1
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Hibshman GN, Bravo JPK, Hooper MM, Dangerfield TL, Zhang H, Finkelstein IJ, Johnson KA, Taylor DW. Unraveling the mechanisms of PAMless DNA interrogation by SpRY-Cas9. Nat Commun 2024; 15:3663. [PMID: 38688943 PMCID: PMC11061278 DOI: 10.1038/s41467-024-47830-3] [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: 02/21/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024] Open
Abstract
CRISPR-Cas9 is a powerful tool for genome editing, but the strict requirement for an NGG protospacer-adjacent motif (PAM) sequence immediately next to the DNA target limits the number of editable genes. Recently developed Cas9 variants have been engineered with relaxed PAM requirements, including SpG-Cas9 (SpG) and the nearly PAM-less SpRY-Cas9 (SpRY). However, the molecular mechanisms of how SpRY recognizes all potential PAM sequences remains unclear. Here, we combine structural and biochemical approaches to determine how SpRY interrogates DNA and recognizes target sites. Divergent PAM sequences can be accommodated through conformational flexibility within the PAM-interacting region, which facilitates tight binding to off-target DNA sequences. Nuclease activation occurs ~1000-fold slower than for Streptococcus pyogenes Cas9, enabling us to directly visualize multiple on-pathway intermediate states. Experiments with SpG position it as an intermediate enzyme between Cas9 and SpRY. Our findings shed light on the molecular mechanisms of PAMless genome editing.
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Affiliation(s)
- Grace N Hibshman
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
- Interdisciplinary Life Sciences Graduate Programs, Austin, TX, 78712, USA
| | - Jack P K Bravo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
| | - Matthew M Hooper
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
- Interdisciplinary Life Sciences Graduate Programs, Austin, TX, 78712, USA
| | - Tyler L Dangerfield
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Hongshan Zhang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Kenneth A Johnson
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
- Interdisciplinary Life Sciences Graduate Programs, Austin, TX, 78712, USA
| | - David W Taylor
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
- Interdisciplinary Life Sciences Graduate Programs, Austin, TX, 78712, USA.
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, 78712, USA.
- LIVESTRONG Cancer Institutes, Dell Medical School, Austin, TX, 78712, USA.
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2
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Yang M, Zhang S, Zheng Z, Zhang P, Liang Y, Tang S. Employing bimodal representations to predict DNA bendability within a self-supervised pre-trained framework. Nucleic Acids Res 2024; 52:e33. [PMID: 38375921 PMCID: PMC11014357 DOI: 10.1093/nar/gkae099] [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: 11/15/2023] [Revised: 01/10/2024] [Accepted: 02/01/2024] [Indexed: 02/21/2024] Open
Abstract
The bendability of genomic DNA, which measures the DNA looping rate, is crucial for numerous biological processes of DNA. Recently, an advanced high-throughput technique known as 'loop-seq' has made it possible to measure the inherent cyclizability of DNA fragments. However, quantifying the bendability of large-scale DNA is costly, laborious, and time-consuming. To close the gap between rapidly evolving large language models and expanding genomic sequence information, and to elucidate the DNA bendability's impact on critical regulatory sequence motifs such as super-enhancers in the human genome, we introduce an innovative computational model, named MIXBend, to forecast the DNA bendability utilizing both nucleotide sequences and physicochemical properties. In MIXBend, a pre-trained language model DNABERT and convolutional neural network with attention mechanism are utilized to construct both sequence- and physicochemical-based extractors for the sophisticated refinement of DNA sequence representations. These bimodal DNA representations are then fed to a k-mer sequence-physicochemistry matching module to minimize the semantic gap between each modality. Lastly, a self-attention fusion layer is employed for the prediction of DNA bendability. In conclusion, the experimental results validate MIXBend's superior performance relative to other state-of-the-art methods. Additionally, MIXBend reveals both novel and known motifs from the yeast. Moreover, MIXBend discovers significant bendability fluctuations within super-enhancer regions and transcription factors binding sites in the human genome.
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Affiliation(s)
- Minghao Yang
- Bioscience and Biomedical Engineering Thrust, System Hub, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511466, China
| | - Shichen Zhang
- Bioscience and Biomedical Engineering Thrust, System Hub, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511466, China
| | - Zhihang Zheng
- Bioscience and Biomedical Engineering Thrust, System Hub, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511466, China
| | - Pengfei Zhang
- Bioscience and Biomedical Engineering Thrust, System Hub, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511466, China
| | - Yan Liang
- School of Artificial Intelligence, South China Normal University, Foshan 528225, China
| | - Shaojun Tang
- Bioscience and Biomedical Engineering Thrust, System Hub, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511466, China
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong SAR 999077, China
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3
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Park J, Kim JJ, Ryu JK. Mechanism of phase condensation for chromosome architecture and function. Exp Mol Med 2024; 56:809-819. [PMID: 38658703 PMCID: PMC11059216 DOI: 10.1038/s12276-024-01226-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 04/26/2024] Open
Abstract
Chromosomal phase separation is involved in a broad spectrum of chromosome organization and functional processes. Nonetheless, the intricacy of this process has left its molecular mechanism unclear. Here, we introduce the principles governing phase separation and its connections to physiological roles in this context. Our primary focus is contrasting two phase separation mechanisms: self-association-induced phase separation (SIPS) and bridging-induced phase separation (BIPS). We provide a comprehensive discussion of the distinct features characterizing these mechanisms and offer illustrative examples that suggest their broad applicability. With a detailed understanding of these mechanisms, we explore their associations with nucleosomes and chromosomal biological functions. This comprehensive review contributes to the exploration of uncharted territory in the intricate interplay between chromosome architecture and function.
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Affiliation(s)
- Jeongveen Park
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jeong-Jun Kim
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Je-Kyung Ryu
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
- Institute of Applied Physics of Seoul National University, Seoul, 08826, South Korea.
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, 08826, South Korea.
- Department of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, 08826, South Korea.
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4
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Xue Y, Ma Y, Sun Z, Liu X, Zhang M, Zhang J, Xi N. Identification and Measurement of Biomarkers at Single Microorganism Level for In Situ Monitoring Deep Ultraviolet Disinfection Process. IEEE Trans Nanobioscience 2024; 23:242-251. [PMID: 37676797 DOI: 10.1109/tnb.2023.3312754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Since the COVID-19 disease has been further aggravated, the prevention of pathogen transmission becomes a vital issue to restrain casualties. Recent research outcomes have shown the possibilities of the viruses existing on inanimate surfaces up to few days, which carry the risk of touch propagation of the disease. Deep ultraviolet germicide irradiation (UVGI) with the wavelength of 255-280nm has been verified to efficiently disinfect various types of bacteria and virus, which could prevent the aggravation of pandemic spread. Even though considerable experiments and approaches have been applied to evaluate the disinfection effects, there are only few reports about how the individual bio-organism behaves after ultraviolet C (UVC) irradiation, especially in the aspect of mechanical changes. Furthermore, since the standard pathway of virus transmission and reproduction requires the host cell to assemble and transport newly generated virus, the dynamic response of infectious cell is always the vital aspect of virology study. In this work, high power LEDs array has been established with 270nm UVC irradiation to evaluate disinfection capability on various types of bio-organism, and incubator embedded atomic force microscopy (AFM) is used to investigate the single bacterium and virus under UVGI. The real-time tracking of the living Vero cells infected with adenovirus has also been presented in this study. The results show that after sufficient UVGI, the outer shell of bacteria and viruses remain intact in structure, however the bio-organisms lost the capability of reproduction and normal metabolism. The experiment results also indicate that once the host cell is infected with adenovirus, the rapid production of newborn virus capsid will gradually destroy the cellular normal metabolism and lose mechanical integrity.
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5
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Chandrasekhar S, Swope TP, Fadaei F, Hollis DR, Bricker R, Houser D, Portman J, Schmidt TL. Bending Unwinds DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.579968. [PMID: 38405957 PMCID: PMC10888926 DOI: 10.1101/2024.02.14.579968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
In biology, DNA is often tightly bent to small radii. Solely based on the groove asymmetry, a 30-year-old theoretical paper predicted that such bending should unwind DNA, but this effect has not been directly experimentally quantified so far. We developed a ligation-based assay with nicked DNA circles of variable length, thereby decoupling the twist-dependent ligation efficiency from the large bending strain which dominates conventional circularization assays. We demonstrate that tightly bent DNA indeed unwinds to over 11 base pairs/turn, exactly as predicted. Our discovery requires reassessing the molecular mechanisms and energetics of all processes where DNA is tightly bent or relaxed again, including DNA packaging, gene regulation and expression.
