1
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Lee D, Kim J, Lee G. Simple methods to determine the dissociation constant, K d. Mol Cells 2024; 47:100112. [PMID: 39293742 DOI: 10.1016/j.mocell.2024.100112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 09/08/2024] [Accepted: 09/09/2024] [Indexed: 09/20/2024] Open
Abstract
The determination of the dissociation constant (Kd) is pivotal in biochemistry and pharmacology for understanding binding affinities in chemical reactions, which is crucial for drug development and comprehending biological systems. Here, we introduce a single-molecule fluorescence resonance energy transfer-based method for determining Kd, alongside the conventional electrophoretic mobility shift assay method of Kd, offering insights into thermodynamic interactions between proteins and substrates. The single-molecule fluorescence resonance energy transfer approach is highlighted for its ability to accurately measure binding and dissociation kinetics through fluorescence labeling and the intrinsic nature of protein-DNA interactions, representing a significant advancement in the fields of molecular biology and pharmacology.
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Affiliation(s)
- Donghun Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Juwon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Gwangrog Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea.
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2
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Shiekh S, Feldt D, Jack A, Kodikara SG, Alfehaid J, Pasha S, Yildiz A, Balci H. Protection of the Telomeric Junction by the Shelterin Complex. J Am Chem Soc 2024; 146:25158-25165. [PMID: 39207958 PMCID: PMC11404488 DOI: 10.1021/jacs.4c08649] [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] [Indexed: 09/04/2024]
Abstract
Shelterin serves critical roles in suppressing superfluous DNA damage repair pathways on telomeres. The junction between double-stranded telomeric tracts (dsTEL) and single-stranded telomeric overhang (ssTEL) is the most accessible region of the telomeric DNA. The shelterin complex contains dsTEL and ssTEL binding proteins and can protect this junction by bridging the ssTEL and dsTEL tracts. To test this possibility, we monitored shelterin binding to telomeric DNA substrates with varying ssTEL and dsTEL lengths and quantified its impact on telomere accessibility using single-molecule fluorescence microscopy methods in vitro. We identified the first dsTEL repeat nearest the junction as the preferred binding site for creating the shelterin bridge. Shelterin requires at least two ssTEL repeats, while the POT1 subunit of shelterin that binds to ssTEL requires longer ssTEL tracts for stable binding to telomeres and effective protection of the junction region. The ability of POT1 to protect the junction is significantly enhanced by the 5'-phosphate at the junction. Collectively, our results show that shelterin enhances the binding stability of POT1 to ssTEL and provides more effective protection compared with POT1 alone by bridging single- and double-stranded telomeric tracts.
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Affiliation(s)
- Sajad Shiekh
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Darion Feldt
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Amanda Jack
- Biophysics Graduate Group, University of California, Berkeley, California 94720, United States
| | - Sineth G Kodikara
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Janan Alfehaid
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Sabaha Pasha
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, California 94720, United States
- Physics Department, University of California, Berkeley, California 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
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3
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Song E, Han S, Uhm H, Kang C, Hohng S. Single-mode termination of phage transcriptions, disclosing bacterial adaptation for facilitated reinitiations. Nucleic Acids Res 2024; 52:9092-9102. [PMID: 39011892 PMCID: PMC11347151 DOI: 10.1093/nar/gkae620] [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: 05/16/2024] [Revised: 06/24/2024] [Accepted: 07/03/2024] [Indexed: 07/17/2024] Open
Abstract
Bacterial and bacteriophage RNA polymerases (RNAPs) have divergently evolved and share the RNA hairpin-dependent intrinsic termination of transcription. Here, we examined phage T7, T3 and SP6 RNAP terminations utilizing the single-molecule fluorescence assays we had developed for bacterial terminations. We discovered the phage termination mode or outcome is virtually single with decomposing termination. Therein, RNAP is displaced forward along DNA and departs both RNA and DNA for one-step decomposition, three-dimensional diffusion and reinitiation at any promoter. This phage displacement-mediated decomposing termination is much slower than readthrough and appears homologous with the bacterial one. However, the phage sole mode of termination contrasts with the bacterial dual mode, where both decomposing and recycling terminations occur compatibly at any single hairpin- or Rho-dependent terminator. In the bacterial recycling termination, RNA is sheared from RNA·DNA hybrid, and RNAP remains bound to DNA for one-dimensional diffusion, which enables facilitated recycling for reinitiation at the nearest promoter located downstream or upstream in the sense or antisense orientation. Aligning with proximity of most terminators to adjacent promoters in bacterial genomes, the shearing-mediated recycling termination could be bacterial adaptation for the facilitated reinitiations repeated at a promoter for accelerated expression and coupled at adjoining promoters for coordinated regulation.
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Affiliation(s)
- Eunho Song
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Sun Han
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Heesoo Uhm
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Changwon Kang
- Department of Biological Sciences, and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
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4
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Shiekh S, Feldt D, Jack A, Kodikara SG, Alfehaid J, Pasha S, Yildiz A, Balci H. Protection of the Telomeric Junction by the Shelterin Complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.18.608453. [PMID: 39229120 PMCID: PMC11370466 DOI: 10.1101/2024.08.18.608453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Shelterin serves critical roles in suppressing superfluous DNA damage repair pathways on telomeres. The junction between double-stranded telomeric tracts (dsTEL) and single-stranded telomeric overhang (ssTEL) is the most accessible region of the telomeric DNA. The shelterin complex contains dsTEL and ssTEL binding proteins and can protect this junction by bridging between the ssTEL and dsTEL tracts. To test this possibility, we monitored shelterin binding to telomeric DNA substrates with varying ssTEL and dsTEL lengths and quantified its impact on telomere accessibility using single-molecule fluorescence microscopy methods in vitro. We identified the first dsTEL repeat nearest to the junction as the preferred binding site for creating the shelterin bridge. Shelterin requires at least two ssTEL repeats while the POT1 subunit of shelterin that binds to ssTEL requires longer ssTEL tracts for stable binding to telomeres and effective protection of the junction region. The ability of POT1 to protect the junction is significantly enhanced by the 5'-phosphate at the junction. Collectively, our results show that shelterin enhances the binding stability of POT1 to ssTEL and provides more effective protection compared to POT1 alone by bridging single- and double-stranded telomeric tracts.
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Affiliation(s)
- Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Darion Feldt
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Amanda Jack
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
| | | | - Janan Alfehaid
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Sabaha Pasha
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
- Physics Department, University of California, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
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5
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Wu JK, Lee YY, Hung H, Chang YP, Tai MH, Fan HF. Binding Behavior of Human Hepatoma-Derived Growth Factor on SMYD1. J Phys Chem B 2024; 128:7722-7735. [PMID: 39091133 PMCID: PMC11331505 DOI: 10.1021/acs.jpcb.4c01854] [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: 03/21/2024] [Revised: 07/21/2024] [Accepted: 07/22/2024] [Indexed: 08/04/2024]
Abstract
The protein-induced fluorescence change technique was employed to investigate the interactions between proteins and their DNA substrates modified with the Cy3 fluorophore. It has been reported that the human hepatoma-derived growth factor (HDGF), containing the chromatin-associated N-terminal proline-tryptophan-tryptophan-proline (PWWP) domain (the N-terminal 100 amino acids of HDGF) capable of binding the SMYD1 promoter, participates in various cellular processes and is involved in human cancer. This project investigated the specific binding behavior of HDGF, the PWWP domain, and the C140 domain (the C-terminal 140 amino acids of HDGF) sequentially using protein-induced fluorescence change. We found that the binding of HDGF and its related proteins on Cy3-labeled 15 bp SMYD1 dsDNA will cause a significant decrease in the recorded Cy3 fluorophore intensity, indicating the occurrence of protein-induced fluorescence quenching. The dissociation equilibrium constant was determined by fitting the bound fraction curve to a binding model. An approximate 10-time weaker SMYD1 binding affinity of the PWWP domain was found in comparison to HDGF. Moreover, the PWWP domain is required for DNA binding, and the C140 domain can enhance the DNA binding affinity. Furthermore, we found that the C140 domain can regulate the sequence-specific binding capability of HDGF on SMYD1.
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Affiliation(s)
- Jan-Kai Wu
- Institute
of Medical Science and Technology, National
Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department
of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Aerosol
Science Research Center, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
| | - Ying-ying Lee
- Institute
of Medical Science and Technology, National
Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department
of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Aerosol
Science Research Center, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
| | - Hsin Hung
- Institute
of Medical Science and Technology, National
Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department
of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Aerosol
Science Research Center, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
| | - Yuan-Ping Chang
- Institute
of Medical Science and Technology, National
Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Aerosol
Science Research Center, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
| | - Ming-Hong Tai
- Institute
of Biomedical Science, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
| | - Hsiu-Fang Fan
- Institute
of Medical Science and Technology, National
Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Department
of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Aerosol
Science Research Center, National Sun Yat-sen
University, Kaohsiung 80424, Taiwan
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6
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Saedi Z, Masroor MJ, Jahangiri-Manesh A, Rezaei A, Siskova K, Nikkhah M. A Label-Free Sensor Array Based on Carbon Quantum Dots for Detection of α-Synuclein Oligomers in Saliva. Anal Chem 2024. [PMID: 39034918 DOI: 10.1021/acs.analchem.4c00874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
Salivary oligomeric α-synuclein (α-Syn) has been introduced as a promising biomarker for the diagnosis of Parkinson's disease. Herein, a fluorescence sensor array based on three carbon quantum dots (CQDs) with different surface functional groups was developed for the identification and quantification of salivary α-Syn oligomers. Each of the CQDs generated a different fluorescence response to the target analyte, and the responses were analyzed by NPLS-DA to create a unique response pattern for the target analyte. The developed three-element sensor array showed a linear response to α-Syn oligomers in the range of 0.5-32 μg/mL and a detection limit (LOD) of 0.5 μg/mL, with a cross-validation accuracy of 92% in aqueous solution. The sensor array could detect the analyte in a mixture of different proteins and in the complex medium of saliva, with the LOD of 0.3 μg/mL indicating the massive potential of CQD arrays for developing sensitive, simple, inexpensive, and label-free sensing platforms.
