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Probing DNA-protein interactions using single-molecule diffusivity contrast. BIOPHYSICAL REPORTS 2021; 1:100009. [PMID: 36425309 PMCID: PMC9680706 DOI: 10.1016/j.bpr.2021.100009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/20/2021] [Indexed: 11/28/2022]
Abstract
Single-molecule fluorescence investigations of protein-nucleic acid interactions require robust means to identify the binding state of individual substrate molecules in real time. Here, we show that diffusivity contrast, widely used in fluorescence correlation spectroscopy at the ensemble level and in single-particle tracking on individual (but slowly diffusing) species, can be used as a general readout to determine the binding state of single DNA molecules with unlabeled proteins in solution. We first describe the technical basis of drift-free single-molecule diffusivity measurements in an anti-Brownian electrokinetic trap. We then cross-validate our method with protein-induced fluorescence enhancement, a popular technique to detect protein binding on nucleic acid substrates with single-molecule sensitivity. We extend an existing hydrodynamic modeling framework to link measured diffusivity to particular DNA-protein structures and obtain good agreement between the measured and predicted diffusivity values. Finally, we show that combining diffusivity contrast with protein-induced fluorescence enhancement allows simultaneous mapping of binding stoichiometry and location on individual DNA-protein complexes, potentially enhancing single-molecule views of relevant biophysical processes.
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2
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Walkowiak JJ, Ballauff M. Interaction of Polyelectrolytes with Proteins: Quantifying the Role of Water. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2100661. [PMID: 34194953 PMCID: PMC8224434 DOI: 10.1002/advs.202100661] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/29/2021] [Indexed: 05/11/2023]
Abstract
A theoretical model is presented for the free energy ΔGb of complex formation between a highly charged polyelectrolyte and a protein. The model introduced here comprises both the effect of released counterions and the uptake or release of water molecules during complex formation. The resulting expression for ΔGb is hence capable of describing the dependence of ΔGb on temperature as well as on the concentration of salt in the system: An increase of the salt concentration in the solution increases the activity of the ions and counterion release becomes less effective for binding. On the other hand, an increased salt concentration leads to the decrease of the activity of water in bulk. Hence, release of water molecules during complex formation will be more advantageous and lead to an increase of the magnitude of ΔGb and the binding constant. It is furthermore demonstrated that the release or uptake of water molecules is the origin of the marked enthalpy-entropy cancellation observed during complex formation of polyelectrolytes with proteins. The comparison with experimental data on complex formation between a synthetic (sulfated dendritic polyglycerol) and natural polyelectrolytes (DNA; heparin) with proteins shows full agreement with theory.
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Affiliation(s)
- Jacek J. Walkowiak
- Institut für Chemie und BiochemieFreie Universität BerlinTaktstraße 3Berlin14195Germany
- Aachen‐Maastricht Institute for Biobased MaterialsMaastricht UniversityBrightlands Chemelot Campus, Urmonderbaan 22Geleen6167 RDThe Netherlands
| | - Matthias Ballauff
- Institut für Chemie und BiochemieFreie Universität BerlinTaktstraße 3Berlin14195Germany
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3
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Achazi K, Haag R, Ballauff M, Dernedde J, Kizhakkedathu JN, Maysinger D, Multhaup G. Understanding the Interaction of Polyelectrolyte Architectures with Proteins and Biosystems. Angew Chem Int Ed Engl 2021; 60:3882-3904. [PMID: 32589355 PMCID: PMC7894192 DOI: 10.1002/anie.202006457] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Indexed: 02/06/2023]
Abstract
The counterions neutralizing the charges on polyelectrolytes such as DNA or heparin may dissociate in water and greatly influence the interaction of such polyelectrolytes with biomolecules, particularly proteins. In this Review we give an overview of studies on the interaction of proteins with polyelectrolytes and how this knowledge can be used for medical applications. Counterion release was identified as the main driving force for the binding of proteins to polyelectrolytes: Patches of positive charge become multivalent counterions of the polyelectrolyte and lead to the release of counterions from the polyelectrolyte and a concomitant increase in entropy. This is shown from investigations on the interaction of proteins with natural and synthetic polyelectrolytes. Special emphasis is paid to sulfated dendritic polyglycerols (dPGS). The Review demonstrates that we are moving to a better understanding of charge-charge interactions in systems of biological relevance. Research along these lines will aid and promote the design of synthetic polyelectrolytes for medical applications.
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Affiliation(s)
- Katharina Achazi
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Rainer Haag
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
| | - Matthias Ballauff
- Institut für Chemie und BiochemieFreie Universität BerlinTakustrasse 314195BerlinGermany
- IRIS AdlershofHumboldt Universität zu BerlinZum Grossen Windkanal 612489BerlinGermany
| | - Jens Dernedde
- Charité-Universitätsmedizin BerlinInstitute of Laboratory MedicineClinical Chemistry, and PathobiochemistryCVK Augustenburger Platz 113353BerlinGermany
| | - Jayachandran N. Kizhakkedathu
- Centre for Blood ResearchDepartment of Pathology and Laboratory MedicineLife Science InstituteDepartment of ChemistrySchool of Biomedical EngineeringUniversity of British ColumbiaVancouverV6T 1Z3Canada
| | - Dusica Maysinger
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
| | - Gerd Multhaup
- Department of Pharmacology and TherapeuticsMcGill UniversityMontrealH3G 1Y6Canada
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4
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Jenkins T, Northall SJ, Ptchelkine D, Lever R, Cubbon A, Betts H, Taresco V, Cooper CDO, McHugh PJ, Soultanas P, Bolt EL. The HelQ human DNA repair helicase utilizes a PWI-like domain for DNA loading through interaction with RPA, triggering DNA unwinding by the HelQ helicase core. NAR Cancer 2021; 3:zcaa043. [PMID: 34316696 PMCID: PMC8210318 DOI: 10.1093/narcan/zcaa043] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/30/2020] [Accepted: 12/16/2020] [Indexed: 01/04/2023] Open
Abstract
Genome instability is a characteristic enabling factor for carcinogenesis. HelQ helicase is a component of human DNA maintenance systems that prevent or reverse genome instability arising during DNA replication. Here, we provide details of the molecular mechanisms that underpin HelQ function-its recruitment onto ssDNA through interaction with replication protein A (RPA), and subsequent translocation of HelQ along ssDNA. We describe for the first time a functional role for the non-catalytic N-terminal region of HelQ, by identifying and characterizing its PWI-like domain. We present evidence that this domain of HelQ mediates interaction with RPA that orchestrates loading of the helicase domains onto ssDNA. Once HelQ is loaded onto the ssDNA, ATP-Mg2+ binding in the catalytic site activates the helicase core and triggers translocation along ssDNA as a dimer. Furthermore, we identify HelQ-ssDNA interactions that are critical for the translocation mechanism. Our data are novel and detailed insights into the mechanisms of HelQ function relevant for understanding how human cells avoid genome instability provoking cancers, and also how cells can gain resistance to treatments that rely on DNA crosslinking agents.
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Affiliation(s)
- Tabitha Jenkins
- School of Life Sciences, The University of Nottingham, NG7 2UH, Nottingham, UK
| | - Sarah J Northall
- School of Life Sciences, The University of Nottingham, NG7 2UH, Nottingham, UK
| | | | - Rebecca Lever
- School of Life Sciences, The University of Nottingham, NG7 2UH, Nottingham, UK
| | - Andrew Cubbon
- School of Life Sciences, The University of Nottingham, NG7 2UH, Nottingham, UK
| | - Hannah Betts
- School of Chemistry, The University of Nottingham, NG7 2RD, Nottingham, UK
| | - Vincenzo Taresco
- School of Pharmacy, The University of Nottingham, NG7 2RD, Nottingham, UK
| | - Christopher D O Cooper
- Department of Biological and Geographical Sciences, School of Applied Sciences, The University of Huddersfield, HD1 3DH, Huddersfield, UK
| | - Peter J McHugh
- MRC Weatherall Institute of Molecular Medicine (WIMM), University of Oxford, OX3 9DS, Oxford, UK
| | - Panos Soultanas
- School of Chemistry, The University of Nottingham, NG7 2RD, Nottingham, UK
| | - Edward L Bolt
- School of Life Sciences, The University of Nottingham, NG7 2UH, Nottingham, UK
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5
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Achazi K, Haag R, Ballauff M, Dernedde J, Kizhakkedathu JN, Maysinger D, Multhaup G. Wechselwirkung von Polyelektrolyt‐Architekturen mit Proteinen und Biosystemen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006457] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Katharina Achazi
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Rainer Haag
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
| | - Matthias Ballauff
- Institut für Chemie und Biochemie Freie Universität Berlin Takustraße 3 14195 Berlin Deutschland
- IRIS Adlershof Humboldt-Universität zu Berlin Zum Großen Windkanal 6 12489 Berlin Deutschland
| | - Jens Dernedde
- Charité-Universitätsmedizin Berlin Institut für Laboratoriumsmedizin Klinische Chemie und Pathobiochemie CVK Augustenburger Platz 1 13353 Berlin Deutschland
| | - Jayachandran N. Kizhakkedathu
- Centre for Blood Research Department of Pathology and Laboratory Medicine Life Science Institute Department of Chemistry School of Biomedical Engineering University of British Columbia Vancouver V6T 1Z3 Kanada
| | - Dusica Maysinger
- Department of Pharmacology and Therapeutics McGill University Montreal H3G 1Y6 Kanada
| | - Gerd Multhaup
- Department of Pharmacology and Therapeutics McGill University Montreal H3G 1Y6 Kanada
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6
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Tavella D, Ertekin A, Schaal H, Ryder SP, Massi F. A Disorder-to-Order Transition Mediates RNA Binding of the Caenorhabditis elegans Protein MEX-5. Biophys J 2020; 118:2001-2014. [PMID: 32294479 PMCID: PMC7175634 DOI: 10.1016/j.bpj.2020.02.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/31/2020] [Accepted: 02/12/2020] [Indexed: 11/17/2022] Open
Abstract
CCCH-type tandem zinc finger (TZF) domains are found in many RNA-binding proteins (RBPs) that regulate the essential processes of post-transcriptional gene expression and splicing through direct protein-RNA interactions. In Caenorhabditis elegans, RBPs control the translation, stability, or localization of maternal messenger RNAs required for patterning decisions before zygotic gene activation. MEX-5 (Muscle EXcess) is a C. elegans protein that leads a cascade of RBP localization events that is essential for axis polarization and germline differentiation after fertilization. Here, we report that at room temperature, the CCCH-type TZF domain of MEX-5 contains an unstructured zinc finger that folds upon binding of its RNA target. We have characterized the structure and dynamics of the TZF domain of MEX-5 and designed a variant MEX-5 in which both fingers are fully folded in the absence of RNA. Within the thermal range experienced by C. elegans, the population of the unfolded state of the TZF domain of MEX-5 varies. We observe that the TZF domain becomes less disordered at lower temperatures and more disordered at higher temperatures. However, in the temperature range in which C. elegans is fertile, when MEX-5 needs to be functional, only one of the two zinc fingers is folded.