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Affiliation(s)
- Soumya Chandrasekhar
- Department of Physics, Kent State University, Kent, OH, 44242, USA
- Contributed equally
| | - Thomas P. Swope
- Department of Physics, Kent State University, Kent, OH, 44242, USA
- Contributed equally
| | - Fatemeh Fadaei
- Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Daniel R. Hollis
- Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Rachel Bricker
- Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - Draven Houser
- Department of Physics, Kent State University, Kent, OH, 44242, USA
| | - John Portman
- Department of Physics, Kent State University, Kent, OH, 44242, USA
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6
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Biswas A, Basu A. The impact of the sequence-dependent physical properties of DNA on chromatin dynamics. Curr Opin Struct Biol 2023; 83:102698. [PMID: 37696706 DOI: 10.1016/j.sbi.2023.102698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 07/07/2023] [Accepted: 08/14/2023] [Indexed: 09/13/2023]
Abstract
The local mechanical properties of DNA depend on local sequence. Here we review recent genomic, structural, and computational efforts at deciphering the "mechanical code", i.e., the mapping between sequence and mechanics. We then discuss works that suggest how evolution has exploited the mechanical code to control the energetics of DNA-deforming biological processes such as nucleosome organization, transcription factor binding, DNA supercoiling, gene regulation, and 3D chromatin organization. As a whole, these recent works suggest that DNA sequence in diverse organisms can encode regulatory information governing diverse processes via the mechanical code.
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Affiliation(s)
- Aditi Biswas
- Department of Biosciences, Durham University, Durham, UK
| | - Aakash Basu
- Department of Biosciences, Durham University, Durham, UK.
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7
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Chen YT, Yang H, Chu JW. Mechanical codes of chemical-scale specificity in DNA motifs. Chem Sci 2023; 14:10155-10166. [PMID: 37772098 PMCID: PMC10529945 DOI: 10.1039/d3sc01671d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/28/2023] [Indexed: 09/30/2023] Open
Abstract
In gene transcription, certain sequences of double-stranded (ds)DNA play a vital role in nucleosome positioning and expression initiation. That dsDNA is deformed to various extents in these processes leads us to ask: Could the genomic DNA also have sequence specificity in its chemical-scale mechanical properties? We approach this question using statistical machine learning to determine the rigidity between DNA chemical moieties. What emerges for the polyA, polyG, TpA, and CpG sequences studied here is a unique trigram that contains the quantitative mechanical strengths between bases and along the backbone. In a way, such a sequence-dependent trigram could be viewed as a DNA mechanical code. Interestingly, we discover a compensatory competition between the axial base-stacking interaction and the transverse base-pairing interaction, and such a reciprocal relationship constitutes the most discriminating feature of the mechanical code. Our results also provide chemical-scale understanding for experimental observables. For example, the long polyA persistence length is shown to have strong base stacking while its complement (polyAc) exhibits high backbone rigidity. The mechanical code concept enables a direct reading of the physical interactions encoded in the sequence which, with further development, is expected to shed new light on DNA allostery and DNA-binding drugs.
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Affiliation(s)
- Yi-Tsao Chen
- Institute of Bioinformatics and Systems Biology, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Republic of China
| | - Haw Yang
- Department of Chemistry, Princeton University Princeton NJ 08544 USA
| | - Jhih-Wei Chu
- Institute of Bioinformatics and Systems Biology, National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Republic of China
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan Republic of China
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8
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Gutiérrez Fosado YA, Landuzzi F, Sakaue T. Coarse Graining DNA: Symmetry, Nonlocal Elasticity, and Persistence Length. PHYSICAL REVIEW LETTERS 2023; 130:058402. [PMID: 36800451 DOI: 10.1103/physrevlett.130.058402] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
While the behavior of double-stranded DNA at mesoscopic scales is fairly well understood, less is known about its relation to the rich mechanical properties in the base-pair scale, which is crucial, for instance, to understand DNA-protein interactions and the nucleosome diffusion mechanism. Here, by employing the rigid base-pair model, we connect its microscopic parameters to the persistence length. Combined with all-atom molecular dynamic simulations, our scheme identifies relevant couplings between different degrees of freedom at each coarse-graining step. This allows us to clarify how the scale dependence of the elastic moduli is determined in a systematic way encompassing the role of previously unnoticed off-site couplings between deformations with different parity.
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Affiliation(s)
- Yair Augusto Gutiérrez Fosado
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom
| | - Fabio Landuzzi
- Centro CMP3VdA, Istituto Italiano di Tecnologia, via Lavoratori Vittime del Col du Mont 28, 11100, Aosta, Italy
| | - Takahiro Sakaue
- Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara-shi, Kanagawa 252-5258, Japan
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9
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Basu A, Bobrovnikov DG, Cieza B, Arcon JP, Qureshi Z, Orozco M, Ha T. Deciphering the mechanical code of the genome and epigenome. Nat Struct Mol Biol 2022; 29:1178-1187. [PMID: 36471057 PMCID: PMC10142808 DOI: 10.1038/s41594-022-00877-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/18/2022] [Indexed: 12/12/2022]
Abstract
Diverse DNA-deforming processes are impacted by the local mechanical and structural properties of DNA, which in turn depend on local sequence and epigenetic modifications. Deciphering this mechanical code (that is, this dependence) has been challenging due to the lack of high-throughput experimental methods. Here we present a comprehensive characterization of the mechanical code. Utilizing high-throughput measurements of DNA bendability via loop-seq, we quantitatively established how the occurrence and spatial distribution of dinucleotides, tetranucleotides and methylated CpG impact DNA bendability. We used our measurements to develop a physical model for the sequence and methylation dependence of DNA bendability. We validated the model by performing loop-seq on mouse genomic sequences around transcription start sites and CTCF-binding sites. We applied our model to test the predictions of all-atom molecular dynamics simulations and to demonstrate that sequence and epigenetic modifications can mechanically encode regulatory information in diverse contexts.
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Affiliation(s)
- Aakash Basu
- Department of Biosciences, Durham University, Durham, UK. .,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Dmitriy G Bobrovnikov
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Basilio Cieza
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Juan Pablo Arcon
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Zan Qureshi
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology, Barcelona, Spain.,Department of Biochemistry and Biomedicine, Universitat de Barcelona, Barcelona, Spain
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA. .,Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA. .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA. .,Howard Hughes Medical Institute, Baltimore, MD, USA.
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10
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DNA mechanical flexibility controls DNA potential to activate cGAS-mediated immune surveillance. Nat Commun 2022; 13:7107. [PMID: 36402783 PMCID: PMC9675814 DOI: 10.1038/s41467-022-34858-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 11/09/2022] [Indexed: 11/21/2022] Open
Abstract
DNA is well-documented to stimulate immune response. However, the nature of the DNA to activate immune surveillance is less understood. Here, we show that the activation of cyclic GMP-AMP synthase (cGAS) depends on DNA mechanical flexibility, which is controlled by DNA-sequence, -damage and -length. Consistently, DNA-sequence was shown to control cGAS activation. Structural analyses revealed that a conserved cGAS residue (mouse R222 or human R236) contributed to the DNA-flexibility detection. And the residue substitution neutralised the flexibility-controlled DNA-potential to activate cGAS, and relaxed the DNA-length specificity of cGAS. Moreover, low dose radiation was shown to mount cGAS-mediated acute immune surveillance (AIS) via repairable (reusable) DNAs in hrs. Loss of cGAS-mediated AIS decreased the regression of local and abscopal tumours in the context of focal radiation and immune checkpoint blockade. Our results build a direct link between immunosurveillance and DNA mechanical feature.
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11
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Balcão VM, Basu A, Cieza B, Rossi FN, Pereira C, Vila MM, Setubal JC, Ha T, da Silva AM. Pseudomonas-tailed lytic phages: genome mechanical analysis and putative correlation with virion morphogenesis yield. Future Microbiol 2022; 17:1009-1026. [PMID: 35880493 DOI: 10.2217/fmb-2021-0293] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To unveil a putative correlation between phage genome flexibility and virion morphogenesis yield. Materials & methods: A deeper analysis of the mechanical properties of three Pseudomonas aeruginosa lytic phage genomes was undertaken, together with full genome cyclizability calculations. Results & conclusion: A putative correlation was established among phage genome flexibility, eclipse timeframe and virion particle morphogenesis yield, with a more flexible phage genome leading to a higher burst size and a more rigid phage genome leading to lower burst sizes. The results obtained are highly relevant to understand the influence of the phage genome plasticity on the virion morphogenesis yield inside the infected bacterial host cells and assumes particular relevance in the actual context of bacterial resistance to antibiotics.
