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Dubrovin EV. Atomic force microscopy-based approaches for single-molecule investigation of nucleic acid- protein complexes. Biophys Rev 2023; 15:1015-1033. [PMID: 37974971 PMCID: PMC10643717 DOI: 10.1007/s12551-023-01111-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/07/2023] [Indexed: 11/19/2023] Open
Abstract
The interaction of nucleic acids with proteins plays an important role in many fundamental biological processes in living cells, including replication, transcription, and translation. Therefore, understanding nucleic acid-protein interaction is of high relevance in many areas of biology, medicine and technology. During almost four decades of its existence atomic force microscopy (AFM) accumulated a significant experience in investigation of biological molecules at a single-molecule level. AFM has become a powerful tool of molecular biology and biophysics providing unique information about properties, structure, and functioning of biomolecules. Despite a great variety of nucleic acid-protein systems under AFM investigations, there are a number of typical approaches for such studies. This review is devoted to the analysis of the typical AFM-based approaches of investigation of DNA (RNA)-protein complexes with a major focus on transcription studies. The basic strategies of AFM analysis of nucleic acid-protein complexes including investigation of the products of DNA-protein reactions and real-time dynamics of DNA-protein interaction are categorized and described by the example of the most relevant research studies. The described approaches and protocols have many universal features and, therefore, are applicable for future AFM studies of various nucleic acid-protein systems.
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Affiliation(s)
- Evgeniy V. Dubrovin
- Lomonosov Moscow State University, Leninskie Gory 1 Bld. 2, 119991 Moscow, Russian Federation
- Moscow Institute of Physics and Technology, Institutskiy Per. 9, Dolgoprudny, 141700 Russian Federation
- Sirius University of Science and Technology, Olimpiyskiy Ave 1, Township Sirius, Krasnodar Region, 354349 Russia
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2
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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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3
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Kim SH, Ganji M, Kim E, van der Torre J, Abbondanzieri E, Dekker C. DNA sequence encodes the position of DNA supercoils. eLife 2018; 7:e36557. [PMID: 30523779 PMCID: PMC6301789 DOI: 10.7554/elife.36557] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022] Open
Abstract
The three-dimensional organization of DNA is increasingly understood to play a decisive role in vital cellular processes. Many studies focus on the role of DNA-packaging proteins, crowding, and confinement in arranging chromatin, but structural information might also be directly encoded in bare DNA itself. Here, we visualize plectonemes (extended intertwined DNA structures formed upon supercoiling) on individual DNA molecules. Remarkably, our experiments show that the DNA sequence directly encodes the structure of supercoiled DNA by pinning plectonemes at specific sequences. We develop a physical model that predicts that sequence-dependent intrinsic curvature is the key determinant of pinning strength and demonstrate this simple model provides very good agreement with the data. Analysis of several prokaryotic genomes indicates that plectonemes localize directly upstream of promoters, which we experimentally confirm for selected promotor sequences. Our findings reveal a hidden code in the genome that helps to spatially organize the chromosomal DNA.
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Affiliation(s)
- Sung Hyun Kim
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Mahipal Ganji
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Eugene Kim
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Jaco van der Torre
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Elio Abbondanzieri
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Cees Dekker
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
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4
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Marchetti M, Malinowska A, Heller I, Wuite GJL. How to switch the motor on: RNA polymerase initiation steps at the single-molecule level. Protein Sci 2017; 26:1303-1313. [PMID: 28470684 DOI: 10.1002/pro.3183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/26/2017] [Accepted: 04/26/2017] [Indexed: 11/06/2022]
Abstract
RNA polymerase (RNAP) is the central motor of gene expression since it governs the process of transcription. In prokaryotes, this holoenzyme is formed by the RNAP core and a sigma factor. After approaching and binding the specific promoter site on the DNA, the holoenzyme-promoter complex undergoes several conformational transitions that allow unwinding and opening of the DNA duplex. Once the first DNA basepairs (∼10 bp) are transcribed in an initial transcription process, the enzyme unbinds from the promoter and proceeds downstream along the DNA while continuously opening the helix and polymerizing the ribonucleotides in correspondence with the template DNA sequence. When the gene is transcribed into RNA, the process generally is terminated and RNAP unbinds from the DNA. The first step of transcription-initiation, is considered the rate-limiting step of the entire process. This review focuses on the single-molecule studies that try to reveal the key steps in the initiation phase of bacterial transcription. Such single-molecule studies have, for example, allowed real-time observations of the RNAP target search mechanism, a mechanism still under debate. Moreover, single-molecule studies using Förster Resonance Energy Transfer (FRET) revealed the conformational changes that the enzyme undergoes during initiation. Force-based techniques such as scanning force microscopy and magnetic tweezers allowed quantification of the energy that drives the RNAP translocation along DNA and its dynamics. In addition to these in vitro experiments, single particle tracking in vivo has provided a direct quantification of the relative populations in each phase of transcription and their locations within the cell.
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Affiliation(s)
- M Marchetti
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | | | - I Heller
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - G J L Wuite
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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5
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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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6
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Horn AE, Goodrich JA, Kugel JF. Single molecule studies of RNA polymerase II transcription in vitro. Transcription 2015; 5:e27608. [PMID: 25764112 DOI: 10.4161/trns.27608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Eukaryotic mRNA transcription by RNA polymerase II (RNAP II) is the first step in gene expression and a key determinant of cellular regulation. Elucidating the mechanism by which RNAP II synthesizes RNA is therefore vital to determining how genes are controlled under diverse biological conditions. Significant advances in understanding RNAP II transcription have been achieved using classical biochemical and structural techniques; however, aspects of the transcription mechanism cannot be assessed using these approaches. The application of single-molecule techniques to study RNAP II transcription has provided new insight only obtainable by studying molecules in this complex system one at a time.
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Affiliation(s)
- Abigail E Horn
- a Department of Chemistry and Biochemistry; University of Colorado; Boulder, CO USA
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7
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Studying RNAP–promoter interactions using atomic force microscopy. Methods 2015; 86:4-9. [DOI: 10.1016/j.ymeth.2015.05.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 05/15/2015] [Accepted: 05/18/2015] [Indexed: 01/02/2023] Open
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8
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Baranello L, Kouzine F, Levens D. DNA topoisomerases beyond the standard role. Transcription 2015; 4:232-7. [PMID: 24135702 DOI: 10.4161/trns.26598] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Chromatin is dynamically changing its structure to accommodate and control DNA-dependent processes inside of eukaryotic cells. These changes are necessarily linked to changes of DNA topology, which might itself serve as a regulatory signal to be detected by proteins. Thus, DNA Topoisomerases may contribute to the regulation of many events occurring during the transcription cycle. In this review we will focus on DNA Topoisomerase functions in transcription, with particular emphasis on the multiplicity of tasks beyond their widely appreciated role in solving topological problems associated with transcription elongation.
