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Wilhelm E, Poirier M, Da Rocha M, Bédard M, McDonald PP, Lavigne P, Hunter CL, Bell B. Mitotic deacetylase complex (MiDAC) recognizes the HIV-1 core promoter to control activated viral gene expression. PLoS Pathog 2024; 20:e1011821. [PMID: 38781120 PMCID: PMC11115230 DOI: 10.1371/journal.ppat.1011821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 04/05/2024] [Indexed: 05/25/2024] Open
Abstract
The human immunodeficiency virus (HIV) integrates into the host genome forming latent cellular reservoirs that are an obstacle for cure or remission strategies. Viral transcription is the first step in the control of latency and depends upon the hijacking of the host cell RNA polymerase II (Pol II) machinery by the 5' HIV LTR. Consequently, "block and lock" or "shock and kill" strategies for an HIV cure depend upon a full understanding of HIV transcriptional control. The HIV trans-activating protein, Tat, controls HIV latency as part of a positive feed-forward loop that strongly activates HIV transcription. The recognition of the TATA box and adjacent sequences of HIV essential for Tat trans-activation (TASHET) of the core promoter by host cell pre-initiation complexes of HIV (PICH) has been shown to be necessary for Tat trans-activation, yet the protein composition of PICH has remained obscure. Here, DNA-affinity chromatography was employed to identify the mitotic deacetylase complex (MiDAC) as selectively recognizing TASHET. Using biophysical techniques, we show that the MiDAC subunit DNTTIP1 binds directly to TASHET, in part via its CTGC DNA motifs. Using co-immunoprecipitation assays, we show that DNTTIP1 interacts with MiDAC subunits MIDEAS and HDAC1/2. The Tat-interacting protein, NAT10, is also present in HIV-bound MiDAC. Gene silencing revealed a functional role for DNTTIP1, MIDEAS, and NAT10 in HIV expression in cellulo. Furthermore, point mutations in TASHET that prevent DNTTIP1 binding block the reactivation of HIV by latency reversing agents (LRA) that act via the P-TEFb/7SK axis. Our data reveal a key role for MiDAC subunits DNTTIP1, MIDEAS, as well as NAT10, in Tat-activated HIV transcription and latency. DNTTIP1, MIDEAS and NAT10 emerge as cell cycle-regulated host cell transcription factors that can control activated HIV gene expression, and as new drug targets for HIV cure strategies.
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Affiliation(s)
| | | | - Morgane Da Rocha
- Département de microbiologie et d’infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Mikaël Bédard
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Patrick P. McDonald
- Pulmonary Division, Medicine Faculty, Université de Sherbrooke; and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Pierre Lavigne
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | | | - Brendan Bell
- Département de microbiologie et d’infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
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2
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Hutin S, Wigge PA, Zubieta C. In Vitro Determination of Temperature-Dependent DNA Binding of the Evening Complex Using Electrophoretic Mobility Shift Assays. Methods Mol Biol 2024; 2795:135-147. [PMID: 38594535 DOI: 10.1007/978-1-0716-3814-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Electrophoretic mobility shift assays (EMSAs) of DNA-binding proteins and labeled DNA allow the qualitative and quantitative characterization of protein-DNA complex formation using native (nondenaturing) polyacrylamide or agarose gel electrophoresis. By varying the incubation temperature of the protein-DNA binding reaction and maintaining this temperature during electrophoresis, temperature-dependent protein-DNA interactions can be investigated. Here, we provide examples of the binding of a transcriptional repressor complex called the Evening Complex, comprising the DNA-binding protein LUX ARRYTHMO (LUX), the scaffold protein EARLY FLOWERING 3 (ELF3), and the adapter protein ELF4, to its cognate DNA and demonstrate direct detection and visualization of thermoresponsive binding in vitro. As negative controls we use the LUX DNA-binding domain and LUX full length protein, which do not exhibit temperature-dependent DNA binding.
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Affiliation(s)
- Stephanie Hutin
- Laboratoire Physiologie Cellulaire et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI, Grenoble, France
| | - Philip A Wigge
- Leibniz-Institut für Gemüse- und Zierpflanzenbau, Großbeeren, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Chloe Zubieta
- Laboratoire Physiologie Cellulaire et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI, Grenoble, France.
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3
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Wang H, Canasto-Chibuque C, Kim JH, Hohl M, Leslie C, Reis-Filho JS, Petrini JH. Chronic Interferon Stimulated Gene Transcription Promotes Oncogene Induced Breast Cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.16.562529. [PMID: 37905095 PMCID: PMC10614814 DOI: 10.1101/2023.10.16.562529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
The Mre11 complex (comprising Mre11, Rad50, Nbs1) is integral to the maintenance of genome stability. We previously showed that a hypomorphic Mre11 mutant mouse strain ( Mre11 ATLD1/ATLD1 ) was highly susceptible to oncogene induced breast cancer. Here we used a mammary organoid system to examine which Mre11 dependent responses are tumor suppressive. We found that Mre11 ATLD1/ATLD1 organoids exhibited an elevated interferon stimulated gene (ISG) signature and sustained changes in chromatin accessibility. This Mre11 ATLD1/ATLD1 phenotype depended on DNA binding of a nuclear innate immune sensor, IFI205. Ablation of Ifi205 in Mre11 ATLD1/ATLD1 organoids restored baseline and oncogene-induced chromatin accessibility patterns to those observed in WT . Implantation of Mre11 ATLD1/ATLD1 organoids and activation of oncogene led to aggressive metastatic breast cancer. This outcome was reversed in implanted Ifi205 -/- Mre11 ATLD1/ATLD1 organoids. These data reveal a connection between innate immune signaling and tumor suppression in mammary epithelium. Given the abundance of aberrant DNA structures that arise in the context of genome instability syndromes, the data further suggest that cancer predisposition in those contexts may be partially attributable to tonic innate immune transcriptional programs.
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4
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Hua L, Wang D, Wang K, Wang Y, Gu J, Zhang Q, You Q, Wang L. Design of Tracers in Fluorescence Polarization Assay for Extensive Application in Small Molecule Drug Discovery. J Med Chem 2023; 66:10934-10958. [PMID: 37561645 DOI: 10.1021/acs.jmedchem.3c00881] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Development of fluorescence polarization (FP) assays, especially in a competitive manner, is a potent and mature tool for measuring the binding affinities of small molecules. This approach is suitable for high-throughput screening (HTS) for initial ligands and is also applicable for further study of the structure-activity relationships (SARs) of candidate compounds for drug discovery. Buffer and tracer, especially rational design of the tracer, play a vital role in an FP assay system. In this perspective, we provided different kinds of approaches for tracer design based on successful cases in recent years. We classified these tracers by different types of ligands in tracers, including peptide, nucleic acid, natural product, and small molecule. To make this technology accessible for more targets, we briefly described the basic theory and workflow, followed by highlighting the design and application of typical FP tracers from a perspective of medicinal chemistry.
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Affiliation(s)
- Liwen Hua
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Danni Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Keran Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Yuxuan Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Jinying Gu
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Qiuyue Zhang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Qidong You
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lei Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
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5
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Ploetz E, Ambrose B, Barth A, Börner R, Erichson F, Kapanidis AN, Kim HD, Levitus M, Lohman TM, Mazumder A, Rueda DS, Steffen FD, Cordes T, Magennis SW, Lerner E. A new twist on PIFE: photoisomerisation-related fluorescence enhancement. ARXIV 2023:arXiv:2302.12455v2. [PMID: 36866225 PMCID: PMC9980184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
PIFE was first used as an acronym for protein-induced fluorescence enhancement, which refers to the increase in fluorescence observed upon the interaction of a fluorophore, such as a cyanine, with a protein. This fluorescence enhancement is due to changes in the rate of cis/trans photoisomerisation. It is clear now that this mechanism is generally applicable to interactions with any biomolecule and, in this review, we propose that PIFE is thereby renamed according to its fundamental working principle as photoisomerisation-related fluorescence enhancement, keeping the PIFE acronym intact. We discuss the photochemistry of cyanine fluorophores, the mechanism of PIFE, its advantages and limitations, and recent approaches to turn PIFE into a quantitative assay. We provide an overview of its current applications to different biomolecules and discuss potential future uses, including the study of protein-protein interactions, protein-ligand interactions and conformational changes in biomolecules.
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Affiliation(s)
- Evelyn Ploetz
- Department of Chemistry and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Benjamin Ambrose
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, UK, Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, UK
| | - Anders Barth
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Richard Börner
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Felix Erichson
- Laserinstitut Hochschule Mittweida, Mittweida University of Applied Sciences, Mittweida, Germany
| | - Achillefs N. Kapanidis
- Kavli Institute for Nanoscience Discovery, Department of Biological Physics, The University of Oxford, UK
| | - Harold D. Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, USA
| | - Marcia Levitus
- School of Molecular Sciences, Arizona State University, 551 E. University Drive, Tempe, AZ, 85287, USA
| | - Timothy M. Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Abhishek Mazumder
- Kavli Institute for Nanoscience Discovery, Department of Biological Physics, The University of Oxford, UK
| | - David S. Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, UK, Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, UK
| | - Fabio D. Steffen
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr, 2-4, 82152 Planegg-Martinsried, Germany
| | - Steven W. Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Eitan Lerner
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, Edmond J. Safra Campus, Hebrew University of Jerusalem; Jerusalem 9190401, Israel, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem; Jerusalem 9190401, Israel
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6
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Henry C, Mbele N, Cox MM. RecF protein targeting to postreplication (daughter strand) gaps I: DNA binding by RecF and RecFR. Nucleic Acids Res 2023; 51:5699-5713. [PMID: 37125642 PMCID: PMC10287957 DOI: 10.1093/nar/gkad311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 04/09/2023] [Accepted: 04/27/2023] [Indexed: 05/02/2023] Open
Abstract
In bacteria, the repair of post-replication gaps by homologous recombination requires the action of the recombination mediator proteins RecF, RecO and RecR. Whereas the role of the RecOR proteins to displace the single strand binding protein (SSB) and facilitate RecA loading is clear, how RecF mediates targeting of the system to appropriate sites remains enigmatic. The most prominent hypothesis relies on specific RecF binding to gap ends. To test this idea, we present a detailed examination of RecF and RecFR binding to more than 40 DNA substrates of varying length and structure. Neither RecF nor the RecFR complex exhibited specific DNA binding that can explain the targeting of RecF(R) to post-replication gaps. RecF(R) bound to dsDNA and ssDNA of sufficient length with similar facility. DNA binding was highly ATP-dependent. Most measured Kd values fell into a range of 60-180 nM. The addition of ssDNA extensions on duplex substrates to mimic gap ends or CPD lesions produces only subtle increases or decreases in RecF(R) affinity. Significant RecFR binding cooperativity was evident with many DNA substrates. The results indicate that RecF or RecFR targeting to post-replication gaps must rely on factors not yet identified, perhaps involving interactions with additional proteins.