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Affiliation(s)
- Victor M Balcão
- PhageLab - Laboratory of Biofilms & Bacteriophages, University of Sorocaba, Sorocaba/SP, 18023-000, Brazil.,Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, Aveiro, P-3810-193, Portugal
| | - Aakash Basu
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Basilio Cieza
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Fernando N Rossi
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | - Carla Pereira
- Department of Biology & CESAM, University of Aveiro, Campus Universitário de Santiago, Aveiro, P-3810-193, Portugal
| | - Marta Mdc Vila
- PhageLab - Laboratory of Biofilms & Bacteriophages, University of Sorocaba, Sorocaba/SP, 18023-000, Brazil
| | - João C Setubal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | - Taekjip Ha
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Aline M da Silva
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
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12
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Yuan X, Luo SZ, Chen L. Novel branched amphiphilic peptides for nucleic acids delivery. Int J Pharm 2022; 624:121983. [PMID: 35803534 DOI: 10.1016/j.ijpharm.2022.121983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022]
Abstract
Highly efficient and safe non-viral vectors for nucleic acids delivery have attracted much attention due to their potential applications in gene therapy, gene editing and vaccination against infectious diseases, and various materials have been investigated and designed as delivery vectors. Herein, we designed a series of branched amphiphilic peptides (BAPs) and tested their applications as pDNA/mRNA delivery vectors. The BAP structure was inspired by the phospholipids, in which lysine oligomers were used as the "polar head", segments containing phenylalanine, histidine and leucine were used as the "hydrophobic tails", and a lysine residue was used as the branching point. By comparing the gel retardation, particle sizes and zeta potentials of the BAP/pDNA complexes of the short-branch BAPs (BAP-V1 ∼ BAP-V4), we determined the optimal lysine oligomer was K6. However, their cell transfection efficiencies were not satisfactory, and thus three long-branch BAPs (BAP-V5 ∼ BAP-V7) were further designed. In these long-branch BAPs, more hydrophobic residues were added and the overall amphiphilicity increased accordingly. The results showed that these three BAPs could effectively compact the nucleic acids, including both pDNA and mRNA, and all could transfect nucleic acids into HEK 293 cells, with low cytotoxicity. Among the three long-branch BAPs, BAP-V7 (bis(FFLFFHHH)-K-K6) showed the best transfection efficiency at N/P = 10, which was better than the commercial transfection reagent PEI-25 K. These results indicate that increased amphiphilicity would also benefit for BAP mediated nucleic acid delivery. The designed BAPs provide more documents of such novel type of nucleic acids delivery vectors, which is worth of further investigation as a new gene theranostic platforms.
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Affiliation(s)
- Xiushuang Yuan
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Shi-Zhong Luo
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Long Chen
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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13
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Müller TG, Zila V, Müller B, Kräusslich HG. Nuclear Capsid Uncoating and Reverse Transcription of HIV-1. Annu Rev Virol 2022; 9:261-284. [PMID: 35704745 DOI: 10.1146/annurev-virology-020922-110929] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
After cell entry, human immunodeficiency virus type 1 (HIV-1) replication involves reverse transcription of the RNA genome, nuclear import of the subviral complex without nuclear envelope breakdown, and integration of the viral complementary DNA into the host genome. Here, we discuss recent evidence indicating that completion of reverse transcription and viral genome uncoating occur in the nucleus rather than in the cytoplasm, as previously thought, and suggest a testable model for nuclear import and uncoating. Multiple recent studies indicated that the cone-shaped capsid, which encases the genome and replication proteins, not only serves as a reaction container for reverse transcription and as a shield from innate immune sensors but also may constitute the elusive HIV-1 nuclear import factor. Rupture of the capsid may be triggered in the nucleus by completion of reverse transcription, by yet-unknown nuclear factors, or by physical damage, and it appears to occur in close temporal and spatial association with the integration process. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Thorsten G Müller
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Vojtech Zila
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Barbara Müller
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany; .,German Center for Infection Research, Heidelberg, Germany
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14
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Cofsky JC, Soczek KM, Knott GJ, Nogales E, Doudna JA. CRISPR-Cas9 bends and twists DNA to read its sequence. Nat Struct Mol Biol 2022; 29:395-402. [PMID: 35422516 PMCID: PMC9189902 DOI: 10.1038/s41594-022-00756-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/01/2022] [Indexed: 12/28/2022]
Abstract
In bacterial defense and genome editing applications, the CRISPR-associated protein Cas9 searches millions of DNA base pairs to locate a 20-nucleotide, guide RNA-complementary target sequence that abuts a protospacer-adjacent motif (PAM). Target capture requires Cas9 to unwind DNA at candidate sequences using an unknown ATP-independent mechanism. Here we show that Cas9 sharply bends and undertwists DNA on PAM binding, thereby flipping DNA nucleotides out of the duplex and toward the guide RNA for sequence interrogation. Cryogenic-electron microscopy (cryo-EM) structures of Cas9-RNA-DNA complexes trapped at different states of the interrogation pathway, together with solution conformational probing, reveal that global protein rearrangement accompanies formation of an unstacked DNA hinge. Bend-induced base flipping explains how Cas9 'reads' snippets of DNA to locate target sites within a vast excess of nontarget DNA, a process crucial to both bacterial antiviral immunity and genome editing. This mechanism establishes a physical solution to the problem of complementarity-guided DNA search and shows how interrogation speed and local DNA geometry may influence genome editing efficiency.
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Affiliation(s)
- Joshua C Cofsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Katarzyna M Soczek
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Gavin J Knott
- Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA.
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA.
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Gladstone Institutes, University of California, San Francisco, CA, USA.
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA.
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15
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Yeou S, Lee NK. Single-Molecule Methods for Investigating the Double-Stranded DNA Bendability. Mol Cells 2022; 45:33-40. [PMID: 34470919 PMCID: PMC8819492 DOI: 10.14348/molcells.2021.0182] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 11/27/2022] Open
Abstract
The various DNA-protein interactions associated with the expression of genetic information involve double-stranded DNA (dsDNA) bending. Due to the importance of the formation of the dsDNA bending structure, dsDNA bending properties have long been investigated in the biophysics field. Conventionally, DNA bendability is characterized by innate averaging data from bulk experiments. The advent of single-molecule methods, such as atomic force microscopy, optical and magnetic tweezers, tethered particle motion, and single-molecule fluorescence resonance energy transfer measurement, has provided valuable tools to investigate not only the static structures but also the dynamic properties of bent dsDNA. Here, we reviewed the single-molecule methods that have been used for investigating dsDNA bendability and new findings related to dsDNA bending. Single-molecule approaches are promising tools for revealing the unknown properties of dsDNA related to its bending, particularly in cells.
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Affiliation(s)
- Sanghun Yeou
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Nam Ki Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
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16
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Li K, Carroll M, Vafabakhsh R, Wang XA, Wang JP. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3142-3154. [PMID: 35288750 PMCID: PMC8989542 DOI: 10.1093/nar/gkac162] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/16/2022] [Accepted: 02/23/2022] [Indexed: 11/16/2022] Open
Abstract
DNA mechanical properties play a critical role in every aspect of DNA-dependent biological processes. Recently a high throughput assay named loop-seq has been developed to quantify the intrinsic bendability of a massive number of DNA fragments simultaneously. Using the loop-seq data, we develop a software tool, DNAcycP, based on a deep-learning approach for intrinsic DNA cyclizability prediction. We demonstrate DNAcycP predicts intrinsic DNA cyclizability with high fidelity compared to the experimental data. Using an independent dataset from in vitro selection for enrichment of loopable sequences, we further verified the predicted cyclizability score, termed C-score, can well distinguish DNA fragments with different loopability. We applied DNAcycP to multiple species and compared the C-scores with available high-resolution chemical nucleosome maps. Our analyses showed that both yeast and mouse genomes share a conserved feature of high DNA bendability spanning nucleosome dyads. Additionally, we extended our analysis to transcription factor binding sites and surprisingly found that the cyclizability is substantially elevated at CTCF binding sites in the mouse genome. We further demonstrate this distinct mechanical property is conserved across mammalian species and is inherent to CTCF binding DNA motif.
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Affiliation(s)
- Keren Li
- Department of Statistics, Northwestern University, 633 Clark Street, Evanston, IL 60208, USA
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL 60208, USA
| | - Matthew Carroll
- Weinberg College IT Solutions (WITS), Northwestern University, 633 Clark Street, Evanston, IL 60208, USA
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Xiaozhong A Wang
- Correspondence may also be addressed to Xiaozhong A. Wang. Tel: +1 847 467 4897;
| | - Ji-Ping Wang
- To whom correspondence should be addressed. Tel: +1 847 467 6896;
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17
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Kim M, Bae S, Oh I, Yoo J, Kim JS. Sequence-dependent twist-bend coupling in DNA minicircles. NANOSCALE 2021; 13:20186-20196. [PMID: 34847218 DOI: 10.1039/d1nr04672a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Looping of double-stranded DNA molecules with 100-200 base pairs into minicircles, catenanes, and rotaxanes has been suggested as a potential tool for DNA nanotechnologies. However, sharp DNA bending into a minicircle with a diameter of several to ten nanometers occurs with alterations in the DNA helical structure and may lead to defective kink formation that hampers the use of DNA minicircles, catenanes, and rotaxanes in nanoscale DNA applications. Here, we investigated local variations of a helical twist in sharply bent DNA using microsecond-long all-atom molecular dynamics simulations of six different DNA minicircles, focusing on the sequence dependence of the coupling between DNA bending and its helical twist. Twist angles between consecutive base pairs were analyzed at different locations relative to the direction of DNA bending and, among 10 unique dinucleotide steps, we identified four dinucleotide steps with strong twist-bend coupling, the pyrimidine-purine dinucleotide steps of TA/TA, CG/CG, and CA/TG and the purine-purine dinucleotide step of GA/TC. This work suggests the sequence-dependent structural responses of DNA to strong mechanical deformation, providing new molecular-level insights into the structure and stability of sharply bent DNA minicircles for nanoscale applications.