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Affiliation(s)
- Davide Tavella
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Asli Ertekin
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Hila Schaal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Sean P Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Francesca Massi
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
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7
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Walkowiak J, Lu Y, Gradzielski M, Zauscher S, Ballauff M. Thermodynamic Analysis of the Uptake of a Protein in a Spherical Polyelectrolyte Brush. Macromol Rapid Commun 2019; 41:e1900421. [DOI: 10.1002/marc.201900421] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/19/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Jacek Walkowiak
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Yan Lu
- Soft Matter and Functional MaterialsHelmholtz‐Zentrum Berlin für Materialen und Energie Hahn‐Meitner‐Platz 1 14109 Berlin Germany
- Institute of ChemistryUniversity of Potsdam 14467 Potsdam Germany
| | - Michael Gradzielski
- Stranski Laboratorium für Physikalische Chemie und Theoretische ChemieInstitut für ChemieStraße des 17. Juni 124Sekr. TC7Technische Universität Berlin D‐10623 Berlin Germany
| | - Stefan Zauscher
- Mechanical Engineering and Material ScienceDuke University Durham NC 27708 USA
| | - Matthias Ballauff
- Soft Matter and Functional MaterialsHelmholtz‐Zentrum Berlin für Materialen und Energie Hahn‐Meitner‐Platz 1 14109 Berlin Germany
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8
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Xu X, Ballauff M. Interaction of Lysozyme with a Dendritic Polyelectrolyte: Quantitative Analysis of the Free Energy of Binding and Comparison to Molecular Dynamics Simulations. J Phys Chem B 2019; 123:8222-8231. [DOI: 10.1021/acs.jpcb.9b07448] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Xiao Xu
- School of Chemical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, 210094 Nanjing, P. R. China
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
- Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
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9
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Velmurugu Y, Vivas P, Connolly M, Kuznetsov SV, Rice PA, Ansari A. Two-step interrogation then recognition of DNA binding site by Integration Host Factor: an architectural DNA-bending protein. Nucleic Acids Res 2019; 46:1741-1755. [PMID: 29267885 PMCID: PMC5829579 DOI: 10.1093/nar/gkx1215] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/08/2017] [Indexed: 12/23/2022] Open
Abstract
The dynamics and mechanism of how site-specific DNA-bending proteins initially interrogate potential binding sites prior to recognition have remained elusive for most systems. Here we present these dynamics for Integration Host factor (IHF), a nucleoid-associated architectural protein, using a μs-resolved T-jump approach. Our studies show two distinct DNA-bending steps during site recognition by IHF. While the faster (∼100 μs) step is unaffected by changes in DNA or protein sequence that alter affinity by >100-fold, the slower (1–10 ms) step is accelerated ∼5-fold when mismatches are introduced at DNA sites that are sharply kinked in the specific complex. The amplitudes of the fast phase increase when the specific complex is destabilized and decrease with increasing [salt], which increases specificity. Taken together, these results indicate that the fast phase is non-specific DNA bending while the slow phase, which responds only to changes in DNA flexibility at the kink sites, is specific DNA kinking during site recognition. Notably, the timescales for the fast phase overlap with one-dimensional diffusion times measured for several proteins on DNA, suggesting that these dynamics reflect partial DNA bending during interrogation of potential binding sites by IHF as it scans DNA.
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Affiliation(s)
- Yogambigai Velmurugu
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Paula Vivas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Mitchell Connolly
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Serguei V Kuznetsov
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Phoebe A Rice
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Anjum Ansari
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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10
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Connolly M, Arra A, Zvoda V, Steinbach PJ, Rice PA, Ansari A. Static Kinks or Flexible Hinges: Multiple Conformations of Bent DNA Bound to Integration Host Factor Revealed by Fluorescence Lifetime Measurements. J Phys Chem B 2018; 122:11519-11534. [DOI: 10.1021/acs.jpcb.8b07405] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mitchell Connolly
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Aline Arra
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Viktoriya Zvoda
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Peter J. Steinbach
- Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Phoebe A. Rice
- Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
| | - Anjum Ansari
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
- Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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11
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Gapsys V, de Groot BL. Alchemical Free Energy Calculations for Nucleotide Mutations in Protein–DNA Complexes. J Chem Theory Comput 2017; 13:6275-6289. [DOI: 10.1021/acs.jctc.7b00849] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vytautas Gapsys
- Computational Biomolecular
Dynamics Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Bert L. de Groot
- Computational Biomolecular
Dynamics Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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12
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Huang S, Gan N, Li T, Zhou Y, Cao Y, Dong Y. Electrochemical aptasensor for multi-antibiotics detection based on endonuclease and exonuclease assisted dual recycling amplification strategy. Talanta 2017; 179:28-36. [PMID: 29310232 DOI: 10.1016/j.talanta.2017.10.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 10/08/2017] [Accepted: 10/10/2017] [Indexed: 01/09/2023]
Abstract
An ultrasensitive electrochemical aptasensor for multiplex antibiotics detection based on endonuclease and exonuclease assisted dual recycling amplification strategy was proposed. Kanamycin and chloramphenicol were selected as candidates. Firstly, aptamers of the antibiotics were immobilized on bar A and then binding with their endonuclease labeled complementary DNA strands to construct enzyme-cleavage probes. Secondly, The nano zirconium-metal organic framework (NMOF) particles with 1,4-benzene-dicarboxylate (BDC) as linker was defined as UiO-66. And its updated version, hierarchically porous UiO-66 (HP-UIO-66) decorated with different electroactive materials as signal tags were synthesized. Then they were immobilized on bar B linked by two duplex DNA strands which can be specifically cleaved by corresponding enzyme-cleavage probes in bar A. Once targets were introduced into system, aptamers can capture them and then release enzyme-cleavage probes. In the presence of exonuclease-I, exonuclease assisted target recycling amplification was triggered and more enzyme-cleavage probes were released into solution. The probes can trigger endonuclease assisted recycles and repeatedly cleave their corresponding duplex DNA strands on bar B then released numerous signal tags into supernatant. Thus two recycling amplification was performed in the system. Finally, MB and Fc in the signal tags were detected by square wave voltammetry after removing bar A/B and the current intensities were correspondent with the concentration of KANA and CAP respectively. Under the optimum condition, the limits of detection for the KANA and CAP were 35fM and 21fM respectively with a wide linear range from 1 × 10-4 to 50nM. This dual recycling amplification detection system exhibited high sensitivities and specificity. It can be easily extended to detect other targets if changing the corresponding aptamers and has potential application values for screening of multiplex antibiotics residues in food safety.
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Affiliation(s)
- Shengfeng Huang
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
| | - Ning Gan
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China.
| | - Tianhua Li
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
| | - You Zhou
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
| | - Yuting Cao
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China.
| | - Youren Dong
- State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
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13
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Kobbe D, Kahles A, Walter M, Klemm T, Mannuss A, Knoll A, Focke M, Puchta H. AtRAD5A is a DNA translocase harboring a HIRAN domain which confers binding to branched DNA structures and is required for DNA repair in vivo. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:521-530. [PMID: 27458713 DOI: 10.1111/tpj.13283] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 07/20/2016] [Accepted: 07/22/2016] [Indexed: 05/26/2023]
Abstract
DNA lesions such as crosslinks represent obstacles for the replication machinery. Nonetheless, replication can proceed via the DNA damage tolerance pathway also known as postreplicative repair pathway. SNF2 ATPase Rad5 homologs, such as RAD5A of the model plant Arabidopsis thaliana, are important for the error-free mode of this pathway. We able to demonstrate before, that RAD5A is a key factor in the repair of DNA crosslinks in Arabidopsis. Here, we show by in vitro analysis that AtRAD5A protein is a DNA translocase able to catalyse fork regression. Interestingly, replication forks with a gap in the leading strand are processed best, in line with its suggested function. Furthermore AtRAD5A catalyses branch migration of a Holliday junction and is furthermore not impaired by the DNA binding of a model protein, which is indicative of its ability to displace other proteins. Rad5 homologs possess HIRAN (Hip116, Rad5; N-terminal) domains. By biochemical analysis we were able to demonstrate that the HIRAN domain variant from Arabidopsis RAD5A mediates structure selective DNA binding without the necessity for a free 3'OH group as has been shown to be required for binding of HIRAN domains in a mammalian RAD5 homolog. The biological importance of the HIRAN domain in AtRAD5A is demonstrated by our result that it is required for its function in DNA crosslink repair in vivo.