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Affiliation(s)
- Camille Henry
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | - Neema Mbele
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
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7
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Ngo K, Gittens TH, Gonzalez DI, Hatmaker EA, Plotkin S, Engle M, Friedman GA, Goldin M, Hoerr RE, Eichman BF, Rokas A, Benton ML, Friedman KL. A comprehensive map of hotspots of de novo telomere addition in Saccharomyces cerevisiae. Genetics 2023; 224:iyad076. [PMID: 37119805 PMCID: PMC10474931 DOI: 10.1093/genetics/iyad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/15/2023] [Accepted: 04/18/2023] [Indexed: 05/01/2023] Open
Abstract
Telomere healing occurs when telomerase, normally restricted to chromosome ends, acts upon a double-strand break to create a new, functional telomere. De novo telomere addition (dnTA) on the centromere-proximal side of a break truncates the chromosome but, by blocking resection, may allow the cell to survive an otherwise lethal event. We previously identified several sequences in the baker's yeast, Saccharomyces cerevisiae, that act as hotspots of dnTA [termed Sites of Repair-associated Telomere Addition (SiRTAs)], but the distribution and functional relevance of SiRTAs is unclear. Here, we describe a high-throughput sequencing method to measure the frequency and location of telomere addition within sequences of interest. Combining this methodology with a computational algorithm that identifies SiRTA sequence motifs, we generate the first comprehensive map of telomere-addition hotspots in yeast. Putative SiRTAs are strongly enriched in subtelomeric regions where they may facilitate formation of a new telomere following catastrophic telomere loss. In contrast, outside of subtelomeres, the distribution and orientation of SiRTAs appears random. Since truncating the chromosome at most SiRTAs would be lethal, this observation argues against selection for these sequences as sites of telomere addition per se. We find, however, that sequences predicted to function as SiRTAs are significantly more prevalent across the genome than expected by chance. Sequences identified by the algorithm bind the telomeric protein Cdc13, raising the possibility that association of Cdc13 with single-stranded regions generated during the response to DNA damage may facilitate DNA repair more generally.
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Affiliation(s)
- Katrina Ngo
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Tristen H Gittens
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - David I Gonzalez
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - E Anne Hatmaker
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37232 USA
| | - Simcha Plotkin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Mason Engle
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Geofrey A Friedman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Melissa Goldin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Remington E Hoerr
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Brandt F Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232 USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37232 USA
| | | | - Katherine L Friedman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
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8
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Ngo K, Gittens TH, Gonzalez DI, Hatmaker EA, Plotkin S, Engle M, Friedman GA, Goldin M, Hoerr RE, Eichman BF, Rokas A, Benton ML, Friedman KL. A comprehensive map of hotspots of de novo telomere addition in Saccharomyces cerevisiae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533556. [PMID: 36993206 PMCID: PMC10055226 DOI: 10.1101/2023.03.20.533556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Telomere healing occurs when telomerase, normally restricted to chromosome ends, acts upon a double-strand break to create a new, functional telomere. De novo telomere addition on the centromere-proximal side of a break truncates the chromosome but, by blocking resection, may allow the cell to survive an otherwise lethal event. We previously identified several sequences in the baker’s yeast, Saccharomyces cerevisiae , that act as hotspots of de novo telomere addition (termed Sites of Repair-associated Telomere Addition or SiRTAs), but the distribution and functional relevance of SiRTAs is unclear. Here, we describe a high-throughput sequencing method to measure the frequency and location of telomere addition within sequences of interest. Combining this methodology with a computational algorithm that identifies SiRTA sequence motifs, we generate the first comprehensive map of telomere-addition hotspots in yeast. Putative SiRTAs are strongly enriched in subtelomeric regions where they may facilitate formation of a new telomere following catastrophic telomere loss. In contrast, outside of subtelomeres, the distribution and orientation of SiRTAs appears random. Since truncating the chromosome at most SiRTAs would be lethal, this observation argues against selection for these sequences as sites of telomere addition per se. We find, however, that sequences predicted to function as SiRTAs are significantly more prevalent across the genome than expected by chance. Sequences identified by the algorithm bind the telomeric protein Cdc13, raising the possibility that association of Cdc13 with single-stranded regions generated during the response to DNA damage may facilitate DNA repair more generally.
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Affiliation(s)
- Katrina Ngo
- Department of Biological Sciences, Vanderbilt University
| | | | | | - E. Anne Hatmaker
- Department of Biological Sciences, Vanderbilt University
- Evolutionary Studies Initiative, Vanderbilt University
| | - Simcha Plotkin
- Department of Biological Sciences, Vanderbilt University
| | - Mason Engle
- Department of Biological Sciences, Vanderbilt University
| | | | - Melissa Goldin
- Department of Biological Sciences, Vanderbilt University
| | | | - Brandt F. Eichman
- Department of Biological Sciences, Vanderbilt University
- Department of Biochemistry, Vanderbilt University
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University
- Evolutionary Studies Initiative, Vanderbilt University
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9
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Smiley AT, Tompkins KJ, Pawlak MR, Krueger AJ, Evans RL, Shi K, Aihara H, Gordon WR. Watson-Crick Base-Pairing Requirements for ssDNA Recognition and Processing in Replication-Initiating HUH Endonucleases. mBio 2023; 14:e0258722. [PMID: 36541758 PMCID: PMC9973303 DOI: 10.1128/mbio.02587-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Replication-initiating HUH endonucleases (Reps) are sequence-specific nucleases that cleave and rejoin single-stranded DNA (ssDNA) during rolling-circle replication. These functions are mediated by covalent linkage of the Rep to its substrate post cleavage. Here, we describe the structures of the endonuclease domain from the Muscovy duck circovirus Rep in complex with its cognate ssDNA 10-mer with and without manganese in the active site. Structural and functional analyses demonstrate that divalent cations play both catalytic and structural roles in Reps by polarizing and positioning their substrate. Further structural comparisons highlight the importance of an intramolecular substrate Watson-Crick (WC) base pairing between the -4 and +1 positions. Subsequent kinetic and functional analyses demonstrate a functional dependency on WC base pairing between these positions regardless of the pair's identity (i.e., A·T, T·A, G·C, or C·G), highlighting a structural specificity for substrate interaction. Finally, considering how well WC swaps were tolerated in vitro, we sought to determine to what extent the canonical -4T·+1A pairing is conserved in circular Rep-encoding single-stranded DNA viruses and found evidence of noncanonical pairings in a minority of these genomes. Altogether, our data suggest that substrate intramolecular WC base pairing is a universal requirement for separation and reunion of ssDNA in Reps. IMPORTANCE Circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses are a ubiquitous group of viruses that infect organisms across all domains of life. These viruses negatively impact both agriculture and human health. All members of this viral family employ a multifunctional nuclease (Rep) to initiate replication. Reps are structurally similar throughout this family, making them targets of interest for viral inhibition strategies. Here, we investigate the functional dependencies of the Rep protein from Muscovy duck circovirus for ssDNA interaction. We demonstrate that this Rep requires an intramolecular Watson-Crick base pairing for origin of replication (Ori) recognition and interaction. We show that noncognate base pair swaps are well tolerated, highlighting a local structural specificity over sequence specificity. Bioinformatic analysis found that the vast majority of CRESS-DNA Oris form base pairs in conserved positions, suggesting this pairing is a universal requirement for replication initiation in the CRESS-DNA virus family.
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Affiliation(s)
- Adam T. Smiley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Kassidy J. Tompkins
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Matthew R. Pawlak
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - August J. Krueger
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Robert L. Evans
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ke Shi
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Wendy R. Gordon
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
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10
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Lee J, Lee S. Non-Invasive, Reliable, and Fast Quantification of DNA Loading on Gold Nanoparticles by a One-Step Optical Measurement. Anal Chem 2023; 95:1856-1866. [PMID: 36633590 DOI: 10.1021/acs.analchem.2c03378] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
An exquisite, versatile, and reproducible quantification of DNA loading on gold nanoparticles (Au NPs) has long been pursued because this loading influences the analytical, therapeutic, and self-assembly behaviors of DNA-Au NPs. Nevertheless, the existing methods used thus far rely solely on the invasive detachment and subsequent spectroscopic quantification of DNA, which are error-prone and highly dependent on trained personnel. Here, we present a non-invasive optical framework that can determine the number of DNA strands on Au NPs by versatile one-step measurement of the visible absorption spectra of DNA-Au NP solutions without any invasive modifications or downstream processes. Using effective medium theory in conjunction with electromagnetic numerical calculation, the change in DNA loading density, resulting from varying the ion concentration, Au NP size, DNA strand length, and surrounding temperature, can be tracked in situ merely by the one-step measurement of visible absorption spectra, which is otherwise impossible to achieve. Moreover, the simplicity and robustness of this method promote reproducible DNA loading quantification regardless of experimental adeptness, which is in stark contrast with existing invasive and multistep methods. Overall, the optical framework outlined in this work can contribute to democratizing research on DNA-Au NPs and facilitating their rapid adoption in transformative applications.
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Affiliation(s)
- Jaewon Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea
| | - Seungwoo Lee
- KU-KIST Graduate School of Converging Science and Technology, Department of Integrative Energy Engineering, Department of Biomicrosystem Technology, and KU Photonics Center, Korea University, Seoul 02841, Republic of Korea
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11
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Analytical Perspectives in the Study of Polyvalent Interactions of Free and Surface-Bound Oligonucleotides and Their Implications in Affinity Biosensing. Int J Mol Sci 2022; 24:ijms24010175. [PMID: 36613616 PMCID: PMC9820729 DOI: 10.3390/ijms24010175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
The high affinity and/or selectivity of oligonucleotide-mediated binding offers a myriad of therapeutical and analytical applications, whose rational design implies an accurate knowledge of the involved molecular mechanisms, concurring equilibrium processes and key affinity parameters. Oligonucleotide-functionalized gold surfaces or nanostructures are regularly employed analytical platforms for the development of label-free optical or electrochemical biosensors, and recently, novel detection platform designs have been increasingly considering the synergistic effect of polyvalent binding, involving the simultaneous interaction of two or several oligonucleotide strands. Considering the general lack of studies involving ternary single-stranded DNA (ssDNA) interactions, a complementary analytical workflow involving capillary gel electrophoretic (CGE) mobility shift assay, microcalorimetry and computational modeling has been deployed for the characterization of a series of free and surface-bound binary and ternary oligonucleotide interactions. As a proof of concept, the DNA analogue of MicroRNA 21 (miR21), a well-known oncogenic short MicroRNA (miRNA) sequence, has been chosen as a target molecule, simulating limiting-case scenarios involved in dual molecular recognition models exploited in affinity (bio)sensing. Novel data for the characterization of oligonucleotide interacting modules is revealed, offering a fast and complete mapping of the specific or non-specific, often competing, binary and ternary order interactions in dynamic equilibria, occurring between various free and metal surface-bound oligonucleotides.
