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1.
Methods Mol Biol ; 2856: 11-22, 2025.
Article in English | MEDLINE | ID: mdl-39283444

ABSTRACT

The Structural Maintenance of Chromosomes (SMC) protein complexes are DNA-binding molecular machines required to shape chromosomes into functional units and to safeguard the genome through cell division. These ring-shaped multi-subunit protein complexes, which are present in all kingdoms of life, achieve this by organizing chromosomes in three-dimensional space. Mechanistically, the SMC complexes hydrolyze ATP to either stably entrap DNA molecules within their lumen, or rapidly reel DNA into large loops, which allow them to link two stretches of DNA in cis or trans. In this chapter, the canonical structure of the SMC complexes is first introduced, followed by a description of the composition and general functions of the main types of eukaryotic and prokaryotic SMC complexes. Thereafter, the current model for how SMC complexes perform in vitro DNA loop extrusion is presented. Lastly, chromosome loop formation by SMC complexes is introduced, and how the DNA loop extrusion mechanism contributes to chromosome looping by SMC complexes in cells is discussed.


Subject(s)
Chromosomes , Chromosomes/chemistry , Multiprotein Complexes/metabolism , Multiprotein Complexes/chemistry , Cell Cycle Proteins/metabolism , Cell Cycle Proteins/genetics , DNA/chemistry , DNA/metabolism , DNA/genetics , Chromosomal Proteins, Non-Histone/metabolism , Chromosomal Proteins, Non-Histone/chemistry , Adenosine Triphosphate/metabolism , DNA-Binding Proteins/metabolism , DNA-Binding Proteins/chemistry
2.
Methods Mol Biol ; 2856: 281-292, 2025.
Article in English | MEDLINE | ID: mdl-39283459

ABSTRACT

Biomolecules contain various heterogeneities in their structures and local chemical properties, and their functions emerge through the dynamics encoded by these heterogeneities. Molecular dynamics model-based studies will greatly contribute to the elucidation of such chemical/mechanical structure-dynamics-function relationships and the mechanisms that generate them. Coarse-grained molecular dynamics models with appropriately designed nonuniform local interactions play an important role in considering the various phenomena caused by large molecular complexes consisting of various proteins and DNA such as nuclear chromosomes. Therefore, in this chapter, we will introduce a method for constructing a coarse-grained molecular dynamics model that simulates the global behavior of each chromosome in the nucleus of a mammalian cell containing many giant chromosomes.


Subject(s)
Cell Nucleus , Molecular Dynamics Simulation , Cell Nucleus/metabolism , Cell Nucleus/chemistry , Animals , Humans , Chromosomes/chemistry , DNA/chemistry , DNA/metabolism , Mammals
3.
Methods Mol Biol ; 2856: 419-432, 2025.
Article in English | MEDLINE | ID: mdl-39283466

ABSTRACT

Imaging-based spatial multi-omics technologies facilitate the analysis of higher-order genomic structures, gene transcription, and the localization of proteins and posttranslational modifications (PTMs) at the single-allele level, thereby enabling detailed observations of biological phenomena, including transcription machinery within cells and tissues. This chapter details the principles of such technologies, with a focus on DNA/RNA/immunofluorescence (IF) sequential fluorescence in situ hybridization (seqFISH). A comprehensive step-by-step protocol for image analysis is provided, covering image preprocessing, spot detection, and data visualization. For practical application, complete Jupyter Notebook codes are made available on GitHub ( https://github.com/Ochiai-Lab/seqFISH_analysis ).


Subject(s)
DNA , Fluorescent Antibody Technique , Image Processing, Computer-Assisted , In Situ Hybridization, Fluorescence , RNA , Software , In Situ Hybridization, Fluorescence/methods , RNA/genetics , RNA/analysis , RNA/metabolism , Image Processing, Computer-Assisted/methods , DNA/genetics , Fluorescent Antibody Technique/methods , Humans , Animals
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 324: 124987, 2025 Jan 05.
Article in English | MEDLINE | ID: mdl-39163774