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Affiliation(s)
- Daniela Kobbe
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Andy Kahles
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Maria Walter
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Tobias Klemm
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Anja Mannuss
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Alexander Knoll
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Manfred Focke
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Holger Puchta
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
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14
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Förster resonance energy transfer and protein-induced fluorescence enhancement as synergetic multi-scale molecular rulers. Sci Rep 2016; 6:33257. [PMID: 27641327 PMCID: PMC5027553 DOI: 10.1038/srep33257] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/24/2016] [Indexed: 01/24/2023] Open
Abstract
Advanced microscopy methods allow obtaining information on (dynamic) conformational changes in biomolecules via measuring a single molecular distance in the structure. It is, however, extremely challenging to capture the full depth of a three-dimensional biochemical state, binding-related structural changes or conformational cross-talk in multi-protein complexes using one-dimensional assays. In this paper we address this fundamental problem by extending the standard molecular ruler based on Förster resonance energy transfer (FRET) into a two-dimensional assay via its combination with protein-induced fluorescence enhancement (PIFE). We show that donor brightness (via PIFE) and energy transfer efficiency (via FRET) can simultaneously report on e.g., the conformational state of double stranded DNA (dsDNA) following its interaction with unlabelled proteins (BamHI, EcoRV, and T7 DNA polymerase gp5/trx). The PIFE-FRET assay uses established labelling protocols and single molecule fluorescence detection schemes (alternating-laser excitation, ALEX). Besides quantitative studies of PIFE and FRET ruler characteristics, we outline possible applications of ALEX-based PIFE-FRET for single-molecule studies with diffusing and immobilized molecules. Finally, we study transcription initiation and scrunching of E. coli RNA-polymerase with PIFE-FRET and provide direct evidence for the physical presence and vicinity of the polymerase that causes structural changes and scrunching of the transcriptional DNA bubble.
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15
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2'-O-methyl nucleotide modified DNA substrates influence the cleavage efficiencies of BamHI and BglII. J Biosci 2015; 39:621-30. [PMID: 25116617 DOI: 10.1007/s12038-014-9466-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Induction of endonucleolytic DNA cleavage is an essential event that links the initiating stimuli to the final effects of cells. The cleavage efficiency and thus the final yield could be affected by many factors, including structures of DNA substrates, composite structures of enzymes-substrates or enzymes-nucleic analogs and so on. However, it is not clear whether a nucleotide derivative-substituted in DNA substrates can influence the efficiency of enzymatic cleavage. To investigate the effect of sugar pucker conformation on DNA-protein interactions, we used 2'-O-methyl modified nucleotides (OMeN) to modify DNA substrates of isocaudemers BamHI and BglII in this study, and used FRET assay as an efficient method for analysis of enzyme cleavage. Experimental results demonstrated that OMeN-substituted recognition sequences influenced the cleavage rates significantly in a position-dependent manner. OMeN substitutions can reduce the cleavage as expected. Surprisingly, OMeN substitutions can also enhance the cleavage rates. The kinetics parameters of Vmax and Km have been obtained by fitting the Michaelis-Menten kinetic equation. These 2'- OMe nucleotides could behave as a regulatory element to modulate the enzymatic activity in vitro, and this property could enrich our understanding about the endonuclease cleavage mechanism and enhance our ability to regulate the enzymatic cleavage efficiency for applications in synthetic biology.
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16
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Sommers JA, Banerjee T, Hinds T, Wan B, Wold MS, Lei M, Brosh RM. Novel function of the Fanconi anemia group J or RECQ1 helicase to disrupt protein-DNA complexes in a replication protein A-stimulated manner. J Biol Chem 2014; 289:19928-41. [PMID: 24895130 DOI: 10.1074/jbc.m113.542456] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Understanding how cellular machinery deals with chromosomal genome complexity is an important question because protein bound to DNA may affect various cellular processes of nucleic acid metabolism. DNA helicases are at the forefront of such processes, yet there is only limited knowledge how they remodel protein-DNA complexes and how these mechanisms are regulated. We have determined that representative human RecQ and Fe-S cluster DNA helicases are potently blocked by a protein-DNA interaction. The Fanconi anemia group J (FANCJ) helicase partners with the single-stranded DNA-binding protein replication protein A (RPA) to displace BamHI-E111A bound to duplex DNA in a specific manner. Protein displacement was dependent on the ATPase-driven function of the helicase and unique properties of RPA. Further biochemical studies demonstrated that the shelterin proteins TRF1 and TRF2, which preferentially bind the telomeric repeat found at chromosome ends, effectively block FANCJ from unwinding the forked duplex telomeric substrate. RPA, but not the Escherichia coli single-stranded DNA-binding protein or shelterin factor Pot1, stimulated FANCJ ejection of TRF1 from the telomeric DNA substrate. FANCJ was also able to displace TRF2 from the telomeric substrate in an RPA-dependent manner. The stimulation of helicase-catalyzed protein displacement is also observed with the DNA helicase RECQ1, suggesting a conserved functional interaction of RPA-interacting helicases. These findings suggest that partnerships between RPA and interacting human DNA helicases may greatly enhance their ability to dislodge proteins bound to duplex DNA, an activity that is likely to be highly relevant to their biological roles in DNA metabolism.
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Affiliation(s)
- Joshua A Sommers
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Taraswi Banerjee
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Twila Hinds
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Bingbing Wan
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - Marc S Wold
- the Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Ming Lei
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - Robert M Brosh
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224,
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17
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Kamps-Hughes N, Quimby A, Zhu Z, Johnson EA. Massively parallel characterization of restriction endonucleases. Nucleic Acids Res 2013; 41:e119. [PMID: 23605040 PMCID: PMC3675476 DOI: 10.1093/nar/gkt257] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Restriction endonucleases are highly specific in recognizing the particular DNA sequence they act on. However, their activity is affected by sequence context, enzyme concentration and buffer composition. Changes in these factors may lead to either ineffective cleavage at the cognate restriction site or relaxed specificity allowing cleavage of degenerate ‘star’ sites. Additionally, uncharacterized restriction endonucleases and engineered variants present novel activities. Traditionally, restriction endonuclease activity is assayed on simple substrates such as plasmids and synthesized oligonucleotides. We present and use high-throughput Illumina sequencing-based strategies to assay the sequence specificity and flanking sequence preference of restriction endonucleases. The techniques use fragmented DNA from sequenced genomes to quantify restriction endonuclease cleavage on a complex genomic DNA substrate in a single reaction. By mapping millions of restriction site–flanking reads back to the Escherichia coli and Drosophila melanogaster genomes we were able to quantitatively characterize the cognate and star site activity of EcoRI and MfeI and demonstrate genome-wide decreases in star activity with engineered high-fidelity variants EcoRI-HF and MfeI-HF, as well as quantify the influence on MfeI cleavage conferred by flanking nucleotides. The methods presented are readily applicable to all type II restriction endonucleases that cleave both strands of double-stranded DNA.
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Affiliation(s)
- Nick Kamps-Hughes
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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18
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Setny P, Bahadur RP, Zacharias M. Protein-DNA docking with a coarse-grained force field. BMC Bioinformatics 2012; 13:228. [PMID: 22966980 PMCID: PMC3522568 DOI: 10.1186/1471-2105-13-228] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 07/19/2012] [Indexed: 11/17/2022] Open
Abstract
Background Protein-DNA interactions are important for many cellular processes, however structural knowledge for a large fraction of known and putative complexes is still lacking. Computational docking methods aim at the prediction of complex architecture given detailed structures of its constituents. They are becoming an increasingly important tool in the field of macromolecular assemblies, complementing particularly demanding protein-nucleic acids X ray crystallography and providing means for the refinement and integration of low resolution data coming from rapidly advancing methods such as cryoelectron microscopy. Results We present a new coarse-grained force field suitable for protein-DNA docking. The force field is an extension of previously developed parameter sets for protein-RNA and protein-protein interactions. The docking is based on potential energy minimization in translational and orientational degrees of freedom of the binding partners. It allows for fast and efficient systematic search for native-like complex geometry without any prior knowledge regarding binding site location. Conclusions We find that the force field gives very good results for bound docking. The quality of predictions in the case of unbound docking varies, depending on the level of structural deviation from bound geometries. We analyze the role of specific protein-DNA interactions on force field performance, both with respect to complex structure prediction, and the reproduction of experimental binding affinities. We find that such direct, specific interactions only partially contribute to protein-DNA recognition, indicating an important role of shape complementarity and sequence-dependent DNA internal energy, in line with the concept of indirect protein-DNA readout mechanism.
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Affiliation(s)
- Piotr Setny
- Physics Department T38, Technical University Munich, James Franck Str. 1, 85748 Garching, Germany.
