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Methods (San Diego, Calif.) Nov 2012We describe a method, Hi-C, to comprehensively detect chromatin interactions in the mammalian nucleus. This method is based on Chromosome Conformation Capture, in which...
We describe a method, Hi-C, to comprehensively detect chromatin interactions in the mammalian nucleus. This method is based on Chromosome Conformation Capture, in which chromatin is crosslinked with formaldehyde, then digested, and re-ligated in such a way that only DNA fragments that are covalently linked together form ligation products. The ligation products contain the information of not only where they originated from in the genomic sequence but also where they reside, physically, in the 3D organization of the genome. In Hi-C, a biotin-labeled nucleotide is incorporated at the ligation junction, enabling selective purification of chimeric DNA ligation junctions followed by deep sequencing. The compatibility of Hi-C with next generation sequencing platforms makes it possible to detect chromatin interactions on an unprecedented scale. This advance gives Hi-C the power to both explore the biophysical properties of chromatin as well as the implications of chromatin structure for the biological functions of the nucleus. A massively parallel survey of chromatin interaction provides the previously missing dimension of spatial context to other genomic studies. This spatial context will provide a new perspective to studies of chromatin and its role in genome regulation in normal conditions and in disease.
Topics: Animals; Cells, Cultured; Chromatin; Chromosome Mapping; Cross-Linking Reagents; DNA; DNA Fragmentation; Epistasis, Genetic; Fixatives; Formaldehyde; Gene Library; Genome, Human; Humans; Nucleic Acid Conformation; Sequence Analysis, DNA; Tissue Fixation
PubMed: 22652625
DOI: 10.1016/j.ymeth.2012.05.001 -
Nucleic Acids Research Jun 2017DNA library preparation for high-throughput sequencing of genomic DNA usually involves ligation of adapters to double-stranded DNA fragments. However, for highly...
DNA library preparation for high-throughput sequencing of genomic DNA usually involves ligation of adapters to double-stranded DNA fragments. However, for highly degraded DNA, especially ancient DNA, library preparation has been found to be more efficient if each of the two DNA strands are converted into library molecules separately. We present a new method for single-stranded library preparation, ssDNA2.0, which is based on single-stranded DNA ligation with T4 DNA ligase utilizing a splinter oligonucleotide with a stretch of random bases hybridized to a 3΄ biotinylated donor oligonucleotide. A thorough evaluation of this ligation scheme shows that single-stranded DNA can be ligated to adapter oligonucleotides in higher concentration than with CircLigase (an RNA ligase that was previously chosen for end-to-end ligation in single-stranded library preparation) and that biases in ligation can be minimized when choosing splinters with 7 or 8 random nucleotides. We show that ssDNA2.0 tolerates higher quantities of input DNA than CircLigase-based library preparation, is less costly and better compatible with automation. We also provide an in-depth comparison of library preparation methods on degraded DNA from various sources. Most strikingly, we find that single-stranded library preparation increases library yields from tissues stored in formalin for many years by several orders of magnitude.
Topics: Animals; Bone and Bones; DNA; DNA Ligases; DNA Primers; DNA, Single-Stranded; Fossils; Gene Library; High-Throughput Nucleotide Sequencing; Horses; Humans; Liver; Nucleic Acid Hybridization; Oligonucleotides; Polymerase Chain Reaction; Sequence Analysis, DNA; Swine
PubMed: 28119419
DOI: 10.1093/nar/gkx033 -
Cell Jul 2018Eukaryotic genomes are packaged into a 3-dimensional structure in the nucleus. Current methods for studying genome-wide structure are based on proximity ligation....
Eukaryotic genomes are packaged into a 3-dimensional structure in the nucleus. Current methods for studying genome-wide structure are based on proximity ligation. However, this approach can fail to detect known structures, such as interactions with nuclear bodies, because these DNA regions can be too far apart to directly ligate. Accordingly, our overall understanding of genome organization remains incomplete. Here, we develop split-pool recognition of interactions by tag extension (SPRITE), a method that enables genome-wide detection of higher-order interactions within the nucleus. Using SPRITE, we recapitulate known structures identified by proximity ligation and identify additional interactions occurring across larger distances, including two hubs of inter-chromosomal interactions that are arranged around the nucleolus and nuclear speckles. We show that a substantial fraction of the genome exhibits preferential organization relative to these nuclear bodies. Our results generate a global model whereby nuclear bodies act as inter-chromosomal hubs that shape the overall packaging of DNA in the nucleus.
