1
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Webb JA, Farrow E, Cain B, Yuan Z, Yarawsky A, Schoch E, Gagliani E, Herr A, Gebelein B, Kovall R. Cooperative Gsx2-DNA binding requires DNA bending and a novel Gsx2 homeodomain interface. Nucleic Acids Res 2024; 52:7987-8002. [PMID: 38874471 PMCID: PMC11260452 DOI: 10.1093/nar/gkae522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 05/28/2024] [Accepted: 06/05/2024] [Indexed: 06/15/2024] Open
Abstract
The conserved Gsx homeodomain (HD) transcription factors specify neural cell fates in animals from flies to mammals. Like many HD proteins, Gsx factors bind A/T-rich DNA sequences prompting the following question: How do HD factors that bind similar DNA sequences in vitro regulate specific target genes in vivo? Prior studies revealed that Gsx factors bind DNA both as a monomer on individual A/T-rich sites and as a cooperative homodimer to two sites spaced precisely 7 bp apart. However, the mechanistic basis for Gsx-DNA binding and cooperativity is poorly understood. Here, we used biochemical, biophysical, structural and modeling approaches to (i) show that Gsx factors are monomers in solution and require DNA for cooperative complex formation, (ii) define the affinity and thermodynamic binding parameters of Gsx2/DNA interactions, (iii) solve a high-resolution monomer/DNA structure that reveals that Gsx2 induces a 20° bend in DNA, (iv) identify a Gsx2 protein-protein interface required for cooperative DNA binding and (v) determine that flexible spacer DNA sequences enhance Gsx2 cooperativity on dimer sites. Altogether, our results provide a mechanistic basis for understanding the protein and DNA structural determinants that underlie cooperative DNA binding by Gsx factors.
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Affiliation(s)
- Jordan A Webb
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Edward Farrow
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children’s Hospital Research Foundation, Cincinnati, OH 45229, USA
- Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Brittany Cain
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7007, Cincinnati, OH 45229, USA
| | - Zhenyu Yuan
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Alexander E Yarawsky
- Division of Immunobiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Emma Schoch
- Department of Medical Education, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Ellen K Gagliani
- Department of Chemistry, Xavier University, Cincinnati, OH 45207, USA
| | - Andrew B Herr
- Division of Immunobiology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7007, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Rhett A Kovall
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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2
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Foster MP, Benedek MJ, Billings TD, Montgomery JS. Dynamics in Cre-loxP site-specific recombination. Curr Opin Struct Biol 2024; 88:102878. [PMID: 39029281 DOI: 10.1016/j.sbi.2024.102878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/15/2024] [Accepted: 06/17/2024] [Indexed: 07/21/2024]
Abstract
Cre recombinase is a phage-derived enzyme that has found utility for precise manipulation of DNA sequences. Cre recognizes and recombines pairs of loxP sequences characterized by an inverted repeat and asymmetric spacer. Cre cleaves and religates its DNA targets such that error-prone repair pathways are not required to generate intact DNA products. Major obstacles to broader applications are lack of knowledge of how Cre recognizes its targets, and how its activity is controlled. The picture emerging from high resolution methods is that the dynamic properties of both the enzyme and its DNA target are important determinants of its activity in both sequence recognition and DNA cleavage. Improved understanding of the role of dynamics in the key steps along the pathway of Cre-loxP recombination should significantly advance our ability to both redirect Cre to new sequences and to control its DNA cleavage activity in the test tube and in cells.
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Affiliation(s)
- Mark P Foster
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
| | - Matthew J Benedek
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Tyler D Billings
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Jonathan S Montgomery
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
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3
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Silva EC, Quinde CA, Cieza B, Basu A, Vila MMDC, Balcão VM. Molecular Characterization and Genome Mechanical Features of Two Newly Isolated Polyvalent Bacteriophages Infecting Pseudomonas syringae pv. garcae. Genes (Basel) 2024; 15:113. [PMID: 38255005 PMCID: PMC10815195 DOI: 10.3390/genes15010113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 01/06/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024] Open
Abstract
Coffee plants have been targeted by a devastating bacterial disease, a condition known as bacterial blight, caused by the phytopathogen Pseudomonas syringae pv. garcae (Psg). Conventional treatments of coffee plantations affected by the disease involve frequent spraying with copper- and kasugamycin-derived compounds, but they are both highly toxic to the environment and stimulate the appearance of bacterial resistance. Herein, we report the molecular characterization and mechanical features of the genome of two newly isolated (putative polyvalent) lytic phages for Psg. The isolated phages belong to class Caudoviricetes and present a myovirus-like morphotype belonging to the genuses Tequatrovirus (PsgM02F) and Phapecoctavirus (PsgM04F) of the subfamilies Straboviridae (PsgM02F) and Stephanstirmvirinae (PsgM04F), according to recent bacterial viruses' taxonomy, based on their complete genome sequences. The 165,282 bp (PsgM02F) and 151,205 bp (PsgM04F) genomes do not feature any lysogenic-related (integrase) genes and, hence, can safely be assumed to follow a lytic lifestyle. While phage PsgM02F produced a morphogenesis yield of 124 virions per host cell, phage PsgM04F produced only 12 virions per host cell, indicating that they replicate well in Psg with a 50 min latency period. Genome mechanical analyses established a relationship between genome bendability and virion morphogenesis yield within infected host cells.
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Affiliation(s)
- Erica C. Silva
- VBlab—Laboratory of Bacterial Viruses, University of Sorocaba, Sorocaba 18023-000, SP, Brazil; (E.C.S.); (M.M.D.C.V.)
| | - Carlos A. Quinde
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA;
| | - Basilio Cieza
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA;
| | - Aakash Basu
- Department of Biosciences, Durham University, Durham DH1 3LE, UK;
| | - Marta M. D. C. Vila
- VBlab—Laboratory of Bacterial Viruses, University of Sorocaba, Sorocaba 18023-000, SP, Brazil; (E.C.S.); (M.M.D.C.V.)
| | - Victor M. Balcão
- VBlab—Laboratory of Bacterial Viruses, University of Sorocaba, Sorocaba 18023-000, SP, Brazil; (E.C.S.); (M.M.D.C.V.)
- Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, P-3810-193 Aveiro, Portugal
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4
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Webb JA, Farrow E, Cain B, Yuan Z, Yarawsky AE, Schoch E, Gagliani EK, Herr AB, Gebelein B, Kovall RA. Cooperative Gsx2-DNA Binding Requires DNA Bending and a Novel Gsx2 Homeodomain Interface. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570805. [PMID: 38106145 PMCID: PMC10723402 DOI: 10.1101/2023.12.08.570805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The conserved Gsx homeodomain (HD) transcription factors specify neural cell fates in animals from flies to mammals. Like many HD proteins, Gsx factors bind A/T-rich DNA sequences prompting the question - how do HD factors that bind similar DNA sequences in vitro regulate specific target genes in vivo? Prior studies revealed that Gsx factors bind DNA both as a monomer on individual A/T-rich sites and as a cooperative homodimer to two sites spaced precisely seven base pairs apart. However, the mechanistic basis for Gsx DNA binding and cooperativity are poorly understood. Here, we used biochemical, biophysical, structural, and modeling approaches to (1) show that Gsx factors are monomers in solution and require DNA for cooperative complex formation; (2) define the affinity and thermodynamic binding parameters of Gsx2/DNA interactions; (3) solve a high-resolution monomer/DNA structure that reveals Gsx2 induces a 20° bend in DNA; (4) identify a Gsx2 protein-protein interface required for cooperative DNA binding; and (5) determine that flexible spacer DNA sequences enhance Gsx2 cooperativity on dimer sites. Altogether, our results provide a mechanistic basis for understanding the protein and DNA structural determinants that underlie cooperative DNA binding by Gsx factors, thereby providing a deeper understanding of HD specificity.
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Affiliation(s)
- Jordan A. Webb
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Edward Farrow
- Graduate Program in Molecular and Developmental Biology, Cincinnati Children’s Hospital Research Foundation, Cincinnati, OH 45229, USA
- Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Brittany Cain
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, MLC 7007, Cincinnati, OH 45229, USA
| | - Zhenyu Yuan
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Alexander E. Yarawsky
- Division of Immunobiology, Cincinnati Children’s Hospital Medical Center, 3333, Burnet Ave, Cincinnati, OH 45229, USA
| | - Emma Schoch
- Department of Medical Education, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Ellen K. Gagliani
- Department of Chemistry, Xavier University, Cincinnati, OH 45207, USA
| | - Andrew B. Herr
- Division of Immunobiology, Cincinnati Children’s Hospital Medical Center, 3333, Burnet Ave, Cincinnati, OH 45229, USA
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, MLC 7007, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Rhett A. Kovall
- Department of Molecular and Cellular Biosciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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5
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Chen J, Lu J, Liu J, Fang J, Zhong X, Song J. DNA conformational dynamics in the context-dependent non-CG CHH methylation by plant methyltransferase DRM2. J Biol Chem 2023; 299:105433. [PMID: 37926286 PMCID: PMC10711165 DOI: 10.1016/j.jbc.2023.105433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/05/2023] [Accepted: 10/29/2023] [Indexed: 11/07/2023] Open
Abstract
DNA methylation provides an important epigenetic mechanism that critically regulates gene expression, genome imprinting, and retrotransposon silencing. In plants, DNA methylation is prevalent not only in a CG dinucleotide context but also in non-CG contexts, namely CHG and CHH (H = C, T, or A) methylation. It has been established that plant non-CG DNA methylation is highly context dependent, with the +1- and +2-flanking sequences enriched with A/T nucleotides. How DNA sequence, conformation, and dynamics influence non-CG methylation remains elusive. Here, we report structural and biochemical characterizations of the intrinsic substrate preference of DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2), a plant DNA methyltransferase responsible for establishing all cytosine methylation and maintaining CHH methylation. Among nine CHH motifs, the DRM2 methyltransferase (MTase) domain shows marked substrate preference toward CWW (W = A or T) motifs, correlating well with their relative abundance in planta. Furthermore, we report the crystal structure of DRM2 MTase in complex with a DNA duplex containing a flexible TpA base step at the +1/+2-flanking sites of the target nucleotide. Comparative structural analysis of the DRM2-DNA complexes provides a mechanism by which flanking nucleotide composition impacts DRM2-mediated DNA methylation. Furthermore, the flexibility of the TpA step gives rise to two alternative DNA conformations, resulting in different interactions with DRM2 and consequently temperature-dependent shift of the substrate preference of DRM2. Together, this study provides insights into how the interplay between the conformational dynamics of DNA and temperature as an environmental factor contributes to the context-dependent CHH methylation by DRM2.