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19
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ESR spectroscopy identifies inhibitory Cu2+ sites in a DNA-modifying enzyme to reveal determinants of catalytic specificity. Proc Natl Acad Sci U S A 2012; 109:E993-1000. [PMID: 22493217 DOI: 10.1073/pnas.1200733109] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The relationship between DNA sequence recognition and catalytic specificity in a DNA-modifying enzyme was explored using paramagnetic Cu(2+) ions as probes for ESR spectroscopic and biochemical studies. Electron spin echo envelope modulation spectroscopy establishes that Cu(2+) coordinates to histidine residues in the EcoRI endonuclease homodimer bound to its specific DNA recognition site. The coordinated His residues were identified by a unique use of Cu(2+)-ion based long-range distance constraints. Double electron-electron resonance data yield Cu(2+)-Cu(2+) and Cu(2+)-nitroxide distances that are uniquely consistent with one Cu(2+) bound to His114 in each subunit. Isothermal titration calorimetry confirms that two Cu(2+) ions bind per complex. Unexpectedly, Mg(2+)-catalyzed DNA cleavage by EcoRI is profoundly inhibited by Cu(2+) binding at these hitherto unknown sites, 13 Å away from the Mg(2+) positions in the catalytic centers. Molecular dynamics simulations suggest a model for inhibition of catalysis, whereby the Cu(2+) ions alter critical protein-DNA interactions and water molecule positions in the catalytic sites. In the absence of Cu(2+), the Mg(2+)-dependence of EcoRI catalysis shows positive cooperativity, which would enhance EcoRI inactivation of foreign DNA by irreparable double-strand cuts, in preference to readily repaired single-strand nicks. Nonlinear Poisson-Boltzmann calculations suggest that this cooperativity arises because the binding of Mg(2+) in one catalytic site makes the surface electrostatic potential in the distal catalytic site more negative, thus enhancing binding of the second Mg(2+). Taken together, our results shed light on the structural and electrostatic factors that affect site-specific catalysis by this class of endonucleases.
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20
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Label-free detection of protein–DNA interactions using electrochemical impedance spectroscopy. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.06.063] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Tang D, Tang J, Su B, Li Q, Chen G. Electrochemical detection of hepatitis C virus with signal amplification using BamHI endonuclease and horseradish peroxidase-encapsulated nanogold hollow spheres. Chem Commun (Camb) 2011; 47:9477-9. [PMID: 21785766 DOI: 10.1039/c1cc13340c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A novel electrochemical method to detect hepatitis C virus was developed based on site-specific cleavage of BamHI endonuclease and enzymatic signal amplification with horseradish peroxidase-encapsulated nanogold hollow spheres.
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Affiliation(s)
- Dianping Tang
- Key Laboratory of Analysis and Detection of Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
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22
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Liu S, Wu P, Li W, Zhang H, Cai C. Ultrasensitive and selective electrochemical identification of hepatitis C virus genotype 1b based on specific endonuclease combined with gold nanoparticles signal amplification. Anal Chem 2011; 83:4752-8. [PMID: 21553883 DOI: 10.1021/ac200624f] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This work proposes a new strategy for the electrochemical detection of hepatitis C virus (HCV) RNA level and identification of HCV-1b genotype based on the site-specific cleavage of BamHI endonuclease combined with gold nanoparticles (AuNPs) signal amplification. The assay procedures include the reverse transcription, polymerase chain reaction (PCR) amplification, and electrochemical detection. The samples of 244 mer sequence of HCV RNA from the highly conserved region of HCV-1a, HCV-1b, HCV-1, and HCV-6a, respectively, were first reverse transcribed into complementary cDNA and amplified by PCR. The PCR-amplified samples were then analyzed using a synthetic 21 mer DNA probe, which has been assembled on the electrode surface via a bifunctional molecule of p-aminobenzoic acid (ABA). The results demonstrated that the developed approach can be used for specifically identification of the HCV-1b genotype and selective and sensitive detection of HCV-1b cDNA (244 mer) with a detection limit as low as (3.1 ± 0.8) × 10(-22) M (less than 200 molecules; the concentration refers to the one before PCR amplification). Moreover, the developed method has an ability to discriminate the HCV-1b cDNA sequence from even single-base mismatched DNA sequence, to assay the HCV-1b cDNA level precisely from the mixture of HCV-1, HCV-1b, HCV-1a, and HCV-6a, and to detect HCV in real clinical samples. The protocol has high potential application in molecular diagnostics of HCV in clinical environments.
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Affiliation(s)
- Shuna Liu
- Jiangsu Key Laboratory of New Power Batteries, Laboratory of Electrochemistry, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097, People's Republic of China
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23
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Little EJ, Dunten PW, Bitinaite J, Horton NC. New clues in the allosteric activation of DNA cleavage by SgrAI: structures of SgrAI bound to cleaved primary-site DNA and uncleaved secondary-site DNA. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2011; 67:67-74. [PMID: 21206063 PMCID: PMC3016018 DOI: 10.1107/s0907444910047785] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 11/17/2010] [Indexed: 11/10/2022]
Abstract
SgrAI is a type II restriction endonuclease that cuts an unusually long recognition sequence and exhibits allosteric self-activation with expansion of DNA-sequence specificity. The three-dimensional crystal structures of SgrAI bound to cleaved primary-site DNA and Mg²(+) and bound to secondary-site DNA with either Mg²(+) or Ca²(+) are presented. All three structures show a conformation of enzyme and DNA similar to the previously determined dimeric structure of SgrAI bound to uncleaved primary-site DNA and Ca²(+) [Dunten et al. (2008), Nucleic Acids Res. 36, 5405-5416], with the exception of the cleaved bond and a slight shifting of the DNA in the SgrAI/cleaved primary-site DNA/Mg²(+) structure. In addition, a new metal ion binding site is located in one of the two active sites in this structure, which is consistent with proposals for the existence of a metal-ion site near the 3'-O leaving group.
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Affiliation(s)
- Elizabeth J. Little
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Pete W. Dunten
- Stanford Synchrotron Radiation Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | | | - Nancy C. Horton
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
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24
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Venkatesh S, Wower J, Byrne ME. Nucleic acid therapeutic carriers with on-demand triggered release. Bioconjug Chem 2009; 20:1773-82. [PMID: 19670897 DOI: 10.1021/bc900187b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biohybrid platforms such as synthetic polymer networks engineered from artificial and natural materials hold immense potential as drug and gene delivery vehicles. Here, we report the synthesis and characterization of novel polymer networks that release oligonucleotide sequences via enzymatic and physical triggers. Chemical monomers and acrylated oligonucleotides were copolymerized into networks, and phosphoimaging revealed that 70% of the oligonucleotides were incorporated into the networks. We observed that the immobilized oligonucleotides were readily cleaved when the networks were incubated with the type II restriction enzyme BamHI. The diffusion of the cleaved fragments through the macromolecular chains resulted in relatively constant release profiles very close to zero-order. To our knowledge, this is the first study which harnesses the sequence-specificity of restriction endonucleases as triggering agents for the cleavage and release of oligonucleotide sequences from a synthetic polymer network. The polymer networks exhibited an oligonucleotide diffusion coefficient of 5.6 x 10(-8) cm(2)/s and a diffusional exponent of 0.92. Sigmoidal temperature responsive characteristics of the networks matched the theoretical melting temperature of the oligonucleotides and indicated a cooperative melting transition of the oligonucleotides. The networks were also triggered to release a RNA-cleaving deoxyribozyme, which degraded a HIV-1 mRNA transcript in vitro. To tailor release profiles of the oligonucleotides, we controlled the structure of the macromolecular architecture of the networks by varying their cross-linking content. When incubated with DNase I, networks of cross-linking content 0.15%, 0.22%, and 0.45% exhibited oligonucleotide diffusion coefficients of 1.67 x 10(-8), 7.65 x 10(-9), and 2.7 x 10(-9) cm(2)/s, and diffusional exponents of 0.55, 0.8, and 0.8, respectively. The modular nature of our platform promises to open new avenues for the creation and optimization of a rich toolbox of novel drug and gene delivery platforms. We anticipate further inquiry into nucleic acid based programmable on-demand switches and modulatory devices of exquisite sensitivity and control.
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Affiliation(s)
- Siddarth Venkatesh
- Biomimetic and Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, USA
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25
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Bellamy SRW, Kovacheva YS, Zulkipli IH, Halford SE. Differences between Ca2+ and Mg2+ in DNA binding and release by the SfiI restriction endonuclease: implications for DNA looping. Nucleic Acids Res 2009; 37:5443-53. [PMID: 19596810 PMCID: PMC2760798 DOI: 10.1093/nar/gkp569] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many enzymes acting on DNA require Mg(2+) ions not only for catalysis but also to bind DNA. Binding studies often employ Ca(2+) as a substitute for Mg(2+), to promote DNA binding whilst disallowing catalysis. The SfiI endonuclease requires divalent metal ions to bind DNA but, in contrast to many systems where Ca(2+) mimics Mg(2+), Ca(2+) causes SfiI to bind DNA almost irreversibly. Equilibrium binding by wild-type SfiI cannot be conducted with Mg(2+) present as the DNA is cleaved so, to study the effect of Mg(2+) on DNA binding, two catalytically-inactive mutants were constructed. The mutants bound DNA in the presence of either Ca(2+) or Mg(2+) but, unlike wild-type SfiI with Ca(2+), the binding was reversible. With both mutants, dissociation was slow with Ca(2+) but was in one case much faster with Mg(2+). Hence, Ca(2+) can affect DNA binding differently from Mg(2+). Moreover, SfiI is an archetypal system for DNA looping; on DNA with two recognition sites, it binds to both sites and loops out the intervening DNA. While the dynamics of looping cannot be measured with wild-type SfiI and Ca(2+), it becomes accessible with the mutant and Mg(2+).