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Affiliation(s)
- Minjung Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Sehui Bae
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Inrok Oh
- LG Chem Ltd, LG Science Park, Seoul 07796, Republic of Korea
| | - Jejoong Yoo
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jun Soo Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.
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18
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Carlsen A, Tabard-Cossa V. Mapping shifts in nanopore signal to changes in protein and protein-DNA conformation. Proteomics 2021; 22:e2100068. [PMID: 34845853 DOI: 10.1002/pmic.202100068] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/28/2021] [Accepted: 11/12/2021] [Indexed: 11/08/2022]
Abstract
Solid-state nanopores have been used extensively in biomolecular studies involving DNA and proteins. However, the interpretation of signals generated by the translocation of proteins or protein-DNA complexes remains challenging. Here, we investigate the behavior of monovalent streptavidin and the complex it forms with short biotinylated DNA over a range of nanopore sizes, salts, and voltages. We describe a simple geometric model that is broadly applicable and employ it to explain observed variations in conductance blockage and dwell time with experimental conditions. The general approach developed here underscores the value of nanopore-based protein analysis and represents progress toward the interpretation of complex translocation signals.
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Affiliation(s)
- Autumn Carlsen
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada
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19
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Bae S, Kim JS. Potential of Mean Force for DNA Wrapping Around a Cationic Nanoparticle. J Chem Theory Comput 2021; 17:7952-7961. [PMID: 34792353 DOI: 10.1021/acs.jctc.1c00797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Sharp bending and wrapping of DNA around proteins and nanoparticles (NPs) has been of extensive research interest. Here, we present the potential of mean force (PMF) for wrapping a DNA double helix around a cationic NP using coarse-grained models of a double-stranded DNA and a cationic NP. Starting from a NP wrapped around by DNA, the PMF was calculated along the distance between the center of the NP and one end of the DNA molecule. A relationship between the distance and the extent of DNA wrapping is used to calculate the PMF as a function of DNA wrapping around a NP. In particular, the PMF was compared for two DNA sequences of (AT)25/(AT)25 and (AC)25/(GT)25, for which the persistence lengths are different by ∼10 nm. The simulation results provide solid evidence of the thermodynamic preference for complex formation of a cationic NP with more flexible DNA over the less flexible DNA. Furthermore, we estimated the elastic energy of DNA bending, which was in good order-of-magnitude agreement with the theoretical prediction of elastic rods. This work suggests that the variation of sequence-dependent DNA flexibility can be utilized in DNA nanotechnologies, in which the position and dynamics of NPs are regulated on large-scale DNA structures, or the structural transformation of DNA is triggered by the sequence-dependent binding of NPs.
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Affiliation(s)
- Sehui Bae
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jun Soo Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
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20
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Loop-seq: A high-throughput technique to measure the mesoscale mechanical properties of DNA. Methods Enzymol 2021; 661:305-326. [PMID: 34776217 DOI: 10.1016/bs.mie.2021.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The local mechanical properties of the DNA polymer influence molecular processes in biology that require mechanical deformations of DNA. Lack of suitable high-throughput experimental techniques had precluded measuring how these properties might vary with sequence along the vast lengths of genomes. Here, we present a detailed protocol for a recently developed experimental technique called loop-seq, which measures at least one local mechanical property of DNA-its propensity to cyclize-in genome-scale throughput. Loop-seq has been used to obtain experimentally derived genome-wide maps of a physical property of DNA. Such measurements have revealed that diverse DNA-deforming processes involved in chromatin organization at various genomic loci are regulated by the genetically encoded, sequence-dependent variations in the mechanical properties of DNA.
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21
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Fogg JM, Judge AK, Stricker E, Chan HL, Zechiedrich L. Supercoiling and looping promote DNA base accessibility and coordination among distant sites. Nat Commun 2021; 12:5683. [PMID: 34584096 PMCID: PMC8478907 DOI: 10.1038/s41467-021-25936-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 08/30/2021] [Indexed: 11/29/2022] Open
Abstract
DNA in cells is supercoiled and constrained into loops and this supercoiling and looping influence every aspect of DNA activity. We show here that negative supercoiling transmits mechanical stress along the DNA backbone to disrupt base pairing at specific distant sites. Cooperativity among distant sites localizes certain sequences to superhelical apices. Base pair disruption allows sharp bending at superhelical apices, which facilitates DNA writhing to relieve torsional strain. The coupling of these processes may help prevent extensive denaturation associated with genomic instability. Our results provide a model for how DNA can form short loops, which are required for many essential processes, and how cells may use DNA loops to position nicks to facilitate repair. Furthermore, our results reveal a complex interplay between site-specific disruptions to base pairing and the 3-D conformation of DNA, which influences how genomes are stored, replicated, transcribed, repaired, and many other aspects of DNA activity.
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Affiliation(s)
- Jonathan M Fogg
- Department of Molecular Virology and Microbiology, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA
- Department of Pharmacology and Chemical Biology, Houston, TX, USA
| | - Allison K Judge
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA
| | - Erik Stricker
- Department of Molecular Virology and Microbiology, Houston, TX, USA
| | - Hilda L Chan
- Graduate Program in Immunology and Microbiology, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
| | - Lynn Zechiedrich
- Department of Molecular Virology and Microbiology, Houston, TX, USA.
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, TX, USA.
- Department of Pharmacology and Chemical Biology, Houston, TX, USA.
- Graduate Program in Immunology and Microbiology, Houston, TX, USA.
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22
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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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23
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Monsen RC, Chakravarthy S, Dean WL, Chaires JB, Trent JO. The solution structures of higher-order human telomere G-quadruplex multimers. Nucleic Acids Res 2021; 49:1749-1768. [PMID: 33469644 PMCID: PMC7897503 DOI: 10.1093/nar/gkaa1285] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/21/2020] [Accepted: 01/13/2021] [Indexed: 12/17/2022] Open
Abstract
Human telomeres contain the repeat DNA sequence 5′-d(TTAGGG), with duplex regions that are several kilobases long terminating in a 3′ single-stranded overhang. The structure of the single-stranded overhang is not known with certainty, with disparate models proposed in the literature. We report here the results of an integrated structural biology approach that combines small-angle X-ray scattering, circular dichroism (CD), analytical ultracentrifugation, size-exclusion column chromatography and molecular dynamics simulations that provide the most detailed characterization to date of the structure of the telomeric overhang. We find that the single-stranded sequences 5′-d(TTAGGG)n, with n = 8, 12 and 16, fold into multimeric structures containing the maximal number (2, 3 and 4, respectively) of contiguous G4 units with no long gaps between units. The G4 units are a mixture of hybrid-1 and hybrid-2 conformers. In the multimeric structures, G4 units interact, at least transiently, at the interfaces between units to produce distinctive CD signatures. Global fitting of our hydrodynamic and scattering data to a worm-like chain (WLC) model indicates that these multimeric G4 structures are semi-flexible, with a persistence length of ∼34 Å. Investigations of its flexibility using MD simulations reveal stacking, unstacking, and coiling movements, which yield unique sites for drug targeting.
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Affiliation(s)
- Robert C Monsen
- Department of Biochemistry & Molecular Genetics, University of Louisville Medical School, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - William L Dean
- James Graham Brown Cancer Center, University of Louisville Medical School, Louisville, KY 40202, USA
| | - Jonathan B Chaires
- Department of Biochemistry & Molecular Genetics, University of Louisville Medical School, Louisville, KY 40202, USA.,James Graham Brown Cancer Center, University of Louisville Medical School, Louisville, KY 40202, USA.,Department of Medicine, University of Louisville Medical School, Louisville, KY 40202, USA
| | - John O Trent
- Department of Biochemistry & Molecular Genetics, University of Louisville Medical School, Louisville, KY 40202, USA.,James Graham Brown Cancer Center, University of Louisville Medical School, Louisville, KY 40202, USA.,Department of Medicine, University of Louisville Medical School, Louisville, KY 40202, USA
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24
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DNA mechanics and its biological impact. J Mol Biol 2021; 433:166861. [PMID: 33539885 DOI: 10.1016/j.jmb.2021.166861] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 02/06/2023]
Abstract
Almost all nucleoprotein interactions and DNA manipulation events involve mechanical deformations of DNA. Extraordinary progresses in single-molecule, structural, and computational methods have characterized the average mechanical properties of DNA, such as bendability and torsional rigidity, in high resolution. Further, the advent of sequencing technology has permitted measuring, in high-throughput, how such mechanical properties vary with sequence and epigenetic modifications along genomes. We review these recent technological advancements, and discuss how they have contributed to the emerging idea that variations in the mechanical properties of DNA play a fundamental role in regulating, genome-wide, diverse processes involved in chromatin organization.