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Affiliation(s)
- Jianbin Chen
- Department of Biochemistry, University of California, Riverside, California, USA
| | - Jiuwei Lu
- Department of Biochemistry, University of California, Riverside, California, USA
| | - Jie Liu
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jian Fang
- Department of Biochemistry, University of California, Riverside, California, USA
| | - Xuehua Zhong
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jikui Song
- Department of Biochemistry, University of California, Riverside, California, USA.
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6
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Back G, Walther D. Predictions of DNA mechanical properties at a genomic scale reveal potentially new functional roles of DNA flexibility. NAR Genom Bioinform 2023; 5:lqad097. [PMID: 37954573 PMCID: PMC10632188 DOI: 10.1093/nargab/lqad097] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 09/28/2023] [Accepted: 10/25/2023] [Indexed: 11/14/2023] Open
Abstract
Mechanical properties of DNA have been implied to influence many of its biological functions. Recently, a new high-throughput method, called loop-seq, which allows measuring the intrinsic bendability of DNA fragments, has been developed. Using loop-seq data, we created a deep learning model to explore the biological significance of local DNA flexibility in a range of different species from different kingdoms. Consistently, we observed a characteristic and largely dinucleotide-composition-driven change of local flexibility near transcription start sites. In the presence of a TATA-box, a pronounced peak of high flexibility can be observed. Furthermore, depending on the transcription factor investigated, flanking-sequence-dependent DNA flexibility was identified as a potential factor influencing DNA binding. Compared to randomized genomic sequences, depending on species and taxa, actual genomic sequences were observed both with increased and lowered flexibility. Furthermore, in Arabidopsis thaliana, mutation rates, both de novo and fixed, were found to be associated with relatively rigid sequence regions. Our study presents a range of significant correlations between characteristic DNA mechanical properties and genomic features, the significance of which with regard to detailed molecular relevance awaits further theoretical and experimental exploration.
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Affiliation(s)
- Georg Back
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Dirk Walther
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
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7
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Ghoshdastidar D, Bansal M. Flexibility of flanking DNA is a key determinant of transcription factor affinity for the core motif. Biophys J 2022; 121:3987-4000. [PMID: 35978548 PMCID: PMC9674967 DOI: 10.1016/j.bpj.2022.08.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/28/2022] [Accepted: 08/15/2022] [Indexed: 11/02/2022] Open
Abstract
Selective gene regulation is mediated by recognition of specific DNA sequences by transcription factors (TFs). The extremely challenging task of searching out specific cognate DNA binding sites among several million putative sites within the eukaryotic genome is achieved by complex molecular recognition mechanisms. Elements of this recognition code include the core binding sequence, the flanking sequence context, and the shape and conformational flexibility of the composite binding site. To unravel the extent to which DNA flexibility modulates TF binding, in this study, we employed experimentally guided molecular dynamics simulations of ternary complex of closely related Hox heterodimers Exd-Ubx and Exd-Scr with DNA. Results demonstrate that flexibility signatures embedded in the flanking sequences impact TF binding at the cognate binding site. A DNA sequence has intrinsic shape and flexibility features. While shape features are localized, our analyses reveal that flexibility features of the flanking sequences percolate several basepairs and allosterically modulate TF binding at the core. We also show that lack of flexibility in the motif context can render the cognate site resistant to protein-induced shape changes and subsequently lower TF binding affinity. Overall, this study suggests that flexibility-guided DNA shape, and not merely the static shape, is a key unexplored component of the complex DNA-TF recognition code.
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Affiliation(s)
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India.
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8
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Evolutionary Invariant of the Structure of DNA Double Helix in RNAP II Core Promoters. Int J Mol Sci 2022; 23:ijms231810873. [PMID: 36142782 PMCID: PMC9504043 DOI: 10.3390/ijms231810873] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/07/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Eukaryotic and archaeal RNA polymerase II (POL II) machinery is highly conserved, regardless of the extreme changes in promoter sequences in different organisms. The goal of our work is to find the cause of this conservatism. The representative sets of aligned promoter sequences of fifteen organisms belonging to different evolutional stages were studied. Their textual profiles, as well as profiles of the indexes that characterize the secondary structure and the mechanical and physicochemical properties, were analyzed. The evolutionarily stable, extremely heterogeneous special secondary structure of POL II core promoters was revealed, which includes two singular regions—hexanucleotide “INR” around TSS and octanucleotide “TATA element” of about −28 bp upstream. Such structures may have developed at some stage of evolution. It turned out to be so well matched for the pre-initiation complex formation and the subsequent initiation of transcription for POL II machinery that in the course of evolution there were selected only those nucleotide sequences that were able to reproduce these structural properties. The individual features of specific sequences representing the singular region of the promoter of each gene can affect the kinetics of DNA-protein complex formation and facilitate strand separation in double-stranded DNA at the TSS position.
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9
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Rohac R, Crack JC, de Rosny E, Gigarel O, Le Brun NE, Fontecilla-Camps JC, Volbeda A. Structural determinants of DNA recognition by the NO sensor NsrR and related Rrf2-type [FeS]-transcription factors. Commun Biol 2022; 5:769. [PMID: 35908109 PMCID: PMC9338935 DOI: 10.1038/s42003-022-03745-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/21/2022] [Indexed: 11/20/2022] Open
Abstract
Several transcription factors of the Rrf2 family use an iron-sulfur cluster to regulate DNA binding through effectors such as nitric oxide (NO), cellular redox status and iron levels. [4Fe-4S]-NsrR from Streptomyces coelicolor (ScNsrR) modulates expression of three different genes via reaction and complex formation with variable amounts of NO, which results in detoxification of this gas. Here, we report the crystal structure of ScNsrR complexed with an hmpA1 gene operator fragment and compare it with those previously reported for [2Fe-2S]-RsrR/rsrR and apo-IscR/hyA complexes. Important structural differences reside in the variation of the DNA minor and major groove widths. In addition, different DNA curvatures and different interactions with the protein sensors are observed. We also report studies of NsrR binding to four hmpA1 variants, which indicate that flexibility in the central region is not a key binding determinant. Our study explores the promotor binding specificities of three closely related transcriptional regulators. The crystal structure of the iron-sulfur protein NsrR from Streptomyces coelicolor bound to a gene operator fragment is reported and compared with other structures, giving insight into the structural determinants of DNA recognition by the NO sensor.
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Affiliation(s)
- Roman Rohac
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Eve de Rosny
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Océane Gigarel
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Juan C Fontecilla-Camps
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France
| | - Anne Volbeda
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, Metalloproteins Unit, F-38000, Grenoble, France.
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10
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Mansel BW, Su CJ, Chen CY, Young CM, Huang YC, Yang CC, Chen HL. Superhelical DNA liquid crystals from dendrimer-induced DNA compaction. SOFT MATTER 2021; 17:7287-7293. [PMID: 34319332 DOI: 10.1039/d1sm00547b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Electrostatic compaction of double stranded DNA induced by a positively charged poly(amidoamine) (PAMAM) dendrimer of generation four (G4) was found to produce two unique types of DNA mesophases, in which the DNA bent into superhelices packed in a tetragonal or hexagonal lattice. The structure formed at a lower dendrimer charge density was three-dimensionally (3D) ordered, as characterized by the P41212 space group with a 41 screw axis in a tetragonal arrangement, showing that the weakly bent DNA superhelices with a pitch length of ca. 5.0 nm possessed both identical handedness and phase conservation. The 3D ordered structure transformed into a 2D mesophase at a higher dendrimer charge density, wherein the strongly bent superhelices with a pitch length of ca. 4.0 nm organized in a hexagonal lattice without lateral coherence of helical trajectory. The counterion valency of the protonic acid that is used to charge the dendrimer was found to influence the phase diagram. Under a given dendrimer charge density, the complex with a multivalent acid-protonated dendrimer tended to form structures with less curved DNA, attesting that the driving force of charge matching was reduced by increasing the counterion valency of the dendrimer.
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Affiliation(s)
- Bradley W Mansel
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
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11
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Abstract
DNA dynamics can only be understood by taking into account its complex mechanical behavior at different length scales. At the micrometer level, the mechanical properties of single DNA molecules have been well-characterized by polymer models and are commonly quantified by a persistence length of 50 nm (~150 bp). However, at the base pair level (~3.4 Å), the dynamics of DNA involves complex molecular mechanisms that are still being deciphered. Here, we review recent single-molecule experiments and molecular dynamics simulations that are providing novel insights into DNA mechanics from such a molecular perspective. We first discuss recent findings on sequence-dependent DNA mechanical properties, including sequences that resist mechanical stress and sequences that can accommodate strong deformations. We then comment on the intricate effects of cytosine methylation and DNA mismatches on DNA mechanics. Finally, we review recently reported differences in the mechanical properties of DNA and double-stranded RNA, the other double-helical carrier of genetic information. A thorough examination of the recent single-molecule literature permits establishing a set of general 'rules' that reasonably explain the mechanics of nucleic acids at the base pair level. These simple rules offer an improved description of certain biological systems and might serve as valuable guidelines for future design of DNA and RNA nanostructures.