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Affiliation(s)
- Stuart R W Bellamy
- The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
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26
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Laurens N, Bellamy SRW, Harms AF, Kovacheva YS, Halford SE, Wuite GJL. Dissecting protein-induced DNA looping dynamics in real time. Nucleic Acids Res 2009; 37:5454-64. [PMID: 19586932 PMCID: PMC2760800 DOI: 10.1093/nar/gkp570] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many proteins that interact with DNA perform or enhance their specific functions by binding simultaneously to multiple target sites, thereby inducing a loop in the DNA. The dynamics and energies involved in this loop formation influence the reaction mechanism. Tethered particle motion has proven a powerful technique to study in real time protein-induced DNA looping dynamics while minimally perturbing the DNA-protein interactions. In addition, it permits many single-molecule experiments to be performed in parallel. Using as a model system the tetrameric Type II restriction enzyme SfiI, that binds two copies of its recognition site, we show here that we can determine the DNA-protein association and dissociation steps as well as the actual process of protein-induced loop capture and release on a single DNA molecule. The result of these experiments is a quantitative reaction scheme for DNA looping by SfiI that is rigorously compared to detailed biochemical studies of SfiI looping dynamics. We also present novel methods for data analysis and compare and discuss these with existing methods. The general applicability of the introduced techniques will further enhance tethered particle motion as a tool to follow DNA-protein dynamics in real time.
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Affiliation(s)
- Niels Laurens
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Stuart R. W. Bellamy
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - August F. Harms
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Yana S. Kovacheva
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Stephen E. Halford
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Gijs J. L. Wuite
- Department of Physics and Astronomy and Laser Centre, VU University, De Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands and The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
- *To whom correspondence should be addressed. Tel: +31 20 5987987; Fax: +31 205987991;
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27
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Liu S, Hu Y, Jin J, Zhang H, Cai C. Electrochemical detection of hepatitis C virus based on site-specific DNA cleavage of BamHI endonuclease. Chem Commun (Camb) 2009:1635-7. [PMID: 19294245 DOI: 10.1039/b900690g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have developed a new electrochemical approach for qualitative and quantitative detection of hepatitis C virus (HCV) based on the site-specific DNA cleavage of BamHI endonuclease.
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Affiliation(s)
- Shuna Liu
- Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097, PR China
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28
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Sanders KL, Catto LE, Bellamy SRW, Halford SE. Targeting individual subunits of the FokI restriction endonuclease to specific DNA strands. Nucleic Acids Res 2009; 37:2105-15. [PMID: 19223323 PMCID: PMC2673415 DOI: 10.1093/nar/gkp046] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Many restriction endonucleases are dimers that act symmetrically at palindromic DNA sequences, with each active site cutting one strand. In contrast, FokI acts asymmetrically at a non-palindromic sequence, cutting ‘top’ and ‘bottom’ strands 9 and 13 nucleotides downstream of the site. FokI is a monomeric protein with one active site and a single monomer covers the entire recognition sequence. To cut both strands, the monomer at the site recruits a second monomer from solution, but it is not yet known which DNA strand is cut by the monomer bound to the site and which by the recruited monomer. In this work, mutants of FokI were used to show that the monomer bound to the site made the distal cut in the bottom strand, whilst the recruited monomer made in parallel the proximal cut in the top strand. Procedures were also established to direct FokI activity, either preferentially to the bottom strand or exclusively to the top strand. The latter extends the range of enzymes for nicking specified strands at specific sequences, and may facilitate further applications of FokI in gene targeting.
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Affiliation(s)
- Kelly L Sanders
- Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol, UK
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29
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Swapna G, Saravanan M, Nagaraja V. Conformational Changes Triggered by Mg2+ Mediate Transactivator Function. Biochemistry 2009; 48:2347-54. [DOI: 10.1021/bi8022448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ganduri Swapna
- Department of Microbiology and Cell Biology, Indian Institute of Science, and Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560012, India
| | - Matheswaran Saravanan
- Department of Microbiology and Cell Biology, Indian Institute of Science, and Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560012, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, and Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560012, India
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30
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Bellamy SRW, Mina P, Retter SE, Halford SE. Fidelity of DNA sequence recognition by the SfiI restriction endonuclease is determined by communications between its two DNA-binding sites. J Mol Biol 2008; 384:557-63. [PMID: 18848951 DOI: 10.1016/j.jmb.2008.09.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 09/18/2008] [Accepted: 09/19/2008] [Indexed: 10/21/2022]
Abstract
The SfiI restriction endonuclease is a tetramer in which two subunits form a dimeric unit that contains one DNA binding cleft and the other two subunits contain a second cleft on the opposite side of the protein. Full activity requires both clefts to be filled with its recognition sequence: SfiI has low activity when bound to one site. The ability of SfiI to cleave non-cognate sites, one base pair different from the true site, was initially tested on substrates that lacked specific sites but which contained either one or multiple non-cognate sites. No cleavage of the DNA with one non-cognate site was detected, while a small fraction of the DNA with multiple sites was nicked. The alternative sequences were, however, cleaved in both strands, albeit at low levels, when the DNA also carried either a recognition site for SfiI or the termini generated by SfiI. Further tests employed a mutant of SfiI, altered at the dimer interface, which was known to be more active than wild-type SfiI when bound to a single site. This mutant similarly failed to cleave DNA with one non-cognate site, but cleaved the substrates with multiple non-cognate sites more readily than did the native enzyme. To cleave additional sites, SfiI thus needs to interact concurrently with either two non-cognate sites or one non-cognate and one cognate site (or the termini thereof), yet this arrangement is still restrained from cleaving the alternative site unless the communication pathway between the two DNA-binding clefts is disrupted.
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Affiliation(s)
- Stuart R W Bellamy
- The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
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31
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Mones L, Kulhánek P, Florián J, Simon I, Fuxreiter M. Probing the two-metal ion mechanism in the restriction endonuclease BamHI. Biochemistry 2007; 46:14514-23. [PMID: 18020376 DOI: 10.1021/bi701630s] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The choreography of restriction endonuclease catalysis is a long-standing paradigm in molecular biology. Bivalent metal ions are required almost for all PD..D/ExK type enzymes, but the number of cofactors essential for the DNA backbone scission remained ambiguous. On the basis of crystal structures and biochemical data for various restriction enzymes, three models have been developed that assign critical roles for one, two, or three metal ions during the phosphodiester hydrolysis. To resolve this apparent controversy, we investigated the mechanism of BamHI catalysis using quantum mechanical/molecular mechanical simulation techniques and determined the activation barriers of three possible pathways that involve a Glu-113 or a neighboring water molecule as a general base or an external nucleophile that penetrated from bulk solution. The extrinsic mechanism was found to be the most favorable with an activation free energy of 23.4 kcal/mol, in reasonable agreement with the experimental data. On the basis of the effect of the individual metal ions on the activation barrier, metal ion A was concluded to be pivotal for the reaction, while the enzyme lacking metal ion B still has moderate efficiency. Thus, we propose that the catalytic scheme of BamHI does not involve a general base for nucleophile generation and requires one obligatory metal ion for catalysis that stabilizes the attacking nucleophile and coordinates it throughout the nucleophilic attack. Such a model may also explain the variation in the number of metal ions in the crystal structures and thus could serve as a framework for a unified catalytic scheme of type II restriction endonucleases.
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Affiliation(s)
- Letif Mones
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary
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32
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Bellamy SRW, Milsom SE, Kovacheva YS, Sessions RB, Halford SE. A switch in the mechanism of communication between the two DNA-binding sites in the SfiI restriction endonuclease. J Mol Biol 2007; 373:1169-83. [PMID: 17870087 PMCID: PMC2082129 DOI: 10.1016/j.jmb.2007.08.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 08/10/2007] [Accepted: 08/14/2007] [Indexed: 11/29/2022]
Abstract
While many Type II restriction enzymes are dimers with a single DNA-binding cleft between the subunits, SfiI is a tetramer of identical subunits. Two of its subunits (a dimeric unit) create one DNA-binding cleft, and the other two create a second cleft on the opposite side of the protein. The two clefts bind specific DNA cooperatively to give a complex of SfiI with two recognition sites. This complex is responsible for essentially all of the DNA-cleavage reactions by SfiI: virtually none is due to the complex with one site. The communication between the DNA-binding clefts was examined by disrupting one of the very few polar interactions in the otherwise hydrophobic interface between the dimeric units: a tyrosine hydroxyl was removed by mutation to phenylalanine. The mutant protein remained tetrameric in solution and could bind two DNA sites. But instead of being activated by binding two sites, like wild-type SfiI, it showed maximal activity when bound to a single site and had a lower activity when bound to two sites. This interaction across the dimer interface thus enforces in wild-type SfiI a cooperative transition between inactive and active states in both dimers, but without this interaction as in the mutant protein, a single dimer can undergo the transition to give a stable intermediate with one inactive dimer and one active dimer.
