scholarly journals R-Loop Tracker: Web Access-Based Tool for R-Loop Detection and Analysis in Genomic DNA Sequences

2021 ◽  
Vol 22 (23) ◽  
pp. 12857
Author(s):  
Václav Brázda ◽  
Jan Havlík ◽  
Jan Kolomazník ◽  
Oldřich Trenz ◽  
Jiří Šťastný
Keyword(s):  
Nucleic Acid ◽  
Dna Sequences ◽  
In Silico ◽  
Genomic Dna ◽  
Loop Formation ◽  
Loop Detection ◽  
Genome Features ◽  
Web Access ◽  
Nucleic Acid Structures ◽  
The Web

R-loops are common non-B nucleic acid structures formed by a three-stranded nucleic acid composed of an RNA–DNA hybrid and a displaced single-stranded DNA (ssDNA) loop. Because the aberrant R-loop formation leads to increased mutagenesis, hyper-recombination, rearrangements, and transcription-replication collisions, it is regarded as important in human diseases. Therefore, its prevalence and distribution in genomes are studied intensively. However, in silico tools for R-loop prediction are limited, and therefore, we have developed the R-loop tracker tool, which was implemented as a part of the DNA Analyser web server. This new tool is focused upon (1) prediction of R-loops in genomic DNA without length and sequence limitations; (2) integration of R-loop tracker results with other tools for nucleic acids analyses, including Genome Browser; (3) internal cross-evaluation of in silico results with experimental data, where available; (4) easy export and correlation analyses with other genome features and markers; and (5) enhanced visualization outputs. Our new R-loop tracker tool is freely accessible on the web pages of DNA Analyser tools, and its implementation on the web-based server allows effective analyses not only for DNA segments but also for full chromosomes and genomes.

scholarly journals RNA strand invasion activity of the Polycomb complex PRC2

2019 ◽  
Author(s):  
Célia Alecki ◽  
Victoria Chiwara ◽  
Lionel A. Sanz ◽  
Daniel Grau ◽  
Osvaldo Arias Pérez ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Epigenetic Regulation ◽  
Dna Sequences ◽  
Polycomb Group ◽  
Epigenetic Mechanism ◽  
Biological Information ◽  
Loop Formation ◽  
Strand Invasion ◽  
Nucleic Acid Structures

AbstractEpigenetic regulation is conveyed through information encoded by specific chromatin features. Non-canonical nucleic acid structures could in principle also convey biological information but their role(s) in epigenetic regulation is not known. Polycomb Group (PcG) proteins form memory of transient transcriptional repression events that is necessary for development. In Drosophila, PcG proteins are recruited to specific DNA sequences, Polycomb Response Elements (PREs). PREs are switchable memory elements that can exist in repressed, active, or unengaged states 1,2. How PcG activities are targeted to PREs to maintain repressed states only in appropriate developmental contexts has been difficult to elucidate. Biochemically, PcG protein complexes modify chromatin to maintain gene repression 1,3,4. However, PcG proteins also interact with both RNA and DNA, and RNA is implicated in the targeting of PcG function. We find that R-loops, three-stranded nucleic acid structures formed when an RNA hybridizes to its complementary DNA and displaces the other DNA strand 5, form at many PREs in Drosophila embryos, and correlate with the repressive state. R-loops are recognized by the PcG complex PRC1 in vitro. Unexpectedly, we find that the PcG complex PRC2 has RNA strand invasion activity, which can drive formation of RNA-DNA hybrids, the key component of R-loops. Our results suggest a new mechanism for targeting PcG function through R-loop formation by PRC2 and recognition by PRC1. More generally, our findings suggest formation and recognition 6 of non-canonical nucleic acid structures as an epigenetic mechanism.

scholarly journals S phase R-loop formation is restricted by PrimPol-mediated repriming

2018 ◽  
Author(s):  
Saša Šviković ◽  
Alastair Crisp ◽  
Sue Mei Tan-Wong ◽  
Thomas A. Guilliam ◽  
Aidan J. Doherty ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Secondary Structure ◽  
Genetic Instability ◽  
S Phase ◽  
Loop Formation ◽  
Dna Motifs ◽  
G Quadruplex ◽  
Nucleic Acid Structures ◽  
Careful Management