Topics: Cell Nucleolus; Cell Nucleus; Chromosome Mapping; Chromosomes; DNA; Eukaryota; Genome; Humans; Structure-Activity Relationship
PubMed: 29887377
DOI: 10.1016/j.cell.2018.05.024 -
Biosensors & Bioelectronics Aug 2022In this study, we uncover a ligation-free DNA extension method in two adjacent fragmented probes, which are hybridized to target RNA, for developing a ligation-free...
In this study, we uncover a ligation-free DNA extension method in two adjacent fragmented probes, which are hybridized to target RNA, for developing a ligation-free nucleic acid amplification reaction. In this reaction, DNA elongation occurs from a forward probe to a phosphorothioated-hairpin probe in the presence of target RNA regardless of ligation. The second DNA elongation then occurs simultaneously at the nick site of the phosphorothioated probe and the self-priming region. Therefore, the binding site of the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) 12a is repeatedly amplified, inducing a fluorescence signal in the presence of CRISPR-Cas12a. This ligation-free isothermal gene amplification method enables the detection of target RNA with 49.2 fM sensitivity. Moreover, two types of mRNA detection are feasible, thus, demonstrating the potential of this method for cancer companion diagnostics. Notably, the proposed method also demonstrates efficacy when applied for the detection of mRNA extracted from human cells and tumor-bearing mouse tissue and urine samples. Hence, this newly developed ligation-free isothermal nucleic acid amplification system is expected to be widely used in a variety of gene detection platforms.
Topics: Animals; Biosensing Techniques; CRISPR-Cas Systems; DNA; Mice; Nucleic Acid Amplification Techniques; RNA; RNA, Messenger
PubMed: 35430408
DOI: 10.1016/j.bios.2022.114256 -
Methods in Enzymology 2021DNA-peptide (DpCs) and DNA-protein cross-links (DPCs) are DNA lesions formed when polypeptides and nuclear proteins become covalently trapped on DNA strands. DNA-protein...
DNA-peptide (DpCs) and DNA-protein cross-links (DPCs) are DNA lesions formed when polypeptides and nuclear proteins become covalently trapped on DNA strands. DNA-protein cross-links are of enormous size and hence pose challenges to cell survival by blocking DNA replication, transcription, and repair. However, DPCs can undergo proteolytic degradation via various pathways to give shorter polypeptide chains (DpCs). The resulting DpC lesions are efficiently bypassed by translesion synthesis (TLS) DNA polymerases like κ, η, δ, etc., although polymerase bypass efficiency as well as correct base insertion depends heavily on size, sequence context, and position of peptides in DpCs. This chapter explores various synthetic methods to generate these lesions including detailed experimental procedures for the construction of DpCs and DPCs via reductive amination and oxime ligation. Further we describe biochemical experiments to investigate the effects of these lesions on DNA polymerase activity and fidelity.
Topics: DNA; DNA Damage; DNA Repair; DNA Replication; DNA-Directed DNA Polymerase; Peptides; Proteins
PubMed: 34776221
DOI: 10.1016/bs.mie.2021.09.005 -
BMC Genomics Dec 2019Cell-free DNA (cfDNA), present in circulating blood plasma, contains information about prenatal health, organ transplant reception, and cancer presence and progression....
BACKGROUND
Cell-free DNA (cfDNA), present in circulating blood plasma, contains information about prenatal health, organ transplant reception, and cancer presence and progression. Originally developed for the genomic analysis of highly degraded ancient DNA, single-stranded DNA (ssDNA) library preparation methods are gaining popularity in the field of cfDNA analysis due to their efficiency and ability to convert short, fragmented DNA into sequencing libraries without altering DNA ends. However, current ssDNA methods are costly and time-consuming.
RESULTS
Here we present an efficient ligation-based single-stranded library preparation method that is engineered to produce complex libraries in under 2.5 h from as little as 1 nanogram of input DNA without alteration to the native ends of template molecules. Our method, called Single Reaction Single-stranded LibrarY or SRSLY, ligates uniquely designed Next-Generation Sequencing (NGS) adapters in a one-step combined phosphorylation/ligation reaction that foregoes end-polishing. Using synthetic DNA oligos and cfDNA, we demonstrate the efficiency and utility of this approach and compare with existing double-stranded and single-stranded approaches for library generation. Finally, we demonstrate that cfDNA NGS data generated from SRSLY can be used to analyze DNA fragmentation patterns to deduce nucleosome positioning and transcription factor binding.
CONCLUSIONS
SRSLY is a versatile tool for converting short and fragmented DNA molecules, like cfDNA fragments, into sequencing libraries while retaining native lengths and ends.
Topics: Cell-Free Nucleic Acids; DNA, Single-Stranded; Gene Library; High-Throughput Nucleotide Sequencing; Humans; Oligonucleotides; Sequence Analysis, DNA
PubMed: 31881841
DOI: 10.1186/s12864-019-6355-0 -
Nucleic Acids Research Aug 2021The low thermal stability of DNA nanostructures is the major drawback in their practical applications. Most of the DNA nanotubes/tiles and the DNA origami structures...