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9
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Cervantes NAG, Gutiérrez-Medina B. Robust deposition of lambda DNA on mica for imaging by AFM in air. SCANNING 2014; 36:561-569. [PMID: 25195672 DOI: 10.1002/sca.21155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/15/2014] [Indexed: 06/03/2023]
Abstract
Long DNA molecules remain difficult to image by atomic force microscopy (AFM) because of their tendency to entanglement and spontaneous formation of networks. We present a comparison of two different DNA deposition methods operating at room temperature and humidity conditions, aimed at reproducible imaging of isolated and relaxed λ DNA conformations by AFM in air. We first demonstrate that a standard deposition procedure, consisting in adsorption of DNA in the presence of divalent cations followed by washing and air-drying steps, yields a coexistence of different types of λ DNA networks with a only a few isolated DNA chains. In contrast, deposition using a spin-coating-based technique results in reproducible coverage of a significant fraction of the substrate area by isolated and relaxed λ DNA molecules, with the added benefit of a reduction in the effect of a residual layer that normally embeds DNA strands and leads to an apparent DNA height closer to the expected value. Furthermore, we show that deposition by spin-coating is also well-suited to visualize DNA-protein complexes. These results indicate that spin-coating is a simple, powerful alternative for reproducible sample preparation for AFM imaging.
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10
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Visualization of retroviral envelope spikes in complex with the V3 loop antibody 447-52D on intact viruses by cryo-electron tomography. J Virol 2014; 88:12265-75. [PMID: 25122783 DOI: 10.1128/jvi.01596-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The gp120 portion of the envelope spike on human immunodeficiency virus type 1 (HIV-1) plays a critical role in viral entry into host cells and is a key target for the humoral immune response, and yet many structural details remain elusive. We have used cryoelectron tomography to visualize the binding of the broadly neutralizing monoclonal antibody (MAb) 447-52D to intact envelope spikes on virions of HIV-1 MN strain. Antibody 447-52D has previously been shown to bind to the tip of the V3 loop. Our results show antibody arms radiating from the sides of the gp120 protomers at a range of angles and place the antibody-bound V3 loop in an orientation that differs from that predicted by most current models but consistent with the idea that antibody binding dislodges the V3 loop from its location in the Env spike, making it flexible and disordered. These data reveal information on the position of the V3 loop and its relative flexibility and suggest that 447-52D neutralizes HIV-1 MN by capturing the V3 loop, blocking its interaction with the coreceptor and altering the structure of the envelope spike. IMPORTANCE Antibody neutralization is one of the primary ways that the body fights infection with HIV. Because HIV is a highly mutable virus, the body must constantly produce new antibodies to counter new strains of HIV that the body itself is producing. Consequently, antibodies capable of neutralizing multiple HIV strains are comparatively few. An improved understanding of the mechanism of antibody neutralization might advance the development of immunogens. Most neutralizing antibodies target the Env glycoprotein spikes found on the virus surface. The broadly neutralizing antibody 447-52D targets the highly conserved β-turn of variable loop 3 (V3) of gp120. The importance of V3 lies in its contribution to the coreceptor binding site on the target cell. We show here that 447-52D binding to V3 converts the Env conformation from closed to open and makes the V3 loop highly flexible, implying disruption of coreceptor binding and attachment to the target cell.
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11
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Affiliation(s)
- Jens Michaelis
- Biophysics
Institute, Faculty of Natural Sciences, Ulm University, Albert-Einstein-Allee
11, 89081 Ulm, Germany
- Center
for Integrated Protein Science Munich (CIPSM), Department
of Chemistry and Biochemistry, Munich University, Butenandtstrasse 5-13, 81377 München, Germany
| | - Barbara Treutlein
- Department
of Bioengineering, Stanford University, James H. Clark Center, E-300, 318
Campus Drive, Stanford, California 94305-5432, United States
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12
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Martinez-Rucobo FW, Cramer P. Structural basis of transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:9-19. [PMID: 22982352 DOI: 10.1016/j.bbagrm.2012.09.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/06/2012] [Accepted: 09/07/2012] [Indexed: 01/13/2023]
Abstract
For transcription elongation, all cellular RNA polymerases form a stable elongation complex (EC) with the DNA template and the RNA transcript. Since the millennium, a wealth of structural information and complementary functional studies provided a detailed three-dimensional picture of the EC and many of its functional states. Here we summarize these studies that elucidated EC structure and maintenance, nucleotide selection and addition, translocation, elongation inhibition, pausing and proofreading, backtracking, arrest and reactivation, processivity, DNA lesion-induced stalling, lesion bypass, and transcriptional mutagenesis. In the future, additional structural and functional studies of elongation factors that control the EC and their possible allosteric modes of action should result in a more complete understanding of the dynamic molecular mechanisms underlying transcription elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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13
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Endo M, Tatsumi K, Terushima K, Katsuda Y, Hidaka K, Harada Y, Sugiyama H. Direct Visualization of the Movement of a Single T7 RNA Polymerase and Transcription on a DNA Nanostructure. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201890] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Endo M, Tatsumi K, Terushima K, Katsuda Y, Hidaka K, Harada Y, Sugiyama H. Direct visualization of the movement of a single T7 RNA polymerase and transcription on a DNA nanostructure. Angew Chem Int Ed Engl 2012; 51:8778-82. [PMID: 22848002 DOI: 10.1002/anie.201201890] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Indexed: 11/08/2022]
Affiliation(s)
- Masayuki Endo
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan.
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15
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Wolfe KC, Hastings WA, Dutta S, Long A, Shapiro BA, Woolf TB, Guthold M, Chirikjian GS. Multiscale modeling of double-helical DNA and RNA: a unification through Lie groups. J Phys Chem B 2012; 116:8556-72. [PMID: 22676719 PMCID: PMC4833121 DOI: 10.1021/jp2126015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Several different mechanical models of double-helical nucleic-acid structures that have been presented in the literature are reviewed here together with a new analysis method that provides a reconciliation between these disparate models. In all cases, terminology and basic results from the theory of Lie groups are used to describe rigid-body motions in a coordinate-free way, and when necessary, coordinates are introduced in a way in which simple equations result. We consider double-helical DNAs and RNAs which, in their unstressed referential state, have backbones that are either straight, slightly precurved, or bent by the action of a protein or other bound molecule. At the coarsest level, we consider worm-like chains with anisotropic bending stiffness. Then, we show how bi-rod models converge to this for sufficiently long filament lengths. At a finer level, we examine elastic networks of rigid bases and show how these relate to the coarser models. Finally, we show how results from molecular dynamics simulation at full atomic resolution (which is the finest scale considered here) and AFM experimental measurements (which is at the coarsest scale) relate to these models.
