1
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Modak A, Kilic Z, Chattrakun K, Terry DS, Kalathur RC, Blanchard SC. Single-Molecule Imaging of Integral Membrane Protein Dynamics and Function. Annu Rev Biophys 2024; 53:427-453. [PMID: 39013028 DOI: 10.1146/annurev-biophys-070323-024308] [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: 07/18/2024]
Abstract
Integral membrane proteins (IMPs) play central roles in cellular physiology and represent the majority of known drug targets. Single-molecule fluorescence and fluorescence resonance energy transfer (FRET) methods have recently emerged as valuable tools for investigating structure-function relationships in IMPs. This review focuses on the practical foundations required for examining polytopic IMP function using single-molecule FRET (smFRET) and provides an overview of the technical and conceptual frameworks emerging from this area of investigation. In this context, we highlight the utility of smFRET methods to reveal transient conformational states critical to IMP function and the use of smFRET data to guide structural and drug mechanism-of-action investigations. We also identify frontiers where progress is likely to be paramount to advancing the field.
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Affiliation(s)
- Arnab Modak
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
| | - Zeliha Kilic
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
| | - Kanokporn Chattrakun
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
| | - Daniel S Terry
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
| | - Ravi C Kalathur
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
| | - Scott C Blanchard
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; , , , , ,
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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2
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Han H, Park C, Lee CY, Ahn JK. Background-filtered telomerase activity assay with cyclic DNA cleavage amplification. NANOSCALE 2023; 15:16669-16674. [PMID: 37801026 DOI: 10.1039/d3nr04132h] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Overexpression of telomerase incites the abnormal proliferation of cancer cells. Thus, it has been regarded as a cancer biomarker and a potential therapeutic target. Existing assays suggest a promising sensing scheme to detect telomerase activity. However, they are complicated in terms of assay preparation and implementation. We herein report a Quenching-Exempt invader Signal Amplification Test, termed 'QUEST'. The assay leverages on a high turnover, specific cleaving enzyme, flap endonuclease I (FEN1), and graphene oxide (GO) for background (BG) filtering. In response to the target, FEN1 significantly boosts the signal with invader signal amplification. To distinguish the target signal, GO filters out the BG. It captures residual reporter invader probes (RP) to quench undesired signals. QUEST is straightforward without any pre-preparatory steps and washing/separation. Its probe design is simple and cost-effective. With QUEST, we investigated telomerase activities in various cell lines. Notably, we discriminated cancer cell lines from normal cell lines. In addition, a candidate inhibitor for telomerase was screened, which showed the promising potential of QUEST in real applications.
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Affiliation(s)
- Hyogu Han
- Material & Component Convergence R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea
- Department of Chemistry, Gangneung-Wonju National University, Gangneung 25457, Korea
| | - Chihyun Park
- Daejeon District Office, National Forensic Service, Daejeon 34054, Korea
| | - Chang Yeol Lee
- Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea
| | - Jun Ki Ahn
- Material & Component Convergence R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan 15588, Korea
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3
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Blair K, Tehseen M, Raducanu VS, Shahid T, Lancey C, Rashid F, Crehuet R, Hamdan SM, De Biasio A. Mechanism of human Lig1 regulation by PCNA in Okazaki fragment sealing. Nat Commun 2022; 13:7833. [PMID: 36539424 PMCID: PMC9767926 DOI: 10.1038/s41467-022-35475-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
During lagging strand synthesis, DNA Ligase 1 (Lig1) cooperates with the sliding clamp PCNA to seal the nicks between Okazaki fragments generated by Pol δ and Flap endonuclease 1 (FEN1). We present several cryo-EM structures combined with functional assays, showing that human Lig1 recruits PCNA to nicked DNA using two PCNA-interacting motifs (PIPs) located at its disordered N-terminus (PIPN-term) and DNA binding domain (PIPDBD). Once Lig1 and PCNA assemble as two-stack rings encircling DNA, PIPN-term is released from PCNA and only PIPDBD is required for ligation to facilitate the substrate handoff from FEN1. Consistently, we observed that PCNA forms a defined complex with FEN1 and nicked DNA, and it recruits Lig1 to an unoccupied monomer creating a toolbelt that drives the transfer of DNA to Lig1. Collectively, our results provide a structural model on how PCNA regulates FEN1 and Lig1 during Okazaki fragments maturation.
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Affiliation(s)
- Kerry Blair
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Muhammad Tehseen
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Vlad-Stefan Raducanu
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Taha Shahid
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Claudia Lancey
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Fahad Rashid
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Ramon Crehuet
- CSIC-Institute for Advanced Chemistry of Catalonia (IQAC) C/ Jordi Girona 18-26, 08034, Barcelona, Spain
| | - Samir M Hamdan
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK.
- Bioscience Program, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
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4
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Bralić A, Tehseen M, Sobhy MA, Tsai CL, Alhudhali L, Yi G, Yu J, Yan C, Ivanov I, Tsutakawa SE, Tainer J, Hamdan S. A scanning-to-incision switch in TFIIH-XPG induced by DNA damage licenses nucleotide excision repair. Nucleic Acids Res 2022; 51:1019-1033. [PMID: 36477609 PMCID: PMC9943652 DOI: 10.1093/nar/gkac1095] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/21/2022] [Accepted: 11/26/2022] [Indexed: 12/12/2022] Open
Abstract
Nucleotide excision repair (NER) is critical for removing bulky DNA base lesions and avoiding diseases. NER couples lesion recognition by XPC to strand separation by XPB and XPD ATPases, followed by lesion excision by XPF and XPG nucleases. Here, we describe key regulatory mechanisms and roles of XPG for and beyond its cleavage activity. Strikingly, by combing single-molecule imaging and bulk cleavage assays, we found that XPG binding to the 7-subunit TFIIH core (coreTFIIH) stimulates coreTFIIH-dependent double-strand (ds)DNA unwinding 10-fold, and XPG-dependent DNA cleavage by up to 700-fold. Simultaneous monitoring of rates for coreTFIIH single-stranded (ss)DNA translocation and dsDNA unwinding showed XPG acts by switching ssDNA translocation to dsDNA unwinding as a likely committed step. Pertinent to the NER pathway regulation, XPG incision activity is suppressed during coreTFIIH translocation on DNA but is licensed when coreTFIIH stalls at the lesion or when ATP hydrolysis is blocked. Moreover, ≥15 nucleotides of 5'-ssDNA is a prerequisite for efficient translocation and incision. Our results unveil a paired coordination mechanism in which key lesion scanning and DNA incision steps are sequentially coordinated, and damaged patch removal is only licensed after generation of ≥15 nucleotides of 5'-ssDNA, ensuring the correct ssDNA bubble size before cleavage.