ABSTRACT

While numerous methods exist for diagnosing tumors through the detection of miRNA within tumor cells, few can simultaneously achieve both tumor diagnosis and treatment. In this study, a novel graphene oxide (GO)-based DNA nanodevice (DND), initiated by miRNA, was developed for fluorescence signal amplification imaging and photodynamic therapy in tumor cells. After entering the cells, tumor-associated miRNA drives DND to Catalyzed hairpin self-assembly (CHA). The CHA reaction generated a multitude of DNA Y-type structures, resulting in a substantial amplification of Ce6 fluorescence release and the generation of numerous singlet oxygen (1O2) species induced by laser irradiation, consequently inducing cell apoptosis. In solution, DND exhibited high selectivity and sensitivity to miRNA-21, with a detection limit of 11.47 pM. Furthermore, DND discriminated between normal and tumor cells via fluorescence imaging and specifically generated O21 species in tumor cells upon laser irradiation, resulting in tumor cells apoptosis. The DND offer a new approach for the early diagnosis and timely treatment of malignant tumors.


Subject(s)
DNA , Graphite , MicroRNAs , Photochemotherapy , Theranostic Nanomedicine , Photochemotherapy/methods , Humans , MicroRNAs/analysis , Graphite/chemistry , Theranostic Nanomedicine/methods , DNA/chemistry , Apoptosis/drug effects , Optical Imaging , Cell Line, Tumor , Singlet Oxygen/metabolism , Singlet Oxygen/chemistry , Neoplasms/drug therapy , Neoplasms/diagnostic imaging
5.
Methods Mol Biol ; 2854: 117-125, 2025.
Article in English | MEDLINE | ID: mdl-39192124

ABSTRACT

Beyond its role as the bearer of genetic material, DNA also plays a crucial role in the activation phase of innate immunity. Pathogen recognition receptors (PRRs) and their homologs, pathogen-associated molecular patterns (PAMPs), form the foundation for driving innate immune activation and the induction of immune responses during infection. In the context of DNA viruses or bacterial infections, specific DNA sequences are recognized and bound by DNA sensors, marking the DNA as a PAMP for host recognition and subsequent activation of innate immunity. The primary DNA sensor pathway known to date is cGAS-STING, which can induce Type I interferons (IFN) and innate immune responses against viruses and bacteria. Additionally, the cGAS-STING pathway has been identified to mediate functions in autophagy and senescence. Herein, we introduce methods for using DNA PAMPs as molecular tools to study the role of cGAS-STING and its signaling pathway in regulating innate immunity, both in vitro and in vivo.


Subject(s)
DNA , Immunity, Innate , Membrane Proteins , Nucleotidyltransferases , Signal Transduction , Nucleotidyltransferases/metabolism , Nucleotidyltransferases/genetics , Membrane Proteins/metabolism , Membrane Proteins/genetics , Humans , DNA/metabolism , DNA/genetics , Animals , Pathogen-Associated Molecular Pattern Molecules/metabolism , Pathogen-Associated Molecular Pattern Molecules/immunology , Mice
6.
Methods Mol Biol ; 2852: 47-64, 2025.
Article in English | MEDLINE | ID: mdl-39235736

ABSTRACT

Electrochemical approaches, along with miniaturization of electrodes, are increasingly being employed to detect and quantify nucleic acid biomarkers. Miniaturization of the electrodes is achieved through the use of screen-printed electrodes (SPEs), which consist of one to a few dozen sets of electrodes, or by utilizing printed circuit boards. Electrode materials used in SPEs include glassy carbon (Chiang H-C, Wang Y, Zhang Q, Levon K, Biosensors (Basel) 9:2-11, 2019), platinum, carbon, and graphene (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). There are numerous modifications to the electrode surfaces as well (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). These approaches offer distinct advantages, primarily due to their demonstrated superior limit of detection without amplification. Using the SPEs and potentiostats, we can detect cells, proteins, DNA, and RNA concentrations in the nanomolar (nM) to attomolar (aM) range. The focus of this chapter is to describe the basic approach adopted for the use of SPEs for nucleic acid measurement.