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25
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Abstract
Mechanical deformations of DNA such as bending are ubiquitous and implicated in diverse cellular functions1. However, the lack of high-throughput tools to directly measure the mechanical properties of DNA limits our understanding of whether and how DNA sequences modulate DNA mechanics and associated chromatin transactions genome-wide. We developed an assay called loop-seq to measure the intrinsic cyclizability of DNA – a proxy for DNA bendability – in high throughput. We measured the intrinsic cyclizabilities of 270,806 50 bp DNA fragments that span the entire length of S. cerevisiae chromosome V and other genomic regions, and also include random sequences. We discovered sequence-encoded regions of unusually low bendability upstream of Transcription Start Sites (TSSs). These regions disfavor the sharp DNA bending required for nucleosome formation and are co-centric with known Nucleosome Depleted Regions (NDRs). We show biochemically that low bendability of linker DNA located about 40 bp away from a nucleosome edge inhibits nucleosome sliding into the linker by the chromatin remodeler INO80. The observation explains how INO80 can create promoter-proximal nucleosomal arrays in the absence of any other factors2 by reading the DNA mechanical landscape. We show that chromosome wide, nucleosomes are characterized by high DNA bendability near dyads and low bendability near the linkers. This contrast increases for nucleosomes deeper into gene bodies, suggesting that DNA mechanics plays a previously unappreciated role in organizing nucleosomes far from the TSS, where nucleosome remodelers predominate. Importantly, random substitution of synonymous codons does not preserve this contrast, suggesting that the evolution of codon choice has been impacted by selective pressure to preserve sequence-encoded mechanical modulations along genes. We also provide evidence that transcription through the TSS-proximal nucleosomes is impacted by local DNA mechanics. Overall, this first genome-scale map of DNA mechanics hints at a ‘mechanical code’ with broad functional implications.
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26
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Saran R, Wang Y, Li ITS. Mechanical Flexibility of DNA: A Quintessential Tool for DNA Nanotechnology. SENSORS (BASEL, SWITZERLAND) 2020; 20:E7019. [PMID: 33302459 PMCID: PMC7764255 DOI: 10.3390/s20247019] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/04/2020] [Accepted: 12/04/2020] [Indexed: 02/06/2023]
Abstract
The mechanical properties of DNA have enabled it to be a structural and sensory element in many nanotechnology applications. While specific base-pairing interactions and secondary structure formation have been the most widely utilized mechanism in designing DNA nanodevices and biosensors, the intrinsic mechanical rigidity and flexibility are often overlooked. In this article, we will discuss the biochemical and biophysical origin of double-stranded DNA rigidity and how environmental and intrinsic factors such as salt, temperature, sequence, and small molecules influence it. We will then take a critical look at three areas of applications of DNA bending rigidity. First, we will discuss how DNA's bending rigidity has been utilized to create molecular springs that regulate the activities of biomolecules and cellular processes. Second, we will discuss how the nanomechanical response induced by DNA rigidity has been used to create conformational changes as sensors for molecular force, pH, metal ions, small molecules, and protein interactions. Lastly, we will discuss how DNA's rigidity enabled its application in creating DNA-based nanostructures from DNA origami to nanomachines.
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Affiliation(s)
- Runjhun Saran
- Department of Chemistry, Biochemistry and Molecular Biology, Irving K. Barber Faculty of Science, The University of British Columbia, Kelowna, BC V1V1V7, Canada;
| | - Yong Wang
- Department of Physics, Materials Science and Engineering Program, Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA;
| | - Isaac T. S. Li
- Department of Chemistry, Biochemistry and Molecular Biology, Irving K. Barber Faculty of Science, The University of British Columbia, Kelowna, BC V1V1V7, Canada;
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27
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Kono H, Ishida H. Nucleosome unwrapping and unstacking. Curr Opin Struct Biol 2020; 64:119-125. [DOI: 10.1016/j.sbi.2020.06.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 05/31/2020] [Accepted: 06/23/2020] [Indexed: 02/07/2023]
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28
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Majumdar D, Bhattacharjee SM. Softening of DNA near melting as disappearance of an emergent property. Phys Rev E 2020; 102:032407. [PMID: 33075941 DOI: 10.1103/physreve.102.032407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 08/27/2020] [Indexed: 06/11/2023]
Abstract
Near the melting transition the bending elastic constant κ, an emergent property of double-stranded DNA (dsDNA), is shown not to follow the rodlike scaling for small-length N. The reduction in κ with temperature is determined by the denatured bubbles for a continuous transition, e.g., when the two strands are Gaussian, but by the broken bonds near the open end in a Y-like configuration for a first-order transition as for strands with excluded volume interactions. In the latter case, a lever rule is operational, implying a phase coexistence although dsDNA is known to be a single phase.
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Affiliation(s)
- Debjyoti Majumdar
- Institute of Physics, Bhubaneswar, Odisha 751005, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
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29
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Saxton MJ. Diffusion of DNA-Binding Species in the Nucleus: A Transient Anomalous Subdiffusion Model. Biophys J 2020; 118:2151-2167. [PMID: 32294478 PMCID: PMC7203007 DOI: 10.1016/j.bpj.2020.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 12/21/2022] Open
Abstract
Single-particle tracking experiments have measured escape times of DNA-binding species diffusing in living cells: CRISPR-Cas9, TetR, and LacI. The observed distribution is a truncated power law. Working backward from the experimental results, the observed distribution appears inconsistent with a Gaussian distribution of binding energies. Working forward, the observed distribution leads to transient anomalous subdiffusion, in which diffusion is anomalous at short times and normal at long times, here only mildly anomalous. Monte Carlo simulations are used to characterize the time-dependent diffusion coefficient D(t) in terms of the anomalous exponent α, the crossover time tcross, and the limits D(0) and D(∞) and to relate these quantities to the escape time distribution. The simplest interpretations identify the escape time as the actual binding time to DNA or the period of one-dimensional diffusion on DNA in the standard model combining one-dimensional and three-dimensional search, but a more complicated interpretation may be required. The model has several implications for cell biophysics. 1) The initial anomalous regime represents the search of the DNA-binding species for its target DNA sequence. 2) Non-target DNA sites have a significant effect on search kinetics. False positives in bioinformatic searches of the genome are potentially rate-determining in vivo. For simple binding, the search would be speeded if false-positive sequences were eliminated from the genome. 3) Both binding and obstruction affect diffusion. Obstruction ought to be measured directly, using as the primary probe the DNA-binding species with the binding site inactivated and eGFP as a calibration standard among laboratories and cell types. 4) Overexpression of the DNA-binding species reduces anomalous subdiffusion because the deepest binding sites are occupied and unavailable. 5) The model provides a coarse-grained phenomenological description of diffusion of a DNA-binding species, useful in larger-scale modeling of kinetics, FCS, and FRAP.
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Affiliation(s)
- Michael J Saxton
- Department of Biochemistry and Molecular Medicine, University of California, Davis, California.
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30
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Liu Q, Song W, Zhou Y, Dong X, Xin Y. Phenotypic divergence of thermotolerance: Molecular basis and cold adaptive evolution related to intrinsic DNA flexibility of glacier‐inhabitingCryobacteriumstrains. Environ Microbiol 2020; 22:1409-1420. [DOI: 10.1111/1462-2920.14957] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 02/01/2020] [Accepted: 02/18/2020] [Indexed: 11/30/2022]
Affiliation(s)
- Qing Liu
- China General Microbiological Culture Collection Center (CGMCC)Institute of Microbiology, Chinese Academy of Sciences Beijing 100101 China
| | - Wei‐Zhi Song
- Centre for Marine Bio‐InnovationUniversity of New South Wales Sydney New South Wales Australia
| | - Yu‐Guang Zhou
- China General Microbiological Culture Collection Center (CGMCC)Institute of Microbiology, Chinese Academy of Sciences Beijing 100101 China
| | - Xiu‐Zhu Dong
- State Key Laboratory of Microbial ResourcesInstitute of Microbiology, Chinese Academy of Sciences Beijing 100101 China
| | - Yu‐Hua Xin
- China General Microbiological Culture Collection Center (CGMCC)Institute of Microbiology, Chinese Academy of Sciences Beijing 100101 China
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31
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Drozdetski AV, Mukhopadhyay A, Onufriev AV. Strongly Bent Double-Stranded DNA: Reconciling Theory and Experiment. FRONTIERS IN PHYSICS 2019; 7:195. [PMID: 32601596 PMCID: PMC7323118 DOI: 10.3389/fphy.2019.00195] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The strong bending of polymers is poorly understood. We propose a general quantitative framework of polymer bending that includes both the weak and strong bending regimes on the same footing, based on a single general physical principle. As the bending deformation increases beyond a certain (polymer-specific) point, the change in the convexity properties of the effective bending energy of the polymer makes the harmonic deformation energetically unfavorable: in this strong bending regime the energy of the polymer varies linearly with the average bending angle as the system follows the convex hull of the deformation energy function. For double-stranded DNA, the effective bending deformation energy becomes non-convex for bends greater than ~ 2° per base-pair, equivalent to the curvature of a closed circular loop of ~ 160 base pairs. A simple equation is derived for the polymer loop energy that covers both the weak and strong bending regimes. The theory shows quantitative agreement with recent DNA cyclization experiments on short DNA fragments, while maintaining the expected agreement with experiment in the weak bending regime. Counter-intuitively, cyclization probability (j-factor) of very short DNA loops is predicted to increase with decreasing loop length; the j-factor reaches its minimum for loops of ≃ 45 base pairs. Atomistic simulations reveal that the attractive component of the short-range Lennard-Jones interaction between the backbone atoms can explain the underlying non-convexity of the DNA effective bending energy, leading to the linear bending regime. Applicability of the theory to protein-DNA complexes, including the nucleosome, is discussed.