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12
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Yu B, Bien KG, Wang T, Iwahara J. Diffusion NMR-based comparison of electrostatic influences of DNA on various monovalent cations. Biophys J 2022; 121:3562-3570. [PMID: 35754184 PMCID: PMC9515368 DOI: 10.1016/j.bpj.2022.06.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/03/2022] [Accepted: 06/22/2022] [Indexed: 11/18/2022] Open
Abstract
Counterions are important constituents for the structure and function of nucleic acids. Using 7Li and 133Cs nuclear magnetic resonance (NMR) spectroscopy, we investigated how ionic radii affect the behavior of counterions around DNA through diffusion measurements of Li+ and Cs+ ions around a 15-bp DNA duplex. Together with our previous data on 23Na+ and 15NH4+ ions around the same DNA under the same conditions, we were able to compare the dynamics of four different monovalent ions around DNA. From the apparent diffusion coefficients at varied concentrations of DNA, we determined the diffusion coefficients of these cations inside and outside the ion atmosphere around DNA (Db and Df, respectively). We also analyzed ionic competition with K+ ions for the ion atmosphere and assessed the relative affinities of these cations for DNA. Interestingly, all cations (i.e., Li+, Na+, NH4+, and Cs+) analyzed by diffusion NMR spectroscopy exhibited nearly identical Db/Df ratios despite the differences in their ionic radii, relative affinities, and diffusion coefficients. These results, along with the theoretical relationship between diffusion and entropy, suggest that the entropy change due to the release of counterions from the ion atmosphere around DNA is also similar regardless of the monovalent ion types. These findings and the experimental diffusion data on the monovalent ions are useful for examination of computational models for electrostatic interactions or ion solvation.
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Affiliation(s)
- Binhan Yu
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas
| | - Karina G Bien
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas
| | - Tianzhi Wang
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas
| | - Junji Iwahara
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas.
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Hamilton DJ, Hein AE, Holmes ZE, Wuttke DS, Batey RT. The DNA-Binding High-Mobility Group Box Domain of Sox Family Proteins Directly Interacts with RNA In Vitro. Biochemistry 2022; 61:10.1021/acs.biochem.2c00218. [PMID: 35511045 PMCID: PMC9636074 DOI: 10.1021/acs.biochem.2c00218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There is a growing body of evidence that a substantial number of protein domains identified as DNA-binding also interact with RNA to regulate biological processes. Several recent studies have revealed that the Sox2 transcription factor binds RNA through its high-mobility group box (HMGB) domain in vitro and in vivo. A high degree of conservation of this domain among members of the Sox family of transcription factors suggests that RNA-binding activity may be a general feature of these proteins. To address this hypothesis, we examined a subset of HMGB domains from human Sox family of proteins for their ability to bind both DNA and RNA in vitro. We observed selective, high-affinity interactions between Sox family HMGB domains and various model RNA elements, including a four-way junction RNA, a hairpin RNA with an internal bulge, G-quadruplex RNA, and a fragment of long noncoding RNA ES2, which is known to directly interact with Sox2. Importantly, the HMGB domains bind these RNA ligands significantly tighter than nonconsensus dsDNA and in some cases with affinities rivaling those of their consensus dsDNA sequences. These data suggest that RNA binding is a conserved feature of the Sox family of transcription factors with the potential to modulate unappreciated biological functions.
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Affiliation(s)
- Desmond J Hamilton
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309-0596, United States
| | - Abigail E Hein
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309-0596, United States
| | - Zachariah E Holmes
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309-0596, United States
| | - Deborah S Wuttke
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309-0596, United States
| | - Robert T Batey
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309-0596, United States
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Novel endosomolytic compounds enable highly potent delivery of antisense oligonucleotides. Commun Biol 2022; 5:185. [PMID: 35233031 PMCID: PMC8888659 DOI: 10.1038/s42003-022-03132-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 02/08/2022] [Indexed: 11/08/2022] Open
Abstract
The therapeutic and research potentials of oligonucleotides (ONs) have been hampered in part by their inability to effectively escape endosomal compartments to reach their cytosolic and nuclear targets. Splice-switching ONs (SSOs) can be used with endosomolytic small molecule compounds to increase functional delivery. So far, development of these compounds has been hindered by a lack of high-resolution methods that can correlate SSO trafficking with SSO activity. Here we present in-depth characterization of two novel endosomolytic compounds by using a combination of microscopic and functional assays with high spatiotemporal resolution. This system allows the visualization of SSO trafficking, evaluation of endosomal membrane rupture, and quantitates SSO functional activity on a protein level in the presence of endosomolytic compounds. We confirm that the leakage of SSO into the cytosol occurs in parallel with the physical engorgement of LAMP1-positive late endosomes and lysosomes. We conclude that the new compounds interfere with SSO trafficking to the LAMP1-positive endosomal compartments while inducing endosomal membrane rupture and concurrent ON escape into the cytosol. The efficacy of these compounds advocates their use as novel, potent, and quick-acting transfection reagents for antisense ONs. Two new endosomolytic small compounds increase delivery of splice-switching oligonucleotides by interfering with their trafficking to the LAMP1-positive endosomal compartments, inducing endosomal membrane rupture and concurrent oligonucleotide escape into the cytosol.
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15
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Determining translocation orientations of nucleic acid helicases. Methods 2021; 204:160-171. [PMID: 34758393 PMCID: PMC9076756 DOI: 10.1016/j.ymeth.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 11/20/2022] Open
Abstract
Helicase enzymes translocate along an RNA or DNA template with a defined polarity to unwind, separate, or remodel duplex strands for a variety of genome maintenance processes. Helicase mutations are commonly associated with a variety of diseases including aging, cancer, and neurodegeneration. Biochemical characterization of these enzymes has provided a wealth of information on the kinetics of unwinding and substrate preferences, and several high-resolution structures of helicases alone and bound to oligonucleotides have been solved. Together, they provide mechanistic insights into the structural translocation and unwinding orientations of helicases. However, these insights rely on structural inferences derived from static snapshots. Instead, continued efforts should be made to combine structure and kinetics to better define active translocation orientations of helicases. This review explores many of the biochemical and biophysical methods utilized to map helicase binding orientation to DNA or RNA substrates and includes several time-dependent methods to unequivocally map the active translocation orientation of these enzymes to better define the active leading and trailing faces.
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16
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Lu WT, Trost CN, Müller-Esparza H, Randau L, Davidson AR. Anti-CRISPR AcrIF9 functions by inducing the CRISPR-Cas complex to bind DNA non-specifically. Nucleic Acids Res 2021; 49:3381-3393. [PMID: 33660777 PMCID: PMC8034650 DOI: 10.1093/nar/gkab092] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 01/28/2021] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
Phages and other mobile genetic elements express anti-CRISPR proteins (Acrs) to protect their genomes from destruction by CRISPR–Cas systems. Acrs usually block the ability of CRISPR–Cas systems to bind or cleave their nucleic acid substrates. Here, we investigate an unusual Acr, AcrIF9, that induces a gain-of-function to a type I-F CRISPR–Cas (Csy) complex, causing it to bind strongly to DNA that lacks both a PAM sequence and sequence complementarity. We show that specific and non-specific dsDNA compete for the same site on the Csy:AcrIF9 complex with rapid exchange, but specific ssDNA appears to still bind through complementarity to the CRISPR RNA. Induction of non-specific DNA-binding is a shared property of diverse AcrIF9 homologues. Substitution of a conserved positively charged surface on AcrIF9 abrogated non-specific dsDNA-binding of the Csy:AcrIF9 complex, but specific dsDNA binding was maintained. AcrIF9 mutants with impaired non-specific dsDNA binding activity in vitro displayed a reduced ability to inhibit CRISPR–Cas activity in vivo. We conclude that misdirecting the CRISPR–Cas complex to bind non-specific DNA is a key component of the inhibitory mechanism of AcrIF9. This inhibitory mechanism is distinct from a previously characterized anti-CRISPR, AcrIF1, that sterically blocks DNA-binding, even though AcrIF1and AcrIF9 bind to the same site on the Csy complex.
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Affiliation(s)
- Wang-Ting Lu
- Department of Biochemistry, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
| | - Chantel N Trost
- Department of Molecular Genetics, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
| | - Hanna Müller-Esparza
- Faculty of Biology, University of Marburg, Karl-von-Frisch-Straße 1, 35043 Marburg, Germany
| | - Lennart Randau
- Faculty of Biology, University of Marburg, Karl-von-Frisch-Straße 1, 35043 Marburg, Germany.,Loewe Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Alan R Davidson
- Department of Biochemistry, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada.,Department of Molecular Genetics, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
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17
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He C, Migawa MT, Chen K, Weston TA, Tanowitz M, Song W, Guagliardo P, Iyer KS, Bennett CF, Fong LG, Seth PP, Young SG, Jiang H. High-resolution visualization and quantification of nucleic acid-based therapeutics in cells and tissues using Nanoscale secondary ion mass spectrometry (NanoSIMS). Nucleic Acids Res 2021; 49:1-14. [PMID: 33275144 PMCID: PMC7797060 DOI: 10.1093/nar/gkaa1112] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/27/2020] [Accepted: 11/04/2020] [Indexed: 01/19/2023] Open
Abstract
Nucleic acid therapeutics (NATs) have proven useful in promoting the degradation of specific transcripts, modifying gene expression, and regulating mRNA splicing. In each situation, efficient delivery of nucleic acids to cells, tissues and intracellular compartments is crucial—both for optimizing efficacy and reducing side effects. Despite successes in NATs, our understanding of their cellular uptake and distribution in tissues is limited. Current methods have yielded insights into distribution of NATs within cells and tissues, but the sensitivity and resolution of these approaches are limited. Here, we show that nanoscale secondary ion mass spectrometry (NanoSIMS) imaging can be used to define the distribution of 5-bromo-2′-deoxythymidine (5-BrdT) modified antisense oligonucleotides (ASO) in cells and tissues with high sensitivity and spatial resolution. This approach makes it possible to define ASO uptake and distribution in different subcellular compartments and to quantify the impact of targeting ligands designed to promote ASO uptake by cells. Our studies showed that phosphorothioate ASOs are associated with filopodia and the inner nuclear membrane in cultured cells, and also revealed substantial cellular and subcellular heterogeneity of ASO uptake in mouse tissues. NanoSIMS imaging represents a significant advance in visualizing uptake and distribution of NATs; this approach will be useful in optimizing efficacy and delivery of NATs for treating human disease.