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Affiliation(s)
- Kevin C. Wolfe
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | | | - Samrat Dutta
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina, United States
| | - Andrew Long
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Bruce A. Shapiro
- Center for Cancer Research Nanobiology Program, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, Maryland, United States
| | - Thomas B. Woolf
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Martin Guthold
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina, United States
| | - Gregory S. Chirikjian
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
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16
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Limanskaya O, Limanskii A. Study of elongation complexes for T7 RNA polymerase. Biophysics (Nagoya-shi) 2012. [DOI: 10.1134/s0006350912040112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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Billingsley DJ, Crampton N, Kirkham J, Thomson NH, Bonass WA. Single-stranded loops as end-label polarity markers for double-stranded linear DNA templates in atomic force microscopy. Nucleic Acids Res 2012; 40:e99. [PMID: 22453274 PMCID: PMC3401461 DOI: 10.1093/nar/gks276] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/13/2012] [Accepted: 03/13/2012] [Indexed: 11/24/2022] Open
Abstract
Visualization of DNA-protein interactions by atomic force microscopy (AFM) has deepened our understanding of molecular processes such as DNA transcription. Interpretation of systems where more than one protein acts on a single template, however, is complicated by protein molecules migrating along the DNA. Single-molecule AFM imaging experiments can reveal more information if the polarity of the template can be determined. A nucleic acid-based approach to end-labelling is desirable because it does not compromise the sample preparation procedures for biomolecular AFM. Here, we report a method involving oligonucleotide loop-primed synthesis for the end labelling of double-stranded DNA to discriminate the polarity of linear templates at the single-molecule level. Single-stranded oligonucleotide primers were designed to allow loop formation while retaining 3'-single-strand extensions to facilitate primer annealing to the template. Following a DNA polymerase extension, the labelled templates were shown to have the ability to form open promoter complexes on a model nested gene template using two Escherichia coli RNA polymerases in a convergent transcription arrangement. Analysis of the AFM images indicates that the added loops have no effect on the ability of the promoters to recruit RNA polymerase. This labelling strategy is proposed as a generic methodology for end-labelling linear DNA for studying DNA-protein interactions by AFM.
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Affiliation(s)
- Daniel J. Billingsley
- School of Physics and Astronomy and Department of Oral Biology, Leeds Dental Institute, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS2 9JT, UK
| | - Neal Crampton
- School of Physics and Astronomy and Department of Oral Biology, Leeds Dental Institute, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS2 9JT, UK
| | - Jennifer Kirkham
- School of Physics and Astronomy and Department of Oral Biology, Leeds Dental Institute, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS2 9JT, UK
| | - Neil H. Thomson
- School of Physics and Astronomy and Department of Oral Biology, Leeds Dental Institute, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS2 9JT, UK
| | - William A. Bonass
- School of Physics and Astronomy and Department of Oral Biology, Leeds Dental Institute, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, LS2 9JT, UK
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18
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Billingsley DJ, Bonass WA, Crampton N, Kirkham J, Thomson NH. Single-molecule studies of DNA transcription using atomic force microscopy. Phys Biol 2012; 9:021001. [PMID: 22473059 DOI: 10.1088/1478-3975/9/2/021001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Atomic force microscopy (AFM) can detect single biomacromolecules with a high signal-to-noise ratio on atomically flat biocompatible support surfaces, such as mica. Contrast arises from the innate forces and therefore AFM does not require imaging contrast agents, leading to sample preparation that is relatively straightforward. The ability of AFM to operate in hydrated environments, including humid air and aqueous buffers, allows structure and function of biological and biomolecular systems to be retained. These traits of the AFM are ensuring that it is being increasingly used to study deoxyribonucleic acid (DNA) structure and DNA-protein interactions down to the secondary structure level. This report focuses in particular on reviewing the applications of AFM to the study of DNA transcription in reductionist single-molecule bottom-up approaches. The technique has allowed new insights into the interactions between ribonucleic acid (RNA) polymerase to be gained and enabled quantification of some aspects of the transcription process, such as promoter location, DNA wrapping and elongation. More recently, the trend is towards studying the interactions of more than one enzyme operating on a single DNA template. These methods begin to reveal the mechanics of gene expression at the single-molecule level and will enable us to gain greater understanding of how the genome is transcribed and translated into the proteome.
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Affiliation(s)
- Daniel J Billingsley
- School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire LS2 9JT, UK
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Mandal SM, Migliolo L, Das S, Mandal M, Franco OL, Hazra TK. Identification and characterization of a bactericidal and proapoptotic peptide from cycas revoluta seeds with DNA binding properties. J Cell Biochem 2011; 113:184-93. [DOI: 10.1002/jcb.23343] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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KUUTTI L, PELTONEN J, PERE J, TELEMAN O. Identification and surface structure of crystalline cellulose studied by atomic force microscopy. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1995.tb03573.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ramachandran S, Teran Arce F, Lal R. Potential role of atomic force microscopy in systems biology. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:702-16. [PMID: 21766465 DOI: 10.1002/wsbm.154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Systems biology is a quantitative approach for understanding a biological system at its global level through systematic perturbation and integrated analysis of all its components. Simultaneous acquisition of information data sets pertaining to the system components (e.g., genome, proteome) is essential to implement this approach. There are limitations to such an approach in measuring gene expression levels and accounting for all proteins in the system. The success of genomic studies is critically dependent on polymerase chain reaction (PCR) for its amplification, but PCR is very uneven in amplifying the samples, ineffective in scarce samples and unreliable in low copy number transcripts. On the other hand, lack of amplifying techniques for proteins critically limits their identification to only a small fraction of high concentration proteins. Atomic force microscopy (AFM), AFM cantilever sensors, and AFM force spectroscopy in particular, could address these issues directly. In this article, we reviewed and assessed their potential role in systems biology.
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22
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Skinner GM, Kalafut BS, Visscher K. Downstream DNA tension regulates the stability of the T7 RNA polymerase initiation complex. Biophys J 2011; 100:1034-41. [PMID: 21320448 DOI: 10.1016/j.bpj.2010.11.092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 11/11/2010] [Accepted: 11/15/2010] [Indexed: 11/25/2022] Open
Abstract
Gene transcription by the enzyme RNA polymerase is tightly regulated. In many cases, such as in the lac operon in Escherichia coli, this regulation is achieved through the action of protein factors on DNA. Because DNA is an elastic polymer, its response to enzymatic processing can lead to mechanical perturbations (e.g., linear stretching and supercoiling) that can affect the operation of other DNA processing complexes acting elsewhere on the same substrate molecule. Using an optical-tweezers assay, we measured the binding kinetics between single molecules of bacteriophage T7 RNA polymerase and DNA, as a function of tension. We found that increasing DNA tension under conditions that favor formation of the open complex results in destabilization of the preinitiation complex. Furthermore, with zero ribonucleotides present, when the closed complex is favored, we find reduced tension sensitivity, implying that it is predominantly the open complex that is sensitive. This result strongly supports the "scrunching" model for T7 transcription initiation, as the applied tension acts against the movement of the DNA into the scrunched state, and introduces linear DNA tension as a potential regulatory quantity for transcription initiation.
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Affiliation(s)
- Gary M Skinner
- Department of Physics, University of Arizona, Tucson, Arizona, USA.