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Affiliation(s)
- Zeinab Saedi
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, 14115-154 Tehran, Iran
| | - Mohammad Javad Masroor
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, 14115-154 Tehran, Iran
| | - Atieh Jahangiri-Manesh
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, 14115-154 Tehran, Iran
| | - Aram Rezaei
- Nano Drug Delivery Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, 6715847141 Kermanshah, Iran
| | - Karolina Siskova
- Department of Experimental Physics, Faculty of Science, Palacky University, CZ-7779 00 Olomouc, Czech Republic
| | - Maryam Nikkhah
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, 14115-154 Tehran, Iran
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7
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Peixoto ML, Madan E. Unraveling the complexity: Advanced methods in analyzing DNA, RNA, and protein interactions. Adv Cancer Res 2024; 163:251-302. [PMID: 39271265 DOI: 10.1016/bs.acr.2024.06.010] [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: 09/15/2024]
Abstract
Exploring the intricate interplay within and between nucleic acids, as well as their interactions with proteins, holds pivotal significance in unraveling the molecular complexities steering cancer initiation and progression. To investigate these interactions, a diverse array of highly specific and sensitive molecular techniques has been developed. The selection of a particular technique depends on the specific nature of the interactions. Typically, researchers employ an amalgamation of these different techniques to obtain a comprehensive and holistic understanding of inter- and intramolecular interactions involving DNA-DNA, RNA-RNA, DNA-RNA, or protein-DNA/RNA. Examining nucleic acid conformation reveals alternative secondary structures beyond conventional ones that have implications for cancer pathways. Mutational hotspots in cancer often lie within sequences prone to adopting these alternative structures, highlighting the importance of investigating intra-genomic and intra-transcriptomic interactions, especially in the context of mutations, to deepen our understanding of oncology. Beyond these intramolecular interactions, the interplay between DNA and RNA leads to formations like DNA:RNA hybrids (known as R-loops) or even DNA:DNA:RNA triplex structures, both influencing biological processes that ultimately impact cancer. Protein-nucleic acid interactions are intrinsic cellular phenomena crucial in both normal and pathological conditions. In particular, genetic mutations or single amino acid variations can alter a protein's structure, function, and binding affinity, thus influencing cancer progression. It is thus, imperative to understand the differences between wild-type (WT) and mutated (MT) genes, transcripts, and proteins. The review aims to summarize the frequently employed methods and techniques for investigating interactions involving nucleic acids and proteins, highlighting recent advancements and diverse adaptations of each technique.
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Affiliation(s)
- Maria Leonor Peixoto
- Champalimaud Center for the Unknown, Lisbon, Portugal; Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Esha Madan
- Department of Surgery, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States; Massey Comprehensive Cancer Center, Virginia Commonwealth University, Richmond, VA, United States; VCU Institute of Molecular Medicine, Department of Human and Molecular Genetics, Virginia Commonwealth University, School of Medicine, Richmond, VA, United States.
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8
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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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9
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Abbas A, Prajapati RK, Aalto-Setälä E, Baykov AA, Malinen AM. Aflatoxin biosynthesis regulators AflR and AflS: DNA binding affinity, stoichiometry, and kinetics. Biochem J 2024; 481:805-821. [PMID: 38829003 DOI: 10.1042/bcj20240084] [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] [Received: 02/28/2024] [Revised: 05/29/2024] [Accepted: 06/03/2024] [Indexed: 06/05/2024]
Abstract
Aflatoxins (AFs), potent foodborne carcinogens produced by Aspergillus fungi, pose significant health risks worldwide and present challenges to food safety and productivity in the food chain. Novel strategies for disrupting AF production, cultivating resilient crops, and detecting contaminated food are urgently needed. Understanding the regulatory mechanisms of AF production is pivotal for targeted interventions to mitigate toxin accumulation in food and feed. The gene cluster responsible for AF biosynthesis encodes biosynthetic enzymes and pathway-specific regulators, notably AflR and AflS. While AflR, a DNA-binding protein, activates gene transcription within the cluster, AflS enhances AF production through mechanisms that are not fully understood. In this study, we developed protocols to purify recombinant AflR and AflS proteins and utilized multiple assays to characterize their interactions with DNA. Our biophysical analysis indicated that AflR and AflS form a complex. AflS exhibited no DNA-binding capability on its own but unexpectedly reduced the DNA-binding affinity of AflR. Additionally, we found that AflR achieves its binding specificity through a mechanism in which either two copies of AflR or its complex with AflS bind to target sites on DNA in a highly cooperative manner. The estimated values of the interaction parameters of AflR, AflS and DNA target sites constitute a fundamental framework against which the function and mechanisms of other AF biosynthesis regulators can be compared.
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Affiliation(s)
- Asmaa Abbas
- Department of Life Technologies, University of Turku, Turku, Finland
| | | | - Emil Aalto-Setälä
- Department of Life Technologies, University of Turku, Turku, Finland
| | - Alexander A Baykov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Anssi M Malinen
- Department of Life Technologies, University of Turku, Turku, Finland
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10
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Szatko M, Forysiak W, Kozub S, Andruniów T, Szweda R. Revealing the Effect of Stereocontrol on Intermolecular Interactions between Abiotic, Sequence-Defined Polyurethanes and a Ligand. ACS Biomater Sci Eng 2024; 10:3727-3738. [PMID: 38804015 PMCID: PMC11167595 DOI: 10.1021/acsbiomaterials.4c00456] [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: 03/07/2024] [Revised: 04/26/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
The development of precision polymer synthesis has facilitated access to a diverse library of abiotic structures wherein chiral monomers are positioned at specific locations within macromolecular chains. These structures are anticipated to exhibit folding characteristics similar to those of biotic macromolecules and possess comparable functionalities. However, the extensive sequence space and numerous variables make selecting a sequence with the desired function challenging. Therefore, revealing sequence-function dependencies and developing practical tools are necessary to analyze their conformations and molecular interactions. In this study, we investigate the effect of stereochemistry, which dictates the spatial location of backbone and pendant groups, on the interaction between sequence-defined oligourethanes and bisphenol A ligands. Various methods are explored to analyze the receptor-like properties of model oligomers and the ligand. The accuracy of molecular dynamics simulations and experimental techniques is assessed to uncover the impact of discrete changes in stereochemical arrangements on the structures of the resulting complexes and their binding strengths. Detailed computational investigations providing atomistic details show that the formed complexes demonstrate significant structural diversity depending on the sequence of stereocenters, thus affecting the oligomer-ligand binding strength. Among the tested techniques, the fluorescence spectroscopy data, fitted to the Stern-Volmer equation, are consistently aligned with the calculations, thus validating the developed simulation methodology. The developed methodology opens a way to engineer the structure of sequence-defined oligomers with receptor-like functionality to explore their practical applications, e.g., as sensory materials.
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Affiliation(s)
- Maksymilian Szatko
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, 54-066 Wroclaw, Poland
- Department
of Chemistry, Wrocław University of
Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Weronika Forysiak
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, 54-066 Wroclaw, Poland
- Faculty
of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Sara Kozub
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, 54-066 Wroclaw, Poland
| | - Tadeusz Andruniów
- Department
of Chemistry, Wrocław University of
Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Roza Szweda
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, 54-066 Wroclaw, Poland
- Center
for Advanced Technologies, Adam Mickiewicz
University, Uniwersytetu Poznańskiego 8, 61-614 Poznan, Poland
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11
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Nguyen B, Hsieh J, Fischer CJ, Lohman TM. Subunit Communication within Dimeric SF1 DNA Helicases. J Mol Biol 2024; 436:168578. [PMID: 38648969 PMCID: PMC11128345 DOI: 10.1016/j.jmb.2024.168578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/11/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Abstract
Monomers of the Superfamily (SF) 1 helicases, E. coli Rep and UvrD, can translocate directionally along single stranded (ss) DNA, but must be activated to function as helicases. In the absence of accessory factors, helicase activity requires Rep and UvrD homo-dimerization. The ssDNA binding sites of SF1 helicases contain a conserved aromatic amino acid (Trp250 in Rep and Trp256 in UvrD) that stacks with the DNA bases. Here we show that mutation of this Trp to Ala eliminates helicase activity in both Rep and UvrD. Rep(W250A) and UvrD(W256A) can still dimerize, bind DNA, and monomers still retain ATP-dependent ssDNA translocase activity, although with ∼10-fold lower rates and lower processivities than wild type monomers. Although neither wtRep monomers nor Rep(W250A) monomers possess helicase activity by themselves, using both ensemble and single molecule methods, we show that helicase activity is achieved upon formation of a Rep(W250A)/wtRep hetero-dimer. An ATPase deficient Rep monomer is unable to activate a wtRep monomer indicating that ATPase activity is needed in both subunits of the Rep hetero-dimer. We find the same results with E. coli UvrD and its equivalent mutant (UvrD(W256A)). Importantly, Rep(W250A) is unable to activate a wtUvrD monomer and UvrD(W256A) is unable to activate a wtRep monomer indicating that specific dimer interactions are required for helicase activity. We also demonstrate subunit communication within the dimer by virtue of Trp fluorescence signals that only are present within the Rep dimer, but not the monomers. These results bear on proposed subunit switching mechanisms for dimeric helicase activity.
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Affiliation(s)
- Binh Nguyen
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave, Saint Louis, MO 63110, USA
| | - John Hsieh
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave, Saint Louis, MO 63110, USA; Biochemistry & Biophysics, Blueprint Medicines, Cambridge, MA 02139, USA
| | | | - Timothy M Lohman
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave, Saint Louis, MO 63110, USA.