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Affiliation(s)
| | | | - Alexey V. Onufriev
- Department of Physics, Virginia Tech, Blacksburg, VA, United States
- Department of Computer Science, Virginia Tech, Blacksburg, VA, United States
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
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32
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Onufriev AV, Schiessel H. The nucleosome: from structure to function through physics. Curr Opin Struct Biol 2019; 56:119-130. [DOI: 10.1016/j.sbi.2018.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 11/07/2018] [Accepted: 11/13/2018] [Indexed: 02/07/2023]
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Jardine PJ. Slow and steady wins the race: physical limits on the rate of viral DNA packaging. Curr Opin Virol 2019; 36:32-37. [PMID: 31003199 DOI: 10.1016/j.coviro.2019.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 12/19/2022]
Abstract
During the assembly of dsDNA viruses such as the tailed bacteriophages and herpesviruses, the viral chromosome is compacted to near crystalline density inside a preformed head shell. DNA translocation is driven by powerful ring ATPase motors that couple ATP binding, hydrolysis, and release to force generation and movement. Studies of the motor of the bacteriophage phi29 have revealed a complex mechanochemistry behind this process that slows as the head fills. Recent studies of the physical behavior of packaging DNA suggest that surprisingly long-time scales of relaxation of DNA inside the head and jamming phenomena during packaging create the physical need for regulation of the rate of packaging. Studies of DNA packaging in viral systems have, therefore, revealed fundamental insight into the complex behavior of DNA and the need for biological systems to accommodate these physical constraints.
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Affiliation(s)
- Paul J Jardine
- Department of Diagnostic and Biological Sciences, University of Minnesota, 18-242 Moos Tower, 515 Delaware St SE, Minneapolis, MN 55455, United States.
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34
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Marin-Gonzalez A, Vilhena JG, Moreno-Herrero F, Perez R. DNA Crookedness Regulates DNA Mechanical Properties at Short Length Scales. PHYSICAL REVIEW LETTERS 2019; 122:048102. [PMID: 30768347 DOI: 10.1103/physrevlett.122.048102] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Indexed: 05/13/2023]
Abstract
Sequence-dependent DNA conformation and flexibility play a fundamental role in the specificity of DNA-protein interactions. Here we quantify the DNA crookedness: a sequence-dependent deformation of DNA that consists of periodic bends of the base pair centers chain. Using extensive 100 μs-long, all-atom molecular dynamics simulations, we found that DNA crookedness and its associated flexibility are bijective, which unveils a one-to-one relation between DNA structure and dynamics. This allowed us to build a predictive model to compute the stretch moduli of different DNA sequences from solely their structure. Sequences with very little crookedness show extremely high stretching stiffness and have been previously shown to form unstable nucleosomes and promote gene expression. Interestingly, the crookedness can be tailored by epigenetic modifications, known to affect gene expression. Our results rationalize the idea that the DNA sequence is not only a chemical code, but also a physical one that allows finely regulating its mechanical properties and, possibly, its 3D arrangement inside the cell.
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Affiliation(s)
- Alberto Marin-Gonzalez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - J G Vilhena
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH 4056 Basel, Switzerland
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Ruben Perez
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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35
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Khanal O, Xu X, Singh N, Traylor SJ, Huang C, Ghose S, Li ZJ, Lenhoff AM. DNA RETENTION ON DEPTH FILTERS. J Memb Sci 2019; 570-571:464-471. [PMID: 31223185 PMCID: PMC6586439 DOI: 10.1016/j.memsci.2018.10.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Depth filtration is a commonly-used bioprocessing unit operation for harvest clarification that reduces the levels of process- and product-related impurities such as cell debris, host-cell proteins, nucleic acids and protein aggregates. Since depth filters comprise multiple components, different functionalities may contribute to such retention, making the mechanisms by which different impurities are removed difficult to decouple. Here we probe the mechanisms by which double-stranded DNA (dsDNA) is retained on depth filter media by visualizing the distribution of fluorescently-labeled retained DNA on spent depth filter discs using confocal fluorescence microscopy. The extent of DNA displacement into the depth filter was found to increase with decreasing DNA length with increasing operational parameters such as wash volume and buffer ionic strength. Finally, using 5ethynyl-2'-deoxyuridine (EdU) to label DNA in dividing CHO cells, we showed that Chinese hamster ovary (CHO) cellular DNA in the lysate supernatant migrates deeper into the depth filter than the lysate re-suspended pellet, elucidating the role of the size of the DNA in its form as an impurity. Apart from aiding DNA purification and removal, our experimental approaches and findings can be leveraged in studying the transport and retention of nucleic acids and other impurities on depth filters at a small scale.
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Affiliation(s)
- Ohnmar Khanal
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
| | - Xuankuo Xu
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Nripen Singh
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Steven J. Traylor
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Chao Huang
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Sanchayita Ghose
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Zheng Jian Li
- Biologics Process Development, Global Product Development and Supply, Bristol‐Myers Squibb Company, Devens, MA 01434, USA
| | - Abraham M. Lenhoff
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
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36
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Zoli M. End-to-end distance and contour length distribution functions of DNA helices. J Chem Phys 2018; 148:214902. [DOI: 10.1063/1.5021639] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Marco Zoli
- School of Science and Technology, University of Camerino, I-62032 Camerino, Italy
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37
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Masuda T, Shibuya Y, Arai S, Kobayashi S, Suzuki S, Kijima J, Itoh T, Sato Y, Nishizawa S, Yamaguchi A. Effect of Cavity Size of Mesoporous Silica on Short DNA Duplex Stability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5545-5550. [PMID: 29715034 DOI: 10.1021/acs.langmuir.8b00437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We studied the stabilities of short (4- and 3-bp) DNA duplexes within silica mesopores modified with a positively charged trimethyl aminopropyl (TMAP) monolayer (BJH pore diameter 1.6-7.4 nm). The DNA fragments with fluorescent dye were introduced into the pores, and their fluorescence resonance energy transfer (FRET) response was measured to estimate the structuring energies of the short DNA duplexes under cryogenic conditions (temperature 233-323 K). The results confirmed the enthalpic stability gain of the duplex within size-matched pores (1.6 and 2.3 nm). The hybridization equilibrium constants found for the size-matched pores were 2 orders of magnitude larger than those for large pores (≥3.5 nm), and this size-matching effect for the enhanced duplex stability was explained by a tight electrostatic interaction between the duplex and the surface TMAP groups. These results indicate the requirement of the precise regulation of mesopore size to ensure the stabilization of hydrogen-bonded supramolecular assemblies.