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Hardin AH, Sarkar SK, Seol Y, Liou GF, Osheroff N, Neuman KC. Direct measurement of DNA bending by type IIA topoisomerases: implications for non-equilibrium topology simplification. Nucleic Acids Res 2011; 39:5729-43. [PMID: 21421557 PMCID: PMC3141238 DOI: 10.1093/nar/gkr109] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Type IIA topoisomerases modify DNA topology by passing one segment of duplex DNA (transfer or T-segment) through a transient double-strand break in a second segment of DNA (gate or G-segment) in an ATP-dependent reaction. Type IIA topoisomerases decatenate, unknot and relax supercoiled DNA to levels below equilibrium, resulting in global topology simplification. The mechanism underlying this non-equilibrium topology simplification remains speculative. The bend angle model postulates that non-equilibrium topology simplification scales with the bend angle imposed on the G-segment DNA by the binding of a type IIA topoisomerase. To test this bend angle model, we used atomic force microscopy and single-molecule Förster resonance energy transfer to measure the extent of bending imposed on DNA by three type IIA topoisomerases that span the range of topology simplification activity. We found that Escherichia coli topoisomerase IV, yeast topoisomerase II and human topoisomerase IIα each bend DNA to a similar degree. These data suggest that DNA bending is not the sole determinant of non-equilibrium topology simplification. Rather, they suggest a fundamental and conserved role for DNA bending in the enzymatic cycle of type IIA topoisomerases.
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Affiliation(s)
- Ashley H Hardin
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Promoter melting triggered by bacterial RNA polymerase occurs in three steps. Proc Natl Acad Sci U S A 2010; 107:12523-8. [PMID: 20615963 DOI: 10.1073/pnas.1003533107] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
RNA synthesis, carried out by DNA-dependent RNA polymerase (RNAP) in a process called transcription, involves several stages. In bacteria, transcription initiation starts with promoter recognition and binding of RNAP holoenzyme, resulting in the formation of the closed (R.P(c)) RNAP-promoter DNA complex. Subsequently, a transition to the open R.P(o) complex occurs, characterized by separation of the promoter DNA strands in an approximately 12 base-pair region to form the transcription bubble. Using coarse-grained self-organized polymer models of Thermus aquatics RNAP holoenzyme and promoter DNA complexes, we performed Brownian dynamics simulations of the R.P(c) --> R.P(o) transition. In the fast trajectories, unwinding of the promoter DNA begins by local melting around the -10 element, which is followed by sequential unzipping of DNA till the +2 site. The R.P(c) --> R.P(o) transition occurs in three steps. In step I, dsDNA melts and the nontemplate strand makes stable interactions with RNAP. In step II, DNA scrunches into RNA polymerase and the downstream base pairs sequentially open to form the transcription bubble, which results in strain build up. Subsequently, downstream dsDNA bending relieves the strain as R.P(o) forms. Entry of the dsDNA into the active-site channel of RNAP requires widening of the channel, which occurs by a swing mechanism involving transient movements of a subdomain of the beta subunit caused by steric repulsion with the DNA template strand. If premature local melting away from the -10 element occurs first then the transcription bubble formation is slow involving reformation of the opened base pairs and subsequent sequential unzipping as in the fast trajectories.
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25
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Klinov DV, Neretina TV, Prokhorov VV, Dobrynina TV, Aldarov KG, Demin VV. High-resolution atomic force microscopy of DNA. BIOCHEMISTRY (MOSCOW) 2010; 74:1150-4. [PMID: 19916928 DOI: 10.1134/s0006297909100113] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A method using high resolution atomic force microscopy for imaging DNA has been elaborated. Using super-sharp probes and modified graphite as support for molecule adsorption, DNA molecule images were obtained whose resolution made possible the observation of their fine structure with repeated helical motifs. The method can be used to visualize individual spread molecules of single-stranded DNA.
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Affiliation(s)
- D V Klinov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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26
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Sanchez H, Kanaar R, Wyman C. Molecular recognition of DNA-protein complexes: a straightforward method combining scanning force and fluorescence microscopy. Ultramicroscopy 2010; 110:844-51. [PMID: 20382478 DOI: 10.1016/j.ultramic.2010.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 01/11/2010] [Accepted: 03/16/2010] [Indexed: 01/10/2023]
Abstract
Combining scanning force and fluorescent microscopy allows simultaneous identification of labeled biomolecules and analysis of their nanometer level architectural arrangement. Fluorescent polystyrene nano-spheres were used as reliable objects for alignment of optical and topographic images. This allowed the precise localization of different fluorescence particles within complex molecular assemblies whose structure was mapped in nanometer detail topography. Our experiments reveal the versatility of this method for analysis of proteins and protein-DNA complexes.
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Affiliation(s)
- Humberto Sanchez
- Department of Cell Biology and Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
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27
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Abstract
RNA polymerase (RNAP) is a complex molecular machine that governs gene expression and its regulation in all cellular organisms. To accomplish its function of accurately producing a full-length RNA copy of a gene, RNAP performs a plethora of chemical reactions and undergoes multiple conformational changes in response to cellular conditions. At the heart of this machine is the active center, the engine, which is composed of distinct fixed and moving parts that serve as the ultimate acceptor of regulatory signals and as the target of inhibitory drugs. Recent advances in the structural and biochemical characterization of RNAP explain the active center at the atomic level and enable new approaches to understanding the entire transcription mechanism, its exceptional fidelity and control.
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Affiliation(s)
- Evgeny Nudler
- Department of Biochemistry, New York University School of Medicine, New York, NY 10016, USA.
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28
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Andrecka J, Treutlein B, Arcusa MAI, Muschielok A, Lewis R, Cheung ACM, Cramer P, Michaelis J. Nano positioning system reveals the course of upstream and nontemplate DNA within the RNA polymerase II elongation complex. Nucleic Acids Res 2009; 37:5803-9. [PMID: 19620213 PMCID: PMC2761271 DOI: 10.1093/nar/gkp601] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Crystallographic studies of the RNA polymerase II (Pol II) elongation complex (EC) revealed the locations of downstream DNA and the DNA-RNA hybrid, but not the course of the nontemplate DNA strand in the transcription bubble and the upstream DNA duplex. Here we used single-molecule Fluorescence Resonance Energy Transfer (smFRET) experiments to locate nontemplate and upstream DNA with our recently developed Nano Positioning System (NPS). In the resulting complete model of the Pol II EC, separation of the nontemplate from the template strand at position +2 involves interaction with fork loop 2. The nontemplate strand passes loop β10-β11 on the Pol II lobe, and then turns to the other side of the cleft above the rudder. The upstream DNA duplex exits at an approximately right angle from the incoming downstream DNA, and emanates from the cleft between the protrusion and clamp. Comparison with published data suggests that the architecture of the complete EC is conserved from bacteria to eukaryotes and that upstream DNA is relocated during the initiation–elongation transition.
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Affiliation(s)
- Joanna Andrecka
- Department of Chemistry and Biochemistry and Center for Integrated Protein Science München, Ludwig-Maximilians-Universität München, Butenandtstr.11, 81377 München, Germany
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29
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Abstract
Protein-bound duplex DNA is often bent or kinked. Yet, quantification of intrinsic DNA bending that might lead to such protein interactions remains enigmatic. DNA cyclization experiments have indicated that DNA may form sharp bends more easily than predicted by the established worm-like chain (WLC) model. One proposed explanation suggests that local melting of a few base pairs introduces flexible hinges. We have expanded this model to incorporate sequence and temperature dependence of the local melting, and tested it for three sequences at temperatures from 23°C to 42°C. We find that small melted bubbles are significantly more flexible than double-stranded DNA and can alter DNA flexibility at physiological temperatures. However, these bubbles are not flexible enough to explain the recently observed very sharp bends in DNA.