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Affiliation(s)
- Amer Bralić
- Bioscience Program, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Tehseen
- Bioscience Program, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Mohamed A Sobhy
- Bioscience Program, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Chi-Lin Tsai
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lubna Alhudhali
- Bioscience Program, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Gang Yi
- Bioscience Program, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Jina Yu
- Department of Chemistry, Georgia State University, Atlanta, GA 30302 USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30302, USA
| | - Chunli Yan
- Department of Chemistry, Georgia State University, Atlanta, GA 30302 USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30302, USA
| | - Ivaylo Ivanov
- Department of Chemistry, Georgia State University, Atlanta, GA 30302 USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30302, USA
| | - Susan E Tsutakawa
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - John A Tainer
- Correspondence may also be addressed to John A. Tainer. Tel: +1 713 563 7725; Fax: +1 713 794 3270;
| | - Samir M Hamdan
- To whom correspondence should be addressed. Tel: +96 628082384; Cell: +96 6544700031;
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5
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Mechanistic investigation of human maturation of Okazaki fragments reveals slow kinetics. Nat Commun 2022; 13:6973. [PMID: 36379932 PMCID: PMC9666535 DOI: 10.1038/s41467-022-34751-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 11/04/2022] [Indexed: 11/16/2022] Open
Abstract
The final steps of lagging strand synthesis induce maturation of Okazaki fragments via removal of the RNA primers and ligation. Iterative cycles between Polymerase δ (Polδ) and Flap endonuclease-1 (FEN1) remove the primer, with an intermediary nick structure generated for each cycle. Here, we show that human Polδ is inefficient in releasing the nick product from FEN1, resulting in non-processive and remarkably slow RNA removal. Ligase 1 (Lig1) can release the nick from FEN1 and actively drive the reaction toward ligation. These mechanisms are coordinated by PCNA, which encircles DNA, and dynamically recruits Polδ, FEN1, and Lig1 to compete for their substrates. Our findings call for investigating additional pathways that may accelerate RNA removal in human cells, such as RNA pre-removal by RNase Hs, which, as demonstrated herein, enhances the maturation rate ~10-fold. They also suggest that FEN1 may attenuate the various activities of Polδ during DNA repair and recombination.
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6
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Sefer A, Kallis E, Eilert T, Röcker C, Kolesnikova O, Neuhaus D, Eustermann S, Michaelis J. Structural dynamics of DNA strand break sensing by PARP-1 at a single-molecule level. Nat Commun 2022; 13:6569. [PMID: 36323657 PMCID: PMC9630430 DOI: 10.1038/s41467-022-34148-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Single-stranded breaks (SSBs) are the most frequent DNA lesions threatening genomic integrity. A highly kinked DNA structure in complex with human PARP-1 domains led to the proposal that SSB sensing in Eukaryotes relies on dynamics of both the broken DNA double helix and PARP-1's multi-domain organization. Here, we directly probe this process at the single-molecule level. Quantitative smFRET and structural ensemble calculations reveal how PARP-1's N-terminal zinc fingers convert DNA SSBs from a largely unperturbed conformation, via an intermediate state into the highly kinked DNA conformation. Our data suggest an induced fit mechanism via a multi-domain assembly cascade that drives SSB sensing and stimulates an interplay with the scaffold protein XRCC1 orchestrating subsequent DNA repair events. Interestingly, a clinically used PARP-1 inhibitor Niraparib shifts the equilibrium towards the unkinked DNA conformation, whereas the inhibitor EB47 stabilizes the kinked state.
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Affiliation(s)
- Anna Sefer
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Eleni Kallis
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Tobias Eilert
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- Boehringer Ingelheim, CoC CMC Statistics & Data Science, Birkendorfer Str. 65, 88400, Biberach, Germany
| | - Carlheinz Röcker
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Olga Kolesnikova
- European Molecular Biology Laboratory (EMBL), Heidelberg Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - David Neuhaus
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Sebastian Eustermann
- European Molecular Biology Laboratory (EMBL), Heidelberg Meyerhofstraße 1, 69117, Heidelberg, Germany.
| | - Jens Michaelis
- Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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7
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Chinnam NB, Syed A, Burnett KH, Hura GL, Tainer JA, Tsutakawa SE. Universally Accessible Structural Data on Macromolecular Conformation, Assembly, and Dynamics by Small Angle X-Ray Scattering for DNA Repair Insights. Methods Mol Biol 2022; 2444:43-68. [PMID: 35290631 PMCID: PMC9020468 DOI: 10.1007/978-1-0716-2063-2_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Structures provide a critical breakthrough step for biological analyses, and small angle X-ray scattering (SAXS) is a powerful structural technique to study dynamic DNA repair proteins. As toxic and mutagenic repair intermediates need to be prevented from inadvertently harming the cell, DNA repair proteins often chaperone these intermediates through dynamic conformations, coordinated assemblies, and allosteric regulation. By measuring structural conformations in solution for both proteins, DNA, RNA, and their complexes, SAXS provides insight into initial DNA damage recognition, mechanisms for validation of their substrate, and pathway regulation. Here, we describe exemplary SAXS analyses of a DNA damage response protein spanning from what can be derived directly from the data to obtaining super resolution through the use of SAXS selection of atomic models. We outline strategies and tactics for practical SAXS data collection and analysis. Making these structural experiments in reach of any basic and clinical researchers who have protein, SAXS data can readily be collected at government-funded synchrotrons, typically at no cost for academic researchers. In addition to discussing how SAXS complements and enhances cryo-electron microscopy, X-ray crystallography, NMR, and computational modeling, we furthermore discuss taking advantage of recent advances in protein structure prediction in combination with SAXS analysis.
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Affiliation(s)
- Naga Babu Chinnam
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - Kathryn H Burnett
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Greg L Hura
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Chemistry and Biochemistry Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Cancer Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Susan E Tsutakawa
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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8
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Tsutakawa SE, Bacolla A, Katsonis P, Bralić A, Hamdan SM, Lichtarge O, Tainer JA, Tsai CL. Decoding Cancer Variants of Unknown Significance for Helicase-Nuclease-RPA Complexes Orchestrating DNA Repair During Transcription and Replication. Front Mol Biosci 2021; 8:791792. [PMID: 34966786 PMCID: PMC8710748 DOI: 10.3389/fmolb.2021.791792] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 11/16/2021] [Indexed: 01/13/2023] Open
Abstract
All tumors have DNA mutations, and a predictive understanding of those mutations could inform clinical treatments. However, 40% of the mutations are variants of unknown significance (VUS), with the challenge being to objectively predict whether a VUS is pathogenic and supports the tumor or whether it is benign. To objectively decode VUS, we mapped cancer sequence data and evolutionary trace (ET) scores onto crystallography and cryo-electron microscopy structures with variant impacts quantitated by evolutionary action (EA) measures. As tumors depend on helicases and nucleases to deal with transcription/replication stress, we targeted helicase–nuclease–RPA complexes: (1) XPB-XPD (within TFIIH), XPF-ERCC1, XPG, and RPA for transcription and nucleotide excision repair pathways and (2) BLM, EXO5, and RPA plus DNA2 for stalled replication fork restart. As validation, EA scoring predicts severe effects for most disease mutations, but disease mutants with low ET scores not only are likely destabilizing but also disrupt sophisticated allosteric mechanisms. For sites of disease mutations and VUS predicted to be severe, we found strong co-localization to ordered regions. Rare discrepancies highlighted the different survival requirements between disease and tumor mutations, as well as the value of examining proteins within complexes. In a genome-wide analysis of 33 cancer types, we found correlation between the number of mutations in each tumor and which pathways or functional processes in which the mutations occur, revealing different mutagenic routes to tumorigenesis. We also found upregulation of ancient genes including BLM, which supports a non-random and concerted cancer process: reversion to a unicellular, proliferation-uncontrolled, status by breaking multicellular constraints on cell division. Together, these genes and global analyses challenge the binary “driver” and “passenger” mutation paradigm, support a gradient impact as revealed by EA scoring from moderate to severe at a single gene level, and indicate reduced regulation as well as activity. The objective quantitative assessment of VUS scoring and gene overexpression in the context of functional interactions and pathways provides insights for biology, oncology, and precision medicine.