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12
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Duan B, Ding P, Navarre WW, Liu J, Xia B. Xenogeneic Silencing and Bacterial Genome Evolution: Mechanisms for DNA Recognition Imply Multifaceted Roles of Xenogeneic Silencers. Mol Biol Evol 2021; 38:4135-4148. [PMID: 34003286 PMCID: PMC8476142 DOI: 10.1093/molbev/msab136] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/08/2021] [Indexed: 12/14/2022] Open
Abstract
Horizontal gene transfer (HGT) is a major driving force for bacterial evolution. To avoid the deleterious effects due to the unregulated expression of newly acquired foreign genes, bacteria have evolved specific proteins named xenogeneic silencers to recognize foreign DNA sequences and suppress their transcription. As there is considerable diversity in genomic base compositions among bacteria, how xenogeneic silencers distinguish self- from nonself DNA in different bacteria remains poorly understood. This review summarizes the progress in studying the DNA binding preferences and the underlying molecular mechanisms of known xenogeneic silencer families, represented by H-NS of Escherichia coli, Lsr2 of Mycobacterium, MvaT of Pseudomonas, and Rok of Bacillus. Comparative analyses of the published data indicate that the differences in DNA recognition mechanisms enable these xenogeneic silencers to have clear characteristics in DNA sequence preferences, which are further correlated with different host genomic features. These correlations provide insights into the mechanisms of how these xenogeneic silencers selectively target foreign DNA in different genomic backgrounds. Furthermore, it is revealed that the genomic AT contents of bacterial species with the same xenogeneic silencer family proteins are distributed in a limited range and are generally lower than those species without any known xenogeneic silencers in the same phylum/class/genus, indicating that xenogeneic silencers have multifaceted roles on bacterial genome evolution. In addition to regulating horizontal gene transfer, xenogeneic silencers also act as a selective force against the GC to AT mutational bias found in bacterial genomes and help the host genomic AT contents maintained at relatively low levels.
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Affiliation(s)
- Bo Duan
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - Pengfei Ding
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - William Wiley Navarre
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
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13
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Mondal M, Yang L, Cai Z, Patra P, Gao YQ. A perspective on the molecular simulation of DNA from structural and functional aspects. Chem Sci 2021; 12:5390-5409. [PMID: 34168783 PMCID: PMC8179617 DOI: 10.1039/d0sc05329e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
As genetic material, DNA not only carries genetic information by sequence, but also affects biological functions ranging from base modification to replication, transcription and gene regulation through its structural and dynamic properties and variations. The motion and structural properties of DNA involved in related biological processes are also multi-scale, ranging from single base flipping to local DNA deformation, TF binding, G-quadruplex and i-motif formation, TAD establishment, compartmentalization and even chromosome territory formation, just to name a few. The sequence-dependent physical properties of DNA play vital role in all these events, and thus it is interesting to examine how simple sequence information affects DNA and the formation of the chromatin structure in these different hierarchical orders. Accordingly, molecular simulations can provide atomistic details of interactions and conformational dynamics involved in different biological processes of DNA, including those inaccessible by current experimental methods. In this perspective, which is mainly based on our recent studies, we provide a brief overview of the atomistic simulations on how the hierarchical structure and dynamics of DNA can be influenced by its sequences, base modifications, environmental factors and protein binding in the context of the protein-DNA interactions, gene regulation and structural organization of chromatin. We try to connect the DNA sequence, the hierarchical structures of DNA and gene regulation.
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Affiliation(s)
- Manas Mondal
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory 518055 Shenzhen China
| | - Lijiang Yang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University 100871 Beijing China
| | - Zhicheng Cai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University 100871 Beijing China.,Biomedical Pioneering Innovation Center, Peking University 100871 Beijing China
| | - Piya Patra
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory 518055 Shenzhen China .,Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University 100871 Beijing China
| | - Yi Qin Gao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory 518055 Shenzhen China .,Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University 100871 Beijing China.,Biomedical Pioneering Innovation Center, Peking University 100871 Beijing China.,Beijing Advanced Innovation Center for Genomics, Peking University 100871 Beijing China
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14
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Klinov DV, Protopopova AD, Andrianov DS, Litvinov RI, Weisel JW. An Improved Substrate for Superior Imaging of Individual Biomacromolecules with Atomic Force Microscopy. Colloids Surf B Biointerfaces 2020; 196:111321. [DOI: 10.1016/j.colsurfb.2020.111321] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 12/12/2022]
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15
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Huang Q, Duan B, Dong X, Fan S, Xia B. GapR binds DNA through dynamic opening of its tetrameric interface. Nucleic Acids Res 2020; 48:9372-9386. [PMID: 32756896 PMCID: PMC7498317 DOI: 10.1093/nar/gkaa644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 07/13/2020] [Accepted: 07/24/2020] [Indexed: 01/27/2023] Open
Abstract
GapR is a nucleoid-associated protein that is an essential regulator of chromosome replication in the cell cycle model Caulobacter crescentus. Here, we demonstrate that free GapR is a homotetramer, but not a dimer as previously reported (Guo et al., Cell 175: 583–597, 2018). We have determined the crystal structure of GapR in complex with a 10-bp A-tract DNA, which has an open tetrameric conformation, different from the closed clamp conformation in the previously reported crystal structure of GapR/DNA complex. The free GapR adopts multiple conformations in dynamic exchange equilibrium, with the major conformation resembling the closed tetrameric conformation, while the open tetrameric conformation is a representative of minor conformers. As it is impossible for the circular genomic DNA to get into the central DNA binding tunnel of the major conformation, we propose that GapR initially binds DNA through the open conformation, and then undergoes structural rearrangement to form the closed conformation which fully encircles the DNA. GapR prefers to bind DNA with 10-bp consecutive A/T base pairs nonselectively (Kd ∼12 nM), while it can also bind GC-rich DNA sequence with a reasonable affinity of about 120 nM. Besides, our results suggest that GapR binding results in widening the minor groove of AT-rich DNA, instead of overtwisting DNA.
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Affiliation(s)
- Qian Huang
- Beijing Nuclear Magnetic Resonance Center, School of Life Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Bo Duan
- Beijing Nuclear Magnetic Resonance Center, School of Life Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Xianzhi Dong
- Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China
| | - Shilong Fan
- The Technology Center for Protein Sciences, Tsinghua University, Beijing 100084, China
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, School of Life Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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16
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Rizzo L, Gernjak W, Krzeminski P, Malato S, McArdell CS, Perez JAS, Schaar H, Fatta-Kassinos D. Best available technologies and treatment trains to address current challenges in urban wastewater reuse for irrigation of crops in EU countries. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 710:136312. [PMID: 32050367 DOI: 10.1016/j.scitotenv.2019.136312] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/21/2019] [Accepted: 12/22/2019] [Indexed: 05/09/2023]
Abstract
Conventional urban wastewater treatment plants (UWTPs) are poorly effective in the removal of most contaminants of emerging concern (CECs), including antibiotics, antibiotic resistant bacteria and antibiotic resistance genes (ARB&ARGs). These contaminants result in some concern for the environment and human health, in particular if UWTPs effluents are reused for crop irrigation. Recently, stakeholders' interest further increased in Europe, because the European Commission is currently developing a regulation on water reuse. Likely, conventional UWTPs will require additional advanced treatment steps to meet water quality limits yet to be officially established for wastewater reuse. Even though it seems that CECs will not be included in the proposed regulation, the aim of this paper is to provide a technical contribution to this discussion as well as to support stakeholders by recommending possible advanced treatment options, in particular with regard to the removal of CECs and ARB&ARGs. Taking into account the current knowledge and the precautionary principle, any new or revised water-related Directive should address such contaminants. Hence, this review paper gathers the efforts of a group of international experts, members of the NEREUS COST Action ES1403, who for three years have been constructively discussing the efficiency of the best available technologies (BATs) for urban wastewater treatment to abate CECs and ARB&ARGs. In particular, ozonation, activated carbon adsorption, chemical disinfectants, UV radiation, advanced oxidation processes (AOPs) and membrane filtration are discussed with regard to their capability to effectively remove CECs and ARB&ARGs, as well as their advantages and drawbacks. Moreover, a comparison among the above-mentioned processes is performed for CECs relevant for crop uptake. Finally, possible treatment trains including the above-discussed BATs are discussed, issuing end-use specific recommendations which will be useful to UWTPs managers to select the most suitable options to be implemented at their own facilities to successfully address wastewater reuse challenges.
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Affiliation(s)
- Luigi Rizzo
- Department of Civil Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy.
| | - Wolfgang Gernjak
- Catalan Institute for Water Research (ICRA), Emili Grahit 101, 17003 Girona, Spain; Catalan Institute for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Pawel Krzeminski
- Section of Systems Engineering and Technology, Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo, Norway
| | - Sixto Malato
- Plataforma Solar de Almería (CIEMAT), Carretera de Senés, km. 4, Tabernas, Almería 04200, Spain; Solar Energy Research Centre (CIESOL), Joint Centre University of Almería-CIEMAT, Universitiy of Almeria, Ctra. Sacramento s/n, ES04120 Almería, Spain
| | - Christa S McArdell
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Jose Antonio Sanchez Perez
- Solar Energy Research Centre (CIESOL), Joint Centre University of Almería-CIEMAT, Universitiy of Almeria, Ctra. Sacramento s/n, ES04120 Almería, Spain; Department of Chemical Engineering, University of Almeria, Ctra. Sacramento s/n, ES04120 Almería, Spain
| | - Heidemarie Schaar
- Technische Universität Wien, Institute for Water Quality and Resource Management, Karlsplatz 13/2261, 1040 Vienna, Austria
| | - Despo Fatta-Kassinos
- Department of Civil and Environmental Engineering and Nireas, International Water Research Center, University of Cyprus, P.O. Box 20537, CY-1678 Nicosia, Cyprus.