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12
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Agyemang E, Gonneville AN, Tiruvadi-Krishnan S, Lamichhane R. Exploring GPCR conformational dynamics using single-molecule fluorescence. Methods 2024; 226:35-48. [PMID: 38604413 PMCID: PMC11098685 DOI: 10.1016/j.ymeth.2024.03.011] [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: 12/06/2023] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/13/2024] Open
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that transmit specific external stimuli into cells by changing their conformation. This conformational change allows them to couple and activate G-proteins to initiate signal transduction. A critical challenge in studying and inferring these structural dynamics arises from the complexity of the cellular environment, including the presence of various endogenous factors. Due to the recent advances in cell-expression systems, membrane-protein purification techniques, and labeling approaches, it is now possible to study the structural dynamics of GPCRs at a single-molecule level both in vitro and in live cells. In this review, we discuss state-of-the-art techniques and strategies for expressing, purifying, and labeling GPCRs in the context of single-molecule research. We also highlight four recent studies that demonstrate the applications of single-molecule microscopy in revealing the dynamics of GPCRs. These techniques are also useful as complementary methods to verify the results obtained from other structural biology tools like cryo-electron microscopy and x-ray crystallography.
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Affiliation(s)
- Eugene Agyemang
- UT-ORNL Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996, USA
| | - Alyssa N Gonneville
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Sriram Tiruvadi-Krishnan
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Rajan Lamichhane
- UT-ORNL Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996, USA; Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
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13
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Kuppa S, Corless E, Caldwell CC, Spies M, Antony E. Generation of site-specifically labelled fluorescent human XPA to investigate DNA binding dynamics during nucleotide excision repair. Methods 2024; 224:47-53. [PMID: 38387709 PMCID: PMC10960328 DOI: 10.1016/j.ymeth.2024.02.006] [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: 11/04/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 02/24/2024] Open
Abstract
Nucleotide excision repair (NER) promotes genomic integrity by removing bulky DNA adducts introduced by external factors such as ultraviolet light. Defects in NER enzymes are associated with pathological conditions such as Xeroderma Pigmentosum, trichothiodystrophy, and Cockayne syndrome. A critical step in NER is the binding of the Xeroderma Pigmentosum group A protein (XPA) to the ss/ds DNA junction. To better capture the dynamics of XPA interactions with DNA during NER we have utilized the fluorescence enhancement through non-canonical amino acids (FEncAA) approach. 4-azido-L-phenylalanine (4AZP or pAzF) was incorporated at Arg-158 in human XPA and conjugated to Cy3 using strain-promoted azide-alkyne cycloaddition. The resulting fluorescent XPA protein (XPACy3) shows no loss in DNA binding activity and generates a robust change in fluorescence upon binding to DNA. Here we describe methods to generate XPACy3 and detail in vitro experimental conditions required to stably maintain the protein during biochemical and biophysical studies.
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Affiliation(s)
- Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Elliot Corless
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Colleen C Caldwell
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Maria Spies
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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14
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Patrick EM, Yadav R, Senanayake K, Cotter K, Putnam AA, Jankowsky E, Comstock MJ. High-resolution fleezers reveal duplex opening and stepwise assembly by an oligomer of the DEAD-box helicase Ded1p. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582829. [PMID: 38496418 PMCID: PMC10942383 DOI: 10.1101/2024.02.29.582829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
DEAD-box RNA helicases are ubiquitous in all domains of life where they bind and remodel RNA and RNA-protein complexes. DEAD-box helicases unwind RNA duplexes by local opening of helical regions without directional movement through the duplexes and some of these enzymes, including Ded1p from Saccharomyces cerevisiae, oligomerize to effectively unwind RNA duplexes. Whether and how DEAD-box helicases coordinate oligomerization and unwinding is not known and it is unclear how many base pairs are actively opened. Using high-resolution optical tweezers and fluorescence, we reveal a highly dynamic and stochastic process of multiple Ded1p protomers assembling on and unwinding an RNA duplex. One Ded1p protomer binds to a duplex-adjacent ssRNA tail and promotes binding and subsequent unwinding of the duplex by additional Ded1p protomers in 4-6 bp steps. The data also reveal rapid duplex unwinding and rezipping linked with binding and dissociation of individual protomers and coordinated with the ATP hydrolysis cycle.
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15
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Kaushik V, Chadda R, Kuppa S, Pokhrel N, Vayyeti A, Grady S, Arnatt C, Antony E. Fluorescent human RPA to track assembly dynamics on DNA. Methods 2024; 223:95-105. [PMID: 38301751 PMCID: PMC10923064 DOI: 10.1016/j.ymeth.2024.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024] Open
Abstract
DNA metabolic processes including replication, repair, recombination, and telomere maintenance occur on single-stranded DNA (ssDNA). In each of these complex processes, dozens of proteins function together on the ssDNA template. However, when double-stranded DNA is unwound, the transiently open ssDNA is protected and coated by the high affinity heterotrimeric ssDNA binding Replication Protein A (RPA). Almost all downstream DNA processes must first remodel/remove RPA or function alongside to access the ssDNA occluded under RPA. Formation of RPA-ssDNA complexes trigger the DNA damage checkpoint response and is a key step in activating most DNA repair and recombination pathways. Thus, in addition to protecting the exposed ssDNA, RPA functions as a gatekeeper to define functional specificity in DNA maintenance and genomic integrity. RPA achieves functional dexterity through a multi-domain architecture utilizing several DNA binding and protein-interaction domains connected by flexible linkers. This flexible and modular architecture enables RPA to adopt a myriad of configurations tailored for specific DNA metabolic roles. To experimentally capture the dynamics of the domains of RPA upon binding to ssDNA and interacting proteins we here describe the generation of active site-specific fluorescent versions of human RPA (RPA) using 4-azido-L-phenylalanine (4AZP) incorporation and click chemistry. This approach can also be applied to site-specific modifications of other multi-domain proteins. Fluorescence-enhancement through non-canonical amino acids (FEncAA) and Förster Resonance Energy Transfer (FRET) assays for measuring dynamics of RPA on DNA are also described. The fluorescent human RPA described here will enable high-resolution structure-function analysis of RPA-ssDNA interactions.
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Affiliation(s)
- Vikas Kaushik
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Abhinav Vayyeti
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Scott Grady
- Department of Chemistry, St. Louis University, St. Louis, MO 63103, USA
| | - Chris Arnatt
- Department of Chemistry, St. Louis University, St. Louis, MO 63103, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA.
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16
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Lou Y, Woodson SA. Co-transcriptional folding of the glmS ribozyme enables a rapid response to metabolite. Nucleic Acids Res 2024; 52:872-884. [PMID: 38000388 PMCID: PMC10810187 DOI: 10.1093/nar/gkad1120] [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: 08/24/2023] [Revised: 10/24/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
The glmS ribozyme riboswitch, located in the 5' untranslated region of the Bacillus subtilis glmS messenger RNA (mRNA), regulates cell wall biosynthesis through ligand-induced self-cleavage and decay of the glmS mRNA. Although self-cleavage of the refolded glmS ribozyme has been studied extensively, it is not known how early the ribozyme folds and self-cleaves during transcription. Here, we combine single-molecule fluorescence with kinetic modeling to show that self-cleavage can occur during transcription before the ribozyme is fully synthesized. Moreover, co-transcriptional folding of the RNA at a physiological elongation rate allows the ribozyme catalytic core to react without the downstream peripheral stability domain. Dimethyl sulfate footprinting further revealed how slow sequential folding favors formation of the native core structure through fraying of misfolded helices and nucleation of a native pseudoknot. Ribozyme self-cleavage at an early stage of transcription may benefit glmS regulation in B. subtilis, as it exposes the mRNA to exoribonuclease before translation of the open reading frame can begin. Our results emphasize the importance of co-transcriptional folding of RNA tertiary structure for cis-regulation of mRNA stability.
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Affiliation(s)
- Yuan Lou
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Sarah A Woodson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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17
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Hwang J, Palmer B, Myong S. Single-molecule observation of G-quadruplex and R-loop formation induced by transcription. Methods Enzymol 2024; 695:71-88. [PMID: 38521591 DOI: 10.1016/bs.mie.2024.01.001] [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: 03/25/2024]
Abstract
Potential G-quadruplex forming sequences (PQS) are enriched in cancer-related genes and immunoglobulin class-switch recombination. They are prevalent in the 5'UTR of transcriptionally active genes, thereby contributing to the regulation of gene expression. We and others previously demonstrated that the PQS located in the non-template strand leads to an R-loop formation followed by a G-quadruplex (G4) formation during transcription. These structural changes increase mRNA production. Here, we present how single-molecule technique was used to observe cotranscriptional G4 and R-loop formation and to examine the impact on transcription, particularly for the initiation and elongation stages.
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Affiliation(s)
- Jihee Hwang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA, United States
| | - Bradleigh Palmer
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, Baltimore, MD, United States
| | - Sua Myong
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA, United States; Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, Baltimore, MD, United States.
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18
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Kumar V, Chunchagatta Lakshman PK, Prasad TK, Manjunath K, Bairy S, Vasu AS, Ganavi B, Jasti S, Kamariah N. Target-based drug discovery: Applications of fluorescence techniques in high throughput and fragment-based screening. Heliyon 2024; 10:e23864. [PMID: 38226204 PMCID: PMC10788520 DOI: 10.1016/j.heliyon.2023.e23864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 12/14/2023] [Accepted: 12/14/2023] [Indexed: 01/17/2024] Open
Abstract
Target-based discovery of first-in-class therapeutics demands an in-depth understanding of the molecular mechanisms underlying human diseases. Precise measurements of cellular and biochemical activities are critical to gain mechanistic knowledge of biomolecules and their altered function in disease conditions. Such measurements enable the development of intervention strategies for preventing or treating diseases by modulation of desired molecular processes. Fluorescence-based techniques are routinely employed for accurate and robust measurements of in-vitro activity of molecular targets and for discovering novel chemical molecules that modulate the activity of molecular targets. In the current review, the authors focus on the applications of fluorescence-based high throughput screening (HTS) and fragment-based ligand discovery (FBLD) techniques such as fluorescence polarization (FP), Förster resonance energy transfer (FRET), fluorescence thermal shift assay (FTSA) and microscale thermophoresis (MST) for the discovery of chemical probe to exploring target's role in disease biology and ultimately, serve as a foundation for drug discovery. Some recent advancements in these techniques for compound library screening against important classes of drug targets, such as G-protein-coupled receptors (GPCRs) and GTPases, as well as phosphorylation- and acetylation-mediated protein-protein interactions, are discussed. Overall, this review presents a landscape of how these techniques paved the way for the discovery of small-molecule modulators and biologics against these targets for therapeutic benefits.