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Affiliation(s)
- Cuiwen He
- Department of Medicine, University of California, Los Angeles, CA 90095, USA
| | | | - Kai Chen
- School of Molecular Sciences, University of Western Australia, Perth 6009, Australia
| | - Thomas A Weston
- Department of Medicine, University of California, Los Angeles, CA 90095, USA
| | | | - Wenxin Song
- Department of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Paul Guagliardo
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Perth 6009, Australia
| | - K Swaminathan Iyer
- School of Molecular Sciences, University of Western Australia, Perth 6009, Australia
| | | | - Loren G Fong
- Department of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Punit P Seth
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Stephen G Young
- Department of Medicine, University of California, Los Angeles, CA 90095, USA.,Department of Human Genetics, University of California, Los Angeles, CA 90095, USA
| | - Haibo Jiang
- School of Molecular Sciences, University of Western Australia, Perth 6009, Australia.,Department of Chemistry, The University of Hong Kong, Hong Kong, China
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18
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Fossépré M, Tuvi-Arad I, Beljonne D, Richeter S, Clément S, Surin M. Binding Mode Multiplicity and Multiscale Chirality in the Supramolecular Assembly of DNA and a π-Conjugated Polymer. Chemphyschem 2020; 21:2543-2552. [PMID: 32910539 DOI: 10.1002/cphc.202000630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/04/2020] [Indexed: 02/04/2023]
Abstract
Water-soluble π-conjugated polymers are increasingly considered for DNA biosensing. However, the conformational rearrangement, supramolecular organization and dynamics upon interaction with DNA have been overlooked, which prevents the rational design of such detection tools. To elucidate the binding of a cationic polythiophene (CPT) to DNA with atomistic resolution, we performed molecular simulations of their supramolecular assembly. Comparison of replicated simulations show a multiplicity of CPT binding geometries that contribute to the wrapping of CPT around DNA. The different binding geometries are stabilized by both electrostatic interactions between CPT lateral cations and DNA phosphodiesters and van der Waals interactions between the CPT backbone and the DNA grooves. Simulated circular dichroism (CD) spectra show that the induced CD signal stems from a conserved geometrical feature across the replicated simulations, i. e. the presence of segments of syn configurations between thiophene units along the CPT chain. At the macromolecular scale, we inspected the different shapes related to the CPT binding modes around the DNA through symmetry metrics. Altogether, molecular dynamics (MD) simulations, model Hamiltonian calculations of the CD spectra, and symmetry indices provide insights into the origin of induced chirality from the atomic to the macromolecular scale. Our multidisciplinary approach points out the hierarchical aspect of CPT chiral organization induced by DNA.
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Affiliation(s)
- Mathieu Fossépré
- Laboratory for Chemistry of Novel Materials, Centre of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 20 Place du Parc, Mons, 7000, Belgium
| | - Inbal Tuvi-Arad
- Department of Natural Sciences, The Open University of Israel, Raanana, Israel
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, Centre of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 20 Place du Parc, Mons, 7000, Belgium
| | | | | | - Mathieu Surin
- Laboratory for Chemistry of Novel Materials, Centre of Innovation and Research in Materials and Polymers (CIRMAP), University of Mons - UMONS, 20 Place du Parc, Mons, 7000, Belgium
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Malhotra L, Goyal HKV, Jhuria S, Dev K, Kumar S, Kumar M, Kaur P, Ethayathulla AS. Curcumin rescue p53Y220C in BxPC-3 pancreatic adenocarcinomas cell line: Evidence-based on computational, biophysical, and in vivo studies. Biochim Biophys Acta Gen Subj 2020; 1865:129807. [PMID: 33278547 DOI: 10.1016/j.bbagen.2020.129807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/19/2020] [Accepted: 11/26/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND The p53, tumor suppressor protein is inactivated upon mutation in the DNA-binding domain and the non-functional protein leads to cancers. The p53Y220C is one of the most frequently observed mutations in p53 with a scope of rescuing the protein function using small molecules. METHODS Using computational modeling, biophysical, and experimental cell-based studies we tried to understand the molecular basis of Curcumin as a potential small molecule to stabilize p53Y220C mutant and restore its function. The pancreatic adenocarcinomas BxPC-3 p53Y220C mutant cell line was used for cell-based assays to determine the therapeutic potential of Curcumin to restore mutant p53 to function like wild type. RESULTS Our results showed that the Curcumin binds p53Y220C with Kd = 3.169 ± 0.257 μM and it increases the DNA binding affinity of the mutant by 4-fold with Kd = 851.29 ± 186.27 nM. By Fluorescence, CD, and IR spectroscopy, we could characterize the secondary structural changes and stabilization of the p53Y220C DNA binding domain upon Curcumin binding. By caspase-3 and Annexin V assays, we could demonstrate that Curcumin at 3 μM to 8 μM concentration could initiate p53 mediated apoptosis in BxPC-3 cell line. Based on our experimental studies, we propose a mechanism for the activation of ATM/Chk1 kinases pathways for apoptosis and/or G2/M cell cycle arrest in the BxPC-3 cell line mediated by functionally restored p53Y220C. CONCLUSION The study indicated that the natural compound Curcumin could rescue mutant p53Y220C in BxPC-3 pancreatic adenocarcinomas cell line to function like wild-type and activate apoptotic pathways.
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Affiliation(s)
- Lakshay Malhotra
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Harsh K V Goyal
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Sunita Jhuria
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Kapil Dev
- Department of Biotechnology, Jamia Milia Islamia, New Delhi 110025, India
| | - Saroj Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Manoj Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Abdul S Ethayathulla
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India.
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20
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Zhao Q, Bai Y, Wang H. Directing a rational design of aptamer-based fluorescence anisotropy assay for sensitive detection of immunoglobulin E by site-specific binding study. Talanta 2020; 217:121018. [PMID: 32498825 DOI: 10.1016/j.talanta.2020.121018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 11/17/2022]
Abstract
Mapping aptamer-protein interactions is important for characterization and applications of aptamers against proteins. We describe here probing affinity interactions between aptamer and immunoglobulin E (IgE) with a fluorescence anisotropy (FA) approach using a series of aptamer probes having single fluorescein (FAM) label at individual nucleotide (A, C, T). Studies of binding between IgE and aptamer probes revealed several possible close-contact sites, e.g., T9, T10, T11, T13, C15, and T17 of a 37-nt aptamer with a stem-loop secondary structure. FAM labeling on these sites resulted in much higher FA values (higher than 0.230 for T10, T11, T13 and C15) of aptamer-IgE complexes than the distant sites (e.g., terminals) of aptamer probably because the bound IgE close to these sites significantly restricted local rotation of FAM. Close-contact site labeled aptamer probes with high affinity allowed to develop a more sensitive FA assay for IgE than distant site labeled aptamers. The FA assay using T10-labeled aptamer with a dissociation constant (Kd) about 0.8 nM enabled selective detection of IgE at 20 pM and large FA increase upon IgE addition. We also found A12, C14, A25, and T27 were important for IgE-aptamer binding as FAM labeling at these sites significantly reduced aptamer affinity. FA study showed the loop region of this stem-loop aptamer was crucial for affinity binding, and IgE bound to the loop. This FA method will be helpful for understanding aptamer-protein binding and making a rational design of aptamer affinity assays for proteins.
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Affiliation(s)
- Qiang Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Yunlong Bai
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Hailin Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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21
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Hoyos-Gonzalez N, Trasviña-Arenas CH, Degiorgi A, Castro-Lara AY, Peralta-Castro A, Jimenez-Sandoval P, Diaz-Quezada C, Lodi T, Baruffini E, Brieba LG. Modeling of pathogenic variants of mitochondrial DNA polymerase: insight into the replication defects and implication for human disease. Biochim Biophys Acta Gen Subj 2020; 1864:129608. [PMID: 32234506 DOI: 10.1016/j.bbagen.2020.129608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 03/07/2020] [Accepted: 03/25/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations in human gene encoding the mitochondrial DNA polymerase γ (HsPolγ) are associated with a broad range of mitochondrial diseases. Here we studied the impact on DNA replication by disease variants clustered around residue HsPolγ-K1191, a residue that in several family-A DNA polymerases interacts with the 3' end of the primer. METHODS Specifically, we examined the effect of HsPolγ carrying pathogenic variants in residues D1184, I1185, C1188, K1191, D1196, and a stop codon at residue T1199, using as a model the yeast mitochondrial DNA polymerase protein, Mip1p. RESULTS The introduction of pathogenic variants C1188R (yV945R), and of a stop codon at residue T1199 (yT956X) abolished both polymerization and exonucleolysis in vitro. HsPolγ substitutions in residues D1184 (yD941), I1185 (yI942), K1191 (yK948) and D1196 (yD953) shifted the balance between polymerization and exonucleolysis in favor of exonucleolysis. HsPolγ pathogenic variants at residue K1191 (yK948) and D1184 (yD941) were capable of nucleotide incorporation albeit with reduced processivity. Structural analysis of mitochondrial DNAPs showed that residue HsPolγ-N864 is placed in an optimal distance to interact with the 3' end of the primer and the phosphate backbone previous to the 3' end. Amino acid changes in residue HsPolγ-N864 to Ala, Ser or Asp result in enzymes that did not decrease their polymerization activity on short templates but exhibited a substantial decrease for processive DNA synthesis. CONCLUSION Our data suggest that in mitochondrial DNA polymerases multiple amino acids are involved in the primer-stand stabilization.
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Affiliation(s)
- Nallely Hoyos-Gonzalez
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Carlos H Trasviña-Arenas
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Andrea Degiorgi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Atzimaba Y Castro-Lara
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Antolín Peralta-Castro
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Pedro Jimenez-Sandoval
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Corina Diaz-Quezada
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Tiziana Lodi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
| | - Luis G Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico.
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22
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Pendergraff H, Schmidt S, Vikeså J, Weile C, Øverup C, W. Lindholm M, Koch T. Nuclear and Cytoplasmatic Quantification of Unconjugated, Label-Free Locked Nucleic Acid Oligonucleotides. Nucleic Acid Ther 2020; 30:4-13. [PMID: 31618108 PMCID: PMC6987631 DOI: 10.1089/nat.2019.0810] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/28/2019] [Indexed: 12/23/2022] Open
Abstract
Methods for the quantification of antisense oligonucleotides (AONs) provide insightful information on biodistribution and intracellular trafficking. However, the established methods have not provided information on the absolute number of molecules in subcellular compartments or about how many AONs are needed for target gene reduction for unconjugated AONs. We have developed a new method for nuclear AON quantification that enables us to determine the absolute number of AONs per nucleus without relying on AON conjugates such as fluorophores that may alter AON distribution. This study describes an alternative and label-free method using subcellular fractionation, nucleus counting, and locked nucleic acid (LNA) sandwich enzyme-linked immunosorbent assay to quantify absolute numbers of oligonucleotides in nuclei. Our findings show compound variability (diversity) by which 247,000-693,000 LNAs/nuclei results in similar target reduction for different compounds. This method can be applied to any antisense drug discovery platform providing information on specific and clinically relevant AONs. Finally, this method can directly compare nuclear entry of AON with target gene knockdown for any compound design and nucleobase sequence, gene target, and phosphorothioate stereochemistry.
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Affiliation(s)
- Hannah Pendergraff
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Steffen Schmidt
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Jonas Vikeså
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Christian Weile
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Charlotte Øverup
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Marie W. Lindholm
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
| | - Troels Koch
- Roche Pharma Research and Early Development, RNA Therapeutics Research, Roche Innovation Center Copenhagen, Hørsholm, Denmark
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23
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Manzanares-Palenzuela CL, Pourrahimi AM, Gonzalez-Julian J, Sofer Z, Pykal M, Otyepka M, Pumera M. Interaction of single- and double-stranded DNA with multilayer MXene by fluorescence spectroscopy and molecular dynamics simulations. Chem Sci 2019; 10:10010-10017. [PMID: 32055358 PMCID: PMC6979399 DOI: 10.1039/c9sc03049b] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 09/09/2019] [Indexed: 12/14/2022] Open
Abstract
The integration of nucleic acids with nanomaterials has attracted great attention from various research communities in search of new nanoscale tools for a range of applications, from electronics to biomedical uses. MXenes are a new class of multielement 2D materials baring exciting properties mostly directed to energy-related fields. These advanced materials are now beginning to enter the biomedical field given their biocompatibility, hydrophilicity and near-infrared absorption. Herein, we elucidate the interaction of MXene Ti3C2T x with fluorophore-tagged DNA by fluorescence measurements and molecular dynamics simulations. The system showed potential for biosensing with unequivocal detection at picomole levels and single-base discrimination. We found that this material possesses a kinetically unique entrapment/release behavior, with potential implications in time-controlled biomolecule delivery. Our findings present MXenes as platforms for binding nucleic acids, contributing to their potential for hybridization-based biosensing and related bio-applications.