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Affiliation(s)
- Robert A Forties
- Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210-1117, USA
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30
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Energetic contributions to the initiation of transcription in E. coli. Biophys Chem 2008; 138:91-8. [PMID: 18834656 DOI: 10.1016/j.bpc.2008.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 09/02/2008] [Accepted: 09/03/2008] [Indexed: 11/21/2022]
Abstract
The thermodynamics of RNA polymerase (RNAP) binding to a 108 base pair (bp) synthetic promoter with consensus sequences at the -35 and -10 bp binding regions upstream from the transcription start point were determined using isothermal titration calorimetry (ITC). The binding constant at 25 degrees C is 2.37+/-0.18x10(7) M(-1), which is reduced to 0.17+/-0.06x10(7) M(-1) with mutations in the -10 bp region but remained the same with mutations in the -35 binding region. The binding reactions were enthalpically-driven with exothermic binding enthalpies ranging from -57+/-6 kJ mol(-1) at 15 degrees C to -271+/-20 kJ mol(-1) at 35 degrees C yielding a large binding heat capacity change of -10.7+/-1.9 kJ mol(-1) K(-1), indicating a conformational change upon binding to the RNAP. Differential scanning calorimetry (DSC) scans of the thermal unfolding of RNAP and the promoter-RNAP complex exhibited an unfolding transition at 55.5+/-0.6 degrees C and at 58.9+/-0.5 degrees C for the RNAP but only one transition at 60.5+/-1.1 degrees C for the complex with van't Hoff enthalpy to transition enthalpy ratios of, resp., 3.2+/-0.3 and 4.3+/-0.5. The single transition of the complex results from a shift to 60.5 degrees C of the low temperature transition upon promoter binding to the structural unit unfolding at the lower temperature in RNAP. The large transition enthalpy ratios indicate that the sigma, alpha, alpha, beta, and beta' subunits unfold as almost independent entities. The dissociation thermodynamics of short transcription "bubble" duplexes of 7 promoters sequenced from -1 to -12 bp were determined from ITC and DSC measurements. The free energy change of the promoter binding to the RNAP and the free energy requirement for formation of the transcription bubble at the low promoter concentrations in the cell are sufficient to drive the initiation of transcription through the isomerization of the closed to the open form step of the RNAP-promoter complex.
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31
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Abstract
Single-molecule techniques have advanced our understanding of transcription by RNA polymerase (RNAP). A new arsenal of approaches, including single-molecule fluorescence, atomic-force microscopy, magnetic tweezers, and optical traps (OTs) have been employed to probe the many facets of the transcription cycle. These approaches supply fresh insights into the means by which RNAP identifies a promoter, initiates transcription, translocates and pauses along the DNA template, proofreads errors, and ultimately terminates transcription. Results from single-molecule experiments complement the knowledge gained from biochemical and genetic assays by facilitating the observation of states that are otherwise obscured by ensemble averaging, such as those resulting from heterogeneity in molecular structure, elongation rate, or pause propensity. Most studies to date have been performed with bacterial RNAP, but work is also being carried out with eukaryotic polymerase (Pol II) and single-subunit polymerases from bacteriophages. We discuss recent progress achieved by single-molecule studies, highlighting some of the unresolved questions and ongoing debates.
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32
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Limanskaya OY, Limanskii AP. Imaging of T7 RNA polymerase elongation complexes by atomic force microscopy. Mol Biol 2008. [DOI: 10.1134/s0026893308030175] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Noah JW, Park S, Whitt JT, Perutka J, Frey W, Lambowitz AM. Atomic force microscopy reveals DNA bending during group II intron ribonucleoprotein particle integration into double-stranded DNA. Biochemistry 2006; 45:12424-35. [PMID: 17029398 PMCID: PMC2526057 DOI: 10.1021/bi060612h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mobile Lactococcus lactis Ll.LtrB group II intron integrates into DNA target sites by a mechanism in which the intron RNA reverse splices into one DNA strand while the intron-encoded protein uses a C-terminal DNA endonuclease domain to cleave the opposite strand and then uses the cleaved 3' end to prime reverse transcription of the inserted intron RNA. These reactions are mediated by an RNP particle that contains the intron-encoded protein and the excised intron lariat RNA, with both the protein and base pairing of the intron RNA used to recognize DNA target sequences. Here, computational analysis indicates that Escherichia coli DNA target sequences that support Ll.LtrB integration have greater predicted bendability than do random E. coli genomic sequences, and atomic force microscopy shows that target DNA is bent during the reaction with Ll.LtrB RNPs. Time course and mutational analyses show that DNA bending occurs after reverse splicing and requires subsequent interactions between the intron-encoded protein and the 3' exon, which lead to two progressively larger bend angles. Our results suggest a model in which RNPs bend the target DNA by maintaining initial contacts with the 5' exon while engaging in subsequent 3' exon interactions that successively position the scissile phosphate for bottom-strand cleavage at the DNA endonuclease active site and then reposition the 3' end of the cleaved bottom strand to the reverse transcriptase active site for initiation of cDNA synthesis. Our findings indicate that bendability of the DNA target site is a significant factor for Ll.LtrB RNP integration.
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Affiliation(s)
- James W. Noah
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, TX 78712−0159 USA
| | - Soyeun Park
- Department of Biomedical Engineering, Texas Materials Institute, and Center for Nano and Molecular Science and Technology, University of Texas at Austin, Austin, Texas 78712−1062 USA
| | - Jacob T. Whitt
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, TX 78712−0159 USA
| | - Jiri Perutka
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, TX 78712−0159 USA
| | - Wolfgang Frey
- Department of Biomedical Engineering, Texas Materials Institute, and Center for Nano and Molecular Science and Technology, University of Texas at Austin, Austin, Texas 78712−1062 USA
| | - Alan M. Lambowitz
- Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, TX 78712−0159 USA
- To whom correspondence should be addressed: Telephone: (512)-232−3418. Fax: (512)-232−3420. E-mail:
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Abstract
The kinetics and mechanisms of transcription are now being investigated by a repertoire of single-molecule techniques, including optical and magnetic tweezers, high-sensitivity fluorescence techniques, and atomic force microscopy. Single-molecule techniques complement traditional biochemical and crystallographic approaches, are capable of detecting the motions and dynamics of individual RNAP molecules and transcription complexes in real time, and make it possible to directly measure RNAP binding to and unwinding of template DNA, as well as RNAP translocation along the DNA during transcript synthesis.