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Affiliation(s)
| | | | - Thazhe Kootteri Prasad
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - Kavyashree Manjunath
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - Sneha Bairy
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - Akshaya S. Vasu
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - B. Ganavi
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - Subbarao Jasti
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
| | - Neelagandan Kamariah
- Centre for Chemical Biology & Therapeutics, inStem & NCBS, Bellary Road, Bangalore, 560065, India
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19
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Kim S, Kim Y, Lee JY. Real-time single-molecule visualization using DNA curtains reveals the molecular mechanisms underlying DNA repair pathways. DNA Repair (Amst) 2024; 133:103612. [PMID: 38128155 DOI: 10.1016/j.dnarep.2023.103612] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 10/06/2023] [Accepted: 12/10/2023] [Indexed: 12/23/2023]
Abstract
The demand for direct observation of biomolecular interactions provides new insights into the molecular mechanisms underlying many biological processes. Single-molecule imaging techniques enable real-time visualization of individual biomolecules, providing direct observations of protein machines. Various single-molecule imaging techniques have been developed and have contributed to breakthroughs in biological research. One such technique is the DNA curtain, a novel, high-throughput, single-molecule platform that integrates lipid fluidity, nano-fabrication, microfluidics, and fluorescence imaging. Many DNA metabolic reactions, such as replication, transcription, and chromatin dynamics, have been studied using DNA curtains. In particular, the DNA curtain platform has been intensively applied in investigating the molecular details of DNA repair processes. This article reviews DNA curtain techniques and their applications for imaging DNA repair proteins.
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Affiliation(s)
- Subin Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Youngseo Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Ja Yil Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea.
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20
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Kaushik V, Chadda R, Kuppa S, Pokhrel N, Vayyeti A, Grady S, Arnatt C, Antony E. Fluorescent human RPA to track assembly dynamics on DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.23.568455. [PMID: 38045304 PMCID: PMC10690285 DOI: 10.1101/2023.11.23.568455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
DNA metabolic processes including replication, repair, recombination, and telomere maintenance occur on single-stranded DNA (ssDNA). In each of these complex processes, dozens of proteins function together on the ssDNA template. However, when double-stranded DNA is unwound, the transiently open ssDNA is protected and coated by the high affinity heterotrimeric ssDNA binding Replication Protein A (RPA). Almost all downstream DNA processes must first remodel/remove RPA or function alongside to access the ssDNA occluded under RPA. Formation of RPA-ssDNA complexes trigger the DNA damage checkpoint response and is a key step in activating most DNA repair and recombination pathways. Thus, in addition to protecting the exposed ssDNA, RPA functions as a gatekeeper to define functional specificity in DNA maintenance and genomic integrity. RPA achieves functional dexterity through a multi-domain architecture utilizing several DNA binding and protein-interaction domains connected by flexible linkers. This flexible and modular architecture enables RPA to adopt a myriad of configurations tailored for specific DNA metabolic roles. To experimentally capture the dynamics of the domains of RPA upon binding to ssDNA and interacting proteins we here describe the generation of active site-specific fluorescent versions of human RPA (RPA) using 4-azido-L-phenylalanine (4AZP) incorporation and click chemistry. This approach can also be applied to site-specific modifications of other multi-domain proteins. Fluorescence-enhancement through non-canonical amino acids (FEncAA) and Förster Resonance Energy Transfer (FRET) assays for measuring dynamics of RPA on DNA are also described.
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Affiliation(s)
- Vikas Kaushik
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Abhinav Vayyeti
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104
| | - Scott Grady
- Department of Chemistry, St. Louis University, St. Louis, MO 63103
| | - Chris Arnatt
- Department of Chemistry, St. Louis University, St. Louis, MO 63103
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104
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21
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Johnson RE, Murray MT, Bycraft LJ, Myler P, Wetmore SD, Manderville RA. Harnessing a 4-Formyl-Aniline Handle to Tune the Stability of a DNA Aptamer-Protein Complex via Fluorescent Surrogates. Bioconjug Chem 2023; 34:2066-2076. [PMID: 37857354 DOI: 10.1021/acs.bioconjchem.3c00373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Interactions between DNA aptamers and protein targets hold promise for the development of pharmaceuticals and diagnostics. As such, the utilization of fluorescent nucleobase surrogates in studying aptamer-protein interactions is a powerful tool due to their ability to provide site-specific information through turn-on fluorescence. Unfortunately, previously described turn-on probes serving as nucleobase replacements have only been strongly disruptive to the affinity of aptamer-protein interactions. Herein, we present a modified TBA15 aptamer for thrombin containing a fluorescent surrogate that provides site-specific turn-on emission with low nanomolar affinity. The modification, referred to as AnBtz, was substituted at position T3 and provided strong turn-on emission (Irel ≈ 4) and brightness (ε·Φ > 20 000 cm-1 M-1) with an apparent dissociation constant (Kd) of 15 nM to afford a limit of detection (LOD) of 10 nM for thrombin in 20% human serum. The probe was selected through a modular "on-strand" synthesis process that utilized a 4-formyl-aniline (4FA) handle. Using this platform, we were able to enhance the affinity of the final aptamer conjugate by ∼30-fold in comparison with the initial conjugate design. Molecular dynamics simulations provide insight into the structural basis for this phenomenon and highlight the importance of targeting hydrophobic protein binding sites with fluorescent nucleobase surrogates to create new contacts with protein targets.
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Affiliation(s)
- Ryan E Johnson
- Departments of Chemistry & Toxicology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Makay T Murray
- Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Lucas J Bycraft
- Departments of Chemistry & Toxicology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Peter Myler
- Departments of Chemistry & Toxicology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Stacey D Wetmore
- Department of Chemistry & Biochemistry, University of Lethbridge, Lethbridge, Alberta T1K 3M4, Canada
| | - Richard A Manderville
- Departments of Chemistry & Toxicology, University of Guelph, Guelph, ON N1G 2W1, Canada
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22
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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. Methods Appl Fluoresc 2023; 12:012001. [PMID: 37726007 PMCID: PMC10570931 DOI: 10.1088/2050-6120/acfb58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 07/24/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
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 ofcis/transphotoisomerisation. It is clear now that this mechanism is generally applicable to interactions with any biomolecule. 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 turning 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, United Kingdom
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, United Kingdom
| | - 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
- Biological Physics Research Group, Department of Physics, University of Oxford, Oxford, United Kingdom
- Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, Oxford, United Kingdom
| | - Harold D Kim
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States of America
| | - Marcia Levitus
- School of Molecular Sciences, Arizona State University, 551 E. University Drive, Tempe, AZ,85287, United States of America
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, United States of America
| | - Abhishek Mazumder
- CSIR-Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700032, West Bengal, India
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, W12 0HS, United Kingdom
- Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, W12 0HS, United Kingdom
| | - Fabio D Steffen
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Großhadernerstr. 2-4, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Steven W Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, United Kingdom
| | - 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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23
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Solomun T, Cordsmeier L, Hallier DC, Seitz H, Hahn MB. Interaction of a Dimeric Single-Stranded DNA-Binding Protein (G5P) with DNA Hairpins. A Molecular Beacon Study. J Phys Chem B 2023; 127:8131-8138. [PMID: 37704207 PMCID: PMC10544328 DOI: 10.1021/acs.jpcb.3c03669] [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: 05/31/2023] [Revised: 08/23/2023] [Indexed: 09/15/2023]
Abstract
Gene-V protein (G5P/GVP) is a single-stranded (ss)DNA-binding protein (SBP) of bacteriophage f1 that is required for DNA synthesis and repair. In solution, it exists as a dimer that binds two antiparallel ssDNA strands with high affinity in a cooperative manner, forming a left-handed helical protein-DNA filament. Here, we report on fluorescence studies of the interaction of G5P with different DNA oligonucleotides having a hairpin structure (molecular beacon, MB) with a seven base-pair stem (dT24-stem7, dT18-stem7), as well as with DNA oligonucleotides (dT38, dT24) without a defined secondary structure. All oligonucleotides were end-labeled with a Cy3-fluorophore and a BHQ2-quencher. In the case of DNA oligonucleotides without a secondary structure, an almost complete quenching of their strong fluorescence (with about 5% residual intensity) was observed upon the binding of G5P. This implies an exact alignment of the ends of the DNA strand(s) in the saturated complex. The interaction of the DNA hairpins with G5P led to the unzipping of the base-paired stem, as revealed by fluorescence measurements, fluorescence microfluidic mixing experiments, and electrophoretic mobility shift assay data. Importantly, the disruption of ssDNA's secondary structure agrees with the behavior of other single-stranded DNA-binding proteins (SBPs). In addition, substantial protein-induced fluorescence enhancement (PIFE) of the Cy3-fluorescence was observed.
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Affiliation(s)
- Tihomir Solomun
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
| | - Leo Cordsmeier
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
- Institut
für Chemie, Freie Universität
Berlin, Berlin 14195, Germany
| | - Dorothea C. Hallier
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
- Institut
für Biochemie und Biologie, Universität
Potsdam, Potsdam 14476, Germany
- Fraunhofer
Institut für Zelltherapie und Immunologie Institutsteil Bioanalytik
und Bioprozesse IZI-BB, Potsdam 14476, Germany
| | - Harald Seitz
- Institut
für Biochemie und Biologie, Universität
Potsdam, Potsdam 14476, Germany
- Fraunhofer
Institut für Zelltherapie und Immunologie Institutsteil Bioanalytik
und Bioprozesse IZI-BB, Potsdam 14476, Germany
| | - Marc Benjamin Hahn
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
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24
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Gidi Y, Robert A, Tordo A, Lovell TC, Ramos-Sanchez J, Sakaya A, Götte M, Cosa G. Binding and Sliding Dynamics of the Hepatitis C Virus Polymerase: Hunting the 3' Terminus. ACS Infect Dis 2023; 9:1488-1498. [PMID: 37436367 DOI: 10.1021/acsinfecdis.3c00048] [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] [Indexed: 07/13/2023]
Abstract
The hepatitis C virus (HCV) nonstructural protein 5B (NS5B) polymerase catalyzes the replication of the (+) single-stranded RNA genome of HCV. In vitro studies have shown that replication can be performed in the absence of a primer. However, the dynamics and mechanism by which NS5B locates the 3'-terminus of the RNA template to initiate de novo synthesis remain elusive. Here, we performed single-molecule fluorescence studies based on protein-induced fluorescence enhancement reporting on NS5B dynamics on a short model RNA substrate. Our results suggest that NS5B exists in a fully open conformation in solution wherefrom it accesses its binding site along RNA and then closes. Our results revealed two NS5B binding modes: an unstable one resulting in rapid dissociation, and a stable one characterized by a larger residence time on the substrate. We associate these bindings to an unproductive and productive orientation, respectively. Addition of extra mono (Na+)- and divalent (Mg2+) ions increases the mobility of NS5B along its RNA substrate. However, only Mg2+ ions induce a decrease in NS5B residence time. Dwell times of residence increase with the length of the single-stranded template, suggesting that NS5B unbinds its substrate by unthreading the template rather than by spontaneous opening.