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17
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Key significance of DNA-target size in lateral flow assay coupled with recombinase polymerase amplification. Anal Chim Acta 2020; 1102:109-118. [DOI: 10.1016/j.aca.2019.12.048] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/25/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023]
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18
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Krzeminski P, Feys E, Anglès d'Auriac M, Wennberg AC, Umar M, Schwermer CU, Uhl W. Combined membrane filtration and 265 nm UV irradiation for effective removal of cell free antibiotic resistance genes from feed water and concentrate. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2019.117676] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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19
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Sayoh I, Rusling DA, Brown T, Fox KR. DNA Structural Changes Induced by Intermolecular Triple Helix Formation. ACS OMEGA 2020; 5:1679-1687. [PMID: 32010842 PMCID: PMC6990630 DOI: 10.1021/acsomega.9b03776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 12/20/2019] [Indexed: 06/10/2023]
Abstract
DNase I footprints of intermolecular DNA triplexes are often accompanied by enhanced cleavage at the 3'-end of the target site at the triplex-duplex junction. We have systematically studied the sequence dependence of this effect by examining oligonucleotide binding to sites flanked by each base in turn. For complexes with a terminal T.AT triplet, the greatest enhancement is seen with ApC, followed by ApG and ApT, with the weakest enhancement at ApA. Similar DNase I enhancements were observed for a triplex with a terminal C+.GC triplet, though with little difference between the different GpN sites. Enhanced reactivity to diethylpyrocarbonate was observed at As that flank the triplex-duplex junction at AAA or AAC but not AAG or AAT. Fluorescence melting experiments demonstrated that the flanking base affected the stability with a 4 °C difference in T m between a flanking C and G. Sequences that produced the strongest enhancement correlated with those having the lower thermal stability. These results are interpreted in terms of oligonucleotide-induced changes in DNA structure and/or flexibility.
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Affiliation(s)
- Ibrahim Sayoh
- School
of Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, U.K.
| | - David A. Rusling
- School
of Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, U.K.
| | - Tom Brown
- Department
of Chemistry, University of Oxford, Oxford OX1 3TA, U.K.
| | - Keith R. Fox
- School
of Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, U.K.
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20
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DNA Modification Readers and Writers and Their Interplay. J Mol Biol 2019:S0022-2836(19)30718-1. [PMID: 31866298 DOI: 10.1016/j.jmb.2019.12.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/28/2019] [Accepted: 12/05/2019] [Indexed: 12/15/2022]
Abstract
Genomic DNA is modified in a postreplicative manner and several modifications, the enzymes responsible for their deposition as well as proteins that read these modifications, have been described. Here, we focus on the impact of DNA modifications on the DNA helix and review the writers and readers of cytosine modifications and how they interplay to shape genome composition, stability, and function.
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21
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Cristofalo M, Kovari D, Corti R, Salerno D, Cassina V, Dunlap D, Mantegazza F. Nanomechanics of Diaminopurine-Substituted DNA. Biophys J 2019; 116:760-771. [PMID: 30795872 DOI: 10.1016/j.bpj.2019.01.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 10/27/2022] Open
Abstract
2,6-diaminopurine (DAP) is a nucleobase analog of adenine. When incorporated into double-stranded DNA (dsDNA), it forms three hydrogen bonds with thymine. Rare in nature, DAP substitution alters the physical characteristics of a DNA molecule without sacrificing sequence specificity. Here, we show that in addition to stabilizing double-strand hybridization, DAP substitution also changes the mechanical and conformational properties of dsDNA. Thermal melting experiments reveal that DAP substitution raises melting temperatures without diminishing sequence-dependent effects. Using a combination of atomic force microscopy (AFM), magnetic tweezer (MT) nanomechanical assays, and circular dichroism spectroscopy, we demonstrate that DAP substitution increases the flexural rigidity of dsDNA yet also facilitates conformational shifts, which manifest as changes in molecule length. DAP substitution increases both the static and dynamic persistence length of DNA (measured by AFM and MT, respectively). In the static case (AFM), in which tension is not applied to the molecule, the contour length of DAP-DNA appears shorter than wild-type (WT)-DNA; under tension (MT), they have similar dynamic contour lengths. At tensions above 60 pN, WT-DNA undergoes characteristic overstretching because of strand separation (tension-induced melting) and spontaneous adoption of a conformation termed S-DNA. Cyclic overstretching and relaxation of WT-DNA at near-zero loading rates typically yields hysteresis, indicative of tension-induced melting; conversely, cyclic stretching of DAP-DNA showed little or no hysteresis, consistent with the adoption of the S-form, similar to what has been reported for GC-rich sequences. However, DAP-DNA overstretching is distinct from GC-rich overstretching in that it happens at a significantly lower tension. In physiological salt conditions, evenly mixed AT/GC DNA typically overstretches around 60 pN. GC-rich sequences overstretch at similar if not slightly higher tensions. Here, we show that DAP-DNA overstretches at 52 pN. In summary, DAP substitution decreases the overall stability of the B-form double helix, biasing toward non-B-form DNA helix conformations at zero tension and facilitating the B-to-S transition at high tension.
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Affiliation(s)
- Matteo Cristofalo
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - Daniel Kovari
- Department of Physics, Emory University, Atlanta, Georgia
| | - Roberta Corti
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - Domenico Salerno
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy.
| | - Valeria Cassina
- School of Medicine and Surgery, Università di Milano-Bicocca, Monza (MB), Italy
| | - David Dunlap
- Department of Physics, Emory University, Atlanta, Georgia.
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22
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Yella VR, Bhimsaria D, Ghoshdastidar D, Rodríguez-Martínez J, Ansari AZ, Bansal M. Flexibility and structure of flanking DNA impact transcription factor affinity for its core motif. Nucleic Acids Res 2018; 46:11883-11897. [PMID: 30395339 PMCID: PMC6294565 DOI: 10.1093/nar/gky1057] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/11/2018] [Accepted: 10/17/2018] [Indexed: 01/13/2023] Open
Abstract
Spatial and temporal expression of genes is essential for maintaining phenotype integrity. Transcription factors (TFs) modulate expression patterns by binding to specific DNA sequences in the genome. Along with the core binding motif, the flanking sequence context can play a role in DNA-TF recognition. Here, we employ high-throughput in vitro and in silico analyses to understand the influence of sequences flanking the cognate sites in binding of three most prevalent eukaryotic TF families (zinc finger, homeodomain and bZIP). In vitro binding preferences of each TF toward the entire DNA sequence space were correlated with a wide range of DNA structural parameters, including DNA flexibility. Results demonstrate that conformational plasticity of flanking regions modulates binding affinity of certain TF families. DNA duplex stability and minor groove width also play an important role in DNA-TF recognition but differ in how exactly they influence the binding in each specific case. Our analyses further reveal that the structural features of preferred flanking sequences are not universal, as similar DNA-binding folds can employ distinct DNA recognition modes.
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Affiliation(s)
- Venkata Rajesh Yella
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
- Department of Biotechnology, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh 522502, India
| | - Devesh Bhimsaria
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - José A Rodríguez-Martínez
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Biology, University of Puerto Rico-Rio Piedras, San Juan, PR 00925, USA
| | - Aseem Z Ansari
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- The Genome Center of Wisconsin, Madison, WI 53706, USA
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
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23
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Duan B, Ding P, Hughes TR, Navarre WW, Liu J, Xia B. How bacterial xenogeneic silencer rok distinguishes foreign from self DNA in its resident genome. Nucleic Acids Res 2018; 46:10514-10529. [PMID: 30252102 PMCID: PMC6212790 DOI: 10.1093/nar/gky836] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/28/2018] [Accepted: 09/18/2018] [Indexed: 12/11/2022] Open
Abstract
Bacterial xenogeneic silencers play important roles in bacterial evolution by recognizing and inhibiting expression from foreign genes acquired through horizontal gene transfer, thereby buffering against potential fitness consequences of their misregulated expression. Here, the detailed DNA binding properties of Rok, a xenogeneic silencer in Bacillus subtilis, was studied using protein binding microarray, and the solution structure of its C-terminal DNA binding domain was determined in complex with DNA. The C-terminal domain of Rok adopts a typical winged helix fold, with a novel DNA recognition mechanism different from other winged helix proteins or xenogeneic silencers. Rok binds the DNA minor groove by forming hydrogen bonds to bases through N154, T156 at the N-terminal of α3 helix and R174 of wing W1, assisted by four lysine residues interacting electrostatically with DNA backbone phosphate groups. These structural features endow Rok with preference towards DNA sequences harboring AACTA, TACTA, and flexible multiple TpA steps, while rigid A-tracts are disfavored. Correspondingly, the Bacillus genomes containing Rok are rich in A-tracts and show a dramatic underrepresentation of AACTA and TACTA, which are significantly enriched in Rok binding regions. These observations suggest that the xenogeneic silencing protein and its resident genome may have evolved cooperatively.