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Affiliation(s)
- Stuart R W Bellamy
- The DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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33
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Solt I, Simon I, Császár AG, Fuxreiter M. Electrostatic versus nonelectrostatic effects in DNA sequence discrimination by divalent ions Mg2+ and Mn2+. J Phys Chem B 2007; 111:6272-9. [PMID: 17497910 DOI: 10.1021/jp0668192] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mg2+ and Mn2+ ions are critical to the functioning of phosphoryl transfer enzymes, such as restriction endonucleases. Although these ions play similar roles in the chemical steps, they govern substrate specificity via modulating sequence discrimination by up to a factor of 10(5) with Mg2+ and only up to a factor of 10 with Mn2+. To explain whether such diversity originates in fundamental differences in the electronic structures of the nucleobase-hydrated-metal ion complexes, structures and interaction energies were determined at the density functional (DFT) and second-order Møller-Plesset (MP2) levels of theory. Although both metal ions favor identical binding sites, Mn2+ complexes exhibit greater distortions from the ideal octahedral geometry and larger variability than the corresponding Mg2+ systems. In inner-shell complexes, with direct contact between the metal and the nucleobase, Mg2+ is preferred over Mn2+ in the gas phase, due primarily to nonelectrostatic effects. The interaction energies of the two metal ions are more similar in the outer-shell complexes, likely due to reduced charge transfer between the hydrated metal ion and the base moieties. Inclusion of solvation effects can amplify the relative nucleobase preferences of Mg2+ and Mn2+, indicating that bulk hydration modulates the balance between electrostatic and nonelectrostatic terms. In most cases, the base substitutions in solution are facilitated more by Mn2+ than by Mg2+. Electrostatic properties of the environment were demonstrated to have a major influence on the nucleobase preferences of the two metal ions. Overall, quantum chemical calculations suggest that the contrasting selectivity of Mg2+ and Mn2+ cofactors toward nucleobases derives from the larger flexibility of the Mn2+ complexes accompanied by the excessive polarization and charge-transfer effects as well as less favorable solvation.
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Affiliation(s)
- Iván Solt
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H-1518 Budapest PO Box 7, Hungary
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34
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Sidorova NY, Muradymov S, Rau DC. Differences in hydration coupled to specific and nonspecific competitive binding and to specific DNA Binding of the restriction endonuclease BamHI. J Biol Chem 2006; 281:35656-66. [PMID: 17008319 DOI: 10.1074/jbc.m608018200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using the osmotic stress technique together with a self-cleavage assay we measure directly differences in sequestered water between specific and nonspecific DNA-BamHI complexes as well as the numbers of water molecules released coupled to specific complex formation. The difference between specific and nonspecific binding free energy of the BamHI scales linearly with solute osmolal concentration for seven neutral solutes used to set water activity. The observed osmotic dependence indicates that the nonspecific DNA-BamHI complex sequesters some 120-150 more water molecules than the specific complex. The weak sensitivity of the difference in number of waters to the solute identity suggests that these waters are sterically inaccessible to solutes. This result is in close agreement with differences in the structures determined by x-ray crystallography. We demonstrate additionally that when the same solutes that were used in competition experiments are used to probe changes accompanying the binding of free BamHI to its specific DNA sequence, the measured number of water molecules released in the binding process is strikingly solute-dependent (with up to 10-fold difference between solutes). This result is expected for reactions resulting in a large change in a surface exposed area.
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Affiliation(s)
- Nina Y Sidorova
- Laboratory of Physical and Structural Biology, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA.
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35
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Catto LE, Ganguly S, Milsom SE, Welsh AJ, Halford SE. Protein assembly and DNA looping by the FokI restriction endonuclease. Nucleic Acids Res 2006; 34:1711-20. [PMID: 16556912 PMCID: PMC1410913 DOI: 10.1093/nar/gkl076] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The FokI restriction endonuclease recognizes an asymmetric DNA sequence and cuts both strands at fixed positions upstream of the site. The sequence is contacted by a single monomer of the protein, but the monomer has only one catalytic centre and forms a dimer to cut both strands. FokI is also known to cleave DNA with two copies of its site more rapidly than DNA with one copy. To discover how FokI acts at a single site and how it acts at two sites, its reactions were examined on a series of plasmids with either one recognition site or with two sites separated by varied distances, sometimes in the presence of a DNA-binding defective mutant of FokI. These experiments showed that, to cleave DNA with one site, the monomer bound to that site associates via a weak protein–protein interaction with a second monomer that remains detached from the recognition sequence. Nevertheless, the second monomer catalyses phosphodiester bond hydrolysis at the same rate as the DNA-bound monomer. On DNA with two sites, two monomers of FokI interact strongly, as a result of being tethered to the same molecule of DNA, and sequester the intervening DNA in a loop.
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Affiliation(s)
| | | | | | | | - Stephen E. Halford
- To whom correspondence should be addressed. Tel: +44 117 928 7429; Fax: +44 117 928 8274;
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36
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van den Broek B, Vanzi F, Normanno D, Pavone FS, Wuite GJ. Real-time observation of DNA looping dynamics of Type IIE restriction enzymes NaeI and NarI. Nucleic Acids Res 2006; 34:167-74. [PMID: 16407332 PMCID: PMC1326248 DOI: 10.1093/nar/gkj432] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Many restriction enzymes require binding of two copies of a recognition sequence for DNA cleavage, thereby introducing a loop in the DNA. We investigated looping dynamics of Type IIE restriction enzymes NaeI and NarI by tracking the Brownian motion of single tethered DNA molecules. DNA containing two endonuclease recognition sites spaced a few 100 bp apart connect small polystyrene beads to a glass surface. The position of a bead is tracked through video microscopy. Protein-mediated looping and unlooping is then observed as a sudden specific change in Brownian motion of the bead. With this method we are able to directly follow DNA looping kinetics of single protein–DNA complexes to obtain loop stability and loop formation times. We show that, in the absence of divalent cations, NaeI induces DNA loops of specific size. In contrast, under these conditions NarI mainly creates non-specific loops, resulting in effective DNA compaction for higher enzyme concentrations. Addition of Ca2+ increases the NaeI-DNA loop lifetime by two orders of magnitude and stimulates specific binding by NarI. Finally, for both enzymes we observe exponentially distributed loop formation times, indicating that looping is dominated by (re)binding the second recognition site.
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Affiliation(s)
| | - Francesco Vanzi
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 150019 Sesto Fiorentino (Firenze), Italy
| | - Davide Normanno
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 150019 Sesto Fiorentino (Firenze), Italy
| | - Francesco S. Pavone
- European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 150019 Sesto Fiorentino (Firenze), Italy
| | - Gijs J.L. Wuite
- To whom correspondence should be addressed. Tel: +31205987987; Fax: +31205987991;
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37
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Hiller DA, Rodriguez AM, Perona JJ. Non-cognate Enzyme–DNA Complex: Structural and Kinetic Analysis of EcoRV Endonuclease Bound to the EcoRI Recognition Site GAATTC. J Mol Biol 2005; 354:121-36. [PMID: 16236314 DOI: 10.1016/j.jmb.2005.09.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 09/14/2005] [Accepted: 09/15/2005] [Indexed: 11/25/2022]
Abstract
The crystal structure of EcoRV endonuclease bound to non-cognate DNA at 2.0 angstroms resolution shows that very small structural adaptations are sufficient to ensure the extreme sequence specificity characteristic of restriction enzymes. EcoRV bends its specific GATATC site sharply by 50 degrees into the major groove at the center TA step, generating unusual base-base interactions along each individual DNA strand. In the symmetric non-cognate complex bound to GAATTC, the center step bend is relaxed to avoid steric hindrance caused by the different placement of the exocyclic thymine methyl groups. The decreased base-pair unstacking in turn leads to small conformational rearrangements in the sugar-phosphate backbone, sufficient to destabilize binding of crucial divalent metal ions in the active site. A second crystal structure of EcoRV bound to the base-analog GAAUTC site shows that the 50 degrees center-step bend of the DNA is restored. However, while divalent metals bind at high occupancy in this structure, one metal ion shifts away from binding at the scissile DNA phosphate to a position near the 3'-adjacent phosphate group. This may explain why the 10(4)-fold attenuated cleavage efficiency toward GAATTC is reconstituted by less than tenfold toward GAAUTC. Examination of DNA binding and bending by equilibrium and stopped-flow florescence quenching and fluorescence resonance energy transfer (FRET) methods demonstrates that the capacity of EcoRV to bend the GAATTC non-cognate site is severely limited, but that full bending of GAAUTC is achieved at only a threefold reduced rate compared with the cognate complex. Together, the structural and biochemical data demonstrate the existence of distinct mechanisms for ensuring specificity at the bending and catalytic steps, respectively. The limited conformational rearrangements observed in the EcoRV non-cognate complex provide a sharp contrast to the extensive structural changes found in a non-cognate BamHI-DNA crystal structure, thus demonstrating a diversity of mechanisms by which restriction enzymes are able to achieve specificity.