SummaryDuring DNA replication, conflicts with ongoing transcription are frequent and require careful management to avoid genetic instability. R-loops, three stranded nucleic acid structures comprising a DNA:RNA hybrid and displaced single stranded DNA, are important drivers of damage arising from such conflicts. How R-loops stall replication and the mechanisms that restrain their formation during S phase are incompletely understood. Here we show in vivo how R-loop formation drives a short purine-rich repeat, (GAA)10, to become a replication impediment that requires the repriming activity of the primase-polymerase PrimPol for its processive replication. Further, we show that loss of PrimPol results in a significant increase in R-loop formation around the repeat during S phase. We extend this observation by showing that PrimPol suppresses R-loop formation in genes harbouring secondary structure-forming sequences, exemplified by G quadruplex and H-DNA motifs, across the genome in both avian and human cells. Thus, R-loops promote the creation of replication blocks at susceptible sequences, while PrimPol-dependent repriming limits the extent of unscheduled R-loop formation at these sequences, mitigating their impact on replication.

scholarly journals DSSR-enabled innovative schematics of 3D nucleic acid structures with PyMOL

2020 ◽  
Author(s):  
Xiang-Jun Lu
Keyword(s):  
Nucleic Acid ◽  
Web Application ◽  
Application Programming Interface ◽  
Command Line Interface ◽  
Application Programming ◽  
Nucleic Acid Structures ◽  
Sophisticated Analysis ◽  
Programming Interface ◽  
The Web ◽  
Base Identity

Abstract Sophisticated analysis and simplified visualization are crucial for understanding complicated structures of biomacromolecules. DSSR (Dissecting the Spatial Structure of RNA) is an integrated computational tool that has streamlined the analysis and annotation of 3D nucleic acid structures. The program creates schematic block representations in diverse styles that can be seamlessly integrated into PyMOL and complement its other popular visualization options. In addition to portraying individual base blocks, DSSR can draw Watson-Crick pairs as long blocks and highlight the minor-groove edges. Notably, DSSR can dramatically simplify the depiction of G-quadruplexes by automatically detecting G-tetrads and treating them as large square blocks. The DSSR-enabled innovative schematics with PyMOL are aesthetically pleasing and highly informative: the base identity, pairing geometry, stacking interactions, double-helical stems, and G-quadruplexes are immediately obvious. These features can be accessed via four interfaces: the command-line interface, the DSSR plugin for PyMOL, the web application, and the web application programming interface. The supplemental PDF serves as a practical guide, with complete and reproducible examples. Thus, even beginners or occasional users can get started quickly, especially via the web application at http://skmatic.x3dna.org.

Gold-Aptamer-Nanoconstructs Engineered to Detect Conserved Enteroviral Nucleic Acid Sequences

2019 ◽  
Author(s):  
Veeren Chauhan ◽  
Mohamed M Elsutohy ◽  
C Patrick McClure ◽  
Will Irving ◽  
Neil Roddis ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
In Silico ◽  
Point Of Care ◽  
Lateral Flow ◽  
Nucleic Acid Sequence ◽  
In Silico Screening ◽  
Lateral Flow Assays ◽  
Life Threatening ◽  
Software And Hardware ◽  
Nucleic Acid Sequences

<p>Enteroviruses are a ubiquitous mammalian pathogen that can produce mild to life-threatening disease. Bearing this in mind, we have developed a rapid, accurate and economical point-of-care biosensor that can detect a nucleic acid sequences conserved amongst 96% of all known enteroviruses. The biosensor harnesses the physicochemical properties of gold nanoparticles and aptamers to provide colourimetric, spectroscopic and lateral flow-based identification of an exclusive enteroviral RNA sequence (23 bases), which was identified through in silico screening. Aptamers were designed to demonstrate specific complementarity towards the target enteroviral RNA to produce aggregated gold-aptamer nanoconstructs. Conserved target enteroviral nucleic acid sequence (≥ 1x10<sup>-7</sup> M, ≥1.4×10<sup>-14</sup> g/mL), initiates gold-aptamer-nanoconstructs disaggregation and a signal transduction mechanism, producing a colourimetric and spectroscopic blueshift (544 nm (purple) > 524 nm (red)). Furthermore, lateral-flow-assays that utilise gold-aptamer-nanoconstructs were unaffected by contaminating human genomic DNA, demonstrated rapid detection of conserved target enteroviral nucleic acid sequence (< 60 s) and could be interpreted with a bespoke software and hardware electronic interface. We anticipate our methodology will translate in-silico screening of nucleic acid databases to a tangible enteroviral desktop detector, which could be readily translated to related organisms. This will pave-the-way forward in the clinical evaluation of disease and complement existing strategies at overcoming antimicrobial resistance.</p>