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Affiliation(s)
- Bo Duan
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University, Beijing 100871, China
| | - Pengfei Ding
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University, Beijing 100871, China
| | - Timothy R Hughes
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - William Wiley Navarre
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Jun Liu
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, School of Life Sciences, Peking University, Beijing 100871, China
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24
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Murray V, Chen JK, Chung LH. The Interaction of the Metallo-Glycopeptide Anti-Tumour Drug Bleomycin with DNA. Int J Mol Sci 2018; 19:E1372. [PMID: 29734689 PMCID: PMC5983701 DOI: 10.3390/ijms19051372] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 11/17/2022] Open
Abstract
The cancer chemotherapeutic drug, bleomycin, is clinically used to treat several neoplasms including testicular and ovarian cancers. Bleomycin is a metallo-glycopeptide antibiotic that requires a transition metal ion, usually Fe(II), for activity. In this review, the properties of bleomycin are examined, especially the interaction of bleomycin with DNA. A Fe(II)-bleomycin complex is capable of DNA cleavage and this process is thought to be the major determinant for the cytotoxicity of bleomycin. The DNA sequence specificity of bleomycin cleavage is found to at 5′-GT* and 5′-GC* dinucleotides (where * indicates the cleaved nucleotide). Using next-generation DNA sequencing, over 200 million double-strand breaks were analysed, and an expanded bleomycin sequence specificity was found to be 5′-RTGT*AY (where R is G or A and Y is T or C) in cellular DNA and 5′-TGT*AT in purified DNA. The different environment of cellular DNA compared to purified DNA was proposed to be responsible for the difference. A number of bleomycin analogues have been examined and their interaction with DNA is also discussed. In particular, the production of bleomycin analogues via genetic manipulation of the modular non-ribosomal peptide synthetases and polyketide synthases in the bleomycin gene cluster is reviewed. The prospects for the synthesis of bleomycin analogues with increased effectiveness as cancer chemotherapeutic agents is also explored.
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Affiliation(s)
- Vincent Murray
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Jon K Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Long H Chung
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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25
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Kumar R, Chaudhuri A, Kapri R. Sequencing of semiflexible polymers of varying bending rigidity using patterned pores. J Chem Phys 2018; 148:164901. [PMID: 29716219 DOI: 10.1063/1.5036529] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the translocation of a semiflexible polymer through extended pores with patterned stickiness, using Langevin dynamics simulations. We find that the consequence of pore patterning on the translocation time dynamics is dramatic and depends strongly on the interplay of polymer stiffness and pore-polymer interactions. For heterogeneous polymers with periodically varying stiffness along their lengths, we find that variation of the block size of the sequences and the orientation results in large variations in the translocation time distributions. We show how this fact may be utilized to develop an effective sequencing strategy. This strategy involving multiple pores with patterned surface energetics can predict heteropolymer sequences having different bending rigidity to a high degree of accuracy.
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Affiliation(s)
- Rajneesh Kumar
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Abhishek Chaudhuri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Rajeev Kapri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
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26
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Khoe CV, Chung LH, Murray V. The sequence specificity of UV-induced DNA damage in a systematically altered DNA sequence. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 183:88-100. [PMID: 29698913 DOI: 10.1016/j.jphotobiol.2018.04.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 03/27/2018] [Accepted: 04/14/2018] [Indexed: 01/17/2023]
Abstract
The sequence specificity of UV-induced DNA damage was investigated in a specifically designed DNA plasmid using two procedures: end-labelling and linear amplification. Absorption of UV photons by DNA leads to dimerisation of pyrimidine bases and produces two major photoproducts, cyclobutane pyrimidine dimers (CPDs) and pyrimidine(6-4)pyrimidone photoproducts (6-4PPs). A previous study had determined that two hexanucleotide sequences, 5'-GCTC*AC and 5'-TATT*AA, were high intensity UV-induced DNA damage sites. The UV clone plasmid was constructed by systematically altering each nucleotide of these two hexanucleotide sequences. One of the main goals of this study was to determine the influence of single nucleotide alterations on the intensity of UV-induced DNA damage. The sequence 5'-GCTC*AC was designed to examine the sequence specificity of 6-4PPs and the highest intensity 6-4PP damage sites were found at 5'-GTTC*CC nucleotides. The sequence 5'-TATT*AA was devised to investigate the sequence specificity of CPDs and the highest intensity CPD damage sites were found at 5'-TTTT*CG nucleotides. It was proposed that the tetranucleotide DNA sequence, 5'-YTC*Y (where Y is T or C), was the consensus sequence for the highest intensity UV-induced 6-4PP adduct sites; while it was 5'-YTT*C for the highest intensity UV-induced CPD damage sites. These consensus tetranucleotides are composed entirely of consecutive pyrimidines and must have a DNA conformation that is highly productive for the absorption of UV photons.
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Affiliation(s)
- Clairine V Khoe
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Long H Chung
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Vincent Murray
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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27
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Ardeleanu R, Dascalu AI, Neamtu A, Peptanariu D, Uritu CM, Maier SS, Nicolescu A, Simionescu BC, Barboiu M, Pinteala M. Multivalent polyrotaxane vectors as adaptive cargo complexes for gene therapy. Polym Chem 2018. [DOI: 10.1039/c7py01256j] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The philosophy to design and construct polyrotaxane carriers, as efficient gene delivery systems.
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Affiliation(s)
- Rodinel Ardeleanu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
| | - Andrei I. Dascalu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
| | - Andrei Neamtu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
- Regional Institute of Oncology (IRO)
| | - Dragos Peptanariu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
| | - Cristina M. Uritu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
| | - Stelian S. Maier
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
- Department of Textile and Leather Chemical Engineering
| | - Alina Nicolescu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
| | - Bogdan C. Simionescu
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
- Department of Natural and Synthetic Polymers
| | - Mihail Barboiu
- Adaptive Supramolecular Nanosystems Group
- Institut
- Européen des Membranes
- ENSCM/UMII/UMR-CNRS 5635
- 34095 Montpellier, Cedex 5
| | - Mariana Pinteala
- Centre of Advanced Research in Bionanoconjugates and Biopolymers
- “Petru Poni” Institute of Macromolecular Chemistry
- 700487 Iasi
- Romania
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Gautam SD, Hardie ME, Murray V. The Sequence Preference of Gamma-Radiation-Induced Damage in End-Labeled DNA after Heat Treatment. Radiat Res 2017; 189:238-250. [PMID: 29286256 DOI: 10.1667/rr14886.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In this work, we examined the DNA sequence preference of gamma-radiation-induced DNA damage in purified DNA sequences after heat treatment. DNA was fluorescently end-labeled and gamma-radiation-induced DNA cleavage was examined using capillary electrophoresis with laser-induced fluorescence detection. Our findings provide evidence that gamma-radiation-induced DNA damage to end-labeled DNA is nonrandom and has a sequence preference. The degree of cleavage was quantified at each nucleotide, and we observed that preferential cleavage occurred at C nucleotides with lesser cleavage at G nucleotides, while being very low at T nucleotides. The differences in percentage cleavage at individual nucleotides ranged up to sixfold. The DNA sequences surrounding the most intense radiation-induced DNA cleavage sites were examined and a consensus sequence 5'-AGGC*C (where C* is the cleavage site) was found. The highest intensity gamma-radiation-induced DNA cleavage sites were found at the dinucleotides, 5'-GG*, 5'-GC*, 5'-C*C and 5'-G*G and at the trinucleotides, 5'-GG*C, 5'-TC*A, 5'-GG*G and 5'-GC*C. These findings have implications for our understanding of ionizing radiation-induced DNA damage.
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Affiliation(s)
- Shweta D Gautam
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Megan E Hardie
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Vincent Murray
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Chuang HM, Reifenberger JG, Cao H, Dorfman KD. Sequence-Dependent Persistence Length of Long DNA. PHYSICAL REVIEW LETTERS 2017; 119:227802. [PMID: 29286779 PMCID: PMC5839665 DOI: 10.1103/physrevlett.119.227802] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Indexed: 05/04/2023]
Abstract
Using a high-throughput genome-mapping approach, we obtained circa 50 million measurements of the extension of internal human DNA segments in a 41 nm×41 nm nanochannel. The underlying DNA sequences, obtained by mapping to the reference human genome, are 2.5-393 kilobase pairs long and contain percent GC contents between 32.5% and 60%. Using Odijk's theory for a channel-confined wormlike chain, these data reveal that the DNA persistence length increases by almost 20% as the percent GC content increases. The increased persistence length is rationalized by a model, containing no adjustable parameters, that treats the DNA as a statistical terpolymer with a sequence-dependent intrinsic persistence length and a sequence-independent electrostatic persistence length.
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Affiliation(s)
- Hui-Min Chuang
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
| | | | - Han Cao
- BioNano Genomics, 9640 Towne Centre Drive, Suite 100, San Diego, California 92121, USA
| | - Kevin D Dorfman
- Department of Chemical Engineering and Materials Science, University of Minnesota-Twin Cities, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA
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DNA Length Modulates the Affinity of Fragments of Genomic DNA for the Nuclear Matrix In Vitro. J Cell Biochem 2017; 118:4487-4497. [DOI: 10.1002/jcb.26106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/01/2017] [Indexed: 01/21/2023]
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Silva-Santiago E, Rivera-Mulia JC, Aranda-Anzaldo A. The Set of Structural DNA-Nuclear Matrix Interactions in Neurons Is Cell-Type Specific and Rather Independent of Functional Constraints. J Cell Biochem 2017; 118:2151-2160. [DOI: 10.1002/jcb.25852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/19/2016] [Indexed: 01/03/2023]
Affiliation(s)
- Evangelina Silva-Santiago
- Facultad de Medicina, Laboratorio de Biología Molecular y Neurociencias; Universidad Autónoma del Estado de México; Toluca 50180 Edo. Méx. Mexico
| | - Juan Carlos Rivera-Mulia
- Facultad de Medicina, Laboratorio de Biología Molecular y Neurociencias; Universidad Autónoma del Estado de México; Toluca 50180 Edo. Méx. Mexico
| | - Armando Aranda-Anzaldo
- Facultad de Medicina, Laboratorio de Biología Molecular y Neurociencias; Universidad Autónoma del Estado de México; Toluca 50180 Edo. Méx. Mexico
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Silva-Santiago E, Pardo JP, Hernández-Muñoz R, Aranda-Anzaldo A. The nuclear higher-order structure defined by the set of topological relationships between DNA and the nuclear matrix is species-specific in hepatocytes. Gene 2017; 597:40-48. [PMID: 27771449 DOI: 10.1016/j.gene.2016.10.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/12/2016] [Accepted: 10/18/2016] [Indexed: 10/20/2022]
Abstract
During the interphase the nuclear DNA of metazoan cells is organized in supercoiled loops anchored to constituents of a nuclear substructure or compartment known as the nuclear matrix. The stable interactions between DNA and the nuclear matrix (NM) correspond to a set of topological relationships that define a nuclear higher-order structure (NHOS). Current evidence suggests that the NHOS is cell-type-specific. Biophysical evidence and theoretical models suggest that thermodynamic and structural constraints drive the actualization of DNA-NM interactions. However, if the topological relationships between DNA and the NM were the subject of any biological constraint with functional significance then they must be adaptive and thus be positively selected by natural selection and they should be reasonably conserved, at least within closely related species. We carried out a coarse-grained, comparative evaluation of the DNA-NM topological relationships in primary hepatocytes from two closely related mammals: rat and mouse, by determining the relative position to the NM of a limited set of target sequences corresponding to highly-conserved genomic regions that also represent a sample of distinct chromosome territories within the interphase nucleus. Our results indicate that the pattern of topological relationships between DNA and the NM is not conserved between the hepatocytes of the two closely related species, suggesting that the NHOS, like the karyotype, is species-specific.