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Affiliation(s)
- Tsubasa Masuda
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Yuuta Shibuya
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Shota Arai
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Sayaka Kobayashi
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Sotaro Suzuki
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Jun Kijima
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
| | - Tetsuji Itoh
- Research Institute for Chemical Process Technology , National Institute of Advanced Industrial Science and Technology (AIST) , Nigatake 4-2-1 , Sendai 983-8551 , Japan
| | - Yusuke Sato
- Department of Chemistry, Graduate School of Science , Tohoku University , Aoba-ku, Sendai 980-8578 , Japan
| | - Seiichi Nishizawa
- Department of Chemistry, Graduate School of Science , Tohoku University , Aoba-ku, Sendai 980-8578 , Japan
| | - Akira Yamaguchi
- Institute of Quantum Beam Science , Ibaraki University , 2-1-1 Bunkyo , Mito , Ibaraki 310-8512 , Japan
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38
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Fenley AT, Anandakrishnan R, Kidane YH, Onufriev AV. Modulation of nucleosomal DNA accessibility via charge-altering post-translational modifications in histone core. Epigenetics Chromatin 2018; 11:11. [PMID: 29548294 PMCID: PMC5856334 DOI: 10.1186/s13072-018-0181-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 03/06/2018] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Controlled modulation of nucleosomal DNA accessibility via post-translational modifications (PTM) is a critical component to many cellular functions. Charge-altering PTMs in the globular histone core-including acetylation, phosphorylation, crotonylation, propionylation, butyrylation, formylation, and citrullination-can alter the strong electrostatic interactions between the oppositely charged nucleosomal DNA and the histone proteins and thus modulate accessibility of the nucleosomal DNA, affecting processes that depend on access to the genetic information, such as transcription. However, direct experimental investigation of the effects of these PTMs is very difficult. Theoretical models can rationalize existing observations, suggest working hypotheses for future experiments, and provide a unifying framework for connecting PTMs with the observed effects. RESULTS A physics-based framework is proposed that predicts the effect of charge-altering PTMs in the histone core, quantitatively for several types of lysine charge-neutralizing PTMs including acetylation, and qualitatively for all phosphorylations, on the nucleosome stability and subsequent changes in DNA accessibility, making a connection to resulting biological phenotypes. The framework takes into account multiple partially assembled states of the nucleosome at the atomic resolution. The framework is validated against experimentally known nucleosome stability changes due to the acetylation of specific lysines, and their effect on transcription. The predicted effect of charge-altering PTMs on DNA accessibility can vary dramatically, from virtually none to a strong, region-dependent increase in accessibility of the nucleosomal DNA; in some cases, e.g., H4K44, H2AK75, and H2BK57, the effect is significantly stronger than that of the extensively studied acetylation sites such H3K56, H3K115 or H3K122. Proximity to the DNA is suggestive of the strength of the PTM effect, but there are many exceptions. For the vast majority of charge-altering PTMs, the predicted increase in the DNA accessibility should be large enough to result in a measurable modulation of transcription. However, a few possible PTMs, such as acetylation of H4K77, counterintuitively decrease the DNA accessibility, suggestive of the repressed chromatin. A structural explanation for the phenomenon is provided. For the majority of charge-altering PTMs, the effect on DNA accessibility is simply additive (noncooperative), but there are exceptions, e.g., simultaneous acetylation of H4K79 and H3K122, where the combined effect is amplified. The amplification is a direct consequence of the nucleosome-DNA complex having more than two structural states. The effect of individual PTMs is classified based on changes in the accessibility of various regions throughout the nucleosomal DNA. The PTM's resulting imprint on the DNA accessibility, "PTMprint," is used to predict effects of many yet unexplored PTMs. For example, acetylation of H4K44 yields a PTMprint similar to the PTMprint of H3K56, and thus acetylation of H4K44 is predicted to lead to a wide range of strong biological effects. CONCLUSION Charge-altering post-translational modifications in the relatively unexplored globular histone core may provide a precision mechanism for controlling accessibility to the nucleosomal DNA.
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Affiliation(s)
- Andrew T. Fenley
- Department of Physics, Virginia Tech, 2160C Torgersen Hall, Blacksburg, VA 24061 USA
| | | | - Yared H. Kidane
- Genetics, Bioinformatics and Computational Biology Program, Virginia Tech, Blacksburg, VA 24061 USA
| | - Alexey V. Onufriev
- Department of Physics, Virginia Tech, 2160C Torgersen Hall, Blacksburg, VA 24061 USA
- Genetics, Bioinformatics and Computational Biology Program, Virginia Tech, Blacksburg, VA 24061 USA
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061 USA
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061 USA
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39
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Kono H, Sakuraba S, Ishida H. Free energy profiles for unwrapping the outer superhelical turn of nucleosomal DNA. PLoS Comput Biol 2018; 14:e1006024. [PMID: 29505570 PMCID: PMC5854429 DOI: 10.1371/journal.pcbi.1006024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 03/15/2018] [Accepted: 02/01/2018] [Indexed: 11/19/2022] Open
Abstract
The eukaryotic genome is packaged into a nucleus in the form of chromatin. The fundamental structural unit of chromatin is a protein-DNA complex, the nucleosome, where 146 or 147 base pairs of DNA wrap 1.75 times around a histone core. To function in cellular processes, however, nucleosomal DNA must be unwrapped. Although this unwrapping has been experimentally investigated, details of the process at an atomic level are not yet well understood. Here, we used molecular dynamics simulation with an enhanced sampling method to calculate the free energy profiles for unwrapping the outer superhelical turn of nucleosomal DNA. A free energy change of about 11.5 kcal/mol for the unwrapping agrees well with values obtained in single molecule experiments. This simulation revealed a variety of conformational states, indicating there are many potential paths to outer superhelicdal turn unwrapping, but the dominant path is likely asymmetric. At one end of the DNA, the first five bps unwrap, after which a second five bps unwrap at the same end with no increase in free energy. The unwrapping then starts at the other end of the DNA, where 10 bps are unwrapped. During further unwrapping of 15 bps, the unwrapping advances at one of the ends, after which the other end of the DNA unwraps to complete the unwrapping of the outer superhelical turn. These results provide insight into the construction, disruption, and repositioning of nucleosomes, which are continuously ongoing during cellular processes.
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Affiliation(s)
- Hidetoshi Kono
- Molecular Modeling and Simulation Group, Department of Quantum Beam Life Science, National Institutes for Quantum and Radiological Science and Technology, Umemidai, Kizugawa, Kyoto, Japan
- * E-mail:
| | - Shun Sakuraba
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan
| | - Hisashi Ishida
- Molecular Modeling and Simulation Group, Department of Quantum Beam Life Science, National Institutes for Quantum and Radiological Science and Technology, Umemidai, Kizugawa, Kyoto, Japan
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40
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Sandmann A, Sticht H. Probing the role of intercalating protein sidechains for kink formation in DNA. PLoS One 2018; 13:e0192605. [PMID: 29432448 PMCID: PMC5809078 DOI: 10.1371/journal.pone.0192605] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/28/2018] [Indexed: 11/18/2022] Open
Abstract
Protein binding can induce DNA kinks, which are for example important to enhance the specificity of the interaction and to facilitate the assembly of multi protein complexes. The respective proteins frequently exhibit amino acid sidechains that intercalate between the DNA base steps at the site of the kink. However, on a molecular level there is only little information available about the role of individual sidechains for kink formation. To unravel structural principles of protein-induced DNA kinking we have performed molecular dynamics (MD) simulations of five complexes that varied in their architecture, function, and identity of intercalated residues. Simulations were performed for the DNA complexes of wildtype proteins (Sac7d, Sox-4, CcpA, TFAM, TBP) and for mutants, in which the intercalating residues were individually or combined replaced by alanine. The work revealed that for systems with multiple intercalated residues, not all of them are necessarily required for kink formation. In some complexes (Sox-4, TBP), one of the residues proved to be essential for kink formation, whereas the second residue has only a very small effect on the magnitude of the kink. In other systems (e.g. Sac7d) each of the intercalated residues proved to be individually capable of conferring a strong kink suggesting a partially redundant role of the intercalating residues. Mutation of the key residues responsible for kinking either resulted in stable complexes with reduced kink angles or caused conformational instability as evidenced by a shift of the kink to an adjacent base step. Thus, MD simulations can help to identify the role of individual inserted residues for kinking, which is not readily apparent from an inspection of the static structures. This information might be helpful for understanding protein-DNA interactions in more detail and for designing proteins with altered DNA binding properties in the future.
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Affiliation(s)
- Achim Sandmann
- Bioinformatik, Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Heinrich Sticht
- Bioinformatik, Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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41
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Whitley KD, Comstock MJ, Chemla YR. Ultrashort Nucleic Acid Duplexes Exhibit Long Wormlike Chain Behavior with Force-Dependent Edge Effects. PHYSICAL REVIEW LETTERS 2018; 120:068102. [PMID: 29481284 DOI: 10.1103/physrevlett.120.068102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/23/2017] [Indexed: 05/22/2023]
Abstract
Despite their importance in biology and use in nanotechnology, the elastic behavior of nucleic acids on "ultrashort" (<15 nt) length scales remains poorly understood. Here, we use optical tweezers combined with fluorescence imaging to observe directly the hybridization of oligonucleotides (7-12 nt) to a complementary strand under tension and to measure the difference in end-to-end extension between the single-stranded and duplex states. Data are consistent with long-polymer models at low forces (<8 pN) but smaller than predicted at higher forces (>8 pN), the result of the sequence-dependent duplex edge effects.