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Affiliation(s)
- Yasser Gidi
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Anaïs Robert
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Alix Tordo
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Terri C Lovell
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Jorge Ramos-Sanchez
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Aya Sakaya
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Matthias Götte
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Gonzalo Cosa
- Department of Chemistry and Quebec Center for Applied Materials (QCAM), McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
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25
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Coñuecar R, Asela I, Rivera M, Galaz-Davison P, González-Higueras J, Hamilton GL, Engelberger F, Ramírez-Sarmiento CA, Babul J, Sanabria H, Medina E. DNA facilitates heterodimerization between human transcription factors FoxP1 and FoxP2 by increasing their conformational flexibility. iScience 2023; 26:107228. [PMID: 37485372 PMCID: PMC10362293 DOI: 10.1016/j.isci.2023.107228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 05/15/2023] [Accepted: 06/20/2023] [Indexed: 07/25/2023] Open
Abstract
Transcription factors regulate gene expression by binding to DNA. They have disordered regions and specific DNA-binding domains. Binding to DNA causes structural changes, including folding and interactions with other molecules. The FoxP subfamily of transcription factors in humans is unique because they can form heterotypic interactions without DNA. However, it is unclear how they form heterodimers and how DNA binding affects their function. We used computational and experimental methods to study the structural changes in FoxP1's DNA-binding domain when it forms a heterodimer with FoxP2. We found that FoxP1 has complex and diverse conformational dynamics, transitioning between compact and extended states. Surprisingly, DNA binding increases the flexibility of FoxP1, contrary to the typical folding-upon-binding mechanism. In addition, we observed a 3-fold increase in the rate of heterodimerization after FoxP1 binds to DNA. These findings emphasize the importance of structural flexibility in promoting heterodimerization to form transcriptional complexes.
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Affiliation(s)
- Ricardo Coñuecar
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Isabel Asela
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Maira Rivera
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
| | - Pablo Galaz-Davison
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
| | - Jorge González-Higueras
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
| | - George L. Hamilton
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Felipe Engelberger
- Institute for Drug Discovery, Leipzig University Medical School, 04107 Leipzig, Germany
| | - César A. Ramírez-Sarmiento
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
- ANID – Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
| | - Jorge Babul
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Hugo Sanabria
- Department of Physics & Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Exequiel Medina
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
- Department of Physics & Astronomy, Clemson University, Clemson, SC 29634, USA
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26
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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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27
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Cruz P, Paredes N, Asela I, Kolimi N, Molina JA, Ramírez-Sarmiento CA, Goutam R, Huang G, Medina E, Sanabria H. Domain tethering impacts dimerization and DNA-mediated allostery in the human transcription factor FoxP1. J Chem Phys 2023; 158:2890482. [PMID: 37184020 DOI: 10.1063/5.0138782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 04/25/2023] [Indexed: 05/16/2023] Open
Abstract
Transcription factors are multidomain proteins with specific DNA binding and regulatory domains. In the human FoxP subfamily (FoxP1, FoxP2, FoxP3, and FoxP4) of transcription factors, a 90 residue-long disordered region links a Leucine Zipper (ZIP)-known to form coiled-coil dimers-and a Forkhead (FKH) domain-known to form domain swapping dimers. We used replica exchange discrete molecular dynamics simulations, single-molecule fluorescence experiments, and other biophysical tools to understand how domain tethering in FoxP1 impacts dimerization at ZIP and FKH domains and how DNA binding allosterically regulates their dimerization. We found that domain tethering promotes FoxP1 dimerization but inhibits a FKH domain-swapped structure. Furthermore, our findings indicate that the linker mediates the mutual organization and dynamics of ZIP and FKH domains, forming closed and open states with and without interdomain contacts, thus highlighting the role of the linkers in multidomain proteins. Finally, we found that DNA allosterically promotes structural changes that decrease the dimerization propensity of FoxP1. We postulate that, upon DNA binding, the interdomain linker plays a crucial role in the gene regulatory function of FoxP1.
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Affiliation(s)
- Perla Cruz
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile
| | - Nicolás Paredes
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile
| | - Isabel Asela
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile
| | - Narendar Kolimi
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - José Alejandro Molina
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago 7820436, Chile
- ANID - Millennium Science Initiative Program - Millennium Institute for Integrative Biology (iBio), Santiago 7820436, Chile
| | - César A Ramírez-Sarmiento
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago 7820436, Chile
- ANID - Millennium Science Initiative Program - Millennium Institute for Integrative Biology (iBio), Santiago 7820436, Chile
| | - Rajen Goutam
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Gangton Huang
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Exequiel Medina
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
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28
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Rodgers ML, O'Brien B, Woodson SA. Small RNAs and Hfq capture unfolded RNA target sites during transcription. Mol Cell 2023; 83:1489-1501.e5. [PMID: 37116495 PMCID: PMC10176597 DOI: 10.1016/j.molcel.2023.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/11/2023] [Accepted: 03/31/2023] [Indexed: 04/30/2023]
Abstract
Small ribonucleoproteins (sRNPs) target nascent precursor RNAs to guide folding, modification, and splicing during transcription. Yet, rapid co-transcriptional folding of the RNA can mask sRNP sites, impeding target recognition and regulation. To examine how sRNPs target nascent RNAs, we monitored binding of bacterial Hfq⋅DsrA sRNPs to rpoS transcripts using single-molecule co-localization co-transcriptional assembly (smCoCoA). We show that Hfq⋅DsrA recursively samples the mRNA before transcription of the target site to poise it for base pairing with DsrA. We adapted smCoCoA to precisely measure when the target site is synthesized and revealed that Hfq⋅DsrA often binds the mRNA during target site synthesis close to RNA polymerase (RNAP). We suggest that targeting transcripts near RNAP allows an sRNP to capture a site before the transcript folds, providing a kinetic advantage over post-transcriptional targeting. We propose that other sRNPs may also use RNAP-proximal targeting to hasten recognition and regulation.
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Affiliation(s)
- Margaret L Rodgers
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Brett O'Brien
- Chemical Biology Interface Program, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sarah A Woodson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
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29
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Donovan BT, Chen H, Eek P, Meng Z, Jipa C, Tan S, Bai L, Poirier MG. Basic helix-loop-helix pioneer factors interact with the histone octamer to invade nucleosomes and generate nucleosome-depleted regions. Mol Cell 2023; 83:1251-1263.e6. [PMID: 36996811 PMCID: PMC10182836 DOI: 10.1016/j.molcel.2023.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/13/2023] [Accepted: 03/06/2023] [Indexed: 03/31/2023]
Abstract
Nucleosomes drastically limit transcription factor (TF) occupancy, while pioneer transcription factors (PFs) somehow circumvent this nucleosome barrier. In this study, we compare nucleosome binding of two conserved S. cerevisiae basic helix-loop-helix (bHLH) TFs, Cbf1 and Pho4. A cryo-EM structure of Cbf1 in complex with the nucleosome reveals that the Cbf1 HLH region can electrostatically interact with exposed histone residues within a partially unwrapped nucleosome. Single-molecule fluorescence studies show that the Cbf1 HLH region facilitates efficient nucleosome invasion by slowing its dissociation rate relative to DNA through interactions with histones, whereas the Pho4 HLH region does not. In vivo studies show that this enhanced binding provided by the Cbf1 HLH region enables nucleosome invasion and ensuing repositioning. These structural, single-molecule, and in vivo studies reveal the mechanistic basis of dissociation rate compensation by PFs and how this translates to facilitating chromatin opening inside cells.
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Affiliation(s)
- Benjamin T Donovan
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Hengye Chen
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA
| | - Priit Eek
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA
| | - Zhiyuan Meng
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Caroline Jipa
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA
| | - Song Tan
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA; Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA; Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Michael G Poirier
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA; Department of Physics, The Ohio State University, Columbus, OH 43210, USA; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
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30
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Zamel J, Chen J, Zaer S, Harris PD, Drori P, Lebendiker M, Kalisman N, Dokholyan NV, Lerner E. Structural and dynamic insights into α-synuclein dimer conformations. Structure 2023; 31:411-423.e6. [PMID: 36809765 PMCID: PMC10081966 DOI: 10.1016/j.str.2023.01.011] [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: 11/20/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 02/22/2023]
Abstract
Parkinson disease is associated with the aggregation of the protein α-synuclein. While α-synuclein can exist in multiple oligomeric states, the dimer has been a subject of extensive debates. Here, using an array of biophysical approaches, we demonstrate that α-synuclein in vitro exhibits primarily a monomer-dimer equilibrium in nanomolar concentrations and up to a few micromolars. We then use spatial information from hetero-isotopic cross-linking mass spectrometry experiments as restrains in discrete molecular dynamics simulations to obtain the ensemble structure of dimeric species. Out of eight structural sub-populations of dimers, we identify one that is compact, stable, abundant, and exhibits partially exposed β-sheet structures. This compact dimer is the only one where the hydroxyls of tyrosine 39 are in proximity that may promote dityrosine covalent linkage upon hydroxyl radicalization, which is implicated in α-synuclein amyloid fibrils. We propose that this α-synuclein dimer features etiological relevance to Parkinson disease.