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Affiliation(s)
- Susan E Tsutakawa
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX, United States
| | - Panagiotis Katsonis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Amer Bralić
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Samir M Hamdan
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Olivier Lichtarge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - John A Tainer
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.,Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX, United States.,Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX, United States
| | - Chi-Lin Tsai
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX, United States
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9
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Sobhy MA, Tehseen M, Takahashi M, Bralić A, De Biasio A, Hamdan SM. Implementing fluorescence enhancement, quenching, and FRET for investigating flap endonuclease 1 enzymatic reaction at the single-molecule level. Comput Struct Biotechnol J 2021; 19:4456-4471. [PMID: 34471492 PMCID: PMC8385120 DOI: 10.1016/j.csbj.2021.07.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/23/2021] [Accepted: 07/25/2021] [Indexed: 11/24/2022] Open
Abstract
Flap endonuclease 1 (FEN1) is an important component of the intricate molecular machinery for DNA replication and repair. FEN1 is a structure-specific 5' nuclease that cleaves nascent single-stranded 5' flaps during the maturation of Okazaki fragments. Here, we review our research primarily applying single-molecule fluorescence to resolve important mechanistic aspects of human FEN1 enzymatic reaction. The methodology presented in this review is aimed as a guide for tackling other biomolecular enzymatic reactions by fluorescence enhancement, quenching, and FRET and their combinations. Using these methods, we followed in real-time the structures of the substrate and product and 5' flap cleavage during catalysis. We illustrate that FEN1 actively bends the substrate to verify its features and continues to mold it to induce a protein disorder-to-order transitioning that controls active site assembly. This mechanism suppresses off-target cleavage of non-cognate substrates and promotes their dissociation with an accuracy that was underestimated from bulk assays. We determined that product release in FEN1 after the 5' flap release occurs in two steps; a brief binding to the bent nicked-product followed by longer binding to the unbent nicked-product before dissociation. Based on our cryo-electron microscopy structure of the human lagging strand replicase bound to FEN1, we propose how this two-step product release mechanism may regulate the final steps during the maturation of Okazaki fragments.
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Affiliation(s)
- Mohamed A Sobhy
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Tehseen
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Masateru Takahashi
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Amer Bralić
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester LE1 7HB, UK
| | - Samir M Hamdan
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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10
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Matsumoto Y, Brooks RC, Sverzhinsky A, Pascal JM, Tomkinson AE. Dynamic DNA-bound PCNA complexes co-ordinate Okazaki fragment synthesis, processing and ligation. J Mol Biol 2020; 432:166698. [PMID: 33157085 DOI: 10.1016/j.jmb.2020.10.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 10/07/2020] [Accepted: 10/27/2020] [Indexed: 11/28/2022]
Abstract
More than a million Okazaki fragments are synthesized, processed and joined during replication of the human genome. After synthesis of an RNA-DNA oligonucleotide by DNA polymerase α holoenzyme, proliferating cell nuclear antigen (PCNA), a homotrimeric DNA sliding clamp and polymerase processivity factor, is loaded onto the primer-template junction by replication factor C (RFC). Although PCNA interacts with the enzymes DNA polymerase δ (Pol δ), flap endonuclease 1 (FEN1) and DNA ligase I (LigI) that complete Okazaki fragment processing and joining, it is not known how the activities of these enzymes are coordinated. Here we describe a novel interaction between Pol δ and LigI that is critical for Okazaki fragment joining in vitro. Both LigI and FEN1 associate with PCNA-Pol δ during gap-filling synthesis, suggesting that gap-filling synthesis is carried out by a complex of PCNA, Pol δ, FEN1 and LigI. Following ligation, PCNA and LigI remain on the DNA, indicating that Pol δ and FEN1 dissociate during 5' end processing and that LigI engages PCNA at the DNA nick generated by FEN1 and Pol δ. Thus, dynamic PCNA complexes coordinate Okazaki fragment synthesis and processing with PCNA and LigI forming a terminal structure of two linked protein rings encircling the ligated DNA.
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Affiliation(s)
- Yoshihiro Matsumoto
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States
| | - Rhys C Brooks
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States
| | - Aleksandr Sverzhinsky
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, Canada
| | - John M Pascal
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Alan E Tomkinson
- Departments of Internal Medicine, Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM 87131, United States.
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11
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Harris PD, Hamdan SM, Habuchi S. Relative Contributions of Base Stacking and Electrostatic Repulsion on DNA Nicks and Gaps. J Phys Chem B 2020; 124:10663-10672. [PMID: 33179916 DOI: 10.1021/acs.jpcb.0c06941] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In duplex DNA, the continuous sugar phosphate backbones prevent the double helix from significant bending, but breaks in the duplex such as nicks, gaps, and flaps present points at which significant bending is possible. The conformational dynamics of these aberrant structures remains poorly understood. Two factors can maintain the duplexlike conformation of these aberrant structures, these being the hydrophobic and aromatic stacking interactions of the nucleobases, and the electrostatic repulsion of the negatively charged backbones. Using confocal single-molecule Förster resonance energy transfer on nicked and gapped DNA structures, we compare the relative contributions of these two factors by modulating the electrostatic repulsion through mono- and divalent cation concentrations. Base stacking interactions dominate the dynamics of nicked DNA, making it behave essentially like duplex DNA. Gapped structures have weaker base stacking and thus backbone electrostatic repulsion becomes important, and shielding from cations results in an average increase in bending around the gap. This bending of gapped structures could be interpreted by increased flexibility of unstacked structures, transient unstacking events, or a combination of the two. Burst variance analysis (BVA) and analysis by photon-by-photon hidden Markov modeling (H2MM), methods capable of detecting submillisecond dynamics of single molecules in solution, only revealed a single state, indicating that dynamics are occurring at time scales shorter than microseconds.