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Affiliation(s)
- C Lorena Manzanares-Palenzuela
- Center for Advanced Functional Nanorobots , Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technická 5 , Prague 6 , 166 28 , Czech Republic .
| | - Amir M Pourrahimi
- Center for Advanced Functional Nanorobots , Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technická 5 , Prague 6 , 166 28 , Czech Republic .
| | - J Gonzalez-Julian
- Forschungszentrum Jülich GmbH , Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1) , 52425 Jülich , Germany
| | - Zdenek Sofer
- Center for Advanced Functional Nanorobots , Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technická 5 , Prague 6 , 166 28 , Czech Republic .
| | - Martin Pykal
- Regional Centre for Advanced Technologies and Materials , Palacký University Olomouc , Šlechtitelů 27 , Olomouc , 771 46 , Czech Republic
| | - Michal Otyepka
- Regional Centre for Advanced Technologies and Materials , Palacký University Olomouc , Šlechtitelů 27 , Olomouc , 771 46 , Czech Republic
| | - Martin Pumera
- Center for Advanced Functional Nanorobots , Department of Inorganic Chemistry , University of Chemistry and Technology Prague , Technická 5 , Prague 6 , 166 28 , Czech Republic .
- Future Energy and Innovation Laboratory , Central European Institute of Technology , Brno University of Technology , Purkyňova 656/123 , Brno , CZ-616 00 , Czech Republic
- Department of Chemical and Biomolecular Engineering , Yonsei University , 50 Yonsei-ro, Seodaemun-gu , Seoul 03722 , Korea
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24
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Sandoval JE, Reich NO. The R882H substitution in the human de novo DNA methyltransferase DNMT3A disrupts allosteric regulation by the tumor supressor p53. J Biol Chem 2019; 294:18207-18219. [PMID: 31640986 DOI: 10.1074/jbc.ra119.010827] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
A myriad of protein partners modulate the activity of the human DNA methyltransferase 3A (DNMT3A), whose interactions with these other proteins are frequently altered during oncogenesis. We show here that the tumor suppressor p53 decreases DNMT3A activity by forming a heterotetramer complex with DNMT3A. Mutational and modeling experiments suggested that p53 interacts with the same region in DNMT3A as does the structurally characterized DNMT3L. We observed that the p53-mediated repression of DNMT3A activity is blocked by amino acid substitutions within this interface, but surprisingly, also by a distal DNMT3A residue, R882H. DNMT3A R882H occurs frequently in various cancers, including acute myeloid leukemia, and our results suggest that the effects of R882H and other DNMT3A mutations may go beyond changes in DNMT3A methylation activity. To further understand the dynamics of how protein-protein interactions modulate DNMT3A activity, we determined that p53 has a greater affinity for DNMT3A than for DNMT3L and that p53 readily displaces DNMT3L from the DNMT3A:DNMT3L heterotetramer. Interestingly, this occurred even when the preformed DNMT3A:DNMT3L complex was actively methylating DNA. The frequently identified p53 substitutions (R248W and R273H), whereas able to regulate DNMT3A function when forming the DNMT3A:p53 heterotetramer, no longer displaced DNMT3L from the DNMT3A:DNMT3L heterotetramer. The results of our work highlight the complex interplay between DNMT3A, p53, and DNMT3L and how these interactions are further modulated by clinically derived mutations in each of the interacting partners.
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Affiliation(s)
- Jonathan E Sandoval
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-9510
| | - Norbert O Reich
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510.
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25
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Song Y, Niederschulte J, Bales KN, Park AH, Bashkin JK, Dupureur CM. DNA binding thermodynamics and site stoichiometry as a function of polyamide size. Biochimie 2019; 165:170-178. [DOI: 10.1016/j.biochi.2019.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 07/29/2019] [Indexed: 12/19/2022]
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26
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Tiwari A, Kuldeep J, Siddiqi MI, Habib S. Plasmodium falciparumApn1 homolog is a mitochondrial base excision repair protein with restricted enzymatic functions. FEBS J 2019; 287:589-606. [DOI: 10.1111/febs.15032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/18/2019] [Accepted: 08/02/2019] [Indexed: 01/14/2023]
Affiliation(s)
- Anupama Tiwari
- Division of Molecular and Structural Biology CSIR‐Central Drug Research Institute Lucknow India
| | - Jitendra Kuldeep
- Division of Molecular and Structural Biology CSIR‐Central Drug Research Institute Lucknow India
| | - Mohammad Imran Siddiqi
- Division of Molecular and Structural Biology CSIR‐Central Drug Research Institute Lucknow India
| | - Saman Habib
- Division of Molecular and Structural Biology CSIR‐Central Drug Research Institute Lucknow India
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27
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Lopez A, Liu J. Fluorescence Polarization for Probing DNA Adsorption by Nanomaterials and Fluorophore/DNA Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9954-9961. [PMID: 31271290 DOI: 10.1021/acs.langmuir.9b01678] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Fluorescence polarization (FP) is attractive for measuring binding interactions and has been recently used to study DNA adsorption on nanomaterials. Since most nanomaterials are strong fluorescence quenchers, correlations among adsorption efficiency, quenching efficiency, and FP need to be interpreted carefully. In this work, carboxyfluorescein (FAM)-labeled DNA oligonucleotides were studied under various quenching conditions. First, quenching was induced by lowering the pH, taking advantage of the fact that FAM is almost nonfluorescent at a pH below 4. Strong interactions were observed between the FAM label and polyadenine DNA, as judged by the increased FP at low pH, while FAM-labeled polythymine DNA was less affected by the pH. Comparisons were also performed with FAM-labeled poly(ethylene glycol) and bovine serum albumin. An equation was derived to calculate the effect of fluorescence quenching and DNA adsorption by nanomaterials. For strongly quenching nanomaterials, such as graphene oxide, DNA adsorption alone does not change the measured FP. Light scattering and weak fluorescence from graphene oxide increase FP in these cases. For comparison, a strongly adsorbing but weak quenching material, Y2O3, was also studied and the result was consistent with a normal binding reaction. Overall, FP is a powerful technique for binding and adsorption assays, but quenched samples need to be interpreted with care.
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Affiliation(s)
- Anand Lopez
- Department of Chemistry, Waterloo Institute for Nanotechnology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
| | - Juewen Liu
- Department of Chemistry, Waterloo Institute for Nanotechnology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada
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28
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Castro NS, Moura I, Carepo MS, Laia CA. Fluorescence anisotropy of fluorescein derivative varies according to pH: Lessons for binding studies. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2018.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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29
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Song Y, Niederschulte J, Bales KN, Bashkin JK, Dupureur CM. Thermodynamics and site stoichiometry of DNA binding by a large antiviral hairpin polyamide. Biochimie 2019; 157:149-157. [PMID: 30481539 DOI: 10.1016/j.biochi.2018.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/22/2018] [Indexed: 12/16/2022]
Abstract
PA1 (dIm-PyPyβPyPyPy-γ-PyPyβPyPyPyPyβ-Ta) is a large (14-ring) hairpin polyamide that was designed to recognize the DNA sequence 5'-W2GW7-3', where W is either A or T. As is common among the smaller 6-8-ring hairpin polyamides (PAs), it binds its target recognition sequence with low nM affinity. However, in addition to its large size, it is distinct from these more extensively characterized PAs in its high tolerance for mismatches and antiviral properties. In ongoing attempts to understand the basis for these distinctions, we conducted thermodynamics studies of PA1-DNA interactions. The temperature dependence of binding affinity was measured using TAMRA-labeled hairpin DNAs containing a single target sequence. PA1 binding to either an ATAT/TATA or an AAAA/TTTT pattern is consistently entropically driven. This is in contrast to the A/T pattern-dependent driving forces for DNA binding by netropsin, distamycin, and smaller hairpin polyamides. Analysis of the salt dependence of PA1-DNA binding reveals that within experimental error, there is no dependence on ionic strength, indicating that the polyelectrolyte effect does not contribute to PA1-DNA binding energetics. This is similar to that observed for smaller PAs. PA1-DNA recognition sequence binding stoichiometries were determined at both nM (fluorescence) and μM (circular dichroism) concentrations. With all sequences and under both conditions, multiple PA1 molecules bind the small DNA hairpin that contains only a single recognition sequence. Implications for these observations are discussed.
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Affiliation(s)
- Yang Song
- Department of Chemistry & Biochemistry, University of Missouri St. Louis, St. Louis, MO, 63121, USA
| | - Jacquelyn Niederschulte
- Department of Chemistry & Biochemistry, University of Missouri St. Louis, St. Louis, MO, 63121, USA
| | - Kristin N Bales
- Department of Chemistry & Biochemistry, University of Missouri St. Louis, St. Louis, MO, 63121, USA
| | - James K Bashkin
- Department of Chemistry & Biochemistry, University of Missouri St. Louis, St. Louis, MO, 63121, USA
| | - Cynthia M Dupureur
- Department of Chemistry & Biochemistry, University of Missouri St. Louis, St. Louis, MO, 63121, USA.
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30
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Kamba PF, Dickson DA, White NA, Ekstrom JL, Koslowsky DJ, Hoogstraten CG. The 27 kDa Trypanosoma brucei Pentatricopeptide Repeat Protein is a G-tract Specific RNA Binding Protein. Sci Rep 2018; 8:16989. [PMID: 30451852 PMCID: PMC6242908 DOI: 10.1038/s41598-018-34377-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/15/2018] [Indexed: 01/30/2023] Open
Abstract
Pentatricopeptide repeat (PPR) proteins, a helical repeat family of organellar RNA binding proteins, play essential roles in post-transcriptional RNA processing. In Trypanosoma brucei, an expanded family of PPR proteins localize to the parasite’s single mitochondrion, where they are believed to perform important roles in both RNA processing and translation. We studied the RNA binding specificity of the simplest T. brucei PPR protein (KRIPP11) using electrophoretic mobility shift assays, fluorescence anisotropy, circular dichroism spectroscopy, and in vitro selection. We found KRIPP11 to be an RNA binding protein with specificity for sequences of four or more consecutive guanosine residues (G-tracts). Such G-tracts are dramatically enriched in T. brucei mitochondrial transcripts that are destined for extensive uridine insertion/deletion editing but are not present in mRNAs following editing. We further found that the quadruplex oligoguanosine RNA conformation is preferentially recognized by KRIPP11 over other conformational forms, and is bound without disruption of the quadruplex structure. In combination with prior data demonstrating association of KRIPP11 with the small ribosomal subunit, these results suggest possible roles for KRIPP11 in bridging mRNA maturation and translation or in facilitating translation of unusual dual-coded open reading frames.
