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Proceedings of the National Academy of... Nov 2023is a zoonotic protist pathogen that infects up to one third of the human population. This apicomplexan parasite contains three genome sequences: nuclear (65 Mb);...
is a zoonotic protist pathogen that infects up to one third of the human population. This apicomplexan parasite contains three genome sequences: nuclear (65 Mb); plastid organellar, ptDNA (35 kb); and mitochondrial organellar, mtDNA (5.9 kb of non-repetitive sequence). We find that the nuclear genome contains a significant amount of NUMTs (nuclear integrants of mitochondrial DNA) and NUPTs (nuclear integrants of plastid DNA) that are continuously acquired and represent a significant source of intraspecific genetic variation. NUOT (nuclear DNA of organellar origin) accretion has generated 1.6% of the extant ME49 nuclear genome-the highest fraction ever reported in any organism. NUOTs are primarily found in organisms that retain the non-homologous end-joining repair pathway. Significant movement of organellar DNA was experimentally captured via amplicon sequencing of a CRISPR-induced double-strand break in non-homologous end-joining repair competent, but not mutant, parasites. Comparisons with , a species that diverged from ~28 mya, revealed that the movement and fixation of five NUMTs predates the split of the two genera. This unexpected level of NUMT conservation suggests evolutionary constraint for cellular function. Most NUMT insertions reside within (60%) or nearby genes (23% within 1.5 kb), and reporter assays indicate that some NUMTs have the ability to function as -regulatory elements modulating gene expression. Together, these findings portray a role for organellar sequence insertion in dynamically shaping the genomic architecture and likely contributing to adaptation and phenotypic changes in this important human pathogen.
Topics: Humans; Toxoplasma; Genome; DNA, Mitochondrial; Mitochondria; Evolution, Molecular; Cell Nucleus; Sequence Analysis, DNA
PubMed: 37917792
DOI: 10.1073/pnas.2308569120 -
British Journal of Cancer Mar 2020Effective DNA repair is essential for cell survival: a failure to correctly repair damage leads to the accumulation of mutations and is the driving force for... (Review)
Review
Effective DNA repair is essential for cell survival: a failure to correctly repair damage leads to the accumulation of mutations and is the driving force for carcinogenesis. Multiple pathways have evolved to protect against both intrinsic and extrinsic genotoxic events, and recent developments have highlighted an unforeseen critical role for RNA in ensuring genome stability. It is currently unclear exactly how RNA molecules participate in the repair pathways, although many models have been proposed and it is possible that RNA acts in diverse ways to facilitate DNA repair. A number of well-documented DNA repair factors have been described to have RNA-binding capacities and, moreover, screens investigating DNA-damage repair mechanisms have identified RNA-binding proteins as a major group of novel factors involved in DNA repair. In this review, we integrate some of these datasets to identify commonalities that might highlight novel and interesting factors for future investigations. This emerging role for RNA opens up a new dimension in the field of DNA repair; we discuss its impact on our current understanding of DNA repair processes and consider how it might influence cancer progression.
Topics: Animals; DNA; DNA Breaks, Double-Stranded; DNA Repair; Humans; RNA
PubMed: 31894141
DOI: 10.1038/s41416-019-0624-1 -
Biomolecules Aug 2018Molecular modeling by means of docking and molecular dynamics (MD) has become an integral part of early drug discovery projects, enabling the screening and enrichment of... (Review)
Review
Molecular modeling by means of docking and molecular dynamics (MD) has become an integral part of early drug discovery projects, enabling the screening and enrichment of large libraries of small molecules. In the past decades, special emphasis was drawn to nucleic acid (NA)-based molecules in the fields of therapy, diagnosis, and drug delivery. Research has increased dramatically with the advent of the SELEX (systematic evolution of ligands by exponential enrichment) technique, which results in single-stranded DNA or RNA sequences that bind with high affinity and specificity to their targets. Herein, we discuss the role and contribution of docking and MD to the development and optimization of new nucleic acid-based molecules. This review focuses on the different approaches currently available for molecular modeling applied to NA interaction with proteins. We discuss topics ranging from structure prediction to docking and MD, highlighting their main advantages and limitations and the influence of flexibility on their calculations.
Topics: Animals; DNA; Drug Discovery; Humans; Models, Molecular; RNA
PubMed: 30150587
DOI: 10.3390/biom8030083 -
Molecular Cell Nov 2022Adaptation in CRISPR-Cas systems immunizes bacteria and archaea against mobile genetic elements. In many DNA-targeting systems, the Cas4-Cas1-Cas2 complex is required...