The low thermal stability of DNA nanostructures is the major drawback in their practical applications. Most of the DNA nanotubes/tiles and the DNA origami structures melt below 60°C due to the presence of discontinuities in the phosphate backbone (i.e., nicks) of the staple strands. In molecular biology, enzymatic ligation is commonly used to seal the nicks in the duplex DNA. However, in DNA nanotechnology, the ligation procedures are neither optimized for the DNA origami nor routinely applied to link the nicks in it. Here, we report a detailed analysis and optimization of the conditions for the enzymatic ligation of the staple strands in four types of 2D square lattice DNA origami. Our results indicated that the ligation takes overnight, efficient at 37°C rather than the usual 16°C or room temperature, and typically requires much higher concentration of T4 DNA ligase. Under the optimized conditions, up to 10 staples ligation with a maximum ligation efficiency of 55% was achieved. Also, the ligation is found to increase the thermal stability of the origami as low as 5°C to as high as 20°C, depending on the structure. Further, our studies indicated that the ligation of the staple strands influences the globular structure/planarity of the DNA origami, and the origami is more compact when the staples are ligated. The globular structure of the native and ligated origami was also found to be altered dynamically and progressively upon ethidium bromide intercalation in a concentration-dependent manner.
Topics: DNA; DNA Ligases; Electrophoresis, Agar Gel; Ethidium; Kinetics; Microscopy, Atomic Force; Nanostructures; Nucleic Acid Conformation; Nucleic Acid Denaturation; Phosphorylation; Temperature; Thermodynamics
PubMed: 34289063
DOI: 10.1093/nar/gkab611 -
Biomolecules Jun 2023Programmable endonucleases, such as Cas (Clustered Regularly-Interspaced Short Repeats-associated proteins) and prokaryotic Argonaute (pAgo), depend on base pairing of... (Review)
Review
Programmable endonucleases, such as Cas (Clustered Regularly-Interspaced Short Repeats-associated proteins) and prokaryotic Argonaute (pAgo), depend on base pairing of the target DNA with the guide RNA or DNA to cleave DNA strands. Therefore, they are capable of recognizing and cleaving DNA sequences at virtually any arbitrary site. The present review focuses on the commonly used in vivo and in vitro recombination-based gene cloning methods and the application of programmable endonucleases in these sequence- and ligation-independent DNA assembly methods. The advantages and shortcomings of the programmable endonucleases utilized as tools for gene cloning are also discussed in this review.
Topics: Endonucleases; DNA; Cloning, Molecular; Prokaryotic Cells
PubMed: 37509059
DOI: 10.3390/biom13071022 -
FEMS Yeast Research Feb 2015DNA assembly is one of the most important foundational technologies for synthetic biology and metabolic engineering. Since the development of the restriction digestion... (Review)
Review
DNA assembly is one of the most important foundational technologies for synthetic biology and metabolic engineering. Since the development of the restriction digestion and ligation method in the early 1970s, a significant amount of effort has been devoted to developing better DNA assembly methods with higher efficiency, fidelity, and modularity, as well as simpler and faster protocols. This review will not only summarize the key DNA assembly methods and their recent applications, but also highlight the innovations in assembly schemes and the challenges in automating the DNA assembly methods.
Topics: DNA; Metabolic Engineering; Synthetic Biology
PubMed: 24903193
DOI: 10.1111/1567-1364.12171 -
Nucleic Acids Research Aug 2022Enzymatic ligation is a popular method in DNA nanotechnology for structural enforcement. When employed as stability switch for chosen components, ligation can be applied...
Enzymatic ligation is a popular method in DNA nanotechnology for structural enforcement. When employed as stability switch for chosen components, ligation can be applied to induce DNA nanostructure reconfiguration. In this study, we investigate the reinforcement effect of ligation on addressable DNA nanostructures assembled entirely from short synthetic strands as the basis of structural reconfiguration. A careful calibration of ligation efficiency is performed on structures with programmable nicks. Systematic investigation using comparative agarose gel electrophoresis enables quantitative assessment of enhanced survivability with ligation treatment on a number of unique structures. The solid ligation performance sets up the foundation for the ligation-based structural reconfiguration. With the capability of switching base pairing status between permanent and transient (ON and OFF) by a simple round of enzymatic treatment, ligation induced reconfiguration can be engineered for DNA nanostructures accordingly.
Topics: DNA; Nanostructures; Nanotechnology; Nucleic Acid Conformation
PubMed: 35880584
DOI: 10.1093/nar/gkac606