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Affiliation(s)
- Joanna Zamel
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Jiaxing Chen
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Sofia Zaer
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paul David Harris
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paz Drori
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Mario Lebendiker
- Wolfson Centre for Applied Structural Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Nir Kalisman
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA; Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA; Departments of Chemistry and Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
| | - Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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31
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Satusky MJ, Johnson CV, Erie DA. Rapid, inexpensive, sequence-independent fluorescent labeling of phosphorothioate DNA. Biophys J 2023; 122:1211-1218. [PMID: 36793216 PMCID: PMC10111259 DOI: 10.1016/j.bpj.2023.02.011] [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: 08/26/2022] [Revised: 01/23/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
Fluorescently labeled oligonucleotides are powerful tools for characterizing DNA processes; however, their use is limited by the cost and sequence requirements of current labeling technologies. Here, we develop an easy, inexpensive, and sequence-independent method for site-specifically labeling DNA oligonucleotides. We utilize commercially synthesized oligonucleotides containing phosphorothioate diester(s) in which a nonbridging oxygen is replaced with a sulfur (PS-DNA). The increased nucleophilicity of the thiophosphoryl sulfur relative to the phosphoryl oxygen permits selective reactivity with iodoacetamide compounds. As such, we leverage a long-existing bifunctional linker, N,N'-bis(α-iodoacetyl)-2-2'-dithiobis(ethylamine) (BIDBE), that reacts with PS-DNAs to leave a free thiol, allowing conjugation of the wide variety of commercial maleimide-functionalized compounds. We optimized BIDBE synthesis and its attachment to PS-DNA and then fluorescently labeled the BIDBE-PS-DNA using standard protocols for labeling cysteines. We purified the individual epimers, and using single-molecule Förster resonance energy transfer (FRET), we show that the FRET efficiency is independent of the epimeric attachment. Subsequently, we demonstrate that an epimeric mixture of double-labeled Holliday junctions (HJs) can be used to characterize their conformational properties in the absence and presence of the structure-specific endonuclease Drosophila melanogaster Gen. Finally, we use a biochemical activity assay to show that this double-labeled HJ is functional for cleavage by Gen and that the double-labeled HJ allows multiple DNA species to be identified in a single experiment. In conclusion, our results indicate that dye-labeled BIDBE-PS-DNAs are comparable to commercially labeled DNAs at a significantly reduced cost. Notably, this technology could be applied to other maleimide-functionalized compounds, such as spin labels, biotin, and proteins. The sequence independence of labeling, coupled with its ease and low cost, enables unrestricted exploration of dye placement and choice, providing the potential for creation of differentially labeled DNA libraries and opening previously inaccessible experimental avenues.
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Affiliation(s)
- Matthew J Satusky
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina
| | - Caitlin V Johnson
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina
| | - Dorothy A Erie
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina.
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32
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Incicco JJ, Roy D, Stuchell-Brereton MD, Soranno A. Fluorescence Correlation Spectroscopy and Phase Separation. Methods Mol Biol 2023; 2563:161-198. [PMID: 36227473 DOI: 10.1007/978-1-0716-2663-4_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
A quantitative understanding of the forces controlling the assembly and functioning of biomolecular condensates requires the identification of phase boundaries at which condensates form as well as the determination of tie-lines. Here, we describe in detail how Fluorescence Correlation Spectroscopy (FCS) provides a versatile approach to estimate phase boundaries of single-component and multicomponent solutions as well as insights about the transport properties of the condensate.
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Affiliation(s)
- Juan Jeremías Incicco
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St. Louis, MO, USA
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St Louis, St. Louis, MO, USA
| | - Debjit Roy
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St. Louis, MO, USA
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St Louis, St. Louis, MO, USA
| | - Melissa D Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St. Louis, MO, USA
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St Louis, St. Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, St. Louis, MO, USA.
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St Louis, St. Louis, MO, USA.
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33
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Ganser LR, Ge Y, Myong S. Single-Molecule Fluorescence Methods to Study Protein-RNA Interactions Underlying Biomolecular Condensates. Methods Mol Biol 2023; 2563:149-160. [PMID: 36227472 DOI: 10.1007/978-1-0716-2663-4_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Many biomolecular condensates, including nucleoli and stress granules, form via dynamic multivalent protein-protein and protein-RNA interactions. These molecular interactions nucleate liquid-liquid phase separation (LLPS) and determine condensate properties, such as size and fluidity. Here, we outline the experimental procedures for single-molecule fluorescence experiments to probe protein-RNA interactions underlying LLPS. The experiments include single-molecule Förster (Fluorescence) resonance energy transfer (smFRET) to monitor protein-induced conformational changes in the RNA, protein-induced fluorescence enhancement (PIFE) to measure protein-RNA encounters, and single-molecule nucleation experiments to quantify the association and buildup of proteins on a nucleating RNA. Together, these experiments provide complementary approaches to elucidate a molecular view of the protein-RNA interactions that drive ribonucleoprotein condensate formation.
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Affiliation(s)
- Laura R Ganser
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Yingda Ge
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
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34
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Bandyopadhyay D, Mishra PP. Revealing the DNA Unwinding Activity and Mechanism of Fork Reversal by RecG While Exposed to Variants of Stalled Replication-fork at Single-Molecular Resolution. J Mol Biol 2022; 434:167822. [PMID: 36108776 DOI: 10.1016/j.jmb.2022.167822] [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] [Received: 01/27/2022] [Revised: 08/23/2022] [Accepted: 09/06/2022] [Indexed: 11/25/2022]
Abstract
RecG, belonging to the category of Superfamily-2 plays a vital role in rescuing different kinds of stalled fork. The elemental mechanism of the helicase activity of RecG with several non-homologous stalled fork structures resembling intermediates formed during the process of DNA repair has been investigated in the present study to capture the dynamic stages of genetic rearrangement. The functional characterization has been exemplified through quantifying the response of the substrate in terms of their molecular heterogeneity and dynamical response by employing single-molecule fluorescence methods. An elevated processivity of RecG is observed for the stalled fork where progression of lagging daughter strand is ahead as compared to that of the leading strand. Through precise alteration of its function in terms of unwinding, depending upon the substrate DNA, RecG catalyzes the formation of Holliday junction from a stalled fork DNA. RecG is found to adopt an asymmetric mode of locomotion to unwind the lagging daughter strand for facilitating formation of Holliday junction that acts as a suitable intermediate for recombinational repair pathway. Our results emphasize the mechanism adopted by RecG during its 'sliding back' mode along the lagging daughter strand to be 'active translocation and passive unwinding'. This also provide clues as to how this helicase decides and controls the mode of translocation along the DNA to unwind.
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Affiliation(s)
- Debolina Bandyopadhyay
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India. https://twitter.com/DebolinaBandyo2
| | - Padmaja Prasad Mishra
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India.
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35
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Chapman JH, Craig JM, Wang CD, Gundlach JH, Neuman K, Hogg J. UPF1 mutants with intact ATPase but deficient helicase activities promote efficient nonsense-mediated mRNA decay. Nucleic Acids Res 2022; 50:11876-11894. [PMID: 36370101 PMCID: PMC9723629 DOI: 10.1093/nar/gkac1026] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/12/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
Abstract
The conserved RNA helicase UPF1 coordinates nonsense-mediated mRNA decay (NMD) by engaging with mRNAs, RNA decay machinery and the terminating ribosome. UPF1 ATPase activity is implicated in mRNA target discrimination and completion of decay, but the mechanisms through which UPF1 enzymatic activities such as helicase, translocase, RNP remodeling, and ATPase-stimulated dissociation influence NMD remain poorly defined. Using high-throughput biochemical assays to quantify UPF1 enzymatic activities, we show that UPF1 is only moderately processive (<200 nt) in physiological contexts and undergoes ATPase-stimulated dissociation from RNA. We combine an in silico screen with these assays to identify and characterize known and novel UPF1 mutants with altered helicase, ATPase, and RNA binding properties. We find that UPF1 mutants with substantially impaired processivity (E797R, G619K/A546H), faster (G619K) or slower (K547P, E797R, G619K/A546H) unwinding rates, and/or reduced mechanochemical coupling (i.e. the ability to harness ATP hydrolysis for work; K547P, R549S, G619K, G619K/A546H) can still support efficient NMD of well-characterized targets in human cells. These data are consistent with a central role for UPF1 ATPase activity in driving cycles of RNA binding and dissociation to ensure accurate NMD target selection.
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Affiliation(s)
- Joseph H Chapman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jonathan M Craig
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Clara D Wang
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jens H Gundlach
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Keir C Neuman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - J Robert Hogg
- To whom correspondence should be addressed. Tel: +1 301 827 0724; Fax: +1 301 451 5459;
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36
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Fang B, Shen Y, Peng B, Bai H, Wang L, Zhang J, Hu W, Fu L, Zhang W, Li L, Huang W. Small‐Molecule Quenchers for Förster Resonance Energy Transfer: Structure, Mechanism, and Applications. Angew Chem Int Ed Engl 2022; 61:e202207188. [DOI: 10.1002/anie.202207188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Bin Fang
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
- State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University 127 West Youyi Road Xi'an 710072 China
| | - Yu Shen
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Bo Peng
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Hua Bai
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Limin Wang
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Jiaxin Zhang
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Wenbo Hu
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
| | - Li Fu
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
- State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University 127 West Youyi Road Xi'an 710072 China
| | - Wei Zhang
- Teaching and Evaluation Center of Air Force Medical University Xi'an 710032 China
| | - Lin Li
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
- The Institute of Flexible Electronics (IFE, Future Technologies) Xiamen University Xiamen 361005, Fujian China
| | - Wei Huang
- Frontiers Science Center for Flexible Electronics Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University Xi'an 710072 China
- The Institute of Flexible Electronics (IFE, Future Technologies) Xiamen University Xiamen 361005, Fujian China
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37
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Kang Y, An S, Min D, Lee JY. Single-molecule fluorescence imaging techniques reveal molecular mechanisms underlying deoxyribonucleic acid damage repair. Front Bioeng Biotechnol 2022; 10:973314. [PMID: 36185427 PMCID: PMC9520083 DOI: 10.3389/fbioe.2022.973314] [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: 06/20/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
Advances in single-molecule techniques have uncovered numerous biological secrets that cannot be disclosed by traditional methods. Among a variety of single-molecule methods, single-molecule fluorescence imaging techniques enable real-time visualization of biomolecular interactions and have allowed the accumulation of convincing evidence. These techniques have been broadly utilized for studying DNA metabolic events such as replication, transcription, and DNA repair, which are fundamental biological reactions. In particular, DNA repair has received much attention because it maintains genomic integrity and is associated with diverse human diseases. In this review, we introduce representative single-molecule fluorescence imaging techniques and survey how each technique has been employed for investigating the detailed mechanisms underlying DNA repair pathways. In addition, we briefly show how live-cell imaging at the single-molecule level contributes to understanding DNA repair processes inside cells.