Adaptation in CRISPR-Cas systems immunizes bacteria and archaea against mobile genetic elements. In many DNA-targeting systems, the Cas4-Cas1-Cas2 complex is required for selection and processing of DNA segments containing PAM sequences prior to integration of these "prespacer" substrates as spacers in the CRISPR array. We determined cryo-EM structures of the Cas4-Cas1-Cas2 adaptation complex from the type I-C system that encodes standalone Cas1 and Cas4 proteins. The structures reveal how Cas4 specifically reads out bases within the PAM sequence and how interactions with both Cas1 and Cas2 activate Cas4 endonuclease activity. The Cas4-PAM interaction ensures tight binding between the adaptation complex and the prespacer, significantly enhancing integration of the non-PAM end into the CRISPR array and ensuring correct spacer orientation. Corroborated with our biochemical results, Cas4-Cas1-Cas2 structures with substrates representing various stages of CRISPR adaptation reveal a temporally resolved mechanism for maturation and integration of functional spacers into the CRISPR array.
Topics: CRISPR-Associated Proteins; CRISPR-Cas Systems; DNA
PubMed: 36272411
DOI: 10.1016/j.molcel.2022.09.030 -
Methods in Enzymology 2017DNA damage outcomes depend upon the efficiency and fidelity of DNA damage responses (DDRs) for different cells and damage. As such, DDRs represent tightly regulated... (Review)
Review
DNA damage outcomes depend upon the efficiency and fidelity of DNA damage responses (DDRs) for different cells and damage. As such, DDRs represent tightly regulated prototypical systems for linking nanoscale biomolecular structure and assembly to the biology of genomic regulation and cell signaling. However, the dynamic and multifunctional nature of DDR assemblies can render elusive the correlation between the structures of DDR factors and specific biological disruptions to the DDR when these structures are altered. In this chapter, we discuss concepts and strategies for combining structural, biophysical, and imaging techniques to investigate DDR recognition and regulation, and thus bridge sequence-level structural biochemistry to quantitative biological outcomes visualized in cells. We focus on representative DDR responses from PARP/PARG/AIF damage signaling in DNA single-strand break repair and nonhomologous end joining complexes in double-strand break repair. Methods with exemplary experimental results are considered with a focus on strategies for probing flexibility, conformational changes, and assembly processes that shape a predictive understanding of DDR mechanisms in a cellular context. Integration of structural and imaging measurements promises to provide foundational knowledge to rationally control and optimize DNA damage outcomes for synthetic lethality and for immune activation with resulting insights for biology and cancer interventions.
Topics: Animals; Apoptosis Inducing Factor; Cryoelectron Microscopy; Crystallography, X-Ray; DNA; DNA Damage; DNA Repair; Genomic Instability; Glycoside Hydrolases; Humans; Microscopy, Fluorescence; Models, Molecular; Neoplasms; Optical Imaging; Poly(ADP-ribose) Polymerases; Signal Transduction
PubMed: 28668129
DOI: 10.1016/bs.mie.2017.04.005 -
Molecular Cell May 2022Next-generation sequencing techniques have led to a new quantitative dimension in the biological sciences. In particular, integrating sequencing techniques with... (Review)
Review
Next-generation sequencing techniques have led to a new quantitative dimension in the biological sciences. In particular, integrating sequencing techniques with biophysical tools allows sequence-dependent mechanistic studies. Using the millions of DNA clusters that are generated during sequencing to perform high-throughput binding affinity and kinetics measurements enabled the construction of energy landscapes in sequence space, uncovering relationships between sequence, structure, and function. Here, we review the approaches to perform ensemble fluorescence experiments on next-generation sequencing chips for variations of DNA, RNA, and protein sequences. As the next step, we anticipate that these fluorescence experiments will be pushed to the single-molecule level, which can directly uncover kinetics and molecular heterogeneity in an unprecedented high-throughput fashion. Molecular biophysics in sequence space, both at the ensemble and single-molecule level, leads to new mechanistic insights. The wide spectrum of applications in biology and medicine ranges from the fundamental understanding of evolutionary pathways to the development of new therapeutics.
Topics: Biophysics; DNA; High-Throughput Nucleotide Sequencing; Molecular Biology; Sequence Analysis, DNA
PubMed: 35561688
DOI: 10.1016/j.molcel.2022.04.024 -
Lab on a Chip Mar 2018Long-read genomic applications, such as genome mapping in nanochannels, require long DNA that is free of small-DNA impurities. We have developed a chip-based system...
Long-read genomic applications, such as genome mapping in nanochannels, require long DNA that is free of small-DNA impurities. We have developed a chip-based system based on entropic trapping that can simultaneously concentrate and purify a long DNA sample under the alternating application of an applied pressure (for sample injection) and an electric field (for filtration and concentration). In contrast, short DNA tends to pass through the filter owing to its comparatively weak entropic penalty for entering the nanoslit. The single-stage prototype developed here, which operates in a continuous pulsatile manner, achieves selectivities of up to 3.5 for λ-phage DNA (48.5 kilobase pairs) compared to a 2 kilobase pair standard based on experimental data for the fraction filtered using pure samples of each species. The device is fabricated in fused silica using standard clean-room methods, making it compatible for integration with long-read genomics technologies.