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Affiliation(s)
- Evangelina Silva-Santiago
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, 50180, Edo. Méx., Mexico
| | - Juan Pablo Pardo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacan, 04510, Ciudad de México, Mexico
| | - Rolando Hernández-Muñoz
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacan, 04510, Ciudad de México, Mexico
| | - Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, 50180, Edo. Méx., Mexico.
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Il'icheva IA, Khodikov MV, Poptsova MS, Nechipurenko DY, Nechipurenko YD, Grokhovsky SL. Structural features of DNA that determine RNA polymerase II core promoter. BMC Genomics 2016; 17:973. [PMID: 27884105 PMCID: PMC5123417 DOI: 10.1186/s12864-016-3292-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 11/15/2016] [Indexed: 01/02/2023] Open
Abstract
Background The general structure and action of all eukaryotic and archaeal RNA polymerases machinery have an astonishing similarity despite the diversity of core promoter sequences in different species. The goal of our work is to find common characteristics of DNA region that define it as a promoter for the RNA polymerase II (Pol II). Results The profiles of a large number of physical and structural characteristics, averaged over representative sets of the Pol II minimal core promoters of the evolutionary divergent species from animals, plants and unicellular fungi were analysed. In addition to the characteristics defined at the base-pair steps, we, for the first time, use profiles of the ultrasonic cleavage and DNase I cleavage indexes, informative for internal properties of each complementary strand. Conclusions DNA of the core promoters of metazoans and Schizosaccharomyces pombe has similar structural organization. Its mechanical and 3D structural characteristics have singular properties at the positions of TATA-box. The minor groove is broadened and conformational motion is decreased in that region. Special characteristics of conformational behavior are revealed in metazoans at the region, which connects the end of TATA-box and the transcription start site (TSS). The intensities of conformational motions in the complementary strands are periodically changed in opposite phases. They are noticeable, best of all, in mammals. Such conformational features are lacking in the core promoters of S. pombe. The profiles of Saccharomyces cerevisiae core promoters significantly differ: their singular region is shifted down thus pointing to the uniqueness of their structural organization. Obtained results may be useful in genetic engineering for artificial modulation of the promoter strength. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3292-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Irina A Il'icheva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
| | - Mingian V Khodikov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | | | | | - Yury D Nechipurenko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sergei L Grokhovsky
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
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Aranda-Anzaldo A, Dent MAR. Why Cortical Neurons Cannot Divide, and Why Do They Usually Die in the Attempt? J Neurosci Res 2016; 95:921-929. [PMID: 27402311 DOI: 10.1002/jnr.23765] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/25/2016] [Accepted: 04/25/2016] [Indexed: 12/19/2022]
Abstract
Cortical neurons are prime examples of terminally differentiated, postmitotic cells. However, under experimental or pathological conditions, they can re-enter the cell cycle and replicate DNA but are unable to divide, dying by apoptosis or becoming either polyploid or aneuploid. Any cellular state that depends on the action of genes and their products can be reverted or bypassed by spontaneous or induced mutations, yet there are currently no reports of dividing cortical neurons. Thus, it seems unlikely that the remarkably stable postmitotic condition of cortical neurons depends on specific gene functions. This Review summarizes evidence that the postmitotic state of cortical neurons depends on the high stability of its underlying nuclear structure that results from an entropy-driven process aimed at dissipating the intrinsic structural stress present in chromosomal DNA in such a way that the structural stability of the neuronal nucleus becomes an insurmountable energy barrier for karyokinesis and mitosis. From this perspective, the integral properties of the nuclear higher order structure in neurons provide an explanation not only for why cortical neurons cannot divide but also for why they usually die if they happen to replicate their DNA. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
| | - Myrna A R Dent
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
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Hong CA, Nam YS. Reducible Dimeric Conjugates of Small Internally Segment Interfering RNA for Efficient Gene Silencing. Macromol Biosci 2016; 16:1442-1449. [PMID: 27273465 DOI: 10.1002/mabi.201600137] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 05/12/2016] [Indexed: 01/29/2023]
Abstract
The condensation of nucleic acids into compact nanoparticles with cationic carriers is a powerful tool for translocating exogenous nucleic acids into cells. To date, most efforts have been focused on the development of novel gene carriers for safe and efficient gene delivery. However, small interfering RNA (siRNA) is generally not strongly associated with cationic carriers due to its stiff structure and low spatial charge density. To overcome this limitation, this work introduces a well-defined dimeric conjugate of small internally segment interfering RNA (sisiRNA) linked via a disulfide bond for enhanced cellular uptake and gene silencing. Dimeric sisiRNA is synthesized through oxidizing two monomeric sisiRNA molecules, each of which consists of a sense strand carrying a nick and an antisense strand modified with a thiol group at the 3'-end. The nick in the sense strand enables the dimeric sisiRNA to be more effectively condensed into nanosized complexes due to the increased structural flexibility, which results in a higher gene silencing efficiency compared with the dimeric siRNA containing the intact sense strands. The results indicate that the discontinuity of the sense strands is a simple method of adding more flexibility to various siRNA-based nanostructures for enhanced gene silencing.
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Affiliation(s)
- Cheol Am Hong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yoon Sung Nam
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea. .,Department of Materials Science and Engineering, and KAIST Institutes for NanoCentury and Health Science and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
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36
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Metal oxide semiconductor field-effect transistor (MOSFET)-based direct monitoring of p53 in spiked serum. J IND ENG CHEM 2016. [DOI: 10.1016/j.jiec.2016.03.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Nikolova EN, Zhou H, Gottardo FL, Alvey HS, Kimsey IJ, Al-Hashimi HM. A historical account of Hoogsteen base-pairs in duplex DNA. Biopolymers 2016; 99:955-68. [PMID: 23818176 DOI: 10.1002/bip.22334] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 06/17/2013] [Indexed: 11/05/2022]
Abstract
In 1957, a unique pattern of hydrogen bonding between N3 and O4 on uracil and N7 and N6 on adenine was proposed to explain how poly(rU) strands can associate with poly(rA)-poly(rU) duplexes to form triplexes. Two years later, Karst Hoogsteen visualized such a noncanonical A-T base-pair through X-ray analysis of co-crystals containing 9-methyladenine and 1-methylthymine. Subsequent X-ray analyses of guanine and cytosine derivatives yielded the expected Watson-Crick base-pairing, but those of adenine and thymine (or uridine) did not yield Watson-Crick base-pairs, instead favoring "Hoogsteen" base-pairing. More than two decades ensued without experimental "proof" for A-T Watson-Crick base-pairs, while Hoogsteen base-pairs continued to surface in AT-rich sequences, closing base-pairs of apical loops, in structures of DNA bound to antibiotics and proteins, damaged and chemically modified DNA, and in polymerases that replicate DNA via Hoogsteen pairing. Recently, NMR studies have shown that base-pairs in duplex DNA exist as a dynamic equilibrium between Watson-Crick and Hoogsteen forms. There is now little doubt that Hoogsteen base-pairs exist in significant abundance in genomic DNA, where they can expand the structural and functional versatility of duplex DNA beyond that which can be achieved based only on Watson-Crick base-pairing. Here, we provide a historical account of the discovery and characterization of Hoogsteen base-pairs, hoping that this will inform future studies exploring the occurrence and functional importance of these alternative base-pairs.
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Affiliation(s)
- Evgenia N Nikolova
- Department of Chemistry & Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109-1055; Integrative Structural & Computational Biology Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037
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Tolstorukov MY, Virnik K, Zhurkin VB, Adhya S. Organization of DNA in a bacterial nucleoid. BMC Microbiol 2016; 16:22. [PMID: 26897370 PMCID: PMC4761138 DOI: 10.1186/s12866-016-0637-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 02/04/2016] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND It is unclear how DNA is packaged in a bacterial cell in the absence of nucleosomes. To investigate the initial level of DNA condensation in bacterial nucleoid we used in vivo DNA digestion coupled with high-throughput sequencing of the digestion-resistant fragments. To this end, we transformed E. coli cells with a plasmid expressing micrococcal nuclease. The nuclease expression was under the control of AraC repressor, which enabled us to perform an inducible digestion of bacterial nucleoid inside a living cell. RESULTS Analysis of the genomic localization of the digestion-resistant fragments revealed their non-random distribution. The patterns observed in the distribution of the sequenced fragments indicate the presence of short DNA segments protected from the enzyme digestion, possibly because of interaction with DNA-binding proteins. The average length of such digestion-resistant segments is about 50 bp and the characteristic repeat in their distribution is about 90 bp. The gene starts are depleted of the digestion-resistant fragments, suggesting that these genomic regions are more exposed than genomic sequences on average. Sequence analysis of the digestion-resistant segments showed that while the GC-content of such sequences is close to the genome-wide value, they are depleted of A-tracts as compared to the bulk genomic DNA or to the randomized sequence of the same nucleotide composition. CONCLUSIONS Our results suggest that DNA is packaged in the bacterial nucleoid in a non-random way that facilitates interaction of the DNA binding factors with regulatory regions of the genome.