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Affiliation(s)
- Lu Bai
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
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35
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Nechaev S, Geiduschek EP. The role of an upstream promoter interaction in initiation of bacterial transcription. EMBO J 2006; 25:1700-9. [PMID: 16601684 PMCID: PMC1440836 DOI: 10.1038/sj.emboj.7601069] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 03/09/2006] [Indexed: 11/09/2022] Open
Abstract
The bacterial RNA polymerase (RNAP) recognizes promoters through sequence-specific contacts of its promoter-specificity components (sigma) with two DNA sequence motifs. Contacts with the upstream ('-35') promoter motif are made by sigma domain 4 attached to the flap domain of the RNAP beta subunit. Bacteriophage T4 late promoters consist solely of an extended downstream ('-10') motif specifically recognized by the T4 gene 55 protein (gp55). Low level basal transcription is sustained by gp55-RNAP holoenzyme. The late transcription coactivator gp33 binds to the beta flap and represses this basal transcription. Gp33 can also repress transcription by Escherichia coli sigma70-RNAP holoenzyme mutated to allow gp33 access to the beta flap. We propose that repression is due to gp33 blocking an upstream sequence-independent DNA-binding site on RNAP (as sigma70 domain 4 does) but, unlike sigma70 domain 4, providing no new DNA interaction. We show that this upstream interaction is essential only at an early step of transcription initiation, and discuss the role of this interaction in promoter recognition and transcriptional regulation.
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Affiliation(s)
- Sergei Nechaev
- Division of Biological Sciences and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0634, USA.
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36
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Tessmer I, Moore T, Lloyd RG, Wilson A, Erie DA, Allen S, Tendler SJB. AFM studies on the role of the protein RdgC in bacterial DNA recombination. J Mol Biol 2005; 350:254-62. [PMID: 15923011 DOI: 10.1016/j.jmb.2005.04.043] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Revised: 04/04/2005] [Accepted: 04/19/2005] [Indexed: 02/03/2023]
Abstract
Genetic studies of rdgC in different bacterial systems suggest that it may play a role in replication and recombination. However, the exact function of the corresponding protein, RdgC, is unknown. In this study, we have imaged complexes of RdgC with both linear and supercoiled circular plasmid DNA using atomic force microscopy. We confirm that RdgC does not target any specific sequences in double-stranded DNA, as has been suggested from biochemical data. However, we detect an increased affinity of the protein to DNA ends, and an ability to promote bending of DNA. Similar binding preferences have been reported for enzymes involved in recombination. Protein complexes with supercoiled plasmid DNA further enabled us to study the effect of RdgC on DNA superstructure. At high concentrations of protein we observed promotion of DNA condensation. Recombination is largely enhanced by close contacts of distant regions along the DNA strands, as can occur, for instance, through condensation. Our data thus support a possible function of RdgC as a midwife of recombination.
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MESH Headings
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Bacterial/ultrastructure
- DNA, Superhelical/chemistry
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- DNA, Superhelical/ultrastructure
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/metabolism
- Escherichia coli Proteins/ultrastructure
- Microscopy, Atomic Force
- Nucleic Acid Conformation
- Plasmids/chemistry
- Plasmids/genetics
- Plasmids/metabolism
- Plasmids/ultrastructure
- Protein Structure, Quaternary
- Recombination, Genetic
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Affiliation(s)
- Ingrid Tessmer
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK
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37
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Kanhere A, Bansal M. Structural properties of promoters: similarities and differences between prokaryotes and eukaryotes. Nucleic Acids Res 2005; 33:3165-75. [PMID: 15939933 PMCID: PMC1143579 DOI: 10.1093/nar/gki627] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
During the process of transcription, RNA polymerase can exactly locate a promoter sequence in the complex maze of a genome. Several experimental studies and computational analyses have shown that the promoter sequences apparently possess some special properties, such as unusual DNA structures and low stability, which make them distinct from the rest of the genome. But most of these studies have been carried out on a particular set of promoter sequences or on promoter sequences from similar organisms. To examine whether the promoters from a wide variety of organisms share these special properties, we have carried out an analysis of sets of promoters from bacteria, vertebrates and plants. These promoters were analyzed with respect to the prediction of three different properties, such as DNA curvature, bendability and stability, which are relevant to transcription. All the promoter sequences are predicted to share certain features, such as stability and bendability profiles, but there are significant differences in DNA curvature profiles and nucleotide composition between the different organisms. These similarities and differences are correlated with some of the known facts about transcription process in the promoters from the three groups of organisms.
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Affiliation(s)
| | - Manju Bansal
- To whom correspondence should be addressed. Tel: +91 80 2293 2534; Fax: +91 80 2360 0535;
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38
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El Kirat K, Burton I, Dupres V, Dufrene YF. Sample preparation procedures for biological atomic force microscopy. J Microsc 2005; 218:199-207. [PMID: 15958012 DOI: 10.1111/j.1365-2818.2005.01480.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Since the late 1980s, atomic force microscopy (AFM) has been increasingly used in biological sciences and it is now established as a versatile tool to address the structure, properties and functions of biological specimens. AFM is unique in that it provides three-dimensional images of biological structures, including biomolecules, lipid films, 2D protein crystals and cells, under physiological conditions and with unprecedented resolution. A crucial prerequisite for successful, reliable biological AFM is that the samples need to be well attached to a solid substrate using appropriate, nondestructive methods. In this review, we discuss common techniques for immobilizing biological specimens for AFM studies.
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Affiliation(s)
- K El Kirat
- Unité de chimie des interfaces, Université catholique de Louvain, Belgium
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39
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Sieira R, Comerci DJ, Pietrasanta LI, Ugalde RA. Integration host factor is involved in transcriptional regulation of the Brucella abortus virB operon. Mol Microbiol 2004; 54:808-22. [PMID: 15491369 DOI: 10.1111/j.1365-2958.2004.04316.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Type IV secretion systems (T4SSs) are multicomponent machineries that play an essential role in pathogenicity of many facultative intracellular bacteria. The virB operon of Brucella abortus codes for a T4SS essential for virulence and intracellular multiplication. Here, virB expression analyses carried out using lacZ transcriptional fusions showed that virB promoter (PvirB) is temporally activated within J774 cells. Primer extension experiments revealed that virB transcription starts at 27 bp upstream of the first gene of the virB operon. Structural analyses showed that PvirB and regulatory sequences involved in intracellular regulation span 430 bp upstream of the transcription start site. A protein able to bind PvirB was isolated and identified. This protein, homologue to integration host factor (IHF), specifically interacts with PvirB and induces a DNA bending with an angle of 50.36 degrees . DNAse I footprinting experiments showed that IHF protects a 51 bp region that contains two overlapped IHF binding consensus motifs. VirB expression experiments carried out with PvirB-lacZ fusions showed that in B. abortus IHF participates in the regulation of PvirB activity during the intracellular and vegetative growth in different media. A mutant strain with a 20 bp IHF binding site replacement failed to turn on the virB operon during the initial stages of macrophage infection and displayed severe intracellular multiplication defects. These data indicate that IHF plays a key role during intracellular virB operon expression being required for the biogenesis of the endoplasmic reticulum-derived replicative vacuole.
