tawani ◽  
Ayeman Amanullah ◽  
Amit Mishra ◽  
Amit Kumar
Keyword(s):  
Dna Sequences ◽  
Quadruplex Dna ◽  
G Quadruplex
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