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Affiliation(s)
- David A Hiller
- Department of Chemistry and Biochemistry, and Interdepartmental Program in Biomolecular Science and Engineering, University of California at Santa Barbara, Santa Barbara, CA 93106-9510, USA
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38
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Morozov AV, Havranek JJ, Baker D, Siggia ED. Protein-DNA binding specificity predictions with structural models. Nucleic Acids Res 2005; 33:5781-98. [PMID: 16246914 PMCID: PMC1270944 DOI: 10.1093/nar/gki875] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Protein-DNA interactions play a central role in transcriptional regulation and other biological processes. Investigating the mechanism of binding affinity and specificity in protein-DNA complexes is thus an important goal. Here we develop a simple physical energy function, which uses electrostatics, solvation, hydrogen bonds and atom-packing terms to model direct readout and sequence-specific DNA conformational energy to model indirect readout of DNA sequence by the bound protein. The predictive capability of the model is tested against another model based only on the knowledge of the consensus sequence and the number of contacts between amino acids and DNA bases. Both models are used to carry out predictions of protein-DNA binding affinities which are then compared with experimental measurements. The nearly additive nature of protein-DNA interaction energies in our model allows us to construct position-specific weight matrices by computing base pair probabilities independently for each position in the binding site. Our approach is less data intensive than knowledge-based models of protein-DNA interactions, and is not limited to any specific family of transcription factors. However, native structures of protein-DNA complexes or their close homologs are required as input to the model. Use of homology modeling can significantly increase the extent of our approach, making it a useful tool for studying regulatory pathways in many organisms and cell types.
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Affiliation(s)
- Alexandre V Morozov
- Center for Studies in Physics and Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
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39
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Gowers DM, Wilson GG, Halford SE. Measurement of the contributions of 1D and 3D pathways to the translocation of a protein along DNA. Proc Natl Acad Sci U S A 2005; 102:15883-8. [PMID: 16243975 PMCID: PMC1262116 DOI: 10.1073/pnas.0505378102] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins that act at specific DNA sequences bind DNA randomly and then translocate to the target site. The translocation is often ascribed to the protein sliding along the DNA while maintaining continuous contact with it. Proteins also can move on DNA by multiple cycles of dissociation/reassociation within the same chain. To distinguish these pathways, a strategy was developed to analyze protein motion between DNA sites. The strategy reveals whether the protein maintains contact with the DNA as it transfers from one site to another by sliding or whether it loses contact by a dissociation/reassociation step. In reactions at low salt, the test protein stayed on the DNA as it traveled between sites, but only when the sites were <50 bp apart. Transfers of >30 bp at in vivo salt, and over distances of >50 bp at any salt, always included at least one dissociation step. Hence, for this enzyme, 1D sliding operates only over short distances at low salt, and 3D dissociation/reassociation is its main mode of translocation.
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Affiliation(s)
- Darren M Gowers
- Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
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40
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Sidorova NY, Muradymov S, Rau DC. Trapping DNA-protein binding reactions with neutral osmolytes for the analysis by gel mobility shift and self-cleavage assays. Nucleic Acids Res 2005; 33:5145-55. [PMID: 16155185 PMCID: PMC1214545 DOI: 10.1093/nar/gki808] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We take advantage of our previous observation that neutral osmolytes can strongly slow down the rate of DNA–protein complex dissociation to develop a method that uses osmotic stress to ‘freeze’ mixtures of DNA–protein complexes and prevent further reaction enabling analysis of the products. We apply this approach to the gel mobility shift assay and use it to modify a self-cleavage assay that uses the nuclease activity of the restriction endonucleases to measure sensitively their specific binding to DNA. At sufficiently high concentrations of neutral osmolytes the cleavage reaction can be triggered at only those DNA fragments with initially bound enzyme. The self-cleavage assay allows measurement of binding equilibrium and kinetics directly in solution avoiding the intrinsic problems of gel mobility shift and filter binding assays while providing the same sensitivity level. Here we compare the self-cleavage and gel mobility shift assays applied to the DNA binding of EcoRI and BamHI restriction endonucleases. Initial results indicate that BamHI dissociation from its specific DNA sequence is strongly linked to water activity with the half-life time of the specific complex increasing ∼20-fold from 0 to 1 osmolal betaine.
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Affiliation(s)
- Nina Y Sidorova
- Laboratory of Physical and Structural Biology, NICHD, National Institutes of Health, Bethesda, MD 20892, USA.
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41
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Ferreiro DU, Dellarole M, Nadra AD, de Prat-Gay G. Free energy contributions to direct readout of a DNA sequence. J Biol Chem 2005; 280:32480-4. [PMID: 16000299 DOI: 10.1074/jbc.m505706200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The energetic contributions of individual DNA-contacting side chains to specific DNA recognition in the human papillomavirus 16 E2C-DNA complex is small (less than 1.0 kcal mol(-1)), independent of the physical and chemical nature of the interaction, and is strictly additive. The sum of the individual contributions differs 1.0 kcal mol(-1) from the binding energy of the wild-type protein. This difference corresponds to the contribution from the deformability of the DNA, known as "indirect readout." Thus, we can dissect the energetic contribution to DNA binding into 90% direct and 10% indirect readout components. The lack of high energy interactions indicates the absence of "hot spots," such as those found in protein-protein interfaces. These results are compatible with a highly dynamic and "wet" protein-DNA interface, yet highly specific and tight, where individual interactions are constantly being formed and broken.
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Affiliation(s)
- Diego U Ferreiro
- Instituto Leloir, Consejo Nacional de Investigaciones Científicas y Técnicas, and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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42
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Bellamy SRW, Milsom SE, Scott DJ, Daniels LE, Wilson GG, Halford SE. Cleavage of individual DNA strands by the different subunits of the heterodimeric restriction endonuclease BbvCI. J Mol Biol 2005; 348:641-53. [PMID: 15826661 DOI: 10.1016/j.jmb.2005.02.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Revised: 02/11/2005] [Accepted: 02/18/2005] [Indexed: 11/26/2022]
Abstract
BbvCI cleaves an asymmetric DNA sequence, 5'-CC downward arrow TCAGC-3'/5'-GC downward arrow TGAGG-3', as indicated. While many Type II restriction enzymes consist of identical subunits, BbvCI has two different subunits: R(1), which acts at GC downward arrow TGAGG; and R(2), which acts at CC downward arrow TCAGC. Some mutants of BbvCI with defects in one subunit, either R(1)(-)R(2)(+) or R(1)(+)R(2)(-), cleave only one strand, that attacked by the native subunit. In analytical ultracentrifugation at various concentrations of protein, wild-type and mutant BbvCI enzymes aggregated extensively, but are R(1)R(2) heterodimers at the concentrations used in DNA cleavage reactions. On a plasmid with one recognition site, wild-type BbvCI cleaved both strands before dissociating from the DNA, while the R(1)(-)R(2)(+) and R(1)(+)R(2)(-) mutants acted almost exclusively on their specified strands, albeit at relatively slow rates. During the wild-type reaction, the DNA is cleaved initially in one strand, mainly that targeted by the R(1) subunit. The other strand is then cleaved slowly by R(2) before the enzyme dissociates from the DNA. Hence, the nicked form accumulates as a transient intermediate. This behaviour differs from that of many other restriction enzymes, which cut both strands at equal rates. However, the activities of the R(1)(+) and R(2)(+) subunits in the wild-type enzyme can differ from their activities in the R(1)(+)R(2)(-) and R(1)(-)R(2)(+) mutants. Each active site in BbvCI therefore influences the other.
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Affiliation(s)
- Stuart R W Bellamy
- Department of Biochemistry, School of Medical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK.
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43
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Fuxreiter M, Mezei M, Simon I, Osman R. Interfacial water as a "hydration fingerprint" in the noncognate complex of BamHI. Biophys J 2005; 89:903-11. [PMID: 15894630 PMCID: PMC1366640 DOI: 10.1529/biophysj.105.063263] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The molecular code of specific DNA recognition by proteins as a paradigm in molecular biology remains an unsolved puzzle primarily because of the subtle interplay between direct protein-DNA interaction and the indirect contribution from water and ions. Transformation of the nonspecific, low affinity complex to a specific, high affinity complex is accompanied by the release of interfacial water molecules. To provide insight into the conversion from the loose to the tight form, we characterized the structure and energetics of water at the protein-DNA interface of the BamHI complex with a noncognate sequence and in the specific complex. The fully hydrated models were produced with Grand Canonical Monte Carlo simulations. Proximity analysis shows that water distributions exhibit sequence dependent variations in both complexes and, in particular, in the noncognate complex they discriminate between the correct and the star site. Variations in water distributions control the number of water molecules released from a given sequence upon transformation from the loose to the tight complex as well as the local entropy contribution to the binding free energy. We propose that interfacial waters can serve as a "hydration fingerprint" of a given DNA sequence.
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Affiliation(s)
- Monika Fuxreiter
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest.