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Affiliation(s)
- Rodrigo Sieira
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de General San Martín, CONICET, San Martín 1650, Buenos Aires, Argentina
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40
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Kepert JF, Tóth KF, Caudron M, Mücke N, Langowski J, Rippe K. Conformation of reconstituted mononucleosomes and effect of linker histone H1 binding studied by scanning force microscopy. Biophys J 2004; 85:4012-22. [PMID: 14645090 PMCID: PMC1303702 DOI: 10.1016/s0006-3495(03)74815-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The conformation of mononucleosome complexes reconstituted with recombinant core histones on a 614-basepair-long DNA fragment containing the Xenopus borealis 5S rRNA nucleosome positioning sequence was studied by scanning/atomic force microscopy in the absence or presence of linker histone H1. Imaging without prior fixation was conducted with air-dried samples and with mononucleosomes that were injected directly into the scanning force microscopy fluid cell and visualized in buffer. From a quantitative analysis of approximately 1,700 complexes, the following results were obtained: i), In the absence of H1, a preferred location of the nucleosome at the X. borealis 5S rRNA sequence in the center of the DNA was detected. From the distribution of nucleosome positions, an energy difference of binding to the 5S rRNA sequence of DeltaDeltaG approximately 3 kcal mol(-1) as compared to a random sequence was estimated. Upon addition of H1, a significantly reduced preference of nucleosome binding to this sequence was observed. ii), The measured entry-exit angles of the DNA at the nucleosome in the absence of H1 showed two maxima at 81 +/- 29 degrees and 136 +/- 18 degrees (air-dried samples), and 78 +/- 25 degrees and 137 +/- 25 degrees (samples imaged in buffer solution). In the presence of H1, the species with the smaller entry-exit angle was stabilized, yielding average values of 88 +/- 34 degrees for complexes in air and 85 +/- 10 degrees in buffer solution. iii), The apparent contour length of the nucleosome complexes was shortened by 34 +/- 13 nm as compared to the free DNA due to wrapping of the DNA around the histone octamer complex. Considering an 11 nm diameter of the nucleosome core complex, this corresponds to a total of 145 +/- 34 basepairs that are wound around the nucleosome.
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Affiliation(s)
- Jochen Felix Kepert
- Kirchhoff-Institut für Physik, AG Molekulare Biophysik (F15), Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
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41
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Affiliation(s)
- Claudio Rivetti
- Dipartimento di Biochimica e Biologia, Molecolare Universita degli Studi, di Parma Parco Area, delle Scienze 23/A 43100, Parma, Italy
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Li J, Gershow M, Stein D, Brandin E, Golovchenko JA. DNA molecules and configurations in a solid-state nanopore microscope. NATURE MATERIALS 2003; 2:611-5. [PMID: 12942073 DOI: 10.1038/nmat965] [Citation(s) in RCA: 567] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2003] [Accepted: 07/27/2003] [Indexed: 05/21/2023]
Abstract
A nanometre-scale pore in a solid-state membrane provides a new way of electronically probing the structure of single linear polymers, including those of biological interest in their native environments. Previous work with biological protein pores wide enough to let through and sense single-stranded DNA molecules demonstrates the power of using nanopores, but many future tasks and applications call for a robust solid-state pore whose nanometre-scale dimensions and properties may be selected, as one selects the lenses of a microscope. Here we demonstrate a solid-state nanopore microscope capable of observing individual molecules of double-stranded DNA and their folding behaviour. We discuss extensions of the nanopore microscope concept to alternative probing mechanisms and applications, including the study of molecular structure and sequencing.
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Affiliation(s)
- Jiali Li
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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Abstract
Active (catalyzed) and passive (intrinsic) nucleosome repositioning is known to be a crucial event during the transcriptional activation of certain eukaryotic genes. Here we consider theoretically the intrinsic mechanism and study in detail the energetics and dynamics of DNA-loop-mediated nucleosome repositioning, as previously proposed by earlier works. The surprising outcome of the present study is the inherent nonlocality of nucleosome motion within this model-being a direct physical consequence of the loop mechanism. On long enough DNA templates the longer jumps dominate over the previously predicted local motion, a fact that contrasts simple diffusive mechanisms considered before. The possible experimental outcome resulting from the considered mechanism is predicted, discussed, and compared to existing experimental findings.
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Affiliation(s)
- I M Kulić
- Max-Planck-Institut für Polymerforschung, Theory Group, Ackermannweg 10, D-55128 Mainz, Germany.
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Rivetti C, Codeluppi S, Dieci G, Bustamante C. Visualizing RNA extrusion and DNA wrapping in transcription elongation complexes of bacterial and eukaryotic RNA polymerases. J Mol Biol 2003; 326:1413-26. [PMID: 12595254 DOI: 10.1016/s0022-2836(03)00042-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Transcription ternary complexes of Escherichia coli RNA polymerase and yeast RNA polymerase III have been analyzed by atomic force microscopy. Using the method of nucleotide omission and different DNA templates, E.coli RNAP has been stalled at position +24, +70 and +379 and RNAP III at position +377 from the starting site. Conformational analysis of E.coli RNAP elongation complexes reveals an average DNA compaction of 22nm and a DNA deformation compatible with approximately 180 degrees DNA wrapping against the enzyme. The extent of protein-DNA interaction attributed to wrapping, however, is less than that of corresponding open promoter complexes. DNA wrapping was also observed for RNAP III elongation complexes, which showed a DNA compaction of 30nm. When the RNA polymerases were stalled far from the promoter (+379 and +377), the growing RNA transcript was often visible and it was prevalently seen exiting from the enzyme on the opposite side relative to the smallest angle subtended by the upstream and downstream DNA arms. Surprisingly, we found that many complexes had a second RNAP, not involved in transcription, bound to the growing RNA of a ternary complex. DNA wrapping in the elongation complex suggests a possible mechanism by which the polymerase may overcome the physical barrier to transcription imposed by the nucleosomes.
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MESH Headings
- Bacterial Proteins/metabolism
- DNA Primers/chemistry
- DNA, Bacterial/chemistry
- DNA, Bacterial/metabolism
- DNA, Fungal/chemistry
- DNA, Fungal/metabolism
- DNA-Binding Proteins/metabolism
- DNA-Directed RNA Polymerases/metabolism
- Electrophoretic Mobility Shift Assay
- Escherichia coli/enzymology
- Escherichia coli/genetics
- Microscopy, Atomic Force
- Nucleic Acid Conformation
- Nucleosomes/metabolism
- Peptide Chain Elongation, Translational
- Polymerase Chain Reaction
- Promoter Regions, Genetic
- Protein Binding
- RNA Polymerase III/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Fungal/chemistry
- RNA, Fungal/metabolism
- Saccharomyces cerevisiae/chemistry
- Saccharomyces cerevisiae/enzymology
- Templates, Genetic
- Transcription, Genetic
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Affiliation(s)
- Claudio Rivetti
- Department of Biochemistry and Molecular Biology, University of Parma, 43100, Parma, Italy.