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Affiliation(s)
- Paul D Harris
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, P.O. Box 4700, Thuwal 23955-6900, Saudi Arabia
| | - Samir M Hamdan
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, P.O. Box 4700, Thuwal 23955-6900, Saudi Arabia
| | - Satoshi Habuchi
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, P.O. Box 4700, Thuwal 23955-6900, Saudi Arabia
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12
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Hammel M, Rosenberg DJ, Bierma J, Hura GL, Thapar R, Lees-Miller SP, Tainer JA. Visualizing functional dynamicity in the DNA-dependent protein kinase holoenzyme DNA-PK complex by integrating SAXS with cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 163:74-86. [PMID: 32966823 DOI: 10.1016/j.pbiomolbio.2020.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/19/2020] [Accepted: 09/17/2020] [Indexed: 12/27/2022]
Abstract
Assembly of KU and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at DNA double strand breaks (DSBs) forms DNA-PK holoenzyme as a critical initiating step for non-homologous end joining (NHEJ) repair of DSBs produced by radiation and chemotherapies. Advanced cryo-electron microscopy (cryo-EM) imaging together with breakthrough macromolecular X-ray crystal (MX) structures of KU and DNA-PKcs recently enabled visualization of the ∼600 kDa DNA-PK assembly at near atomic resolution. These important static structures provide the foundation for definition and interpretation of functional movements crucial to mechanistic understanding that can be tested through solution state structure analysis. We herein therefore leverage Cryo-EM and MX structures for the interpretation of synchrotron small-angle X-ray scattering (SAXS) data on DNA-PK conformations in solution to inform the structural mechanism for NHEJ initiation. SAXS, which measures thermodynamic solution-state conformational states and assemblies outside of cryo- and solid-state conditions, unveils the inherent flexibility of KU, DNA-PKcs and DNA-PK. The combined structural measurements reveal mobility of KU80 C-terminal region (KU80CTR), motion/plasticity of HEAT (DNA-PKcs Huntingtin, Elongation Factor 3, PP2 A, and TOR1) regions, allosteric switching upon DNA-PKcs autophosphorylation, and dimeric arrangements of DNA-PK assembly. Importantly, the results uncover displacement of the N-terminal HEAT domain during autophosphorylation as suitable for a regulated release mechanism of DNA-PKcs from DNA-PK to control unproductive access to toxic and mutagenic DNA repair intermediates. These integrated analyses show that the marriage of SAXS with cryo-EM leverages the strengths of both techniques to enable assessment of functional conformations and flexibility defining atomic-resolution molecular mechanisms for DSB repair.
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Affiliation(s)
- Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Daniel J Rosenberg
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA; Graduate Group in Biophysics, University of California, Berkeley, CA, 94720, USA
| | - Jan Bierma
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Gregory L Hura
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Roopa Thapar
- Department of Cancer Biology, Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, University of Calgary, Alberta, T2N 4N1, Canada
| | - John A Tainer
- Department of Cancer Biology, Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
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13
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Huang W, Tang H, Wen F, Lu X, Li Q, Shu P. Jianpi-yangwei decoction inhibits DNA damage repair in the drug resistance of gastric cancer by reducing FEN1 expression. BMC Complement Med Ther 2020; 20:196. [PMID: 32586310 PMCID: PMC7318551 DOI: 10.1186/s12906-020-02983-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/05/2020] [Indexed: 12/31/2022] Open
Abstract
Background Flap Endonuclease 1(FEN1) has been considered as a new tumor marker in recent years and Jianpi Yangwei Decoction (JPYW) is a basic Traditional Chinese Medicine (TCM) for the treatment of gastric cancer. This study aimed to explore the role of FEN1-mediated DNA damage repair in the drug resistance of gastric cancer and the effect of JPYW on it by employing BGC823/5-Fu drug-resistant cell model. Methods The DNA repair efficiency of BGC823 and BGC823/5-Fu was compared intracellularly and extracellularly using an extrachromosomal assay system and the reconstituted base excision repair assay. By comparing gene and protein expression and identifying cell survival rates after knockdown or high expression of FEN1, the correlation between FEN1 high expression and 5-Fluorouracil (5-Fu) drug resistance was revealed. The effect of JPYW on DNA damage repair and FEN1 expression was observed by the degree of γ-H2AX phosphorylation in the cells, DNA repair efficiency and enzyme activity, et al. Results BGC823/5-Fu had a higher DNA repair efficiency than BGC823(P < 0.001), which proved to be both intracellular and extracellular. FEN1 was highly expressed in BGC823/5-Fu regardless of gene level(P < 0.001) or protein level. Furthermore, manipulating FEN1 altered the sensitivity of cancer cells to chemotherapeutic drug 5-Fu. Different concentrations of JPYW were used to investigate the inhibitory effect on the expression of FEN1 and DNA damage repair. JPYW inhibited DNA damage repair both intracellularly and extracellularly: the phosphorylation of γ-H2AX increased, with more DNA damage in the cells; the synthetic 8-oxo dG damage repair was reduced; and the ability of cell lysates to repair DNA damage decreased. The decrease of FEN1 expression in BGC823/5-Fu had a concentration dependent relationship with JYPW. In addition, JPYW inhibited the activity of FEN1 at the enzymatic level, as the amount of cut-off synthetic 32p labeled DNA substrates were decreased. Conclusion FEN1 was highly expressed in drug-resistance gastric cancer cells BGC823/5-Fu, which leading to BGC823 resistant to (5-Fu) by acting on DNA damage repair. JPYW inhibited DNA damage repair and reversed 5-Fu drug resistance by reducing FEN1 expression and inhibiting FEN1 functional activity.
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Affiliation(s)
- Wenjie Huang
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China
| | - Huijuan Tang
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China.,Department of Clinical and Molecular Sciences, Università Politenica delle Marche, 60126, Ancona, Italy
| | - Fang Wen
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China
| | - Xiaona Lu
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China
| | - Qingpei Li
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China
| | - Peng Shu
- Oncology Department, Affiliated Hospital of Nanjing University of Chinese Medicine, 155 Hanzhong Road, Jiangsu province, Nanjing, 210029, China.
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14
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Human XPG nuclease structure, assembly, and activities with insights for neurodegeneration and cancer from pathogenic mutations. Proc Natl Acad Sci U S A 2020; 117:14127-14138. [PMID: 32522879 PMCID: PMC7321962 DOI: 10.1073/pnas.1921311117] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
DNA repair is essential to life and to avoidance of genome instability and cancer. Xeroderma pigmentosum group G (XPG) protein acts in multiple DNA repair pathways, both as an active enzyme and as a scaffold for coordinating with other repair proteins. We present here the structure of the catalytic domain responsible for its DNA binding and nuclease activity. Our analysis provides structure-based hypotheses for how XPG recognizes its bubble DNA substrate and predictions of the structural impacts of XPG disease mutations associated with two phenotypically distinct diseases: xeroderma pigmentosum (XP, skin cancer prone) or Cockayne syndrome (XP/CS, severe progressive developmental defects). Xeroderma pigmentosum group G (XPG) protein is both a functional partner in multiple DNA damage responses (DDR) and a pathway coordinator and structure-specific endonuclease in nucleotide excision repair (NER). Different mutations in the XPG gene ERCC5 lead to either of two distinct human diseases: Cancer-prone xeroderma pigmentosum (XP-G) or the fatal neurodevelopmental disorder Cockayne syndrome (XP-G/CS). To address the enigmatic structural mechanism for these differing disease phenotypes and for XPG’s role in multiple DDRs, here we determined the crystal structure of human XPG catalytic domain (XPGcat), revealing XPG-specific features for its activities and regulation. Furthermore, XPG DNA binding elements conserved with FEN1 superfamily members enable insights on DNA interactions. Notably, all but one of the known pathogenic point mutations map to XPGcat, and both XP-G and XP-G/CS mutations destabilize XPG and reduce its cellular protein levels. Mapping the distinct mutation classes provides structure-based predictions for disease phenotypes: Residues mutated in XP-G are positioned to reduce local stability and NER activity, whereas residues mutated in XP-G/CS have implied long-range structural defects that would likely disrupt stability of the whole protein, and thus interfere with its functional interactions. Combined data from crystallography, biochemistry, small angle X-ray scattering, and electron microscopy unveil an XPG homodimer that binds, unstacks, and sculpts duplex DNA at internal unpaired regions (bubbles) into strongly bent structures, and suggest how XPG complexes may bind both NER bubble junctions and replication forks. Collective results support XPG scaffolding and DNA sculpting functions in multiple DDR processes to maintain genome stability.