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Affiliation(s)
- Kevin D Whitley
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Matthew J Comstock
- Department of Physics, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Yann R Chemla
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Physics, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
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42
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Becker NA, Peters JP, Maher LJ. High-Resolution Characterization of DNA/Protein Complexes in Living Bacteria. Methods Mol Biol 2018; 1837:95-115. [PMID: 30109607 DOI: 10.1007/978-1-4939-8675-0_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The occurrence of DNA looping is ubiquitous. This process plays a well-documented role in the regulation of prokaryotic gene expression, such as the Escherichia coli lactose (lac) operon. Here, we present two complementary methods for high-resolution in vivo detection of DNA/protein binding within the bacterial nucleoid by using either chromatin immunoprecipitation combined with phage λ exonuclease digestion (ChIP-exo) or chromatin endogenous cleavage (ChEC), coupled with ligation-mediated polymerase chain reaction (LM-PCR) and Southern blot analysis. As an example we apply these in vivo protein-mapping methods to E. coli to show direct binding of architectural proteins in the Lac repressor-mediated DNA repression loop.
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Affiliation(s)
- Nicole A Becker
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - Justin P Peters
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA.
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43
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Alexandrov LB, Rasmussen KØ, Bishop AR, Alexandrov BS. Evaluating the role of coherent delocalized phonon-like modes in DNA cyclization. Sci Rep 2017; 7:9731. [PMID: 28851939 PMCID: PMC5575098 DOI: 10.1038/s41598-017-09537-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 07/27/2017] [Indexed: 12/11/2022] Open
Abstract
The innate flexibility of a DNA sequence is quantified by the Jacobson-Stockmayer's J-factor, which measures the propensity for DNA loop formation. Recent studies of ultra-short DNA sequences revealed a discrepancy of up to six orders of magnitude between experimentally measured and theoretically predicted J-factors. These large differences suggest that, in addition to the elastic moduli of the double helix, other factors contribute to loop formation. Here, we develop a new theoretical model that explores how coherent delocalized phonon-like modes in DNA provide single-stranded "flexible hinges" to assist in loop formation. We combine the Czapla-Swigon-Olson structural model of DNA with our extended Peyrard-Bishop-Dauxois model and, without changing any of the parameters of the two models, apply this new computational framework to 86 experimentally characterized DNA sequences. Our results demonstrate that the new computational framework can predict J-factors within an order of magnitude of experimental measurements for most ultra-short DNA sequences, while continuing to accurately describe the J-factors of longer sequences. Further, we demonstrate that our computational framework can be used to describe the cyclization of DNA sequences that contain a base pair mismatch. Overall, our results support the conclusion that coherent delocalized phonon-like modes play an important role in DNA cyclization.
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Affiliation(s)
- Ludmil B Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
- University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, 87102, USA
| | - Kim Ø Rasmussen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
| | - Alan R Bishop
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America
| | - Boian S Alexandrov
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, United States of America.
- University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, 87102, USA.
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44
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Mitchell JS, Glowacki J, Grandchamp AE, Manning RS, Maddocks JH. Sequence-Dependent Persistence Lengths of DNA. J Chem Theory Comput 2017; 13:1539-1555. [DOI: 10.1021/acs.jctc.6b00904] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Jaroslaw Glowacki
- Ecole Polytechnique Fédérale de Lausanne, Lausanne CH 1273, Switzerland
| | | | | | - John H. Maddocks
- Ecole Polytechnique Fédérale de Lausanne, Lausanne CH 1273, Switzerland
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45
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Avila L, Aps L, Ploscariu N, Sukthankar P, Guo R, Wilkinson K, Games P, Szoszkiewicz R, Alves R, Diniz M, Fang Y, Ferreira L, Tomich J. Gene delivery and immunomodulatory effects of plasmid DNA associated with Branched Amphiphilic Peptide Capsules. J Control Release 2016; 241:15-24. [DOI: 10.1016/j.jconrel.2016.08.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/27/2016] [Accepted: 08/31/2016] [Indexed: 01/08/2023]
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46
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Jeong J, Le TT, Kim HD. Single-molecule fluorescence studies on DNA looping. Methods 2016; 105:34-43. [PMID: 27064000 PMCID: PMC4967024 DOI: 10.1016/j.ymeth.2016.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 04/01/2016] [Accepted: 04/05/2016] [Indexed: 11/17/2022] Open
Abstract
Structure and dynamics of DNA impact how the genetic code is processed and maintained. In addition to its biological importance, DNA has been utilized as building blocks of various nanomachines and nanostructures. Thus, understanding the physical properties of DNA is of fundamental importance to basic sciences and engineering applications. DNA can undergo various physical changes. Among them, DNA looping is unique in that it can bring two distal sites together, and thus can be used to mediate interactions over long distances. In this paper, we introduce a FRET-based experimental tool to study DNA looping at the single molecule level. We explain the connection between experimental measurables and a theoretical concept known as the J factor with the intent of raising awareness of subtle theoretical details that should be considered when drawing conclusions. We also explore DNA looping-assisted protein diffusion mechanism called intersegmental transfer using protein induced fluorescence enhancement (PIFE). We present some preliminary results and future outlooks.
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Affiliation(s)
- Jiyoun Jeong
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta 30332, USA.
| | - Tung T Le
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta 30332, USA.
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta 30332, USA.
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47
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Tavakoli S, Panaretos VM. Detecting and Localizing Differences in Functional Time Series Dynamics: A Case Study in Molecular Biophysics. J Am Stat Assoc 2016. [DOI: 10.1080/01621459.2016.1147355] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Shahin Tavakoli
- Statistical Laboratory, University of Cambridge, Cambridge, UK
| | - Victor M. Panaretos
- Institut de Mathématiques, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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48
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Lee OC, Kim C, Kim JY, Lee NK, Sung W. Two conformational states in D-shaped DNA: Effects of local denaturation. Sci Rep 2016; 6:28239. [PMID: 27339114 PMCID: PMC4919636 DOI: 10.1038/srep28239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/26/2016] [Indexed: 11/09/2022] Open
Abstract
The bending of double-stranded(ds) DNA on the nano-meter scale plays a key role in many cellular processes such as nucleosome packing, transcription-control, and viral-genome packing. In our recent study, a nanometer-sized dsDNA bent into a D shape was formed by hybridizing a circular single-stranded(ss) DNA and a complementary linear ssDNA. Our fluorescence resonance energy transfer (FRET) measurement of D-DNA revealed two types of conformational states: a less-bent state and a kinked state, which can transform into each other. To understand the origin of the two deformed states of D-DNA, here we study the presence of open base-pairs in the ds portion by using the breathing-DNA model to simulate the system. We provide strong evidence that the two states are due to the emergence of local denaturation, i.e., a bubble in the middle and two forks at ends of the dsDNA portion. We also study the system analytically and find that the free-energy landscape is bistable with two minima representative of the two states. The kink and fork sizes estimated by the analytical calculation are also in excellent agreement with the results of the simulation. Thus, this combined experimental-simulation-analytical study corroborates that highly bent D-DNA reduces bending stress via local denaturation.
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Affiliation(s)
- O-Chul Lee
- Department of Physics and Postech Center for Theoretical Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.,Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Cheolhee Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Jae-Yeol Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Nam Ki Lee
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
| | - Wokyung Sung
- Department of Physics and Postech Center for Theoretical Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.,Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
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49
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Tokuda JM, Pabit SA, Pollack L. Protein-DNA and ion-DNA interactions revealed through contrast variation SAXS. Biophys Rev 2016; 8:139-149. [PMID: 27551324 PMCID: PMC4991782 DOI: 10.1007/s12551-016-0196-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/10/2016] [Indexed: 12/29/2022] Open
Abstract
Understanding how DNA carries out its biological roles requires knowledge of its interactions with biological partners. Since DNA is a polyanionic polymer, electrostatic interactions contribute significantly. These interactions are mediated by positively charged protein residues or charge compensating cations. Direct detection of these partners and/or their effect on DNA conformation poses challenges, especially for monitoring conformational dynamics in real time. Small-angle x-ray scattering (SAXS) is uniquely sensitive to both the conformation and local environment (i.e. protein partner and associated ions) of the DNA. The primary challenge of studying multi-component systems with SAXS lies in resolving how each component contributes to the measured scattering. Here, we review two contrast variation (CV) strategies that enable targeted studies of the structures of DNA or its associated partners. First, solution contrast variation enables measurement of DNA conformation within a protein-DNA complex by masking out the protein contribution to the scattering profile. We review a specific example, in which the real-time unwrapping of DNA from a nucleosome core particle is measured during salt-induced disassembly. The second method, heavy atom isomorphous replacement, reports the spatial distribution of the cation cloud around duplex DNA by exploiting changes in the scattering strength of cations with varying atomic numbers. We demonstrate the application of this approach to provide the spatial distribution of monovalent cations (Na+, K+, Rb+, Cs+) around a standard 25-base pair DNA. The CV strategies presented here are valuable tools for understanding DNA interactions with its biological partners.
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Affiliation(s)
- Joshua M. Tokuda
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 USA
| | - Suzette A. Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 USA
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 USA
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50
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In-Phase Assembly of Slim DNA Lattices with Small Circular DNA Motifs via Short Connections of 11 and 16 Base Pairs. Chembiochem 2016; 17:1132-7. [DOI: 10.1002/cbic.201600054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Indexed: 12/14/2022]
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