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Affiliation(s)
- Pakoyo F Kamba
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Graduate Program in Cell and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Makerere University, Kampala, Uganda
| | - David A Dickson
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Sackler School of Graduate Biomedical Sciences, Tufts University, Medford, Massachusetts, USA
| | - Neil A White
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Jennifer L Ekstrom
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan, USA
| | - Donna J Koslowsky
- Graduate Program in Cell and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48824-1319, USA
| | - Charles G Hoogstraten
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.
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31
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Lahiri S, Li Y, Hingorani MM, Mukerji I. MutSγ-Induced DNA Conformational Changes Provide Insights into Its Role in Meiotic Recombination. Biophys J 2018; 115:2087-2101. [PMID: 30467025 DOI: 10.1016/j.bpj.2018.10.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/16/2018] [Accepted: 10/22/2018] [Indexed: 01/11/2023] Open
Abstract
In many organisms, MutSγ plays a role in meiotic recombination, facilitating crossover formation between homologous chromosomes. Failure to form crossovers leads to improper segregation of chromosomes and aneuploidy, which in humans result in infertility and birth defects. To improve current understanding of MutSγ function, this study investigates the binding affinities and structures of MutSγ in complex with DNA substrates that model homologous recombination intermediates. For these studies, we overexpressed and isolated from Escherichia coli the yeast MutSγ protein Saccharomyces cerevisiae (Sc) Msh4-Msh5. Sc Msh4-Msh5 binds Holliday junction (HJ)-like substrates, 3' overhangs, single-stranded (ss) forks, and the displacement loop with nanomolar affinity. The weakest binding affinities are detected for an intact duplex and open-junction construct. Similar to the human protein, Sc Msh4-Msh5 exhibits the highest affinity for the HJ with a Kd < 0.4 nM in solution. Energy-transfer experiments further demonstrate that DNA structure is modulated by the binding interaction with the largest changes associated with substrates containing an ss end. Upon binding, Sc Msh4-Msh5 displaces the ss away from the duplex in most of the ss-containing intermediates, potentially enabling the binding of RPA and other proteins. In the case of the junction-like intermediates, Msh4-Msh5 binding either stabilizes the existing stacked structure or induces formation of the stacked X conformation. Significantly, we find that upon binding, Msh4-Msh5 stacks an open-junction construct to the same extent as the standard junction. Stabilization of the junction in the stacked conformation is generally refractory to branch migration, which is consistent with a potential role for MutSγ to stabilize HJs and prevent branch migration until resolution by MutLγ. The different binding modalities observed suggest that Msh4-Msh5 not only binds to and stabilizes stacked junctions but also participates in meiotic recombination before junction formation through the stabilization of single-end invasion intermediates.
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Affiliation(s)
- Sudipta Lahiri
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Yan Li
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Manju M Hingorani
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Ishita Mukerji
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut.
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32
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Taylor EL, Kesavan PM, Wolfe AE, O'Brien PJ. Distinguishing Specific and Nonspecific Complexes of Alkyladenine DNA Glycosylase. Biochemistry 2018; 57:4440-4454. [PMID: 29940097 DOI: 10.1021/acs.biochem.8b00531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Human alkyladenine DNA glycosylase (AAG) recognizes many alkylated and deaminated purine lesions and excises them to initiate the base excision DNA repair pathway. AAG employs facilitated diffusion to rapidly scan nonspecific sites and locate rare sites of damage. Nonspecific DNA binding interactions are critical to the efficiency of this search for damage, but little is known about the binding footprint or the affinity of AAG for nonspecific sites. We used biochemical and biophysical approaches to characterize the binding of AAG to both undamaged and damaged DNA. Although fluorescence anisotropy is routinely used to study DNA binding, we found unexpected complexities in the data for binding of AAG to DNA. Systematic comparison of different fluorescent labels and different lengths of DNA allowed binding models to be distinguished and demonstrated that AAG can bind with high affinity and high density to nonspecific DNA. Fluorescein-labeled DNA gave the most complex behavior but also showed the greatest potential to distinguish specific and nonspecific binding modes. We suggest a unified model that is expected to apply to many DNA binding proteins that exhibit affinity for nonspecific DNA. Although AAG strongly prefers to excise lesions from duplex DNA, nonspecific binding is comparable for single- and double-stranded nonspecific sites. The electrostatically driven binding of AAG to small DNA sites (∼5 nucleotides of single-stranded and ∼6 base pairs of duplex) facilitates the search for DNA damage in chromosomal DNA, which is bound by nucleosomes and other proteins.
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Affiliation(s)
- Erin L Taylor
- Department of Biological Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Preethi M Kesavan
- Department of Biological Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Abigail E Wolfe
- Department of Biological Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Patrick J O'Brien
- Department of Biological Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
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33
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Makowski MM, Gräwe C, Foster BM, Nguyen NV, Bartke T, Vermeulen M. Global profiling of protein-DNA and protein-nucleosome binding affinities using quantitative mass spectrometry. Nat Commun 2018; 9:1653. [PMID: 29695722 PMCID: PMC5916898 DOI: 10.1038/s41467-018-04084-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 04/03/2018] [Indexed: 01/02/2023] Open
Abstract
Interaction proteomics studies have provided fundamental insights into multimeric biomolecular assemblies and cell-scale molecular networks. Significant recent developments in mass spectrometry-based interaction proteomics have been fueled by rapid advances in label-free, isotopic, and isobaric quantitation workflows. Here, we report a quantitative protein–DNA and protein–nucleosome binding assay that uses affinity purifications from nuclear extracts coupled with isobaric chemical labeling and mass spectrometry to quantify apparent binding affinities proteome-wide. We use this assay with a variety of DNA and nucleosome baits to quantify apparent binding affinities of monomeric and multimeric transcription factors and chromatin remodeling complexes. Quantitative mass spectrometry enables the proteome-wide assessment of biomolecular binding affinities. While previous approaches mainly focused on protein–small molecule interactions, the authors here present a method to probe protein–DNA and protein–nucleosome binding affinities at proteome scale.
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Affiliation(s)
- Matthew M Makowski
- Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, 6500 HB, The Netherlands.,Oncode Institute, Radboud University, Nijmegen, 6500 HB, The Netherlands
| | - Cathrin Gräwe
- Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, 6500 HB, The Netherlands.,Oncode Institute, Radboud University, Nijmegen, 6500 HB, The Netherlands
| | - Benjamin M Foster
- Institute of Functional Epigenetics, Helmholtz Zentrum München, 85764, Neuherberg, Germany.,MRC London Institute of Medical Sciences (LMS), London, W12 0NN, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Nhuong V Nguyen
- MRC London Institute of Medical Sciences (LMS), London, W12 0NN, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Till Bartke
- Institute of Functional Epigenetics, Helmholtz Zentrum München, 85764, Neuherberg, Germany. .,MRC London Institute of Medical Sciences (LMS), London, W12 0NN, UK. .,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, W12 0NN, UK.
| | - Michiel Vermeulen
- Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, 6500 HB, The Netherlands. .,Oncode Institute, Radboud University, Nijmegen, 6500 HB, The Netherlands.
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34
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Pokhrel N, Origanti S, Davenport EP, Gandhi D, Kaniecki K, Mehl RA, Greene EC, Dockendorff C, Antony E. Monitoring Replication Protein A (RPA) dynamics in homologous recombination through site-specific incorporation of non-canonical amino acids. Nucleic Acids Res 2017; 45:9413-9426. [PMID: 28934470 PMCID: PMC5766198 DOI: 10.1093/nar/gkx598] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/09/2017] [Indexed: 12/23/2022] Open
Abstract
An essential coordinator of all DNA metabolic processes is Replication Protein A (RPA). RPA orchestrates these processes by binding to single-stranded DNA (ssDNA) and interacting with several other DNA binding proteins. Determining the real-time kinetics of single players such as RPA in the presence of multiple DNA processors to better understand the associated mechanistic events is technically challenging. To overcome this hurdle, we utilized non-canonical amino acids and bio-orthogonal chemistry to site-specifically incorporate a chemical fluorophore onto a single subunit of heterotrimeric RPA. Upon binding to ssDNA, this fluorescent RPA (RPAf) generates a quantifiable change in fluorescence, thus serving as a reporter of its dynamics on DNA in the presence of multiple other DNA binding proteins. Using RPAf, we describe the kinetics of facilitated self-exchange and exchange by Rad51 and mediator proteins during various stages in homologous recombination. RPAf is widely applicable to investigate its mechanism of action in processes such as DNA replication, repair and telomere maintenance.
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Affiliation(s)
- Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | - Sofia Origanti
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | | | - Disha Gandhi
- Department of Chemistry, Marquette University, Milwaukee, WI 53201, USA
| | - Kyle Kaniecki
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Chris Dockendorff
- Department of Chemistry, Marquette University, Milwaukee, WI 53201, USA
| | - Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
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35
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Havali-Shahriari Z, Weinfeld M, Glover JNM. Characterization of DNA Substrate Binding to the Phosphatase Domain of the DNA Repair Enzyme Polynucleotide Kinase/Phosphatase. Biochemistry 2017; 56:1737-1745. [PMID: 28276686 DOI: 10.1021/acs.biochem.6b01236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Polynucleotide kinase/phosphatase (PNKP) is a DNA strand break repair enzyme that uses separate 5' kinase and 3' phosphatase active sites to convert damaged 5'-hydroxyl/3'-phosphate strand termini to ligatable 5'-phosphate/3'-hydroxyl ends. The phosphatase active site has received particular attention as a target of inhibition in cancer therapy development. The phosphatase domain dephosphorylates a range of single- and double-stranded substrates; however, structural studies have shown that the phosphatase catalytic cleft can bind only single-stranded substrates. Here we use a catalytically inactive but structurally intact phosphatase mutant to probe interactions between PNKP and a variety of single- and double-stranded DNA substrates using an electrophoretic mobility shift assay. This work indicates that the phosphatase domain binds 3'-phosphorylated single-stranded DNAs in a manner that is highly dependent on the presence of the 3'-phosphate. Double-stranded substrate binding, in contrast, is not as dependent on the 3'-phosphate. Experiments comparing blunt-end, 3'-overhanging, and frayed-end substrates indicate that the predicted loss of energy due to base pair disruption upon binding of the phosphatase active site is likely balanced by favorable interactions between the liberated complementary strand and PNKP. Comparison of the effects on substrate binding of mutations within the phosphatase active site cleft with mutations in surrounding positively charged surfaces suggests that the surrounding surfaces are important for binding to double-stranded substrates. We further show that while fluorescence polarization methods can detect specific binding of single-stranded DNAs with the phosphatase domain, this method does not detect specific interactions between the PNKP phosphatase and double-stranded substrates.