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15
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Raducanu VS, Tehseen M, Shirbini A, Raducanu DV, Hamdan SM. Two chromatographic schemes for protein purification involving the biotin/avidin interaction under native conditions. J Chromatogr A 2020; 1621:461051. [DOI: 10.1016/j.chroma.2020.461051] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/13/2020] [Accepted: 03/15/2020] [Indexed: 11/25/2022]
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16
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Lancey C, Tehseen M, Raducanu VS, Rashid F, Merino N, Ragan TJ, Savva CG, Zaher MS, Shirbini A, Blanco FJ, Hamdan SM, De Biasio A. Structure of the processive human Pol δ holoenzyme. Nat Commun 2020; 11:1109. [PMID: 32111820 PMCID: PMC7048817 DOI: 10.1038/s41467-020-14898-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/07/2020] [Indexed: 01/01/2023] Open
Abstract
In eukaryotes, DNA polymerase δ (Pol δ) bound to the proliferating cell nuclear antigen (PCNA) replicates the lagging strand and cooperates with flap endonuclease 1 (FEN1) to process the Okazaki fragments for their ligation. We present the high-resolution cryo-EM structure of the human processive Pol δ–DNA–PCNA complex in the absence and presence of FEN1. Pol δ is anchored to one of the three PCNA monomers through the C-terminal domain of the catalytic subunit. The catalytic core sits on top of PCNA in an open configuration while the regulatory subunits project laterally. This arrangement allows PCNA to thread and stabilize the DNA exiting the catalytic cleft and recruit FEN1 to one unoccupied monomer in a toolbelt fashion. Alternative holoenzyme conformations reveal important functional interactions that maintain PCNA orientation during synthesis. This work sheds light on the structural basis of Pol δ’s activity in replicating the human genome. Pol δ bound to the proliferating cell nuclear antigen (PCNA) replicates the lagging strand in eukaryotes and cooperates with flap endonuclease 1 (FEN1) to process the Okazaki fragments for their ligation. Here, the authors present a Cryo-EM structure of the human 4-subunit Pol δ bound to DNA and PCNA in a replicating state with an incoming nucleotide in the active site.
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Affiliation(s)
- Claudia Lancey
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Muhammad Tehseen
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Vlad-Stefan Raducanu
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Fahad Rashid
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Nekane Merino
- CIC bioGUNE, Parque Tecnológico de Bizkaia Edificio 800, 48160, Derio, Spain
| | - Timothy J Ragan
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Christos G Savva
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK
| | - Manal S Zaher
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Afnan Shirbini
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Francisco J Blanco
- CIC bioGUNE, Parque Tecnológico de Bizkaia Edificio 800, 48160, Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Samir M Hamdan
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
| | - Alfredo De Biasio
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, Lancaster Rd, Leicester, LE1 7HB, UK.
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17
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Tehseen M, Raducanu VS, Rashid F, Shirbini A, Takahashi M, Hamdan SM. Proliferating cell nuclear antigen-agarose column: A tag-free and tag-dependent tool for protein purification affinity chromatography. J Chromatogr A 2019; 1602:341-349. [DOI: 10.1016/j.chroma.2019.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 06/01/2019] [Accepted: 06/03/2019] [Indexed: 10/26/2022]
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18
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Thompson MJ, Gotham VJB, Ciani B, Grasby JA. A conserved loop-wedge motif moderates reaction site search and recognition by FEN1. Nucleic Acids Res 2019; 46:7858-7872. [PMID: 29878258 PMCID: PMC6125683 DOI: 10.1093/nar/gky506] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 05/23/2018] [Indexed: 12/24/2022] Open
Abstract
DNA replication and repair frequently involve intermediate two-way junction structures with overhangs, or flaps, that must be promptly removed; a task performed by the essential enzyme flap endonuclease 1 (FEN1). We demonstrate a functional relationship between two intrinsically disordered regions of the FEN1 protein, which recognize opposing sides of the junction and order in response to the requisite substrate. Our results inform a model in which short-range translocation of FEN1 on DNA facilitates search for the annealed 3'-terminus of a primer strand, which is recognized by breaking the terminal base pair to generate a substrate with a single nucleotide 3'-flap. This recognition event allosterically signals hydrolytic removal of the 5'-flap through reaction in the opposing junction duplex, by controlling access of the scissile phosphate diester to the active site. The recognition process relies on a highly-conserved 'wedge' residue located on a mobile loop that orders to bind the newly-unpaired base. The unanticipated 'loop-wedge' mechanism exerts control over substrate selection, rate of reaction and reaction site precision, and shares features with other enzymes that recognize irregular DNA structures. These new findings reveal how FEN1 precisely couples 3'-flap verification to function.
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Affiliation(s)
- Mark J Thompson
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
| | - Victoria J B Gotham
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
| | - Barbara Ciani
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
| | - Jane A Grasby
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK
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19
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Broadwater DWB, Altman RB, Blanchard SC, Kim HD. ERASE: a novel surface reconditioning strategy for single-molecule experiments. Nucleic Acids Res 2019; 47:e14. [PMID: 30462308 PMCID: PMC6379648 DOI: 10.1093/nar/gky1168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/02/2018] [Accepted: 11/01/2018] [Indexed: 11/13/2022] Open
Abstract
While surface-based single-molecule experiments have revolutionized our understanding of biology and biomolecules, the workflow in preparing for such experiments, especially surface cleaning and functionalization, remains labor-intensive and time-consuming. Even worse, meticulously assembled flow channels can be used only once for most experiments. A reusable surface would thus dramatically increase productivity and efficiency of single-molecule experiments. In this paper, we report a novel surface reconditioning strategy termed ERASE (Epitaxial Removal Aided by Strand Exchange) that allows a single flow cell to be used for vast repetition of single-molecule experiments. In this method, biomolecules immobilized to the surface through a nucleic acid duplex are liberated when a competing DNA strand disrupts the duplex via toehold-mediated strand displacement. We demonstrate the wide-range applicability of this method with various common surface preparation techniques, fluorescent dyes, and biomolecules including the bacterial ribosome. Beyond time and cost savings, we also show ERASE can assort molecules based on a nucleic acid barcode sequence, thus allowing experiments on different molecules in parallel. Our method increases the utility of prepared surfaces and is a significant improvement to the current single-use paradigm.