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Affiliation(s)
- Michael Y Tolstorukov
- Department of Molecular Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA.
| | - Konstantin Virnik
- Laboratory of Immunoregulation, Division of Viral Products, Office of Vaccines, Center for Biologics, FDA, Silver Spring, MD, 20993, USA.
| | - Victor B Zhurkin
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Sankar Adhya
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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Abstract
We study the elasticity of DNA based on local principal axes of bending identified from over 0.9-μs all-atom molecular dynamics simulations of DNA oligos. The calculated order parameters describe motion of DNA as an elastic rod. In 10 possible dinucleotide steps, bending about the two principal axes is anisotropic yet linearly elastic. Twist about the centroid axis is largely decoupled from bending, but DNA tends to overtwist for unbending beyond the typical range of thermal motion, which is consistent with experimentally observed twist-stretch coupling. The calculated elastic stiffness of dinucleotide steps yield sequence-dependent persistence lengths consistent with previous single-molecule experiments, which is further analyzed by performing coarse-grained simulations of DNA. Flexibility maps of oligos constructed from simulation also match with those from the precalculated stiffness of dinucleotide steps. These support the premise that base pair interaction at the dinucleotide-level is mainly responsible for the elasticity of DNA. Furthermore, we analyze 1381 crystal structures of protein-DNA complexes. In most structures, DNAs are mildly deformed and twist takes the highest portion of the total elastic energy. By contrast, in structures with the elastic energy per dinucleotide step greater than about 4.16 kBT (kBT: thermal energy), the major bending becomes dominant. The extensional energy of dinucleotide steps takes at most 35% of the total elastic energy except for structures containing highly deformed DNAs where linear elasticity breaks down. Such partitioning between different deformational modes provides quantitative insights into the conformational dynamics of DNA as well as its interaction with other molecules and surfaces.
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Affiliation(s)
- Xiaojing Teng
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843, United States
| | - Wonmuk Hwang
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843, United States
- Department of Materials Science and Engineering, Texas A&M University , College Station, Texas 77843, United States
- School of Computational Sciences, Korea Institute for Advanced Study , Seoul, Korea 02455
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Aranda-Anzaldo A. The interphase mammalian chromosome as a structural system based on tensegrity. J Theor Biol 2016; 393:51-9. [PMID: 26780650 DOI: 10.1016/j.jtbi.2016.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 12/11/2015] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
Abstract
Each mammalian chromosome is constituted by a DNA fiber of macroscopic length that needs to be fitted in a microscopic nucleus. The DNA fiber is subjected at physiological temperature to random thermal bending and looping that must be constrained so as achieve structural stability thus avoiding spontaneous rupturing of the fiber. Standard textbooks assume that chromatin proteins are primarily responsible for the packaging of DNA and so of its protection against spontaneous breakage. Yet the dynamic nature of the interactions between chromatin proteins and DNA is unlikely to provide the necessary long-term structural stability for the chromosomal DNA. On the other hand, longstanding evidence indicates that stable interactions between DNA and constituents of a nuclear compartment commonly known as the nuclear matrix organize the chromosomal DNA as a series of topologically constrained, supercoiled loops during interphase. This results in a primary level of DNA condensation and packaging within the nucleus, as well as in protection against spontaneous DNA breakage, independently of chromatin proteins which nevertheless increase and dynamically modulate the degree of DNA packaging and its role in the regulation of DNA function. Thus current evidence, presented hereunder, supports a model for the organization of the interphase chromosome as resilient system that satisfies the principles of structural tensegrity.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan y Jesús Carranza s/n, Toluca, 50180 Edo. Méx., México.
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41
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Stützer A, Liokatis S, Kiesel A, Schwarzer D, Sprangers R, Söding J, Selenko P, Fischle W. Modulations of DNA Contacts by Linker Histones and Post-translational Modifications Determine the Mobility and Modifiability of Nucleosomal H3 Tails. Mol Cell 2016; 61:247-59. [PMID: 26778125 DOI: 10.1016/j.molcel.2015.12.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 09/23/2015] [Accepted: 12/03/2015] [Indexed: 10/22/2022]
Abstract
Post-translational histone modifications and linker histone incorporation regulate chromatin structure and genome activity. How these systems interface on a molecular level is unclear. Using biochemistry and NMR spectroscopy, we deduced mechanistic insights into the modification behavior of N-terminal histone H3 tails in different nucleosomal contexts. We find that linker histones generally inhibit modifications of different H3 sites and reduce H3 tail dynamics in nucleosomes. These effects are caused by modulations of electrostatic interactions of H3 tails with linker DNA and largely depend on the C-terminal domains of linker histones. In agreement, linker histone occupancy and H3 tail modifications segregate on a genome-wide level. Charge-modulating modifications such as phosphorylation and acetylation weaken transient H3 tail-linker DNA interactions, increase H3 tail dynamics, and, concomitantly, enhance general modifiability. We propose that alterations of H3 tail-linker DNA interactions by linker histones and charge-modulating modifications execute basal control mechanisms of chromatin function.
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Affiliation(s)
- Alexandra Stützer
- Laboratory of Chromatin Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stamatios Liokatis
- Department of NMR-Supported Structural Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Rössle Strasse 10, 13125 Berlin, Germany
| | - Anja Kiesel
- Research Group of Computational Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Dirk Schwarzer
- Department of Chemical Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Rössle Strasse 10, 13125 Berlin, Germany
| | - Remco Sprangers
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Johannes Söding
- Research Group of Computational Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Gene Center and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Philipp Selenko
- Department of NMR-Supported Structural Biology, Leibniz Institute of Molecular Pharmacology (FMP Berlin), Robert-Rössle Strasse 10, 13125 Berlin, Germany.
| | - Wolfgang Fischle
- Laboratory of Chromatin Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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Rahbani JF, Hariri AA, Cosa G, Sleiman HF. Dynamic DNA Nanotubes: Reversible Switching between Single and Double-Stranded Forms, and Effect of Base Deletions. ACS NANO 2015; 9:11898-11908. [PMID: 26556531 DOI: 10.1021/acsnano.5b04387] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
DNA nanotubes hold great potential as drug delivery vehicles and as programmable templates for the organization of materials and biomolecules. Existing methods for their construction produce assemblies that are entirely double-stranded and rigid, and thus have limited intrinsic dynamic character, or they rely on chemically modified and ligated DNA structures. Here, we report a simple and efficient synthesis of DNA nanotubes from 11 short unmodified strands, and the study of their dynamic behavior by atomic force microscopy and in situ single molecule fluorescence microscopy. This method allows the programmable introduction of DNA structural changes within the repeat units of the tubes. We generate and study fully double-stranded nanotubes, and convert them to nanotubes with one, two and three single-stranded sides, using strand displacement strategies. The nanotubes can be reversibly switched between these forms without compromising their stability and micron-scale lengths. We then site-specifically introduce DNA strands that shorten two sides of the nanotubes, while keeping the length of the third side. The nanotubes undergo bending with increased length mismatch between their sides, until the distortion is significant enough to shorten them, as measured by AFM and single-molecule fluorescence photobleaching experiments. The method presented here produces dynamic and robust nanotubes that can potentially behave as actuators, and allows their site-specific addressability while using a minimal number of component strands.
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Affiliation(s)
- Janane F Rahbani
- Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University , 801 Sherbrooke Street West, Montreal, H3A 0B8, Canada
| | - Amani A Hariri
- Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University , 801 Sherbrooke Street West, Montreal, H3A 0B8, Canada
| | - Gonzalo Cosa
- Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University , 801 Sherbrooke Street West, Montreal, H3A 0B8, Canada
| | - Hanadi F Sleiman
- Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University , 801 Sherbrooke Street West, Montreal, H3A 0B8, Canada
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Carvalho ATP, Gouveia L, Kanna CR, Wärmländer SKTS, Platts JA, Kamerlin SCL. Understanding the structural and dynamic consequences of DNA epigenetic modifications: computational insights into cytosine methylation and hydroxymethylation. Epigenetics 2015; 9:1604-12. [PMID: 25625845 PMCID: PMC4622728 DOI: 10.4161/15592294.2014.988043] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We report a series of molecular dynamics (MD) simulations of up to a microsecond combined simulation time designed to probe epigenetically modified DNA sequences. More specifically, by monitoring the effects of methylation and hydroxymethylation of cytosine in different DNA sequences, we show, for the first time, that DNA epigenetic modifications change the molecule's dynamical landscape, increasing the propensity of DNA toward different values of twist and/or roll/tilt angles (in relation to the unmodified DNA) at the modification sites. Moreover, both the extent and position of different modifications have significant effects on the amount of structural variation observed. We propose that these conformational differences, which are dependent on the sequence environment, can provide specificity for protein binding.