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Affiliation(s)
- Yujin Kang
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Soyeong An
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Duyoung Min
- Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Ja Yil Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
- Center for Genomic Integrity, Institute of Basic Sciences, Ulsan, South Korea
- *Correspondence: Ja Yil Lee,
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38
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Harris PD, Lerner E. Identification and quantification of within-burst dynamics in singly labeled single-molecule fluorescence lifetime experiments. BIOPHYSICAL REPORTS 2022; 2. [PMID: 36204594 PMCID: PMC9534301 DOI: 10.1016/j.bpr.2022.100071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Single-molecule spectroscopy has revolutionized molecular biophysics and provided means to probe how structural moieties within biomolecules spatially reorganize at different timescales. There are several single-molecule methodologies that probe local structural dynamics in the vicinity of a single dye-labeled residue, which rely on fluorescence lifetimes as readout. Nevertheless, an analytical framework to quantify dynamics in such single-molecule single dye fluorescence bursts, at timescales of microseconds to milliseconds, has not yet been demonstrated. Here, we suggest an analytical framework for identifying and quantifying within-burst lifetime-based dynamics, such as conformational dynamics recorded in single-molecule photo-isomerization-related fluorescence enhancement. After testing the capabilities of the analysis on simulations, we proceed to exhibit within-burst millisecond local structural dynamics in the unbound α-synuclein monomer. The analytical framework provided in this work paves the way for extracting a full picture of the energy landscape for the coordinate probed by fluorescence lifetime-based single-molecule measurements.
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Affiliation(s)
- Paul David Harris
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.,The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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39
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Purkait D, Islam F, Mishra PP. A single-molecule approach to unravel the molecular mechanism of the action of Deinococcus radiodurans RecD2 and its interaction with SSB and RecA in DNA repair. Int J Biol Macromol 2022; 221:653-664. [PMID: 36096248 DOI: 10.1016/j.ijbiomac.2022.09.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/02/2022] [Accepted: 09/06/2022] [Indexed: 11/28/2022]
Abstract
Helicases are ATP-driven molecular machines that directionally remodel nucleic acid polymers in all three domains of life. They are responsible for resolving double-stranded DNA (dsDNA) into single-strands, which is essential for DNA replication, nucleotide excision repair, and homologous recombination. RecD2 from Deinococcus radiodurans (DrRecD2) has important contributions to the organism's unusually high tolerance to gamma radiation and hydrogen peroxide. Although the results from X-ray Crystallography studies have revealed the structural characteristics of the protein, direct experimental evidence regarding the dynamics of the DNA unwinding process by DrRecD2 in the context of other accessory proteins is yet to be found. In this study, we have probed the exact binding event and processivity of DrRecD2 at single-molecule resolution using Protein-induced fluorescence enhancement (smPIFE) and Forster resonance energy transfer (smFRET). We have found that the protein prefers to bind at the 5' terminal end of the single-stranded DNA (ssDNA) by Drift and has helicase activity even in absence of ATP. However, a faster and iterative mode of DNA unwinding was evident in presence of ATP. The rate of translocation of the protein was found to be slower on dsDNA compared to ssDNA. We also showed that DrRecD2 is recruited at the binding site by the single-strand binding protein (SSB) and during the unwinding, it can displace RecA from ssDNA.
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Affiliation(s)
- Debayan Purkait
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India
| | - Farhana Islam
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India
| | - Padmaja P Mishra
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhaba National Institute, Mumbai, India.
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40
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Du J, Dartawan R, Rice W, Gao F, Zhou JH, Sheng J. Fluorescent Platforms for RNA Chemical Biology Research. Genes (Basel) 2022; 13:1348. [PMID: 36011259 PMCID: PMC9407474 DOI: 10.3390/genes13081348] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 12/03/2022] Open
Abstract
Efficient detection and observation of dynamic RNA changes remain a tremendous challenge. However, the continuous development of fluorescence applications in recent years enhances the efficacy of RNA imaging. Here we summarize some of these developments from different aspects. For example, single-molecule fluorescence in situ hybridization (smFISH) can detect low abundance RNA at the subcellular level. A relatively new aptamer, Mango, is widely applied to label and track RNA activities in living cells. Molecular beacons (MBs) are valid for quantifying both endogenous and exogenous mRNA and microRNA (miRNA). Covalent binding enzyme labeling fluorescent group with RNA of interest (ROI) partially overcomes the RNA length limitation associated with oligonucleotide synthesis. Forced intercalation (FIT) probes are resistant to nuclease degradation upon binding to target RNA and are used to visualize mRNA and messenger ribonucleoprotein (mRNP) activities. We also summarize the importance of some fluorescence spectroscopic techniques in exploring the function and movement of RNA. Single-molecule fluorescence resonance energy transfer (smFRET) has been employed to investigate the dynamic changes of biomolecules by covalently linking biotin to RNA, and a focus on dye selection increases FRET efficiency. Furthermore, the applications of fluorescence assays in drug discovery and drug delivery have been discussed. Fluorescence imaging can also combine with RNA nanotechnology to target tumors. The invention of novel antibacterial drugs targeting non-coding RNAs (ncRNAs) is also possible with steady-state fluorescence-monitored ligand-binding assay and the T-box riboswitch fluorescence anisotropy assay. More recently, COVID-19 tests using fluorescent clustered regularly interspaced short palindromic repeat (CRISPR) technology have been demonstrated to be efficient and clinically useful. In summary, fluorescence assays have significant applications in both fundamental and clinical research and will facilitate the process of RNA-targeted new drug discovery, therefore deserving further development and updating.
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Affiliation(s)
| | | | | | | | | | - Jia Sheng
- Department of Chemistry, The RNA Institute, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA; (J.D.); (R.D.); (W.R.); (F.G.); (J.H.Z.)
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41
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Shestopal SA, Parunov LA, Olivares P, Chun H, Ovanesov MV, Pettersson JR, Sarafanov AG. Isolated Variable Domains of an Antibody Can Assemble on Blood Coagulation Factor VIII into a Functional Fv-like Complex. Int J Mol Sci 2022; 23:ijms23158134. [PMID: 35897712 PMCID: PMC9330781 DOI: 10.3390/ijms23158134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 11/29/2022] Open
Abstract
Single-chain variable fragments (scFv) are antigen-recognizing variable fragments of antibodies (FV) where both subunits (VL and VH) are connected via an artificial linker. One particular scFv, iKM33, directed against blood coagulation factor VIII (FVIII) was shown to inhibit major FVIII functions and is useful in FVIII research. We aimed to investigate the properties of iKM33 enabled with protease-dependent disintegration. Three variants of iKM33 bearing thrombin cleavage sites within the linker were expressed using a baculovirus system and purified by two-step chromatography. All proteins retained strong binding to FVIII by surface plasmon resonance, and upon thrombin cleavage, dissociated into VL and VH as shown by size-exclusion chromatography. However, in FVIII activity and low-density lipoprotein receptor-related protein 1 binding assays, the thrombin-cleaved iKM33 variants were still inhibitory. In a pull-down assay using an FVIII-affinity sorbent, the isolated VH, a mixture of VL and VH, and intact iKM33 were carried over via FVIII analyzed by electrophoresis. We concluded that the isolated VL and VH assembled into scFv-like heterodimer on FVIII, and the isolated VH alone also bound FVIII. We discuss the potential use of both protease-cleavable scFvs and isolated Fv subunits retaining high affinity to the antigens in various practical applications such as therapeutics, diagnostics, and research.
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42
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Fang B, Shen Y, Peng B, Bai H, Wang L, Zhang J, Hu W, Fu L, Zhang W, Li L, Huang W. Small Molecule Quenchers for Förster Resonance Energy Transfer: Structure, Mechanism and Applications. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Bin Fang
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Yu Shen
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Bo Peng
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Hua Bai
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Limin Wang
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Jiaxin Zhang
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Wenbo Hu
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Li Fu
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
| | - Wei Zhang
- Air Force Medical University Teaching and Evaluation Center CHINA
| | - Lin Li
- Nanjing Tech University Institute of Advanced Materials 30 South Puzhu Road 210008 Nanjing CHINA
| | - Wei Huang
- Northwestern Polytechnical University Frontiers Science Center for Flexible Electronics CHINA
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43
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Dziuba D. Environmentally sensitive fluorescent nucleoside analogues as probes for nucleic acid - protein interactions: molecular design and biosensing applications. Methods Appl Fluoresc 2022; 10. [PMID: 35738250 DOI: 10.1088/2050-6120/ac7bd8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/23/2022] [Indexed: 11/12/2022]
Abstract
Fluorescent nucleoside analogues (FNAs) are indispensable in studying the interactions of nucleic acids with nucleic acid-binding proteins. By replacing one of the poorly emissive natural nucleosides, FNAs enable real-time optical monitoring of the binding interactions in solutions, under physiologically relevant conditions, with high sensitivity. Besides that, FNAs are widely used to probe conformational dynamics of biomolecular complexes using time-resolved fluorescence methods. Because of that, FNAs are tools of high utility for fundamental biological research, with potential applications in molecular diagnostics and drug discovery. Here I review the structural and physical factors that can be used for the conversion of the molecular binding events into a detectable fluorescence output. Typical environmentally sensitive FNAs, their properties and applications, and future challenges in the field are discussed.