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Affiliation(s)
- D W Bo Broadwater
- School of Physics, Georgia Institute of Technology, 770 State Street NW, Atlanta, GA 30318, USA
| | - Roger B Altman
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 770 State Street NW, Atlanta, GA 30318, USA
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20
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Zaher MS, Rashid F, Song B, Joudeh LI, Sobhy MA, Tehseen M, Hingorani MM, Hamdan SM. Missed cleavage opportunities by FEN1 lead to Okazaki fragment maturation via the long-flap pathway. Nucleic Acids Res 2019; 46:2956-2974. [PMID: 29420814 PMCID: PMC5888579 DOI: 10.1093/nar/gky082] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/27/2018] [Indexed: 12/11/2022] Open
Abstract
RNA–DNA hybrid primers synthesized by low fidelity DNA polymerase α to initiate eukaryotic lagging strand synthesis must be removed efficiently during Okazaki fragment (OF) maturation to complete DNA replication. In this process, each OF primer is displaced and the resulting 5′-single-stranded flap is cleaved by structure-specific 5′-nucleases, mainly Flap Endonuclease 1 (FEN1), to generate a ligatable nick. At least two models have been proposed to describe primer removal, namely short- and long-flap pathways that involve FEN1 or FEN1 along with Replication Protein A (RPA) and Dna2 helicase/nuclease, respectively. We addressed the question of pathway choice by studying the kinetic mechanism of FEN1 action on short- and long-flap DNA substrates. Using single molecule FRET and rapid quench-flow bulk cleavage assays, we showed that unlike short-flap substrates, which are bound, bent and cleaved within the first encounter between FEN1 and DNA, long-flap substrates can escape cleavage even after DNA binding and bending. Notably, FEN1 can access both substrates in the presence of RPA, but bending and cleavage of long-flap DNA is specifically inhibited. We propose that FEN1 attempts to process both short and long flaps, but occasional missed cleavage of the latter allows RPA binding and triggers the long-flap OF maturation pathway.
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Affiliation(s)
- Manal S Zaher
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
| | - Fahad Rashid
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
| | - Bo Song
- Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, CT 06459, USA
| | - Luay I Joudeh
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
| | - Mohamed A Sobhy
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
| | - Muhammad Tehseen
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
| | - Manju M Hingorani
- Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, CT 06459, USA
| | - Samir M Hamdan
- King Abdullah University of Science and Technology, Division of Biological and Environmental Science and Engineering, Thuwal 23955, Saudi Arabia
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21
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Bennet IA, Finger LD, Baxter NJ, Ambrose B, Hounslow AM, Thompson MJ, Exell JC, Shahari NNBM, Craggs TD, Waltho JP, Grasby JA. Regional conformational flexibility couples substrate specificity and scissile phosphate diester selectivity in human flap endonuclease 1. Nucleic Acids Res 2019; 46:5618-5633. [PMID: 29718417 PMCID: PMC6009646 DOI: 10.1093/nar/gky293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/09/2018] [Indexed: 02/07/2023] Open
Abstract
Human flap endonuclease-1 (hFEN1) catalyzes the divalent metal ion-dependent removal of single-stranded DNA protrusions known as flaps during DNA replication and repair. Substrate selectivity involves passage of the 5'-terminus/flap through the arch and recognition of a single nucleotide 3'-flap by the α2-α3 loop. Using NMR spectroscopy, we show that the solution conformation of free and DNA-bound hFEN1 are consistent with crystal structures; however, parts of the arch region and α2-α3 loop are disordered without substrate. Disorder within the arch explains how 5'-flaps can pass under it. NMR and single-molecule FRET data show a shift in the conformational ensemble in the arch and loop region upon addition of DNA. Furthermore, the addition of divalent metal ions to the active site of the hFEN1-DNA substrate complex demonstrates that active site changes are propagated via DNA-mediated allostery to regions key to substrate differentiation. The hFEN1-DNA complex also shows evidence of millisecond timescale motions in the arch region that may be required for DNA to enter the active site. Thus, hFEN1 regional conformational flexibility spanning a range of dynamic timescales is crucial to reach the catalytically relevant ensemble.
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Affiliation(s)
- Ian A Bennet
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - L David Finger
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Nicola J Baxter
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK.,Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester, Manchester M1 7DN, UK
| | - Benjamin Ambrose
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Andrea M Hounslow
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK
| | - Mark J Thompson
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Jack C Exell
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Nur Nazihah B Md Shahari
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Timothy D Craggs
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
| | - Jonathan P Waltho
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S10 2TN, UK.,Manchester Institute of Biotechnology, School of Chemistry, The University of Manchester, Manchester M1 7DN, UK
| | - Jane A Grasby
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute for Biomolecular Research, The University of Sheffield, Sheffield S3 7HF, UK
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22
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Rashid F, Raducanu VS, Zaher MS, Tehseen M, Habuchi S, Hamdan SM. Initial state of DNA-Dye complex sets the stage for protein induced fluorescence modulation. Nat Commun 2019; 10:2104. [PMID: 31068591 PMCID: PMC6506533 DOI: 10.1038/s41467-019-10137-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/15/2019] [Indexed: 01/27/2023] Open
Abstract
Protein-induced fluorescence enhancement (PIFE) is a popular tool for characterizing protein-DNA interactions. PIFE has been explained by an increase in local viscosity due to the presence of the protein residues. This explanation, however, denies the opposite effect of fluorescence quenching. This work offers a perspective for understanding PIFE mechanism and reports the observation of a phenomenon that we name protein-induced fluorescence quenching (PIFQ), which exhibits an opposite effect to PIFE. A detailed characterization of these two fluorescence modulations reveals that the initial fluorescence state of the labeled mediator (DNA) determines whether this mediator-conjugated dye undergoes PIFE or PIFQ upon protein binding. This key role of the mediator DNA provides a protocol for the experimental design to obtain either PIFQ or PIFE, on-demand. This makes the arbitrary nature of the current experimental design obsolete, allowing for proper integration of both PIFE and PIFQ with existing bulk and single-molecule fluorescence techniques. Protein-induced fluorescence enhancement (PIFE) is a popular tool for characterizing protein-DNA interactions. Here, authors provide a perspective on understanding the general phenomenon of induced fluorescence modulation
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Affiliation(s)
- Fahad Rashid
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia
| | - Vlad-Stefan Raducanu
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia
| | - Manal S Zaher
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia
| | - Muhammad Tehseen
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia
| | - Satoshi Habuchi
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia
| | - Samir M Hamdan
- King Abdullah University of Science and Technology, Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955, Saudi Arabia.