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44
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Sapienza PJ, Dela Torre CA, McCoy WH, Jana SV, Jen-Jacobson L. Thermodynamic and kinetic basis for the relaxed DNA sequence specificity of "promiscuous" mutant EcoRI endonucleases. J Mol Biol 2005; 348:307-24. [PMID: 15811370 DOI: 10.1016/j.jmb.2005.02.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2004] [Revised: 02/15/2005] [Accepted: 02/17/2005] [Indexed: 11/18/2022]
Abstract
Promiscuous mutant EcoRI endonucleases produce lethal to sublethal effects because they cleave Escherichia coli DNA despite the presence of the EcoRI methylase. Three promiscuous mutant forms, Ala138Thr, Glu192Lys and His114Tyr, have been characterized with respect to their binding affinities and first-order cleavage rate constants towards the three classes of DNA sites: specific, miscognate (EcoRI*) and non-specific. We have made the unanticipated and counterintuitive observations that the mutant restriction endonucleases that exhibit relaxed specificity in vivo nevertheless bind more tightly than the wild-type enzyme to the specific recognition sequence in vitro, and show even greater preference for binding to the cognate GAATTC site over miscognate sites. Binding preference for EcoRI* over non-specific DNA is also improved. The first-order cleavage rate constants of the mutant enzymes are normal for the cognate site GAATTC, but are greater than those of the wild-type enzyme at EcoRI* sites. Thus, the mutant enzymes use two mechanisms to partially bypass the multiple fail-safe mechanisms that protect against cleavage of genomic DNA in cells carrying the wild-type EcoRI restriction-modification system: (a) binding to EcoRI* sites is more probable than for wild-type enzyme because non-specific DNA is less effective as a competitive inhibitor; (b) the combination of increased affinity and elevated cleavage rate constants at EcoRI* sites makes double-strand cleavage of these sites a more probable outcome than it is for the wild-type enzyme. Semi-quantitative estimates of rates of EcoRI* site cleavage in vivo, predicted using the binding and cleavage constants measured in vitro, are in accord with the observed lethal phenotypes associated with the three mutations.
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Affiliation(s)
- Paul J Sapienza
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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45
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Nikolajewa S, Beyer A, Friedel M, Hollunder J, Wilhelm T. Common patterns in type II restriction enzyme binding sites. Nucleic Acids Res 2005; 33:2726-33. [PMID: 15888729 PMCID: PMC1097771 DOI: 10.1093/nar/gki575] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Restriction enzymes are among the best studied examples of DNA binding proteins. In order to find general patterns in DNA recognition sites, which may reflect important properties of protein–DNA interaction, we analyse the binding sites of all known type II restriction endonucleases. We find a significantly enhanced GC content and discuss three explanations for this phenomenon. Moreover, we study patterns of nucleotide order in recognition sites. Our analysis reveals a striking accumulation of adjacent purines (R) or pyrimidines (Y). We discuss three possible reasons: RR/YY dinucleotides are characterized by (i) stronger H-bond donor and acceptor clusters, (ii) specific geometrical properties and (iii) a low stacking energy. These features make RR/YY steps particularly accessible for specific protein–DNA interactions. Finally, we show that the recognition sites of type II restriction enzymes are underrepresented in host genomes and in phage genomes.
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Affiliation(s)
| | | | | | | | - Thomas Wilhelm
- To whom correspondence should be addressed. Tel: +49 3641 65 6208; Fax: +49 3641 65 6191;
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46
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van den Broek B, Noom MC, Wuite GJL. DNA-tension dependence of restriction enzyme activity reveals mechanochemical properties of the reaction pathway. Nucleic Acids Res 2005; 33:2676-84. [PMID: 15886396 PMCID: PMC1092278 DOI: 10.1093/nar/gki565] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type II restriction endonucleases protect bacteria against phage infections by cleaving recognition sites on foreign double-stranded DNA (dsDNA) with extraordinary specificity. This capability arises primarily from large conformational changes in enzyme and/or DNA upon target sequence recognition. In order to elucidate the connection between the mechanics and the chemistry of DNA recognition and cleavage, we used a single-molecule approach to measure rate changes in the reaction pathway of EcoRV and BamHI as a function of DNA tension. We show that the induced-fit rate of EcoRV is strongly reduced by such tension. In contrast, BamHI is found to be insensitive, providing evidence that both substrate binding and hydrolysis are not influenced by this force. Based on these results, we propose a mechanochemical model of induced-fit reactions on DNA, allowing determination of induced-fit rates and DNA bend angles. Finally, for both enzymes a strongly decreased association rate is obtained on stretched DNA, presumably due to the absence of intradomain dissociation/re-association between non-specific sites (jumping). The obtained results should apply to many other DNA-associated proteins.
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Affiliation(s)
| | | | - Gijs J. L. Wuite
- To whom correspondence should be addressed. Tel: +31205987987; Fax: +31205987991;
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47
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Zhang C, Liu S, Zhu Q, Zhou Y. A knowledge-based energy function for protein-ligand, protein-protein, and protein-DNA complexes. J Med Chem 2005; 48:2325-35. [PMID: 15801826 DOI: 10.1021/jm049314d] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We developed a knowledge-based statistical energy function for protein-ligand, protein-protein, and protein-DNA complexes by using 19 atom types and a distance-scale finite ideal-gas reference (DFIRE) state. The correlation coefficients between experimentally measured protein-ligand binding affinities and those predicted by the DFIRE energy function are around 0.63 for one training set and two testing sets. The energy function also makes highly accurate predictions of binding affinities of protein-protein and protein-DNA complexes. Correlation coefficients between theoretical and experimental results are 0.73 for 82 protein-protein (peptide) complexes and 0.83 for 45 protein-DNA complexes, despite the fact that the structures of protein-protein (peptide) and protein-DNA complexes were not used in training the energy function. The results of the DFIRE energy function on protein-ligand complexes are compared to the published results of 12 other scoring functions generated from either physical-based, knowledge-based, or empirical methods. They include AutoDock, X-Score, DrugScore, four scoring functions in Cerius 2 (LigScore, PLP, PMF, and LUDI), four scoring functions in SYBYL (F-Score, G-Score, D-Score, and ChemScore), and BLEEP. While the DFIRE energy function is only moderately successful in ranking native or near native conformations, it yields the strongest correlation between theoretical and experimental binding affinities of the testing sets and between rmsd values and energy scores of docking decoys in a benchmark of 100 protein-ligand complexes. The parameters and the program of the all-atom DFIRE energy function are freely available for academic users at http://theory.med.buffalo.edu.
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Affiliation(s)
- Chi Zhang
- Howard Hughes Medical Institute Center for Single Molecule Biophysics, Department of Physiology & Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, New York 14214, USA
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48
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Abstract
Heat capacity (Cp) is one of several major thermodynamic quantities commonly measured in proteins. With more than half a dozen definitions, it is the hardest of these quantities to understand in physical terms, but the richest in insight. There are many ramifications of observed Cp changes: The sign distinguishes apolar from polar solvation. It imparts a temperature (T) dependence to entropy and enthalpy that may change their signs and which of them dominate. Protein unfolding usually has a positive deltaCp, producing a maximum in stability and sometimes cold denaturation. There are two heat capacity contributions, from hydration and protein-protein interactions; which dominates in folding and binding is an open question. Theoretical work to date has dealt mostly with the hydration term and can account, at least semiquantitatively, for the major Cp-related features: the positive and negative Cp of hydration for apolar and polar groups, respectively; the convergence of apolar group hydration entropy at T approximately 112 degrees C; the decrease in apolar hydration Cp with increasing T; and the T-maximum in protein stability and cold denaturation.
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Affiliation(s)
- Ninad V Prabhu
- E.R. Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, USA.
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49
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Kurpiewski MR, Engler LE, Wozniak LA, Kobylanska A, Koziolkiewicz M, Stec WJ, Jen-Jacobson L. Mechanisms of coupling between DNA recognition specificity and catalysis in EcoRI endonuclease. Structure 2005; 12:1775-88. [PMID: 15458627 DOI: 10.1016/j.str.2004.07.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2004] [Revised: 07/25/2004] [Accepted: 07/28/2004] [Indexed: 10/26/2022]
Abstract
Proteins that bind to specific sites on DNA often do so in order to carry out catalysis or specific protein-protein interaction while bound to the recognition site. Functional specificity is enhanced if this second function is coupled to correct DNA site recognition. To analyze the structural and energetic basis of coupling between recognition and catalysis in EcoRI endonuclease, we have studied stereospecific phosphorothioate (PS) or methylphosphonate (PMe) substitutions at the scissile phosphate GpAATTC or at the adjacent phosphate GApATTC in combination with molecular-dynamics simulations of the catalytic center with bound Mg2+. The results show the roles in catalysis of individual phosphoryl oxygens and of DNA distortion and suggest that a "crosstalk ring" in the complex couples recognition to catalysis and couples the two catalytic sites to each other.
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Affiliation(s)
- Michael R Kurpiewski
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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50
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Abstract
MOTIVATION Localizing protein binding sites within genomic DNA is of considerable importance, but remains difficult for protein families, such as transcription factors, which have loosely defined target sequences. It is generally assumed that protein affinity for DNA involves additive contributions from successive nucleotide pairs within the target sequence. This is not necessarily true, and non-additive effects have already been experimentally demonstrated in a small number of cases. The principal origin of non-additivity involves the so-called indirect component of protein-DNA recognition which is related to the sequence dependence of DNA deformation induced during complex formation. Non-additive effects are difficult to study because they require the identification of many more binding sequences than are normally necessary for describing additive specificity (typically via the construction of weight matrices). RESULTS In the present work we will use theoretically estimated binding energies as a basis for overcoming this problem. Our approach enables us to study the full combinatorial set of sequences for a variety of DNA-binding proteins, make a detailed analysis of non-additive effects and exploit this information to improve binding site predictions using either weight matrices or support vector machines. The results underline the fact that, even in the presence of significant deformation, non-additive effects may involve only a limited number of dinucleotide steps. This information helps to reduce the number of binding sites which need to be identified for successful predictions and to avoid problems of over-fitting. AVAILABILITY The SVM software is available upon request from the authors.
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Affiliation(s)
- R A O'Flanagan
- Department of Physics and Astronomy, BioMaps Institute, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA
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