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Affiliation(s)
| | - Michael Weinfeld
- Department of Oncology, University of Alberta, Cross Cancer Institute , 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - J N Mark Glover
- Department of Biochemistry, University of Alberta , Edmonton, Alberta T6G 2H7, Canada
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36
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DNA-conjugated gold nanoparticles based colorimetric assay to assess helicase activity: a novel route to screen potential helicase inhibitors. Sci Rep 2017; 7:44358. [PMID: 28287182 PMCID: PMC5347027 DOI: 10.1038/srep44358] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 02/08/2017] [Indexed: 12/28/2022] Open
Abstract
Helicase are essential enzymes which are widespread in all life-forms. Due to their central role in nucleic acid metabolism, they are emerging as important targets for anti-viral, antibacterial and anti-cancer drugs. The development of easy, cheap, fast and robust biochemical assays to measure helicase activity, overcoming the limitations of the current methods, is a pre-requisite for the discovery of helicase inhibitors through high-throughput screenings. We have developed a method which exploits the optical properties of DNA-conjugated gold nanoparticles (AuNP) and meets the required criteria. The method was tested with the catalytic domain of the human RecQ4 helicase and compared with a conventional FRET-based assay. The AuNP-based assay produced similar results but is simpler, more robust and cheaper than FRET. Therefore, our nanotechnology-based platform shows the potential to provide a useful alternative to the existing conventional methods for following helicase activity and to screen small-molecule libraries as potential helicase inhibitors.
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Baldock BL, Hutchison JE. UV–Visible Spectroscopy-Based Quantification of Unlabeled DNA Bound to Gold Nanoparticles. Anal Chem 2016; 88:12072-12080. [DOI: 10.1021/acs.analchem.6b02640] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Brandi L. Baldock
- Department of Chemistry and
Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403-1253, United States
| | - James E. Hutchison
- Department of Chemistry and
Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403-1253, United States
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Sanchez JL, Romero Z, Quinones A, Torgeson KR, Horton NC. DNA Binding and Cleavage by the Human Parvovirus B19 NS1 Nuclease Domain. Biochemistry 2016; 55:6577-6593. [PMID: 27809499 DOI: 10.1021/acs.biochem.6b00534] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Infection with human parvovirus B19 (B19V) has been associated with a myriad of illnesses, including erythema infectiosum (Fifth disease), hydrops fetalis, arthropathy, hepatitis, and cardiomyopathy, and also possibly the triggering of any number of different autoimmune diseases. B19V NS1 is a multidomain protein that plays a critical role in viral replication, with predicted nuclease, helicase, and gene transactivation activities. Herein, we investigate the biochemical activities of the nuclease domain (residues 2-176) of B19V NS1 (NS1-nuc) in sequence-specific DNA binding of the viral origin of replication sequences, as well as those of promoter sequences, including the viral p6 and the human p21, TNFα, and IL-6 promoters previously identified in NS1-dependent transcriptional transactivation. NS1-nuc was found to bind with high cooperativity and with multiple (five to seven) copies to the NS1 binding elements (NSBE) found in the viral origin of replication and the overlapping viral p6 promoter DNA sequence. NS1-nuc was also found to bind cooperatively with at least three copies to the GC-rich Sp1 binding sites of the human p21 gene promoter. Only weak or nonspecific binding of NS1-nuc to the segments of the TNFα and IL-6 promoters was found. Cleavage of DNA by NS1-nuc occurred at the expected viral sequence (the terminal resolution site), but only in single-stranded DNA, and NS1-nuc was found to covalently attach to the 5' end of the DNA at the cleavage site. Off-target cleavage by NS1-nuc was also identified.
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Affiliation(s)
- Jonathan L Sanchez
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Zachary Romero
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States.,Undergraduate Research Opportunities Consortium-Minorities Health Disparity Program (UROC-MHD), University of Arizona Graduate College, University of Arizona , Tucson, Arizona 85721, United States
| | - Angelica Quinones
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States.,Undergraduate Research Opportunities Consortium-Minorities Health Disparity Program (UROC-MHD), University of Arizona Graduate College, University of Arizona , Tucson, Arizona 85721, United States.,BUILDing SCHOLARS Program, University of Texas at El Paso , El Paso, Texas 79968, United States
| | - Kristiane R Torgeson
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
| | - Nancy C Horton
- Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States
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Valenzuela RAP, Onizuka K, Ball-Jones AA, Hu T, Suter SR, Beal PA. Guide Strand 3'-End Modifications Regulate siRNA Specificity. Chembiochem 2016; 17:2340-2345. [PMID: 27731539 DOI: 10.1002/cbic.201600453] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Indexed: 02/05/2023]
Abstract
Short interfering RNA (siRNA)-triggered gene knockdown through the RNA interference (RNAi) pathway is widely used to study gene function, and siRNA-based therapeutics are in development. However, as the guide strand of an siRNA can function like a natural microRNA (miRNA), siRNAs often repress hundreds of off-target transcripts with complementarity only to the seed region (nucleotides 2-8) of the guide strand. Here, we describe novel guide strand 3'-end modifications derived from 1-ethynylribose (1-ER) and copper-catalyzed azide-alkyne cycloaddition reactions and evaluate their impact on target versus miRNA-like off-target knockdown. Surprisingly, when positioned at the guide strand 3'-end, the parent 1-ER modification substantially reduced off-target knockdown while having no measurable effect on on-target knockdown potency. In addition, these modifications were shown to modulate siRNA affinity for the hAgo2 PAZ domain. However, the change in PAZ domain binding affinity was not sufficient to predict the modification's effect on miRNA-like off targeting.
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Affiliation(s)
- Rachel A P Valenzuela
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Kazumitsu Onizuka
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Alexi A Ball-Jones
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Tiannan Hu
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Scott R Suter
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
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Hall MD, Yasgar A, Peryea T, Braisted JC, Jadhav A, Simeonov A, Coussens NP. Fluorescence polarization assays in high-throughput screening and drug discovery: a review. Methods Appl Fluoresc 2016; 4:022001. [PMID: 28809163 DOI: 10.1088/2050-6120/4/2/022001] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The sensitivity of fluorescence polarization (FP) and fluorescence anisotropy (FA) to molecular weight changes has enabled the interrogation of diverse biological mechanisms, ranging from molecular interactions to enzymatic activity. Assays based on FP/FA technology have been widely utilized in high-throughput screening (HTS) and drug discovery due to the homogenous format, robust performance and relative insensitivity to some types of interferences, such as inner filter effects. Advancements in assay design, fluorescent probes, and technology have enabled the application of FP assays to increasingly complex biological processes. Herein we discuss different types of FP/FA assays developed for HTS, with examples to emphasize the diversity of applicable targets. Furthermore, trends in target and fluorophore selection, as well as assay type and format, are examined using annotated HTS assays within the PubChem database. Finally, practical considerations for the successful development and implementation of FP/FA assays for HTS are provided based on experience at our center and examples from the literature, including strategies for flagging interference compounds among a list of hits.
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Affiliation(s)
- Matthew D Hall
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
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41
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Cooperative autoinhibition and multi-level activation mechanisms of calcineurin. Cell Res 2016; 26:336-49. [PMID: 26794871 DOI: 10.1038/cr.2016.14] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 10/12/2015] [Accepted: 11/27/2015] [Indexed: 11/08/2022] Open
Abstract
The Ca(2+)/calmodulin-dependent protein phosphatase calcineurin (CN), a heterodimer composed of a catalytic subunit A and an essential regulatory subunit B, plays critical functions in various cellular processes such as cardiac hypertrophy and T cell activation. It is the target of the most widely used immunosuppressants for transplantation, tacrolimus (FK506) and cyclosporin A. However, the structure of a large part of the CNA regulatory region remains to be determined, and there has been considerable debate concerning the regulation of CN activity. Here, we report the crystal structure of full-length CN (β isoform), which revealed a novel autoinhibitory segment (AIS) in addition to the well-known autoinhibitory domain (AID). The AIS nestles in a hydrophobic intersubunit groove, which overlaps the recognition site for substrates and immunosuppressant-immunophilin complexes. Indeed, disruption of this AIS interaction results in partial stimulation of CN activity. More importantly, our biochemical studies demonstrate that calmodulin does not remove AID from the active site, but only regulates the orientation of AID with respect to the catalytic core, causing incomplete activation of CN. Our findings challenge the current model for CN activation, and provide a better understanding of molecular mechanisms of CN activity regulation.
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Zhang H, Wu Q, Berezin MY. Fluorescence anisotropy (polarization): from drug screening to precision medicine. Expert Opin Drug Discov 2015; 10:1145-61. [PMID: 26289575 DOI: 10.1517/17460441.2015.1075001] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Fluorescence anisotropy (FA) is one of the major established methods accepted by industry and regulatory agencies for understanding the mechanisms of drug action and selecting drug candidates utilizing a high-throughput format. AREAS COVERED This review covers the basics of FA and complementary methods, such as fluorescence lifetime anisotropy and their roles in the drug discovery process. The authors highlight the factors affecting FA readouts, fluorophore selection and instrumentation. Furthermore, the authors describe the recent development of a successful, commercially valuable FA assay for long QT syndrome drug toxicity to illustrate the role that FA can play in the early stages of drug discovery. EXPERT OPINION Despite the success in drug discovery, the FA-based technique experiences competitive pressure from other homogeneous assays. That being said, FA is an established yet rapidly developing technique, recognized by academic institutions, the pharmaceutical industry and regulatory agencies across the globe. The technical problems encountered in working with small molecules in homogeneous assays are largely solved, and new challenges come from more complex biological molecules and nanoparticles. With that, FA will remain one of the major work-horse techniques leading to precision (personalized) medicine.
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Affiliation(s)
- Hairong Zhang
- a 1 Washington University School of Medicine, Department of Radiology , St. Louis 63110, USA
| | - Qian Wu
- a 1 Washington University School of Medicine, Department of Radiology , St. Louis 63110, USA
| | - Mikhail Y Berezin
- a 1 Washington University School of Medicine, Department of Radiology , St. Louis 63110, USA.,b 2 Washington University School of Medicine, Institute of Materials Science and Engineering, Department of Radiology , 510 S. Kingshighway, Barnard Bldg, 6th floor, 6604A, St. Louis, MO, USA +1 314 747 0701 ; +1 314 747 5191 ;
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Taylor JA, Pastrana CL, Butterer A, Pernstich C, Gwynn EJ, Sobott F, Moreno-Herrero F, Dillingham MS. Specific and non-specific interactions of ParB with DNA: implications for chromosome segregation. Nucleic Acids Res 2015; 43:719-31. [PMID: 25572315 PMCID: PMC4333373 DOI: 10.1093/nar/gku1295] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The segregation of many bacterial chromosomes is dependent on the interactions of ParB proteins with centromere-like DNA sequences called parS that are located close to the origin of replication. In this work, we have investigated the binding of Bacillus subtilis ParB to DNA in vitro using a variety of biochemical and biophysical techniques. We observe tight and specific binding of a ParB homodimer to the parS sequence. Binding of ParB to non-specific DNA is more complex and displays apparent positive co-operativity that is associated with the formation of larger, poorly defined, nucleoprotein complexes. Experiments with magnetic tweezers demonstrate that non-specific binding leads to DNA condensation that is reversible by protein unbinding or force. The condensed DNA structure is not well ordered and we infer that it is formed by many looping interactions between neighbouring DNA segments. Consistent with this view, ParB is also able to stabilize writhe in single supercoiled DNA molecules and to bridge segments from two different DNA molecules in trans. The experiments provide no evidence for the promotion of non-specific DNA binding and/or condensation events by the presence of parS sequences. The implications of these observations for chromosome segregation are discussed.
