scholarly journals Topology-based classification of tetrads and quadruplex structures

2019 ◽  
Vol 36 (4) ◽  
pp. 1129-1134 ◽  
Author(s):  
Mariusz Popenda ◽  
Joanna Miskiewicz ◽  
Joanna Sarzynska ◽  
Tomasz Zok ◽  
Marta Szachniuk
Keyword(s):  
Nucleic Acid ◽  
3D Structure ◽  
Data Bank ◽  
Supplementary Information ◽  
The Novel ◽  
Disease Treatment ◽  
Structure Topology ◽  
Secondary Structure Topology ◽  
Nucleic Acid Structures

Abstract Motivation Quadruplexes attract the attention of researchers from many fields of bio-science. Due to a specific structure, these tertiary motifs are involved in various biological processes. They are also promising therapeutic targets in many strategies of drug development, including anticancer and neurological disease treatment. The uniqueness and diversity of their forms cause that quadruplexes show great potential in novel biological applications. The existing approaches for quadruplex analysis are based on sequence or 3D structure features and address canonical motifs only. Results In our study, we analyzed tetrads and quadruplexes contained in nucleic acid molecules deposited in Protein Data Bank. Focusing on their secondary structure topology, we adjusted its graphical diagram and proposed new dot-bracket and arc representations. We defined the novel classification of these motifs. It can handle both canonical and non-canonical cases. Based on this new taxonomy, we implemented a method that automatically recognizes the types of tetrads and quadruplexes occurring as unimolecular structures. Finally, we conducted a statistical analysis of these motifs found in experimentally determined nucleic acid structures in relation to the new classification. Availability and implementation https://github.com/tzok/eltetrado/ Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals G-Quadruplex-Forming Aptamers—Characteristics, Applications, and Perspectives

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3781 ◽  
Author(s):  
Carolina Roxo ◽  
Weronika Kotkowiak ◽  
Anna Pasternak
Keyword(s):  
Nucleic Acid ◽  
Production Costs ◽  
Biological Processes ◽  
Disease Treatment ◽  
Diagnostic Potential ◽  
G Quadruplex ◽  
Fast Development ◽  
Systematic Evolution ◽  
Nucleic Acid Structures ◽  
Exponential Enrichment

G-quadruplexes constitute a unique class of nucleic acid structures formed by G-rich oligonucleotides of DNA- or RNA-type. Depending on their chemical nature, loops length, and localization in the sequence or structure molecularity, G-quadruplexes are highly polymorphic structures showing various folding topologies. They may be formed in the human genome where they are believed to play a pivotal role in the regulation of multiple biological processes such as replication, transcription, and translation. Thus, natural G-quadruplex structures became prospective targets for disease treatment. The fast development of systematic evolution of ligands by exponential enrichment (SELEX) technologies provided a number of G-rich aptamers revealing the potential of G-quadruplex structures as a promising molecular tool targeted toward various biologically important ligands. Because of their high stability, increased cellular uptake, ease of chemical modification, minor production costs, and convenient storage, G-rich aptamers became interesting therapeutic and diagnostic alternatives to antibodies. In this review, we describe the recent advances in the development of G-quadruplex based aptamers by focusing on the therapeutic and diagnostic potential of this exceptional class of nucleic acid structures.

scholarly journals New functionality of RNAComposer: application to shape the axis of miR160 precursor structure

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Maciej Antczak ◽  
Mariusz Popenda ◽  
Tomasz Zok ◽  
Joanna Sarzynska ◽  
Tomasz Ratajczak ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Structure Prediction ◽  
Web Application ◽  
3D Model ◽  
Secondary Structure Prediction ◽  
3D Structure ◽  
Structure Topology ◽  
Precursor Structure ◽  
Secondary Structure Topology ◽  
Main Components

RNAComposer is a fully automated, web-interfaced system for RNA 3D structure prediction, freely available at http://rnacomposer.cs.put.poznan.pl/ and http://rnacomposer.ibch.poznan.pl/. Its main components are: manually curated database of RNA 3D structure elements, highly efficient computational engine and user-friendly web application. In this paper, we demonstrate how the latest additions to the system allow the user to significantly affect the process of 3D model composition on several computational levels. Although in general our method is based on the knowledge of secondary structure topology, currently RNAComposer offers a choice of six incorporated programs for secondary structure prediction. It allows also to apply conditional search in the database of 3D structure elements and introduce user-provided elements into the final 3D model. This new functionality contributes to a significant improvement of the predicted 3D model reliability and it facilitates better model adjustment to the experimental data. This is exemplified based on RNAComposer application for modelling of the 3D structures of precursors of miR160 family members.