Subject(s)
Biosensing Techniques , Electrochemical Techniques , Electrodes , Graphite , Graphite/chemistry , Electrochemical Techniques/methods , Electrochemical Techniques/instrumentation , Biosensing Techniques/methods , Biosensing Techniques/instrumentation , Nucleic Acids/analysis , Humans , DNA/analysis
7.
Rev. biol. trop ; 72(1): e49359, ene.-dic. 2024. graf
Article in English | LILACS, SaludCR | ID: biblio-1559319

ABSTRACT

Abstract Introduction: A recent revision of the generic classification of the Trochilidae based on DNA sequences revealed many inconsistencies with the current generic classification, largely based on plumage characters subject to homoplasy, especially in the Trochilini, the largest tribe. A thorough generic reorganization brought the classification into accord with the phylogeny, but due to lack of genetic data, two species remained unclassified. One of these was the Mangrove Hummingbird, "Amazilia" boucardi, endemic to Costa Rica and included in the IUCN red list of threatened species. Objective: To obtain molecular evidence to clarify the generic relationships of "A." boucardi. Methods: We isolated DNA from tissues of this species and amplified 4 nuclear and 4 mitochondrial fragments and compared these with homologous fragments from 56 species in the Trochilini, constructing phylogenetic trees with maximum likelihood and Bayesian methods. Results: Our phylogenetic analyses confirmed the placement of boucardi in the Trochilini and definitely excluded it from Amazilia but placed it with high confidence in the genus Chrysuronia Bonaparte, 1850, within which its closest relative is C. coeruleogularis, which also inhabits mangroves. Conclusions: Our genetic data based on nuclear and mitochondrial regions clearly indicate the relationship of A. boucardi and L. coeruleogularis. Moreover, it is also supported by their habitat distribution in the mangroves of the Pacific coast of Costa Rica and Western Panama. Therefore, we suggested to exclude A. boucardi as "incertae sedis".


Resumen Introducción: Una revisión reciente de la clasificación de la familia Trochilidae con base en secuencias de ADN demostró muchas incongruencias con la clasificación genérica previa, que había sido hecho con base en caracteres del plumaje muy sujetos a homoplasia, especialmente en la tribu más grande, Trochillini. Una reorganización de los géneros logró llevar su clasificación genérica a la concordancia con la filogenia, pero debido a la ausencia de datos genéticos, dos especies permanecieron sin clasificar. Una de estas fue el colibrí de manglar Amazilia boucardi, una especie endémica de Costa Rica, considerada como amenazada en la lista roja de la UICN. Objetivo: Obtener evidencia molecular para esclarecer las relaciones genéricas de A. boucardi. Métodos: Se aisló ADN de tejidos de esta especie y se amplificaron 4 fragmentos de ADN del núcleo y 5 de la mitocondria, y se compararon con fragmentos homólogos de 56 especies en la tribu Trochillini, generando árboles filogenéticos con métodos de máxima verosimilitud y bayesiano. Resultados: Los análisis filogénticos obtenidos confirmaron la ubicación de boucardi en Trochilini y definitivamente la excluyó del género Amazilia, pero la ubicó con un alto grado de confianza en el género Chrysuronia Bonaparte, 1850, dentro los cuales su pariente más cercano es C. coeruleogularis, que también habita manglares. Conclusiones: Nuestros datos genéticos basados en regiones nucleares y mitocondriales indican claramente la relación entre A. boucardi and L. coeruleogularis. Es más, lo anterior se sustenta por su distribución en los manglares de la costa Pacífica de Costa Rica y oeste de Panamá. Por lo tanto, sugerimos excluir a A. boucardi como "incertae sedis".


Subject(s)
Animals , Birds/classification , DNA/analysis , Phylogeny , Costa Rica , Genes, Mitochondrial
8.
Biomolecules ; 14(9)2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39334949