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Affiliation(s)
- James A Taylor
- DNA:Protein Interactions Unit, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Cesar L Pastrana
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Annika Butterer
- Biomolecular & Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Christian Pernstich
- DNA:Protein Interactions Unit, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Emma J Gwynn
- DNA:Protein Interactions Unit, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Frank Sobott
- Biomolecular & Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium Center for Proteomics (CFP-CeProMa), University of Antwerp, 2020 Antwerpen, Belgium
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain
| | - Mark S Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
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FRET-based analysis of protein-nucleic acid interactions by genetically incorporating a fluorescent amino acid. Amino Acids 2014; 47:729-34. [PMID: 25540052 DOI: 10.1007/s00726-014-1900-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
Abstract
Protein-nucleic acid interaction is an important process in many biological phenomena. In this study, a fluorescence resonance energy transfer (FRET)-based protein-DNA binding assay has been developed, in which a fluorescent amino acid is genetically incorporated into a DNA-binding protein. A coumarin-containing amino acid was incorporated into a DNA-binding protein, and the mutant protein specifically produced a FRET signal upon binding to its cognate DNA labeled with a fluorophore. The protein-DNA binding affinity was then measured under equilibrium conditions. This method is advantageous for studying protein-nucleic acid interactions, because it is performed under equilibrium conditions, technically easy, and applicable to any nucleic acid-binding protein.
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Babcock JJ, Brancaleon L. The effect of local dynamics of Atto 390-labeled lysozyme on fluorescence anisotropy modeling. Biopolymers 2014; 103:285-95. [PMID: 25431279 DOI: 10.1002/bip.22596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/14/2014] [Accepted: 11/18/2014] [Indexed: 11/07/2022]
Abstract
Fluorescence anisotropy decay is a popular optical technique to study the structure, size, shape, and even functions of biomolecules. The method measures the time dependence of the depolarization of a fluorophore and is therefore sensitive to the changes in the rotational motion (e.g., aggregation and binding) or changes in the mobility of segments of biopolymers (such as the ones associated with tertiary structure changes). Fluorescence anisotropy decay often requires the use of fluorescent dyes that need to be covalently attached to the biomolecule. The location of the attachment on the biomolecule (e.g., a protein) and the linker used, affect the mobility of the dye and its anisotropy decay. With this study we have combined the experimental data with molecular dynamic simulations to offer a more correct interpretation of the fluorescence anisotropy decay of a popular fluorescent dye (Atto 390) attached to the N-terminus of Hen Egg White Lysozyme (HEWL). Our model showed how the use of relatively simple molecular dynamics computation to simulate the motion of the dye, provide a model to interpret the experimental fluorescence anisotropy decay that yields a better estimate of the hydrodynamic radius of HEWL. The improvement is provided by a more detailed description of the segmental motion of the dye attached to the protein.
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Affiliation(s)
- Jeremiah J Babcock
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78242
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46
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Xu J, Yoshimura K, Mon H, Li Z, Zhu L, Iiyama K, Kusakabe T, Lee JM. Establishment of Caenorhabditis elegans SID-1-dependent DNA delivery system in cultured silkworm cells. Mol Biotechnol 2014; 56:193-8. [PMID: 23979877 DOI: 10.1007/s12033-013-9694-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The systemic RNA interference defective-1 (SID-1) can transport double-stranded RNA (dsRNA) into cytosol across the cytoplasmic membrane. We report here that ectopic expression of Caenorhabditis elegans SID-1 allows BmN4 cells to import extracellular plasmid dsDNA into cells via the direct soaking method. Interestingly, BmN4-SID1 cells incorporate dsRNA and plasmid DNA simultaneously. Furthermore, the ectopic SID-1 allows us to establish a stably transformed cell line by the simple soaking method. Our results provide an alternative method for silkworm gene function analysis with low cost and low cell toxicity.
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Affiliation(s)
- Jian Xu
- Laboratory of Silkworm Science, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, 6-10-1 Hakozaki Higashi-ku, Fukuoka, 812-8581, Japan
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47
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Schauer GD, Huber KD, Leuba SH, Sluis-Cremer N. Mechanism of allosteric inhibition of HIV-1 reverse transcriptase revealed by single-molecule and ensemble fluorescence. Nucleic Acids Res 2014; 42:11687-96. [PMID: 25232099 PMCID: PMC4191400 DOI: 10.1093/nar/gku819] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are routinely used to treat HIV-1 infection, yet their mechanism of action remains unclear despite intensive investigation. In this study, we developed complementary single-molecule fluorescence and ensemble fluorescence anisotropy approaches to discover how NNRTIs modulate the intra-molecular conformational changes and inter-molecular dynamics of RT-template/primer (T/P) and RT–T/P–dNTP complexes. We found that NNRTI binding to RT induces opening of the fingers and thumb subdomains, which increases the dynamic sliding motion of the enzyme on the T/P and reduces dNTP binding affinity. Further, efavirenz promotes formation of the E138-K101 salt bridge between the p51 and p66 subunits of RT, which contributes to opening of the thumb/fingers subdomains. Engineering a more polar salt bridge between p51 and p66 resulted in even greater increases in the thumb/fingers opening, RT sliding, dNTP binding disruption and in vitro and in vivo RT inhibition than were observed with wild-type RT. We also observed that K103N, a clinically relevant NNRTI resistance mutation, does not prevent binding between efavirenz and RT-T/P but instead allows formation of a stable and productive RT–T/P–dNTP complex, possibly through disruption of the E138-K101 salt bridge. Collectively, these data describe unique structure–activity–resistance relationships that could be exploited for drug development.
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Affiliation(s)
- Grant D Schauer
- Program in Molecular Biophysics and Structural Biology, University of Pittsburgh School of Medicine, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA Department of Cell Biology, University of Pittsburgh School of Medicine, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
| | - Kelly D Huber
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA
| | - Sanford H Leuba
- Program in Molecular Biophysics and Structural Biology, University of Pittsburgh School of Medicine, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA Department of Cell Biology, University of Pittsburgh School of Medicine, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
| | - Nicolas Sluis-Cremer
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA
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Real-time fluorescence assays to monitor duplex unwinding and ATPase activities of helicases. Nat Protoc 2014; 9:1645-61. [PMID: 24945382 DOI: 10.1038/nprot.2014.112] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Many physiological functions of helicases are dependent on their ability to unwind nucleic acid duplexes in an ATP-dependent fashion. Determining the kinetic frameworks of these processes is crucial to understanding how these proteins function. We recently developed a fluorescence assay to monitor RNA duplex unwinding by DEAD-box helicases in real time. In this assay, two fluorescently modified short reporter oligonucleotides are annealed to an unmodified RNA loading strand of any length so that the fluorescent moieties of the two reporters find themselves in close proximity to each other and fluorescence is quenched. One reporter is modified with cyanine 3 (Cy3), whereas the other is modified with a spectrally paired black-hole quencher (BHQ). As the helicase unwinds the loading strand, the enzyme displaces the Cy3-modified reporter, which will bind to a capture or competitor DNA strand, permanently separating it from the BHQ-modified reporter. Complete separation of the Cy3-modified reporter strand is thus detected as an increase in total fluorescence. This assay is compatible with reagentless biosensors to monitor ATPase activity so that the coupling between ATP hydrolysis and duplex unwinding can be determined. With the protocol described, obtaining data and analyzing results of unwinding and ATPase assays takes ∼4 h.
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49
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Fluorescent methods to study transcription initiation and transition into elongation. EXPERIENTIA SUPPLEMENTUM (2012) 2014; 105:105-30. [PMID: 25095993 PMCID: PMC4430081 DOI: 10.1007/978-3-0348-0856-9_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The DNA-dependent RNA polymerases induce specific conformational changes in the promoter DNA during transcription initiation. Fluorescence spectroscopy sensitively monitors these DNA conformational changes in real time and at equilibrium providing powerful ways to estimate interactions in transcriptional complexes and to assess how transcription is regulated by the promoter DNA sequence, transcription factors, and small ligands. Ensemble fluorescence methods described here probe the individual steps of promoter binding, bending, opening, and transition into the elongation using T7 phage and mitochondrial transcriptional systems as examples.
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50
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Aung KMM, New SY, Hong S, Sutarlie L, Lim MGL, Tan SK, Cheung E, Su X. Studying forkhead box protein A1-DNA interaction and ligand inhibition using gold nanoparticles, electrophoretic mobility shift assay, and fluorescence anisotropy. Anal Biochem 2013; 448:95-104. [PMID: 24291642 DOI: 10.1016/j.ab.2013.11.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/11/2013] [Accepted: 11/17/2013] [Indexed: 10/26/2022]
Abstract
Forkhead box protein 1 (FoxA1) is a member of the forkhead family of winged helix transcription factors that plays pivotal roles in the development and differentiation of multiple organs and in the regulation of estrogen-stimulated genes. Conventional analytical methods-electrophoretic mobility shift assay (EMSA) and fluorescence anisotropy (FA)-as well as a gold nanoparticles (AuNPs)-based assay were used to study DNA binding properties of FoxA1 and ligand interruption of FoxA1-DNA binding. In the AuNPs assay, the distinct ability of protein-DNA complex to protect AuNPs against salt-induced aggregation was exploited to screen sequence selectivity and determine the binding affinity constant based on AuNPs color change and absorbance spectrum shift. Both conventional EMSA and FA and the AuNPs assay suggested that FoxA1 binds to DNA in a core sequence-dependent manner and the flanking sequence also played a role to influence the affinity. The EMSA and AuNPs were found to be more sensitive than FA in differentiation of sequence-dependent affinity. With the addition of a spin filtration step, AuNPs assay has been extended for studying small molecular ligand inhibition of FoxA1-DNA interactions enabling drug screening. The results correlate very well with those obtained using FA.
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Affiliation(s)
- Khin Moh Moh Aung
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Siu Yee New
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Shuzhen Hong
- Cancer Biology and Pharmacology, Genome Institute of Singapore, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Laura Sutarlie
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Michelle Gek Liang Lim
- Cancer Biology and Pharmacology, Genome Institute of Singapore, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Si Kee Tan
- Cancer Biology and Pharmacology, Genome Institute of Singapore, Agency for Science, Technology, and Research (A(*)STAR), Singapore
| | - Edwin Cheung
- Cancer Biology and Pharmacology, Genome Institute of Singapore, Agency for Science, Technology, and Research (A(*)STAR), Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; School of Biological Sciences, Nanyang Technological University, Singapore.
| | - Xiaodi Su
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A(*)STAR), Singapore.
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