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23
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Sobhy MA, Bralić A, Raducanu VS, Takahashi M, Tehseen M, Rashid F, Zaher MS, Hamdan SM. Resolution of the Holliday junction recombination intermediate by human GEN1 at the single-molecule level. Nucleic Acids Res 2019; 47:1935-1949. [PMID: 30590761 PMCID: PMC6393306 DOI: 10.1093/nar/gky1280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/19/2018] [Accepted: 12/13/2018] [Indexed: 01/18/2023] Open
Abstract
Human GEN1 is a cytosolic homologous recombination protein that resolves persisting four-way Holliday junctions (HJ) after the dissolution of the nuclear membrane. GEN1 dimerization has been suggested to play key role in the resolution of the HJ, but the kinetic details of its reaction remained elusive. Here, single-molecule FRET shows how human GEN1 binds the HJ and always ensures its resolution within the lifetime of the GEN1-HJ complex. GEN1 monomer generally follows the isomer bias of the HJ in its initial binding and subsequently distorts it for catalysis. GEN1 monomer remains tightly bound with no apparent dissociation until GEN1 dimer is formed and the HJ is fully resolved. Fast on- and slow off-rates of GEN1 dimer and its increased affinity to the singly-cleaved HJ enforce the forward reaction. Furthermore, GEN1 monomer binds singly-cleaved HJ tighter than intact HJ providing a fail-safe mechanism if GEN1 dimer or one of its monomers dissociates after the first cleavage. The tight binding of GEN1 monomer to intact- and singly-cleaved HJ empowers it as the last resort to process HJs that escape the primary mechanisms.
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Affiliation(s)
- Mohamed A Sobhy
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Amer Bralić
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Vlad-Stefan Raducanu
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Masateru Takahashi
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Tehseen
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Fahad Rashid
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Manal S Zaher
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Samir M Hamdan
- Laboratory of DNA Replication and Recombination, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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24
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Algasaier SI, Finger LD, Bennet IA, Grasby JA. Flap Endonuclease 1 Mutations A159V and E160D Cause Genomic Instability by Slowing Reaction on Double-Flap Substrates. Biochemistry 2018; 57:6838-6847. [DOI: 10.1021/acs.biochem.8b00891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Sana I. Algasaier
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, U.K
| | - L. David Finger
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, U.K
| | - Ian A. Bennet
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, U.K
| | - Jane A. Grasby
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Sheffield S3 7HF, U.K
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25
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Wang Q, Li Y, Xu J, Wang Y, Shi D, Liu L, Leung ELH, Yao X. Computational study on the selective inhibition mechanism of MS402 to the first and second bromodomains of BRD4. Proteins 2018; 87:3-11. [PMID: 30260047 DOI: 10.1002/prot.25611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 09/15/2018] [Accepted: 09/20/2018] [Indexed: 12/14/2022]
Abstract
As a member of the bromodomain and extraterminal domain (BET) family, BRD4 is considered as a potential target for cancer treatment. However, because of the highly conservation of its two homologous bromodomains (BD1/BD2), selective inhibition of each bromodomain remains a challenge. MS402 is a domain-selective inhibitor of BRD4-BD1 over BRD4-BD2 reported recently. Understanding the selectivity mechanism would be very useful for the further design of more potent BD1-selectivity inhibitors. Molecular dynamics simulation, adaptive biasing force and multiple-walker adaptive biasing force were performed to study the inhibition and domain-selective mechanism of MS402 toward BRD4-BD1 over BRD4-BD2 here. Results demonstrate BRD4-BD1 binds to MS402 with lower binding free energy than BRD4-BD2. Residues Gln85, Pro86, Asn140, and Ile146 are crucial for MS402's selectively binding to BRD4-BD1. MS402 needs to overcome more energy barrier to dissociate from BD1 than from BD2 pocket. These findings will be helpful for rational structural modification of existing inhibitors to increase their BD1-selectivity.
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Affiliation(s)
- Qianqian Wang
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Ying Li
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Jiahui Xu
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Yuwei Wang
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Danfeng Shi
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
| | - Liang Liu
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Elaine Lai-Han Leung
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China
| | - Xiaojun Yao
- State Key Laboratory of Quality Research in Chinese Medicine/Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Macau, China.,State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
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26
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Yu Y, Ma L, Li L, Deng Y, Xu L, Liu H, Xiao L, Su X. Digestion of Dynamic Substrate by Exonuclease Reveals High Single-Mismatch Selectivity. Anal Chem 2018; 90:13655-13662. [DOI: 10.1021/acs.analchem.8b03963] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yingjie Yu
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Liang Ma
- Clinical laboratory, China-Japan Friendship Hospital, Beijing 100029, China
| | - Lidan Li
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yingnan Deng
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Lida Xu
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hua Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Lehui Xiao
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Xin Su
- College of Life Science and Technology, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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27
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Syed A, Tainer JA. The MRE11-RAD50-NBS1 Complex Conducts the Orchestration of Damage Signaling and Outcomes to Stress in DNA Replication and Repair. Annu Rev Biochem 2018; 87:263-294. [PMID: 29709199 PMCID: PMC6076887 DOI: 10.1146/annurev-biochem-062917-012415] [Citation(s) in RCA: 255] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genomic instability in disease and its fidelity in health depend on the DNA damage response (DDR), regulated in part from the complex of meiotic recombination 11 homolog 1 (MRE11), ATP-binding cassette-ATPase (RAD50), and phosphopeptide-binding Nijmegen breakage syndrome protein 1 (NBS1). The MRE11-RAD50-NBS1 (MRN) complex forms a multifunctional DDR machine. Within its network assemblies, MRN is the core conductor for the initial and sustained responses to DNA double-strand breaks, stalled replication forks, dysfunctional telomeres, and viral DNA infection. MRN can interfere with cancer therapy and is an attractive target for precision medicine. Its conformations change the paradigm whereby kinases initiate damage sensing. Delineated results reveal kinase activation, posttranslational targeting, functional scaffolding, conformations storing binding energy and enabling access, interactions with hub proteins such as replication protein A (RPA), and distinct networks at DNA breaks and forks. MRN biochemistry provides prototypic insights into how it initiates, implements, and regulates multifunctional responses to genomic stress.
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Affiliation(s)
- Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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28
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Valero J, Pal N, Dhakal S, Walter NG, Famulok M. A bio-hybrid DNA rotor-stator nanoengine that moves along predefined tracks. NATURE NANOTECHNOLOGY 2018; 13:496-503. [PMID: 29632399 PMCID: PMC5994166 DOI: 10.1038/s41565-018-0109-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 03/01/2018] [Indexed: 05/25/2023]
Abstract
Biological motors are highly complex protein assemblies that generate linear or rotary motion, powered by chemical energy. Synthetic motors based on DNA nanostructures, bio-hybrid designs or synthetic organic chemistry have been assembled. However, unidirectionally rotating biomimetic wheel motors with rotor-stator units that consume chemical energy are elusive. Here, we report a bio-hybrid nanoengine consisting of a catalytic stator that unidirectionally rotates an interlocked DNA wheel, powered by NTP hydrolysis. The engine consists of an engineered T7 RNA polymerase (T7RNAP-ZIF) attached to a dsDNA nanoring that is catenated to a rigid rotating dsDNA wheel. The wheel motor produces long, repetitive RNA transcripts that remain attached to the engine and are used to guide its movement along predefined ssDNA tracks arranged on a DNA nanotube. The simplicity of the design renders this walking nanoengine adaptable to other biological nanoarchitectures, facilitating the construction of complex bio-hybrid structures that achieve NTP-driven locomotion.