ABSTRACT

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with a highly variable expression of phenotypes (restricted interest or activity and repetitive behavior in communication and social interactions), genes (mutation), markers (alteration of transcription) and pathways. Loss of function of the CC2D1A gene appears to primarily affect the brain, leading to a range of behavioral problems in humans. In our study published in 2020, we found that the expressions of miR-19a-3p, miR-361-5p, miR-150-5p, miR-3613-3p, miR-126-3p and miR-499a-5p were downregulated in the serum samples of autistic patients, their families and mouse models (Cc2d1a +/- and valproic acid treated males). Here, acquired non-Mendelian hereditary character in a genetically defined mouse model of autism (Cc2d1a +/-) correlates with the transcriptional alteration of five miRNAs. We seek to test the hypothesis that miRNA levels vary by changes in RNA/DNA structure during development, thereby creating transcription alteration and cell memory. Behavioral tests were conducted on the offspring of Cc2d1a (+/-) mutant and control mice, such as novel object, social interaction, marble burying and tail suspension behavior. Two RNA fractions were isolated from mouse hippocampal tissues and sperm cells via standard TRIzol extraction: free RNA and the fraction of RNA bound to DNA in the form of a DNA/RNA hybrid (R-loop). The expression levels of miR-19a-3p, miR-361-5p, miR-150-5p, miR-126-3p and miR-499a-5p were investigated by quantitative real-time RT-PCR. We report differences in the distribution of five miRNAs in the hippocampus between male and female mice, particularly in colonies of Cc2d1a (+/-) mice. Furthermore, the number of miRNAs engaged in the DNA/RNA hybrid fraction is generally higher in the mutant pedigree than in the control group. On the other hand, in sperm, both fractions are at lower levels than in controls. R-loops contribute to the physiology and pathology of organisms including human disease. Here, we report a variation in five miRNA levels between gender and tissue. Our results suggest that the transcription levels of these five miRNAs are directly regulated by their RNA.


Subject(s)
Heterozygote , MicroRNAs , Animals , MicroRNAs/genetics , MicroRNAs/metabolism , Mice , Male , Female , Disease Models, Animal , Autism Spectrum Disorder/genetics , Autism Spectrum Disorder/metabolism , Autistic Disorder/genetics , Autistic Disorder/metabolism , Humans , DNA/genetics , Behavior, Animal
9.
Biomolecules ; 14(9)2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39334951

ABSTRACT

Saccharomyces cerevisiae HMO1 is an architectural nuclear DNA-binding protein that stimulates the activity of some remodelers and regulates the transcription of ribosomal protein genes, often binding to a DNA motif called IFHL. However, the molecular mechanism dictating this sequence specificity is unclear. Our circular dichroism spectroscopy studies show that the HMO1:DNA complex forms without noticeable changes in the structure of DNA and HMO1. Molecular modeling/molecular dynamics studies of the DNA complex with HMO1 Box B reveal two extended sites at the N-termini of helices I and II of Box B that are involved in the formation of the complex and stabilize the DNA bend induced by intercalation of the F114 side chain between base pairs. A comparison of the affinities of HMO1 for 24 bp DNA fragments containing either randomized or IFHL sequences reveals a twofold increase in the stability of the complex in the latter case, which may explain the selectivity in the recognition of the IFHL-containing promoter regions.


Subject(s)
Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae Proteins/chemistry , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae/genetics , Protein Binding , DNA/metabolism , DNA/chemistry , Molecular Dynamics Simulation , DNA, Fungal/metabolism , DNA, Fungal/chemistry , Nucleic Acid Conformation , High Mobility Group Proteins/metabolism , High Mobility Group Proteins/chemistry , High Mobility Group Proteins/genetics , Circular Dichroism
10.
Genes (Basel) ; 15(9)2024 Aug 27.
Article in English | MEDLINE | ID: mdl-39336720

ABSTRACT

To date, studies on microbial forensics have focused mainly on sequence analysis and generally do not include information on the quantification of and comparison between the human and bacterial DNA present in forensic samples. Knowing the amount of each type of DNA can be important for determining when and how best to employ bacterial DNA analysis, especially when there is insufficient human DNA for successful short tandem repeat (STR) typing. The goal of this work was to develop a quantitative PCR (qPCR) assay that simultaneously quantifies human and bacterial DNA that would be simple and cost-effective for laboratories to implement. Through a reproducibility study and several small-scale experiments, the reliability of a custom qPCR assay was established. A reproducibility study illustrated that the multiplex assay produced data comparable to that of previously established bacterial DNA and human DNA qPCR assays. The small-scale experiments showed that common surfaces such as keyboards (6.76 pg/µL), elevator buttons (11.9 pg/µL), cleaning supplies (7.17 pg/µL), and dispensers (16.4 pg/µL) failed to produce human DNA quantities sufficient for quality STR analysis (≥250 pg). However, all tested surfaces produced bacterial DNA quantities suitable for reaching 1 ng of amplified bacterial targets necessary for sequence analysis. In fact, bacterial DNA concentrations down to 10-8 ng/uL produce enough amplified product for sequencing. The newly developed qPCR multiplex tool will allow scientists to make better decisions regarding whether human or bacterial DNA analysis methods can be pursued during forensic or other investigations.