HELIX: a new modular nucleic acid crystallization screen

2014 ◽  
Vol 47 (3) ◽  
pp. 948-955 ◽  
Author(s):  
Julia Viladoms ◽  
Gary N. Parkinson
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Data Bank ◽  
Diverse Range ◽  
X Ray Crystallography ◽  
Molecular Weights ◽  
Anomalous Data ◽  
Crystallization Conditions ◽  
Nucleic Acid Structures ◽  
Screen Layout

Crystallization of nucleic acids remains a bottleneck to their structural characterization by X-ray crystallography. A new 96-well-format initial screen for nucleic acids, called HELIX, has been developed at UCL School of Pharmacy, London, on the basis of a detailed analysis of the crystallization conditions from 1450 nucleic acid structures deposited in the Protein Data Bank (PDB), combined with observations and experience acquired in the authors' nucleic acids crystallography laboratory during the crystallization of DNA/RNA quadruplexes and ligand complexes. Despite using traditional buffers, precipitants and salts, the resulting modular screen is designed to offer a variety of approaches to enhance successful crystallization of oligonucleotides with a diverse range of topologies, sequences and molecular weights. HELIX includes a set of 24 conditions divided into four sets that can be mixed (inter- and intra-set) to provide a customizable orthogonal screening tool for experienced users, termed VariX. Additionally, mindful of synchrotron anomalous data collection, cacodylate buffers are avoided in the formulations and an optimized cryocrystallization module is included. This article reviews the crystallization trends and data derived from the PDB and discusses the HELIX screen layout, formulation and results from in-house crystallization trials.

scholarly journals New restraints and validation approaches for nucleic acid structures in PDB-REDO

2021 ◽  
Vol 77 (9) ◽  
pp. 1127-1141
Author(s):  
Ida de Vries ◽  
Tim Kwakman ◽  
Xiang-Jun Lu ◽  
Maarten L. Hekkelman ◽  
Mandar Deshpande ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Nucleic Acid ◽  
Protein Data Bank ◽  
Base Pair ◽  
Data Bank ◽  
Macromolecular Structure ◽  
Base Pair Stacking ◽  
Nucleic Acid Structures ◽  
Positive Effect

The quality of macromolecular structure models crucially depends on refinement and validation targets, which optimally describe the expected chemistry. Commonly used software for these two procedures has been designed and developed in a protein-centric manner, resulting in relatively few established features for the refinement and validation of nucleic acid-containing structure models. Here, new nucleic acid-specific approaches implemented in PDB-REDO are described, including a new restraint model using noncovalent geometries (base-pair hydrogen bonding and base-pair stacking) as refinement targets. New validation routines are also presented, including a metric for Watson–Crick base-pair geometry normality (Z bpG). Applying the PDB-REDO pipeline with the new restraint model to the whole Protein Data Bank (PDB) demonstrates an overall positive effect on the quality of nucleic acid-containing structure models. Finally, we discuss examples of improvements in the geometry of specific nucleic acid structures in the PDB. The new PDB-REDO models and pipeline are available at https://pdb-redo.eu/.

KEC: unique sequence search by K-mer exclusion

2021 ◽  
Author(s):  
Pavel Beran ◽  
Dagmar Stehlíková ◽  
Stephen P Cohen ◽  
Vladislav Čurn
Keyword(s):  
Amino Acid ◽  
Nucleic Acid ◽  
Source Code ◽  
Unique Sequence ◽  
Supplementary Information ◽  
Supplementary Data ◽  
Laptop Computers ◽  
Sequence Search ◽  
Target Sequences ◽  
Cross Reference

Abstract Summary Searching for amino acid or nucleic acid sequences unique to one organism may be challenging depending on size of the available datasets. K-mer elimination by cross-reference (KEC) allows users to quickly and easily find unique sequences by providing target and non-target sequences. Due to its speed, it can be used for datasets of genomic size and can be run on desktop or laptop computers with modest specifications. Availability and implementation KEC is freely available for non-commercial purposes. Source code and executable binary files compiled for Linux, Mac and Windows can be downloaded from https://github.com/berybox/KEC. Supplementary information Supplementary data are available at Bioinformatics online.

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

scholarly journals Overlapping but distinct: a new model for G-quadruplex biochemical specificity

2021 ◽  
Author(s):  
Martin Volek ◽  
Sofia Kolesnikova ◽  
Katerina Svehlova ◽  
Pavel Srb ◽  
Ráchel Sgallová ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Drug Design ◽  
Solution Structure ◽  
Biochemical Data ◽  
Biological Regulation ◽  
New Model ◽  
G Quadruplex ◽  
Range Of Functions ◽  
Nucleic Acid Structures ◽  
Sequence Requirements

Abstract G-quadruplexes are noncanonical nucleic acid structures formed by stacked guanine tetrads. They are capable of a range of functions and thought to play widespread biological roles. This diversity raises an important question: what determines the biochemical specificity of G-quadruplex structures? The answer is particularly important from the perspective of biological regulation because genomes can contain hundreds of thousands of G-quadruplexes with a range of functions. Here we analyze the specificity of each sequence in a 496-member library of variants of a reference G-quadruplex with respect to five functions. Our analysis shows that the sequence requirements of G-quadruplexes with these functions are different from one another, with some mutations altering biochemical specificity by orders of magnitude. Mutations in tetrads have larger effects than mutations in loops, and changes in specificity are correlated with changes in multimeric state. To complement our biochemical data we determined the solution structure of a monomeric G-quadruplex from the library. The stacked and accessible tetrads rationalize why monomers tend to promote a model peroxidase reaction and generate fluorescence. Our experiments support a model in which the sequence requirements of G-quadruplexes with different functions are overlapping but distinct. This has implications for biological regulation, bioinformatics, and drug design.

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