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Affiliation(s)
- Julián Valero
- LIMES Program Unit Chemical Biology & Medicinal Chemistry, c/o Kekulé Institut für Organische Chemie und Biochemie, University of Bonn, Bonn, Germany
- Center of Advanced European Studies and Research (CAESAR), Bonn, Germany
| | - Nibedita Pal
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Soma Dhakal
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Michael Famulok
- LIMES Program Unit Chemical Biology & Medicinal Chemistry, c/o Kekulé Institut für Organische Chemie und Biochemie, University of Bonn, Bonn, Germany.
- Center of Advanced European Studies and Research (CAESAR), Bonn, Germany.
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29
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Moiani D, Ronato DA, Brosey CA, Arvai AS, Syed A, Masson JY, Petricci E, Tainer JA. Targeting Allostery with Avatars to Design Inhibitors Assessed by Cell Activity: Dissecting MRE11 Endo- and Exonuclease Activities. Methods Enzymol 2018. [PMID: 29523233 DOI: 10.1016/bs.mie.2017.11.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
For inhibitor design, as in most research, the best system is question dependent. We suggest structurally defined allostery to design specific inhibitors that target regions beyond active sites. We choose systems allowing efficient quality structures with conformational changes as optimal for structure-based design to optimize inhibitors. We maintain that evolutionarily related targets logically provide molecular avatars, where this Sanskrit term for descent includes ideas of functional relationships and of being a physical embodiment of the target's essential features without requiring high sequence identity. Appropriate biochemical and cell assays provide quantitative measurements, and for biomedical impacts, any inhibitor's activity should be validated in human cells. Specificity is effectively shown empirically by testing if mutations blocking target activity remove cellular inhibitor impact. We propose this approach to be superior to experiments testing for lack of cross-reactivity among possible related enzymes, which is a challenging negative experiment. As an exemplary avatar system for protein and DNA allosteric conformational controls, we focus here on developing separation-of-function inhibitors for meiotic recombination 11 nuclease activities. This was achieved not by targeting the active site but rather by geometrically impacting loop motifs analogously to ribosome antibiotics. These loops are neighboring the dimer interface and active site act in sculpting dsDNA and ssDNA into catalytically competent complexes. One of our design constraints is to preserve DNA substrate binding to geometrically block competing enzymes and pathways from the damaged site. We validate our allosteric approach to controlling outcomes in human cells by reversing the radiation sensitivity and genomic instability in BRCA mutant cells.
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Affiliation(s)
- Davide Moiani
- The University of Texas, M.D. Anderson Cancer Center, Houston, TX, United States
| | - Daryl A Ronato
- Genome Stability Laboratory, CHU de Québec Research Center, Québec City, QC, Canada; Laval University Cancer Research Center, Québec City, QC, Canada
| | - Chris A Brosey
- The University of Texas, M.D. Anderson Cancer Center, Houston, TX, United States
| | - Andrew S Arvai
- The Scripps Research Institute, La Jolla, CA, United States
| | - Aleem Syed
- The University of Texas, M.D. Anderson Cancer Center, Houston, TX, United States
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, Québec City, QC, Canada; Laval University Cancer Research Center, Québec City, QC, Canada
| | | | - John A Tainer
- The University of Texas, M.D. Anderson Cancer Center, Houston, TX, United States; Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
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30
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Song B, Hamdan SM, Hingorani MM. Positioning the 5'-flap junction in the active site controls the rate of flap endonuclease-1-catalyzed DNA cleavage. J Biol Chem 2018; 293:4792-4804. [PMID: 29462789 DOI: 10.1074/jbc.ra117.001137] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 02/08/2018] [Indexed: 12/14/2022] Open
Abstract
Flap endonucleases catalyze cleavage of single-stranded DNA flaps formed during replication, repair, and recombination and are therefore essential for genome processing and stability. Recent crystal structures of DNA-bound human flap endonuclease (hFEN1) offer new insights into how conformational changes in the DNA and hFEN1 may facilitate the reaction mechanism. For example, previous biochemical studies of DNA conformation performed under non-catalytic conditions with Ca2+ have suggested that base unpairing at the 5'-flap:template junction is an important step in the reaction, but the new structural data suggest otherwise. To clarify the role of DNA changes in the kinetic mechanism, we measured a series of transient steps, from substrate binding to product release, during the hFEN1-catalyzed reaction in the presence of Mg2+ We found that whereas hFEN1 binds and bends DNA at a fast, diffusion-limited rate, much slower Mg2+-dependent conformational changes in DNA around the active site are subsequently necessary and rate-limiting for 5'-flap cleavage. These changes are reported overall by fluorescence of 2-aminopurine at the 5'-flap:template junction, indicating that local DNA distortion (e.g. disruption of base stacking observed in structures), associated with positioning the 5'-flap scissile phosphodiester bond in the hFEN1 active site, controls catalysis. hFEN1 residues with distinct roles in the catalytic mechanism, including those binding metal ions (Asp-34 and Asp-181), steering the 5'-flap through the active site and binding the scissile phosphate (Lys-93 and Arg-100), and stacking against the base 5' to the scissile phosphate (Tyr-40), all contribute to these rate-limiting conformational changes, ensuring efficient and specific cleavage of 5'-flaps.
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Affiliation(s)
- Bo Song
- Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut 06459
| | - Samir M Hamdan
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Manju M Hingorani
- Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut 06459.
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31
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Tainer JA. Uncovering the secrets of protein interactions with the DNA enforcing genomic stability. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 127:89-92. [PMID: 28709479 DOI: 10.1016/j.pbiomolbio.2017.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Holcombe Blvd., Houston, TX 77030, United States; SIBYLS, Advanced Light Source, Lawrence Berkeley National Lab, United States. http://bl1231.als.lbl.gov
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32
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Phosphate steering by Flap Endonuclease 1 promotes 5'-flap specificity and incision to prevent genome instability. Nat Commun 2017; 8:15855. [PMID: 28653660 PMCID: PMC5490271 DOI: 10.1038/ncomms15855] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/05/2017] [Indexed: 12/13/2022] Open
Abstract
DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5′-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5′-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5′polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via ‘phosphate steering’, basic residues energetically steer an inverted ss 5′-flap through a gateway over FEN1’s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA)n repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5′-flap specificity and catalysis, preventing genomic instability. Flap Endonuclease 1 is a DNA replication and repair enzyme indispensable for maintaining genomic stability. Here the authors provide mechanistic details on how FEN1 selects for 5′-flaps and promotes catalysis to avoid large-scale repeat expansion by a process termed ‘phosphate steering’.
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