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Key Words
- AFM, Atomic Force Microscopy
- DDD, Dickerson-Drew Dodecamer
- DFT, Density Functional Theory
- DNA methylation
- DNA, Deoxyribonucleic Acid
- DNMT, DNA Methyltransferase
- LINEs, Long Interspred Transposable Elements
- MD, Molecular Dynamics
- MM, Molecular Mechanics
- MeCP, Methylated CpG-binding proteins
- PBC, Periodic Boundary Conditions
- QM, Quantum Mechanics
- RDF, Radial Distribution Functions
- RESP, Restrained Electrostatic Potentials Model
- SINEs, Short Interspred Transposable Elements
- SPME, Smooth Particle-Mesh Ewald
- TET, Translocation Proteins
- WT, Wild Type
- epigenetics
- indirect readout
- molecular dynamics
- recognition
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Affiliation(s)
- Alexandra T P Carvalho
- a Science for Life Laboratory; Department of Cell and Molecular Biology ; Uppsala University ; Uppsala , Sweden
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45
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Brečević L, Rinčić M, Krsnik Ž, Sedmak G, Hamid AB, Kosyakova N, Galić I, Liehr T, Borovečki F. Association of new deletion/duplication region at chromosome 1p21 with intellectual disability, severe speech deficit and autism spectrum disorder-like behavior: an all-in approach to solving the DPYD enigma. Transl Neurosci 2015; 6:59-86. [PMID: 28123791 PMCID: PMC4936614 DOI: 10.1515/tnsci-2015-0007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 12/29/2014] [Indexed: 12/14/2022] Open
Abstract
We describe an as yet unreported neocentric small supernumerary marker chromosome (sSMC) derived from chromosome 1p21.3p21.2. It was present in 80% of the lymphocytes in a male patient with intellectual disability, severe speech deficit, mild dysmorphic features, and hyperactivity with elements of autism spectrum disorder (ASD). Several important neurodevelopmental genes are affected by the 3.56 Mb copy number gain of 1p21.3p21.2, which may be considered reciprocal in gene content to the recently recognized 1p21.3 microdeletion syndrome. Both 1p21.3 deletions and the presented duplication display overlapping symptoms, fitting the same disorder category. Contribution of coding and non-coding genes to the phenotype is discussed in the light of cellular and intercellular homeostasis disequilibrium. In line with this the presented 1p21.3p21.2 copy number gain correlated to 1p21.3 microdeletion syndrome verifies the hypothesis of a cumulative effect of the number of deregulated genes - homeostasis disequilibrium leading to overlapping phenotypes between microdeletion and microduplication syndromes. Although miR-137 appears to be the major player in the 1p21.3p21.2 region, deregulation of the DPYD (dihydropyrimidine dehydrogenase) gene may potentially affect neighboring genes underlying the overlapping symptoms present in both the copy number loss and copy number gain of 1p21. Namely, the all-in approach revealed that DPYD is a complex gene whose expression is epigenetically regulated by long non-coding RNAs (lncRNAs) within the locus. Furthermore, the long interspersed nuclear element-1 (LINE-1) L1MC1 transposon inserted in DPYD intronic transcript 1 (DPYD-IT1) lncRNA with its parasites, TcMAR-Tigger5b and pair of Alu repeats appears to be the “weakest link” within the DPYD gene liable to break. Identification of the precise mechanism through which DPYD is epigenetically regulated, and underlying reasons why exactly the break (FRA1E) happens, will consequently pave the way toward preventing severe toxicity to the antineoplastic drug 5-fluorouracil (5-FU) and development of the causative therapy for the dihydropyrimidine dehydrogenase deficiency.
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Affiliation(s)
- Lukrecija Brečević
- Croatian Institute for Brain Research, University of Zagreb Medical School, Šalata 12, 10000 Zagreb, Croatia
- Department for Functional Genomics, Center for Translational and Clinical Research, University of Zagreb Medical School, University Hospital Center Zagreb, Šalata 2, 10000 Zagreb, Croatia
- E-mail: ;
| | - Martina Rinčić
- Croatian Institute for Brain Research, University of Zagreb Medical School, Šalata 12, 10000 Zagreb, Croatia
- Department for Functional Genomics, Center for Translational and Clinical Research, University of Zagreb Medical School, University Hospital Center Zagreb, Šalata 2, 10000 Zagreb, Croatia
- Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, 07743 Jena, Germany
| | - Željka Krsnik
- Croatian Institute for Brain Research, University of Zagreb Medical School, Šalata 12, 10000 Zagreb, Croatia
| | - Goran Sedmak
- Croatian Institute for Brain Research, University of Zagreb Medical School, Šalata 12, 10000 Zagreb, Croatia
| | - Ahmed B. Hamid
- Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, 07743 Jena, Germany
| | - Nadezda Kosyakova
- Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, 07743 Jena, Germany
| | - Ivan Galić
- Center for Rehabilitation Stančić, Stančić bb, 10370 Stančić, Croatia
| | - Thomas Liehr
- Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, 07743 Jena, Germany
| | - Fran Borovečki
- Department for Functional Genomics, Center for Translational and Clinical Research, University of Zagreb Medical School, University Hospital Center Zagreb, Šalata 2, 10000 Zagreb, Croatia
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46
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Affiliation(s)
- Robert K McGinty
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Song Tan
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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47
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Mazur AK, Maaloum M. Atomic force microscopy study of DNA flexibility on short length scales: smooth bending versus kinking. Nucleic Acids Res 2014; 42:14006-12. [PMID: 25414337 PMCID: PMC4267637 DOI: 10.1093/nar/gku1192] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The apparently anomalous flexibility of DNA on short length scales has attracted a lot of attention in recent years. We use atomic force microscopy (AFM) in solution to directly study the DNA bending statistics for small lengths down to one helical turn. The accuracy of experimental estimates could be improved due to a large data volume and a refined algorithm for image processing and measuring bend angles. It is found that, at length scales beyond two helical turns (7 nm), DNA is well described by the harmonic worm-like chain (WLC) model with the bending persistence length of 56 nm. Below this threshold, the AFM data are also described by the WLC model assuming that the accuracy of measured bend angles is limited by the physical width of the double helix. We conclude that the double helical DNA behaves as a uniform elastic rod even at very short length scales. Strong bends due to kinks, melting bubbles and other deviations from the WLC model are statistically negligible.
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Affiliation(s)
- Alexey K Mazur
- UPR9080 CNRS, Université Paris Diderot, Sorbonne Paris Cité, Institut de Biologie Physico-Chimique, 13, rue Pierre et Marie Curie, Paris 75005, France
| | - Mounir Maaloum
- Institut Charles Sadron, CNRS-University of Strasbourg, 23 rue du Loess, BP 84087, 67034 Strasbourg Cedex 2, France
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48
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Affiliation(s)
- Daniel Duzdevich
- Department of Biological Sciences, Department of Chemistry, and Department of
Biochemistry and Molecular
Biophysics and the Howard Hughes Medical Institute, Columbia University, 650 West 168th Street, New York, New York 10032, United
States
| | - Sy Redding
- Department of Biological Sciences, Department of Chemistry, and Department of
Biochemistry and Molecular
Biophysics and the Howard Hughes Medical Institute, Columbia University, 650 West 168th Street, New York, New York 10032, United
States
| | - Eric C. Greene
- Department of Biological Sciences, Department of Chemistry, and Department of
Biochemistry and Molecular
Biophysics and the Howard Hughes Medical Institute, Columbia University, 650 West 168th Street, New York, New York 10032, United
States
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49
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Lindemose S, Nielsen PE, Valentin-Hansen P, Møllegaard NE. A novel indirect sequence readout component in the E. coli cyclic AMP receptor protein operator. ACS Chem Biol 2014; 9:752-60. [PMID: 24387622 DOI: 10.1021/cb4008309] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The cyclic AMP receptor protein (CRP) from Escherichia coli has been extensively studied for several decades. In particular, a detailed characterization of CRP interaction with DNA has been obtained. The CRP dimer recognizes a consensus sequence AANTGTGANNNNNNTCACANTT through direct amino acid nucleobase interactions in the major groove of the two operator half-sites. Crystal structure analyses have revealed that the interaction results in two strong kinks at the TG/CA steps closest to the 6-base-pair spacer (N6). This spacer exhibits high sequence variability among the more than 100 natural binding sites in the E. coli genome, but the exact role of the N6 region in CRP interaction has not previously been systematic examined. Here we employ an in vitro selection system based on a randomized N6 spacer region to demonstrate that CRP binding to the lacP1 site may be enhanced up to 14-fold or abolished by varying the N6 spacer sequences. Furthermore, on the basis of sequence analysis and uranyl (UO2(2+)) probing data, we propose that the underlying mechanism relies on N6 deformability.
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Affiliation(s)
- Søren Lindemose
- Department
of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Peter Eigil Nielsen
- Department
of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Poul Valentin-Hansen
- Department
of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Niels Erik Møllegaard
- Department
of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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50
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Negureanu L, Salsbury FR. Non-specificity and synergy at the binding site of the carboplatin-induced DNA adduct via molecular dynamics simulations of the MutSα-DNA recognition complex. J Biomol Struct Dyn 2013; 32:969-92. [PMID: 23799640 DOI: 10.1080/07391102.2013.799437] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
MutSα is the most abundant mismatch-binding factor of human DNA mismatch repair (MMR) proteins. MMR maintains genetic stability by recognizing and repairing DNA defects. Failure to accomplish their function may lead to cancer. In addition, MutSα recognizes at least some types of DNA damage making it a target for anticancer agents. Here, complementing scarce experimental data, we report unique hydrogen-bonding motifs associated with the recognition of the carboplatin induced DNA damage by MutSα. These data predict that carboplatin and cisplatin induced damaging DNA adducts are recognized by MutSα in a similar manner. Our simulations also indicate that loss of base pairing at the damage site results in (1) non-specific binding and (2) changes in the atomic flexibility at the lesion site and beyond. To further quantify alterations at MutSα-DNA interface in response to damage recognition, non-bonding interactions and salt bridges were investigated. These data indicate (1) possible different packing and (2) disruption of the salt bridges at the MutSα-DNA interface in the damaged complex. These findings (1) underscore the general observation of disruptions at the MutSα-DNA interface and (2) highlight the nature of the anticancer effect of the carboplatin agent. The analysis was carried out from atomistic simulations.
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