Design and in-silico screening of Peptide Nucleic Acid (PNA) inspired novel pronucleotide scaffolds targeting COVID-19

2020 ◽  
Vol 16 ◽  
Author(s):  
Bichismita Sahu ◽  
Santosh Kumar Behera ◽  
Rudradip Das ◽  
Tanay Dalvi ◽  
Arnab Chowdhury ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
In Silico ◽  
Peptide Nucleic Acid ◽  
Large Set ◽  
Nonstructural Proteins ◽  
In Silico Screening ◽  
Replication Process ◽  
Enveloped Virus ◽  
Treatment Regimens ◽  
Novel Coronavirus

Introduction: The outburst of the novel coronavirus COVID-19, at the end of December 2019 has turned itself into a pandemic taking a heavy toll on human lives. The causal agent being SARS-CoV-2, a member of the long-known Coronaviridae family, is a positive sense single-stranded enveloped virus and quite closely related to SARS-CoV. It has become the need of the hour to understand the pathophysiology of this disease, so that drugs, vaccines, treatment regimens and plausible therapeutic agents can be produced. Methods: In this regard, recent studies uncovered the fact that the viral genome of SARS-CoV-2 encodes nonstructural proteins like RNA dependent RNA polymerase (RdRp) which is an important tool for its transcription and replication process. A large number of nucleic acid based anti-viral drugs are being repurposed for treating COVID-19 targeting RdRp. Few of them are in the advanced stage of clinical trials including Remdesivir. While performing close investigation of the large set of nucleic acid based drugs, we were surprised to find that the synthetic nucleic acid backbone is explored very little or rare. Results: We have designed scaffolds derived from peptide nucleic acid (PNA) and subjected them for in-silico screening systematically. These designed molecules have demonstrated excellent binding towards RdRp. Compound 12 was found to possess similar binding affinity as Remdesivir with comparable pharmacokinetics. However, the in-silico toxicity prediction indicates compound 12 may be a superior molecule which can be explored further due to its excellent safety-profile with LD50 (12,000mg/kg) as opposed to Remdesivir (LD50 =1000mg/kg). Conclusion: Compound 12 falls in the safe category of class 6. Synthetic feasibility, equipotent binding and very low toxicity of this peptide nucleic acid derived compounds can serve as a leading scaffold to design, synthesize and evaluate many of similar compounds for the treatment of COVID-19.

scholarly journals A CRISPR-Cas autocatalysis-driven feedback amplification network for supersensitive DNA diagnostics

2021 ◽  
Vol 7 (5) ◽  
pp. eabc7802
Author(s):  
Kai Shi ◽  
Shiyi Xie ◽  
Renyun Tian ◽  
Shuo Wang ◽  
Qin Lu ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Genomic Dna ◽  
Reaction Network ◽  
Clinical Samples ◽  
Great Promise ◽  
Base Specificity ◽  
Nucleotide Mutation ◽  
Positive Feedback Circuit ◽  
Stringent Target ◽  
And Function

Artificial nucleic acid circuits with precisely controllable dynamic and function have shown great promise in biosensing, but their utility in molecular diagnostics is still restrained by the inability to process genomic DNA directly and moderate sensitivity. To address this limitation, we present a CRISPR-Cas–powered catalytic nucleic acid circuit, namely, CRISPR-Cas–only amplification network (CONAN), for isothermally amplified detection of genomic DNA. By integrating the stringent target recognition, helicase activity, and trans-cleavage activity of Cas12a, a Cas12a autocatalysis-driven artificial reaction network is programmed to construct a positive feedback circuit with exponential dynamic in CONAN. Consequently, CONAN achieves one-enzyme, one-step, real-time detection of genomic DNA with attomolar sensitivity. Moreover, CONAN increases the intrinsic single-base specificity of Cas12a, and enables the effective detection of hepatitis B virus infection and human bladder cancer–associated single-nucleotide mutation in clinical samples, highlighting its potential as a powerful tool for disease diagnostics.

scholarly journals Characterization of squalene synthase gene from Gymnema sylvestre R. Br.