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Hizume K, Yoshimura SH, Maruyama H, Kim J, Wada H, Takeyasu K. Chromatin reconstitution: development of a salt-dialysis method monitored by nano-technology. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2002; 65:405-13. [PMID: 12680456 DOI: 10.1679/aohc.65.405] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The regulation of DNA replication and transcription is achieved by dynamic structural changes of chromatin in which a series of proteins will acquire accessibility to specific regions of the DNA strand. A combination of biochemistry and nano-technology is essential to address questions regarding the structural basis for such macromolecular mechanisms. In the present study, we established an efficient salt-dialysis method of chromatin reconstitution and employed atomic force microscopy (AFM) as a single-molecule-imaging technique, to monitor the efficiency of the reconstitution. At first, the reconstitution efficiency with short DNA molecules of several kilo-base pairs was low, although the salt dialysis yielded a "beads-on-a-string" structure of oligonucleosomes with each nucleosome trapping 158+/-27 bp DNA. However, the efficiency for nucleosome formation became higher when longer DNA molecules with a super-helical constraint were used. A statistical analysis of the obtained AFM images identified a first-order relationship between the efficiency of the reconstitution and the length of the super-coiled DNA used. A high efficiency of approximately 290 bp/nucleosome that is close to the in vivo situation was obtained with a approximately 100 kbp template DNA. This enabled the structure-function studies of long chromatin molecules under well-defined conditions.
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Affiliation(s)
- Kohji Hizume
- Laboratory of Plasma Membrane and Nuclear Signaling, Kyoto University Graduate School of Biostudies, Kyoto, Japan
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Cherepanov AV, de Vries S. Dynamic mechanism of nick recognition by DNA ligase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5993-9. [PMID: 12473094 DOI: 10.1046/j.1432-1033.2002.03309.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA ligases are the enzymes responsible for the repair of single-stranded and double-stranded nicks in dsDNA. DNA ligases are structurally similar, possibly sharing a common molecular mechanism of nick recognition and ligation catalysis. This mechanism remains unclear, in part because the structure of ligase in complex with dsDNA has yet to be solved. DNA ligases share common structural elements with DNA polymerases, which have been cocrystallized with dsDNA. Based on the observed DNA polymerase-dsDNA interactions, we propose a mechanism for recognition of a single-stranded nick by DNA ligase. According to this mechanism, ligase induces a B-to-A DNA helix transition of the enzyme-bound dsDNA motif, which results in DNA contraction, bending and unwinding. For non-nicked dsDNA, this transition is reversible, leading to dissociation of the enzyme. For a nicked dsDNA substrate, the contraction of the enzyme-bound DNA motif (a) triggers an opened-closed conformational change of the enzyme, and (b) forces the motif to accommodate the strained A/B-form hybrid conformation, in which the nicked strand tends to retain a B-type helix, while the non-nicked strand tends to form a shortened A-type helix. We propose that this conformation is the catalytically competent transition state, which leads to the formation of the DNA-AMP intermediate and to the subsequent sealing of the nick.
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Affiliation(s)
- Alexei V Cherepanov
- Kluyver Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
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Abstract
The consensus 23 base-pair T7 DNA promoter is classically divided into two domains, an upstream binding domain (-17 to -5), and a downstream initiation domain (-4 to +6) relative to the transcription start site at +1. During transcription initiation, T7 RNA polymerase (T7 RNAP) melts specifically the -4 to +2/+3 (TATAGG/G) region of the duplex DNA promoter to form a pre-initiation open complex. No external energy source is used and the energy for open complex formation is derived from the free energy of specific interactions with the binding domain, particularly the specificity region (-13 to -6). Using 2-aminopurine fluorescence-based equilibrium and kinetic measurements, we have measured the binding affinities of various topologically modified DNA promoters (40 bp in length) that represent initial, final, and transition-state analogs of the promoter DNA in the T7 RNAP-DNA complex, to determine the energy of specific binding interactions, and the energy required for forming an initiation bubble. The results indicate that 16-16.5 kcal mol(-1) of free energy is made available upon T7 RNAP binding (through specificity loop) to the promoter binding domain. To melt the TATAGG/G sequence 7-8 kcal mol(-1) of free energy is utilized; this compares with approximately 6 kcal mol(-1) predicted from nearest neighbor analysis. The remaining 8.5-9.5 kcal mol(-1) of net free energy is retained for stabilization of the specific pre-initiation binary complex. Of the 7-8 kcal mol(-1) energy that is used to generate the pre-initiation DNA bubble in the open complex, we estimate that one half (3.5-4 kcal mol(-1)) is utilized for nucleation/deformation process (through bending, untwisting, etc.) in the melting region (-4 to -1 TATA) of the initiation domain (-4 to +6), and appears to be independent of the nucleation site within this region. The other half is utilized in unpairing the +1 to +2/+3 GG/G sequence for initiation. The interactions of T7 RNAP with a 20-bp non-specific DNA on the other hand are very weak (DeltaG<-5k cal mol(-1)), which is not sufficient to melt and stabilize an open complex of a non-specific DNA.
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Affiliation(s)
- Rajiv P Bandwar
- Department of Biochemistry, UMDNJ Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA
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Seong GH, Yanagida Y, Aizawa M, Kobatake E. Atomic force microscopy identification of transcription factor NFkappaB bound to streptavidin-pin-holding DNA probe. Anal Biochem 2002; 309:241-7. [PMID: 12413457 DOI: 10.1016/s0003-2697(02)00303-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A novel method for identifying DNA-binding proteins from image analysis using AFM was developed. Here, transcription factor NFkappaB, which a well-studied example of transcription activator proteins, was used as a target protein. 5'-biotinlynated double-stranded DNA probe was labeled site specifically through high affinity with streptavidin. When the biotinylated DNA fragments were incubated with the streptavidin at a 1:2 molar ratio of DNA:streptavidin, the overall efficiency of labeling was over 90%. The double-stranded DNA probes were immobilized on a mica surface by the adsorption of streptavidin that attached to the 5'-end of DNA and applied for selection of the target protein NFkappaB in solution and then AFM was used to image the DNA probe-NFkappaB complexes. The length of the distance between 5'-labeled streptavidin and NFkappaB bound on DNA probes from AFM images is 0.64, the normalized position of the NFkappaB binding site, and this result is in close agreement with the expected 299 and 167bp values.
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Affiliation(s)
- Gi Hun Seong
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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Lloyd GS, Niu W, Tebbutt J, Ebright RH, Busby SJW. Requirement for two copies of RNA polymerase alpha subunit C-terminal domain for synergistic transcription activation at complex bacterial promoters. Genes Dev 2002; 16:2557-65. [PMID: 12368266 PMCID: PMC187446 DOI: 10.1101/gad.237502] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transcription activation by the Escherichia coli cyclic AMP receptor protein (CRP) at different promoters has been studied using RNA polymerase holoenzyme derivatives containing two full-length alpha subunits, or containing one full-length alpha subunit and one truncated alpha subunit lacking the alpha C-terminal domain (alpha CTD). At a promoter having a single DNA site for CRP, activation requires only one full-length alpha subunit. Likewise, at a promoter having a single DNA site for CRP and one adjacent UP-element subsite (high-affinity DNA site for alpha CTD), activation requires only one full-length alpha subunit. In contrast, at promoters having two DNA sites for CRP, or one DNA site for CRP and two UP-element subsites, activation requires two full-length alpha subunits. We conclude that a single copy of alpha CTD is sufficient to interact with one CRP molecule and one adjacent UP-element subsite, but two copies of alpha CTD are required to interact with two CRP molecules or with one CRP molecule and two UP-element subsites.
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Affiliation(s)
- Georgina S Lloyd
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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