Subject(s)
DNA, Bacterial , Real-Time Polymerase Chain Reaction , Humans , DNA, Bacterial/genetics , Real-Time Polymerase Chain Reaction/methods , Real-Time Polymerase Chain Reaction/standards , Microsatellite Repeats/genetics , Reproducibility of Results , DNA/genetics , Forensic Genetics/methods , Bacteria/genetics , Bacteria/classification , Multiplex Polymerase Chain Reaction/methods
11.
Genes (Basel) ; 15(9)2024 Sep 03.
Article in English | MEDLINE | ID: mdl-39336752

ABSTRACT

R-loops, structures that play a crucial role in various biological processes, are integral to gene expression, the maintenance of genome stability, and the formation of epigenomic signatures. When these R-loops are deregulated, they can contribute to the development of serious health conditions, including cancer and neurodegenerative diseases. The detection of R-loops is a complex process that involves several approaches. These include S9.6 antibody- or RNAse H-based immunoprecipitation, non-denaturing bisulfite footprinting, gel electrophoresis, and electron microscopy. Each of these methods offers unique insights into the nature and behavior of R-loops. In our study, we introduce a novel protocol that has been developed based on a single-molecule DNA combing assay. This innovative approach allows for the direct and simultaneous visualization of RNA:DNA hybrids and replication forks, providing a more comprehensive understanding of these structures. Our findings confirm the transcriptional origin of the hybrids, adding to the body of knowledge about their formation. Furthermore, we demonstrate that these hybrids have an inhibitory effect on the progression of replication forks, highlighting their potential impact on DNA replication and cellular function.


Subject(s)
DNA Replication , DNA , R-Loop Structures , RNA , R-Loop Structures/genetics , DNA Replication/genetics , Humans , DNA/genetics , RNA/genetics , Ribonuclease H/metabolism , Ribonuclease H/genetics
12.
Genes (Basel) ; 15(9)2024 Sep 12.
Article in English | MEDLINE | ID: mdl-39336790

ABSTRACT

The introduction of PCR into forensic science and the rapid increases in the sensitivity, specificity and discrimination power of DNA profiling that followed have been fundamental in shaping the field of forensic biology. Despite these developments, the challenges associated with the DNA profiling of trace, inhibited and degraded samples remain. Thus, any improvement to the performance of sub-optimal samples in DNA profiling would be of great value to the forensic community. The potential exists to optimise the PCR performance of samples by altering the cycling conditions used. If the effects of changing cycling conditions upon the quality of a DNA profile can be well understood, then the PCR process can be manipulated to achieve a specific goal. This work is a proof-of-concept study for the development of a smart PCR system, the theoretical foundations of which are outlined in part 1 of this publication. The first steps needed to demonstrate the performance of our smart PCR goal involved the manual alteration of cycling conditions and assessment of the DNA profiles produced. In this study, the timing and temperature of the denaturation and annealing stages of the PCR were manually altered to achieve the goal of reducing PCR runtime while maintaining an acceptable quality and quantity of DNA product. A real-time feedback system was also trialled using an STR PCR and qPCR reaction mix, and the DNA profiles generated were compared to profiles produced using the standard STR PCR kits. The aim of this work was to leverage machine learning to enable real-time adjustments during a PCR, allowing optimisation of cycling conditions towards predefined user goals. A set of parameters was found that yielded similar results to the standard endpoint PCR methodology but was completed 30 min faster. The development of an intelligent system would have significant implications for the various biological disciplines that are reliant on PCR technology.