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Affiliation(s)
- Dmytro Dziuba
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Université de Strasbourg, 74 Route du Rhin, Illkirch-Graffenstaden, Grand Est, 67401, FRANCE
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44
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Paul T, Opresko PL, Ha T, Myong S. Vectorial folding of telomere overhang promotes higher accessibility. Nucleic Acids Res 2022; 50:6271-6283. [PMID: 35687089 PMCID: PMC9226509 DOI: 10.1093/nar/gkac401] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/20/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Human telomere overhang composed of tandem repeats of TTAGGG folds into G-quadruplex (G4). Unlike in an experimental setting in the test tube in which the entire length is allowed to fold at once, inside the cell, the overhang is expected to fold as it is synthesized directionally (5' to 3') and released segmentally by a specialized enzyme, the telomerase. To mimic such vectorial G4 folding process, we employed a superhelicase, Rep-X which can unwind DNA to release the TTAGGG repeats in 5' to 3' direction. We demonstrate that the folded conformation achieved by the refolding of full sequence is significantly different from that of the vectorial folding for two to eight TTAGGG repeats. Strikingly, the vectorially folded state leads to a remarkably higher accessibility to complementary C-rich strand and the telomere binding protein POT1, reflecting a less stably folded state resulting from the vectorial folding. Importantly, our study points to an inherent difference between the co-polymerizing and post-polymerized folding of telomere overhang that can impact telomere architecture and downstream processes.
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Affiliation(s)
- Tapas Paul
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, PA15213, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA.,Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Sua Myong
- Department of Biophysics, Johns Hopkins University, Baltimore, MD21218, USA.,Physics Frontier Center (Center for Physics of Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
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45
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Rho-dependent transcription termination proceeds via three routes. Nat Commun 2022; 13:1663. [PMID: 35351884 PMCID: PMC8964686 DOI: 10.1038/s41467-022-29321-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 03/09/2022] [Indexed: 01/26/2023] Open
Abstract
Rho is a general transcription termination factor in bacteria, but many aspects of its mechanism of action are unclear. Diverse models have been proposed for the initial interaction between the RNA polymerase (RNAP) and Rho (catch-up and stand-by pre-terminational models); for the terminational release of the RNA transcript (RNA shearing, RNAP hyper-translocation or displacing, and allosteric models); and for the post-terminational outcome (whether the RNAP dissociates or remains bound to the DNA). Here, we use single-molecule fluorescence assays to study those three steps in transcription termination mediated by E. coli Rho. We find that different mechanisms previously proposed for each step co-exist, but apparently occur on various timescales and tend to lead to specific outcomes. Our results indicate that three kinetically distinct routes take place: (1) the catch-up mode leads first to RNA shearing for RNAP recycling on DNA, and (2) later to RNAP displacement for decomposition of the transcriptional complex; (3) the last termination usually follows the stand-by mode with displacing for decomposing. This three-route model would help reconcile current controversies on the mechanisms. Rho is a general transcription termination factor in bacteria. Here, Song et al. use single-molecule fluorescence assays to provide evidence that Rho-mediated transcription termination can occur via three kinetically different routes.
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46
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Nielsen LDF, Hansen-Bruhn M, Nijenhuis MAD, Gothelf KV. Protein-Induced Fluorescence Enhancement and Quenching in a Homogeneous DNA-Based Assay for Rapid Detection of Small-Molecule Drugs in Human Plasma. ACS Sens 2022; 7:856-865. [PMID: 35239321 DOI: 10.1021/acssensors.1c02642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Homogeneous assays for determining the concentration of small molecules in biological fluids are of importance for monitoring blood levels of critical drugs in patients. We have developed a strand displacement competition assay for the drugs dabigatran, methotrexate, and linezolid, which allows detection and determination of the concentration of the drugs in plasma; however, a surprising kinetic behavior of the assay was observed with an initial rapid change in apparent FRET values. We found that protein-induced fluorescent enhancement or quenching (PIFE/Q) caused the initial change in fluorescence within the first minute after addition of protein, which could be exploited to construct assays for concentration determination within minutes in the low nanomolar range in plasma. A kinetic model for the assay was established, and when taking the new finding into account, the in silico simulations were in good agreement with the experimentally observed results. Utilizing these findings, a simpler assay was constructed for detection of dabigatran, which allowed for detection within minutes without any time dependencies.
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Affiliation(s)
- Line D. F. Nielsen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Malthe Hansen-Bruhn
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Minke A. D. Nijenhuis
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Kurt V. Gothelf
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
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47
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Yadav R, Widom JR, Chauvier A, Walter NG. An anionic ligand snap-locks a long-range interaction in a magnesium-folded riboswitch. Nat Commun 2022; 13:207. [PMID: 35017489 PMCID: PMC8752731 DOI: 10.1038/s41467-021-27827-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 12/02/2021] [Indexed: 01/22/2023] Open
Abstract
The archetypical transcriptional crcB fluoride riboswitch from Bacillus cereus is an intricately structured non-coding RNA element enhancing gene expression in response to toxic levels of fluoride. Here, we used single molecule FRET to uncover three dynamically interconverting conformations appearing along the transcription process: two distinct undocked states and one pseudoknotted docked state. We find that the fluoride anion specifically snap-locks the magnesium-induced, dynamically docked state. The long-range, nesting, single base pair A40-U48 acts as the main linchpin, rather than the multiple base pairs comprising the pseudoknot. We observe that the proximally paused RNA polymerase further fine-tunes the free energy to promote riboswitch docking. Finally, we show that fluoride binding at short transcript lengths is an early step toward partitioning folding into the docked conformation. These results reveal how the anionic fluoride ion cooperates with the magnesium-associated RNA to govern regulation of downstream genes needed for fluoride detoxification of the cell.
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Affiliation(s)
- Rajeev Yadav
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, 97403, USA
| | - Adrien Chauvier
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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48
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Małecka EM, Hua B, Woodson SA. Single-Molecule FRET Studies of RNA Structural Rearrangements and RNA-RNA Interactions. Methods Mol Biol 2022; 2518:271-289. [PMID: 35666451 PMCID: PMC10052914 DOI: 10.1007/978-1-0716-2421-0_16] [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] [Indexed: 06/15/2023]
Abstract
RNA-guided regulation of gene expression is found in all cell types. In this mode of regulation, antisense interactions between the regulatory RNA and its target are typically facilitated by a protein partner. Single-molecule fluorescence microscopy is a powerful tool for dissecting the conformational states and intermediates that contribute to target recognition. This chapter describes protocols for studying target recognition by bacterial small RNAs and their chaperone Hfq on the single-molecule level, using a total internal reflection fluorescence microscope. The sections cover the design of suitable RNA substrates for sRNA-mRNA annealing reactions, preparation of internally labeled mRNA for detecting conformational changes in the target, and key steps of the data analysis. These protocols can be adapted to other RNA-binding proteins that chaperone RNA interactions.
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Affiliation(s)
- Ewelina M Małecka
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Boyang Hua
- Department of Molecular Biology and Genetics, Johns Hopkins Medical School, Baltimore, MD, USA
| | - Sarah A Woodson
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
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49
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Chen XF, Zhao X, Yang Z. Aptasensors for the detection of infectious pathogens: design strategies and point-of-care testing. Mikrochim Acta 2022; 189:443. [PMID: 36350388 PMCID: PMC9643942 DOI: 10.1007/s00604-022-05533-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/10/2022] [Indexed: 11/11/2022]
Abstract
The epidemic of infectious diseases caused by contagious pathogens is a life-threatening hazard to the entire human population worldwide. A timely and accurate diagnosis is the critical link in the fight against infectious diseases. Aptamer-based biosensors, the so-called aptasensors, employ nucleic acid aptamers as bio-receptors for the recognition of target pathogens of interest. This review focuses on the design strategies as well as state-of-the-art technologies of aptasensor-based diagnostics for infectious pathogens (mainly bacteria and viruses), covering the utilization of three major signal transducers, the employment of aptamers as recognition moieties, the construction of versatile biosensing platforms (mostly micro and nanomaterial-based), innovated reporting mechanisms, and signal enhancement approaches. Advanced point-of-care testing (POCT) for infectious disease diagnostics are also discussed highlighting some representative ready-to-use devices to address the urgent needs of currently prevalent coronavirus disease 2019 (COVID-19). Pressing issues in aptamer-based technology and some future perspectives of aptasensors are provided for the implementation of aptasensor-based diagnostics into practical application.
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Affiliation(s)
- Xiao-Fei Chen
- Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Test Technology, Institute of Analysis, Guangdong Academy of Sciences (China National Analytical Center, Guangzhou), Guangzhou, 510070, People's Republic of China
| | - Xin Zhao
- Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Test Technology, Institute of Analysis, Guangdong Academy of Sciences (China National Analytical Center, Guangzhou), Guangzhou, 510070, People's Republic of China.
| | - Zifeng Yang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, People's Republic of China.
- Guangzhou Laboratory, Guangzhou, 510320, People's Republic of China.
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou, 510005, People's Republic of China.
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50
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Monitoring protein conformational changes using fluorescent nanoantennas. Nat Methods 2022; 19:71-80. [PMID: 34969985 DOI: 10.1038/s41592-021-01355-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 11/10/2021] [Indexed: 01/03/2023]
Abstract
Understanding the relationship between protein structural dynamics and function is crucial for both basic research and biotechnology. However, methods for studying the fast dynamics of structural changes are limited. Here, we introduce fluorescent nanoantennas as a spectroscopic technique to sense and report protein conformational changes through noncovalent dye-protein interactions. Using experiments and molecular simulations, we detect and characterize five distinct conformational states of intestinal alkaline phosphatase, including the transient enzyme-substrate complex. We also explored the universality of the nanoantenna strategy with another model protein, Protein G and its interaction with antibodies, and demonstrated a rapid screening strategy to identify efficient nanoantennas. These versatile nanoantennas can be used with diverse dyes to monitor small and large conformational changes, suggesting that they could be used to characterize diverse protein movements or in high-throughput screening applications.
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