Topics: Bacteriophage lambda; DNA; Entropy
PubMed: 29469139
DOI: 10.1039/c7lc01355h -
BMC Medical Genomics Jun 2022Hepatitis B virus (HBV) related hepatocellular carcinoma (HCC) is heterogeneous and frequently contains multifocal tumors, but how the multifocal tumors relate to each...
BACKGROUND
Hepatitis B virus (HBV) related hepatocellular carcinoma (HCC) is heterogeneous and frequently contains multifocal tumors, but how the multifocal tumors relate to each other in terms of HBV integration and other genomic patterns is not clear.
METHODS
To interrogate heterogeneity of HBV-HCC, we developed a HBV genome enriched single cell sequencing (HGE-scSeq) procedure and a computational method to identify HBV integration sites and infer DNA copy number variations (CNVs).
RESULTS
We performed HGE-scSeq on 269 cells from four tumor sites and two tumor thrombi of a HBV-HCC patient. HBV integrations were identified in 142 out of 269 (53%) cells sequenced, and were enriched in two HBV integration hotspots chr1:34,397,059 (CSMD2) and chr8:118,557,327 (MED30/EXT1). There were also 162 rare integration sites. HBV integration sites were enriched in DNA fragile sites and sequences around HBV integration sites were enriched for microhomologous sequences between human and HBV genomes. CNVs were inferred for each individual cell and cells were grouped into four clonal groups based on their CNVs. Cells in different clonal groups had different degrees of HBV integration heterogeneity. All of 269 cells carried chromosome 1q amplification, a recurrent feature of HCC tumors, suggesting that 1q amplification occurred before HBV integration events in this case study. Further, we performed simulation studies to demonstrate that the sequential events (HBV infecting transformed cells) could result in the observed phenotype with biologically reasonable parameters.
CONCLUSION
Our HGE-scSeq data reveals high heterogeneity of HCC tumor cells in terms of both HBV integrations and CNVs. There were two HBV integration hotspots across cells, and cells from multiple tumor sites shared some HBV integration and CNV patterns.
Topics: Carcinoma, Hepatocellular; DNA Copy Number Variations; DNA, Viral; Hepatitis B virus; Humans; Liver Neoplasms; Virus Integration
PubMed: 35710421
DOI: 10.1186/s12920-022-01264-2 -
Viruses Apr 2017Long terminal repeat (LTR) retrotransposons occupy a special place among all mobile genetic element families. The structure of LTR retrotransposons that have three open... (Review)
Review
Long terminal repeat (LTR) retrotransposons occupy a special place among all mobile genetic element families. The structure of LTR retrotransposons that have three open reading frames is identical to DNA forms of retroviruses that are integrated into the host genome. Several lines of evidence suggest that LTR retrotransposons share a common ancestry with retroviruses and thus are highly relevant to understanding mechanisms of transposition. Drosophila melanogaster is an exceptionally convenient model for studying the mechanisms of retrotransposon movement because many such elements in its genome are transpositionally active. Moreover, two LTRretrotransposons of D. melanogaster, gypsy and ZAM, have been found to have infectious properties and have been classified as errantiviruses. Despite numerous studies focusing on retroviral integration process, there is still no clear understanding of integration specificity in a target site. Most LTR retrotransposons non-specifically integrate into a target site. Site-specificity of integration at vertebrate retroviruses is rather relative. At the same time, sequence-specific integration is the exclusive property of errantiviruses and their derivatives with two open reading frames. The possible basis for the errantivirus integration specificity is discussed in the present review.
Topics: Animals; Drosophila melanogaster; Open Reading Frames; Recombination, Genetic; Retroelements; Retroviridae; Terminal Repeat Sequences; Transcription, Genetic; Virus Integration
PubMed: 28420154
DOI: 10.3390/v9040081 -
Sensors (Basel, Switzerland) Jan 2023This systematic review describes and discusses three commercially available integrated systems for forensic DNA analysis, i.e., ParaDNA, RapidHIT, and ANDE. A variety of... (Review)
Review
This systematic review describes and discusses three commercially available integrated systems for forensic DNA analysis, i.e., ParaDNA, RapidHIT, and ANDE. A variety of aspects, such as performance, time-to-result, ease-of-use, portability, and costs (per analysis run) of these three (modified) rapid DNA analysis systems, are considered. Despite their advantages and developmental progress, major steps still have to be made before rapid systems can be broadly applied at crime scenes for full DNA profiling. Aspects in particular that need (further) improvement are portability, performance, the possibility to analyze a (wider) variety of (complex) forensic samples, and (cartridge) costs. Moreover, steps forward regarding ease-of-use and time-to-result will benefit the broader use of commercial rapid DNA systems. In fact, it would be a profit if rapid DNA systems could be used for full DNA profile generation as well as indicative analyses that can give direction to forensic investigators which will speed up investigations.
Topics: Forensic Genetics; Microsatellite Repeats; Polymerase Chain Reaction; DNA Fingerprinting; DNA
PubMed: 36772114
DOI: 10.3390/s23031075