Subject(s)
Machine Learning , Polymerase Chain Reaction , Humans , Polymerase Chain Reaction/methods , DNA Fingerprinting/methods , DNA/genetics , Forensic Genetics/methods
13.
Sci Rep ; 14(1): 22465, 2024 Sep 28.
Article in English | MEDLINE | ID: mdl-39341868

ABSTRACT

Hydroxamic acids represent a group of weak organic acids, both naturally occurring and synthetically derived, characterized by the general formula RC(= O)N(R'OH). In this study, we investigated the binding behavior of N-m-tolyl-4-chlorophenoxyaceto hydroxamic acid with calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) through a combination of techniques including UV-visible spectroscopy, fluorescence emission analysis, viscometry, and computational simulations using AutoDock4 software. Our findings reveal that the mode of binding between the compound and the nucleic acids is consistent with intercalation. Competitive binding experiments demonstrated that the complex competes effectively with ethidium bromide (EB) for binding to ct-DNA/t-RNA, displacing EB from its binding sites. Additionally, the introduction of the compound into the DNA-EB system resulted in a quenching of fluorescence emission peaks. Analysis of absorption spectra indicated a red shift and hypochromic shift when the compound interacted with DNA, further supporting the intercalative binding mode. The calculated binding constant (Kb) value for the compound is 6.62 × 104 M-1 and 5.40 × 103 M-1 indicating a strong interaction with ct-DNA and t-RNA respectively. We determined the Stern-Volmer constants for ct-DNA and t-RNA as 9.96 × 104 M-1 and 8.13 × 105 M-1, respectively. The binding free energy values for ct-DNA/t-RNA were calculated to be - 3.741 × 107 and - 5.425 × 108 kcal/mol, respectively. Viscometric studies corroborated the UV results, showing a continuous increase in relative viscosity of ct-DNA/t-RNA solutions with the addition of the optimal hydroxamic acid concentration. Furthermore, we assessed the antioxidant activity of the compound using DPPH-radical scavenging and ß-carotene linoleic acid assays. Gel electrophoresis results demonstrated the compound's remarkable efficacy in preventing DNA damage. Collectively, all experimental evidence supports the conclusion that N-m-tolyl-4-chlorophenoxyaceto hydroxamic acid binds to ct-DNA/t-RNA through an intercalative mechanism, which is consistent with our molecular docking simulations.


Subject(s)
Antioxidants , DNA , Hydroxamic Acids , DNA/metabolism , DNA/chemistry , Antioxidants/chemistry , Antioxidants/pharmacology , Antioxidants/metabolism , Hydroxamic Acids/chemistry , Hydroxamic Acids/pharmacology , Hydroxamic Acids/metabolism , Animals , Cattle , Molecular Docking Simulation , Binding Sites , RNA, Fungal/metabolism , RNA, Fungal/chemistry , Ethidium/metabolism , Ethidium/chemistry , Spectrometry, Fluorescence , Binding, Competitive
14.
Commun Biol ; 7(1): 1202, 2024 Sep 28.
Article in English | MEDLINE | ID: mdl-39341999

ABSTRACT

The human glycosylase OGG1 extrudes and excises the oxidized DNA base 8-oxoguanine (8-oxoG) to initiate base excision repair and plays important roles in many pathological conditions such as cancer, inflammation, and neurodegenerative diseases. Previous structural studies have used a truncated protein and short linear DNA, so it has been unclear how full-length OGG1 operates on longer DNA or on nucleosomes. Here we report cryo-EM structures of human OGG1 bound to a 35-bp long DNA containing an 8-oxoG within an unmethylated Cp-8-oxoG dinucleotide as well as to a nucleosome with an 8-oxoG at super-helical location (SHL)-5. The 8-oxoG in the linear DNA is flipped out by OGG1, consistent with previous crystallographic findings with a 15-bp DNA. OGG1 preferentially binds near dsDNA ends at the nucleosomal entry/exit sites. Such preference may underlie the enzyme's function in DNA double-strand break repair. Unexpectedly, we find that OGG1 bends the nucleosomal entry DNA, flips an undamaged guanine, and binds to internal nucleosomal DNA sites such as SHL-5 and SHL+6. We suggest that the DNA base search mechanism by OGG1 may be chromatin context-dependent and that OGG1 may partner with chromatin remodelers to excise 8-oxoG at the nucleosomal internal sites.