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Kuldeepsingh A. Kalariya ◽  
Ram Prasnna Meena ◽  
Lipi Poojara ◽  
Deepa Shahi ◽  
Sandip Patel
Keyword(s):  
Dna Sequences ◽  
Genomic Dna ◽  
Competitive Inhibition ◽  
Sequence Data ◽  
Homology Model ◽  
Squalene Synthase ◽  
Gymnema Sylvestre ◽  
Gardenia Jasminoides ◽  
Ramachandran Plots ◽  
Flanking Regions

Abstract Background Squalene synthase (SQS) is a rate-limiting enzyme necessary to produce pentacyclic triterpenes in plants. It is an important enzyme producing squalene molecules required to run steroidal and triterpenoid biosynthesis pathways working in competitive inhibition mode. Reports are available on information pertaining to SQS gene in several plants, but detailed information on SQS gene in Gymnema sylvestre R. Br. is not available. G. sylvestre is a priceless rare vine of central eco-region known for its medicinally important triterpenoids. Our work aims to characterize the GS-SQS gene in this high-value medicinal plant. Results Coding DNA sequences (CDS) with 1245 bp length representing GS-SQS gene predicted from transcriptome data in G. sylvestre was used for further characterization. The SWISS protein structure modeled for the GS-SQS amino acid sequence data had MolProbity Score of 1.44 and the Clash Score 3.86. The quality estimates and statistical score of Ramachandran plots analysis indicated that the homology model was reliable. For full-length amplification of the gene, primers designed from flanking regions of CDS encoding GS-SQS were used to get amplification against genomic DNA as template which resulted in approximately 6.2-kb sized single-band product. The sequencing of this product through NGS was carried out generating 2.32 Gb data and 3347 number of scaffolds with N50 value of 457 bp. These scaffolds were compared to identify similarity with other SQS genes as well as the GS-SQSs of the transcriptome. Scaffold_3347 representing the GS-SQS gene harbored two introns of 101 and 164 bp size. Both these intronic regions were validated by primers designed from adjoining outside regions of the introns on the scaffold representing GS-SQS gene. The amplification took place when the template was genomic DNA and failed when the template was cDNA confirmed the presence of two introns in GS-SQS gene in Gymnema sylvestre R. Br. Conclusion This study shows GS-SQS gene was very closely related to Coffea arabica and Gardenia jasminoides and this gene harbored two introns of 101 and 164 bp size.

Rapid Amplification of Uncharacterized Transposon-tagged DNA Sequences from Genomic DNA

Yeast ◽  
1997 ◽  
Vol 13 (3) ◽  
pp. 233-240 ◽  
Author(s):  
KRISTIN T. CHUN ◽  
HOWARD J. EDENBERG ◽  
MARK R. KELLEY ◽  
MARK G. GOEBL
Keyword(s):  
Dna Sequences ◽  
Genomic Dna ◽  
Rapid Amplification

scholarly journals Novel nucleic acid origami structures and conventional molecular beacon–based platforms: a comparison in biosensing applications

2021 ◽  
Author(s):  
Noemi Bellassai ◽  
Roberta D’Agata ◽  
Giuseppe Spoto
Keyword(s):  
Nucleic Acid ◽  
Structural Properties ◽  
Molecular Beacon ◽  
Dna Origami ◽  
Molecular Beacons ◽  
Conformational Polymorphism ◽  
Functional Systems ◽  
Similarities And Differences ◽  
Nucleic Acid Structures ◽  
Nucleic Acid Sequences

AbstractNucleic acid nanotechnology designs and develops synthetic nucleic acid strands to fabricate nanosized functional systems. Structural properties and the conformational polymorphism of nucleic acid sequences are inherent characteristics that make nucleic acid nanostructures attractive systems in biosensing. This review critically discusses recent advances in biosensing derived from molecular beacon and DNA origami structures. Molecular beacons belong to a conventional class of nucleic acid structures used in biosensing, whereas DNA origami nanostructures are fabricated by fully exploiting possibilities offered by nucleic acid nanotechnology. We present nucleic acid scaffolds divided into conventional hairpin molecular beacons and DNA origami, and discuss some relevant examples by focusing on peculiar aspects exploited in biosensing applications. We also critically evaluate analytical uses of the synthetic nucleic acid structures in biosensing to point out similarities and differences between traditional hairpin nucleic acid sequences and DNA origami. Graphical abstract

Sign in / Sign up

Export Citation Format

Share Document