Subject(s)
DNA Glycosylases , DNA , Nucleosomes , DNA Glycosylases/metabolism , DNA Glycosylases/chemistry , Humans , Nucleosomes/metabolism , DNA/metabolism , DNA/chemistry , Protein Binding , Guanine/analogs & derivatives , Guanine/metabolism , DNA Repair , Cryoelectron Microscopy
15.
Int J Mol Sci ; 25(18)2024 Sep 23.
Article in English | MEDLINE | ID: mdl-39337699

ABSTRACT

Here, we employ polymer physics models of chromatin to investigate the 3D folding of a 2 Mb wide genomic region encompassing the human LTN1 gene, a crucial DNA locus involved in key cellular functions. Through extensive Molecular Dynamics simulations, we reconstruct in silico the ensemble of single-molecule LTN1 3D structures, which we benchmark against recent in situ Hi-C 2.0 data. The model-derived single molecules are then used to predict structural folding features at the single-cell level, providing testable predictions for super-resolution microscopy experiments.


Subject(s)
Chromatin , Molecular Dynamics Simulation , Nucleic Acid Conformation , Chromatin/chemistry , Chromatin/genetics , Chromatin/metabolism , Humans , DNA/chemistry , DNA/genetics , Polymers/chemistry
16.
Sensors (Basel) ; 24(18)2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39338832

ABSTRACT

Laser and molecular detection techniques that have been used to overcome the limitations of fluorescent DNA labeling have presented new challenges. To address some of these challenges, we developed a DNA laser that uses a solid-state silica microsphere as a ring resonator and a site for DNA-binding reactions, as well as a platform to detect and sequence target DNA molecules. We detected target DNA using laser emission from a DNA-labeling dye and a developed solid-state silica microsphere ring resonator. The microsphere was sensitive; a single base mismatch in the DNA resulted in the absence of an optical signal. As each individual microsphere can be utilized as a parallel DNA analysis chamber, this optical digital detection scheme allows for high-throughput and rapid analysis. More importantly, the solid-state DNA laser is free from deformation, which guarantees stable lasing characteristics, and can be manipulated freely outside the solution. Thus, this promising advanced DNA laser scheme can be implemented on platforms other than optofluidic chips.


Subject(s)
DNA , Lasers , Microspheres , Silicon Dioxide , Silicon Dioxide/chemistry , DNA/chemistry , DNA/analysis , Biosensing Techniques/methods , Biosensing Techniques/instrumentation , Fluorescent Dyes/chemistry
17.
Sensors (Basel) ; 24(18)2024 Sep 23.
Article in English | MEDLINE | ID: mdl-39338884

ABSTRACT

Direct detection of miRNA is currently limited by the complex amplification and reverse transcription processes of existing methods, leading to low sensitivity and high operational demands. Herein, we developed a CRISPR/Cas13a-mediated photoelectrochemical (PEC) biosensing platform for direct and sensitive detection of miRNA-21. The direct and specific recognition of target miRNA-21 by crRNA-21 eliminates the need for pre-amplification and reverse transcription of miRNA-21, thereby preventing signal distortion and enhancing the sensitivity and precision of target detection. When crRNA-21 binds to miRNA-21, it activates the trans-cleavage activity of CRISPR/Cas13a, leading to the non-specific cleavage of biotin-modified DNA with uracil bases (biotin-rU-DNA). This cleavage prevents the biotin-rU-DNA from being immobilized on the electrode surface. As a result, streptavidin cannot attach to the electrode via specific biotin binding, reducing spatial resistance and causing a positively correlated increase in the photocurrent response. This Cas-PEC biosensor has good analytical capabilities, linear responses between 10 fM and 10 nM, a minimum detection limit of 9 fM, and an excellent recovery rate in the analysis of real human serum samples. This work presented an innovative solution for detecting other biomarkers in bioanalysis and clinical diagnostics.


Subject(s)
Biosensing Techniques , CRISPR-Cas Systems , Electrochemical Techniques , MicroRNAs , Biosensing Techniques/methods , MicroRNAs/blood , MicroRNAs/analysis , MicroRNAs/genetics , Electrochemical Techniques/methods , Humans , Limit of Detection , Biotin/chemistry , DNA/chemistry , DNA/genetics , Electrodes
18.
Molecules ; 29(18)2024 Sep 13.
Article in English | MEDLINE | ID: mdl-39339356

ABSTRACT

DNA structure has many potential places where endogenous compounds and xenobiotics can bind. Therefore, xenobiotics bind along the sites of the nucleic acid with the aim of changing its structure, its genetic message, and, implicitly, its functions. Currently, there are several mechanisms known to be involved in DNA binding. These mechanisms are covalent and non-covalent interactions. The covalent interaction or metal base coordination is an irreversible binding and it is represented by an intra-/interstrand cross-link. The non-covalent interaction is generally a reversible binding and it is represented by intercalation between DNA base pairs, insertion, major and/or minor groove binding, and electrostatic interactions with the sugar phosphate DNA backbone. In the present review, we focus on the types of DNA-metal complex interactions (including some representative examples) and on presenting the methods currently used to study them.


Subject(s)
DNA , Metals , DNA/chemistry , Metals/chemistry , Nucleic Acid Conformation , Humans , Xenobiotics/chemistry
19.
Molecules ; 29(18)2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39339453

ABSTRACT

The dynamic landscape of non-canonical DNA G-quadruplex (G4) folding into G-triplex intermediates has led to the study of G-triplex structures and their ability to serve as peroxidase-mimetic DNAzymes. Here we report the formation, stability, and catalytic activity of a 5'-truncated c-MYC promoter region G-triplex, c-MYC-G3. Through circular dichroism, we demonstrated that c-MYC-G3 adopts a stable, parallel-stranded G-triplex conformation. The chemiluminescent oxidation of luminol by the peroxidase mimicking DNAzyme activity of c-MYC-G3 was increased in the presence of Ca2+ ions. We utilized surface plasmon resonance to characterize both c-MYC-G3 G-triplex formation and its interaction with hemin. The detailed study of c-MYC-G3 and its ability to form a G-triplex structure and its DNAzyme activity identifies issues that can be addressed in future G-triplex DNAzyme designs.


Subject(s)
Calcium , DNA, Catalytic , DNA , Luminescence , Promoter Regions, Genetic , Calcium/metabolism , Calcium/chemistry , DNA, Catalytic/chemistry , DNA, Catalytic/metabolism , DNA, Catalytic/genetics , DNA/chemistry , Catalysis , Proto-Oncogene Proteins c-myc/genetics , G-Quadruplexes , Circular Dichroism , Humans , Luminol/chemistry , Oxidation-Reduction , Hemin/chemistry , Nucleic Acid Conformation
20.
Molecules ; 29(18)2024 Sep 21.
Article in English | MEDLINE | ID: mdl-39339485

ABSTRACT

In this study, a turn-on fluorescence sensor for the detection of adenosine 5'-triphosphate (ATP) was developed and tested using ATP-DNA2-Ag NCs. The results showed that the fluorescence of ATP-DNA2-Ag NCs was significantly enhanced with the addition of ATP. The fluorescence enhancement was a result of the specific binding activity of the ATP aptamer and ATP, which caused G-rich sequences to approach the dark DNA-Ag NCs, owing to the alteration in ATP aptamer conformation. The proposed sensor demonstrated a good linear range of 18-42 mM and a limit of detection (LOD) of 2.8 µM. The sensor's features include sensitivity, selectivity, and simple operation. In addition, the proposed sensor successfully measured ATP in 100-fold diluted fetal bovine serum.


Subject(s)
Adenosine Triphosphate , Aptamers, Nucleotide , Biosensing Techniques , DNA , Metal Nanoparticles , Silver , Spectrometry, Fluorescence , Adenosine Triphosphate/analysis , Adenosine Triphosphate/chemistry , Silver/chemistry , Biosensing Techniques/methods , Metal Nanoparticles/chemistry , DNA/chemistry , Aptamers, Nucleotide/chemistry , Spectrometry, Fluorescence/methods , Limit of Detection , Fluorescence , Animals , Cattle
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