1
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Sangeeta, Mishra SK, Bhattacherjee A. Role of Shape Deformation of DNA-Binding Sites in Regulating the Efficiency and Specificity in Their Recognition by DNA-Binding Proteins. JACS AU 2024; 4:2640-2655. [PMID: 39055163 PMCID: PMC11267559 DOI: 10.1021/jacsau.4c00393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/21/2024] [Accepted: 05/22/2024] [Indexed: 07/27/2024]
Abstract
Accurate transcription of genetic information is crucial, involving precise recognition of the binding motifs by DNA-binding proteins. While some proteins rely on short-range hydrophobic and hydrogen bonding interactions at binding sites, others employ a DNA shape readout mechanism for specific recognition. In this mechanism, variations in DNA shape at the binding motif resulted from either inherent flexibility or binding of proteins at adjacent sites are sensed and capitalized by the searching proteins to locate them specifically. Through extensive computer simulations, we investigate both scenarios to uncover the underlying mechanism and origin of specificity in the DNA shape readout mechanism. Our findings reveal that deformation in shape at the binding motif creates an entropy funnel, allowing information about altered shapes to manifest as fluctuations in minor groove widths. This signal enhances the efficiency of nonspecific search of nearby proteins by directing their movement toward the binding site, primarily driven by a gain in entropy. We propose this as a generic mechanism for DNA shape readout, where specificity arises from the alignment between the molecular frustration of the searching protein and the ruggedness of the entropic funnel governed by molecular features of the protein and arrangement of the DNA bases at the binding site, respectively.
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Affiliation(s)
- Sangeeta
- School of Computational & Integrative
Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sujeet Kumar Mishra
- School of Computational & Integrative
Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Arnab Bhattacherjee
- School of Computational & Integrative
Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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2
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Rogoulenko E, Levy Y. Skipping events impose repeated binding attempts: profound kinetic implications of protein-DNA conformational changes. Nucleic Acids Res 2024; 52:6763-6776. [PMID: 38721783 PMCID: PMC11229352 DOI: 10.1093/nar/gkae333] [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: 01/30/2024] [Revised: 04/09/2024] [Accepted: 04/16/2024] [Indexed: 07/09/2024] Open
Abstract
The kinetics of protein-DNA recognition, along with its thermodynamic properties, including affinity and specificity, play a central role in shaping biological function. Protein-DNA recognition kinetics are characterized by two key elements: the time taken to locate the target site amid various nonspecific alternatives; and the kinetics involved in the recognition process, which may necessitate overcoming an energetic barrier. In this study, we developed a coarse-grained (CG) model to investigate interactions between a transcription factor called the sex-determining region Y (SRY) protein and DNA, in order to probe how DNA conformational changes affect SRY-DNA recognition and binding kinetics. We find that, not only does a requirement for such a conformational DNA transition correspond to a higher energetic barrier for binding and therefore slower kinetics, it may further impede the recognition kinetics by increasing unsuccessful binding events (skipping events) where the protein partially binds its DNA target site but fails to form the specific protein-DNA complex. Such skipping events impose the need for additional cycles protein search of nonspecific DNA sites, thus significantly extending the overall recognition time. Our results highlight a trade-off between the speed with which the protein scans nonspecific DNA and the rate at which the protein recognizes its specific target site. Finally, we examine molecular approaches potentially adopted by natural systems to enhance protein-DNA recognition despite its intrinsically slow kinetics.
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Affiliation(s)
- Elena Rogoulenko
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yaakov Levy
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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3
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Al Masri C, Wan B, Yu J. Nonspecific vs. specific DNA binding free energetics of a transcription factor domain protein. Biophys J 2023; 122:4476-4487. [PMID: 37897044 PMCID: PMC10722393 DOI: 10.1016/j.bpj.2023.10.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/06/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
Transcription factor (TF) proteins regulate gene expression by binding to specific sites on the genome. In the facilitated diffusion model, an optimized search process is achieved by the TF alternating between 3D diffusion in the bulk and 1D diffusion along DNA. While undergoing 1D diffusion, the protein can switch from a search mode for fast diffusion along nonspecific DNA to a recognition mode for stable binding to specific DNA. It was recently noticed that, for a small TF domain protein, reorientations on DNA happen between the nonspecific and specific DNA binding. We here conducted all-atom molecular dynamics simulations with steering forces to reveal the protein-DNA binding free energetics, confirming that the search and recognition modes are distinguished primarily by protein orientations on the DNA. As the binding free energy difference between the specific and nonspecific DNA system slightly deviates from that being estimated directly from dissociation constants on 15-bp DNA constructs, we hypothesize that the discrepancy can come from DNA sequences flanking the 6-bp central binding sites that impact on the dissociation kinetics measurements. The hypothesis is supported by a simplified spherical protein-DNA model along with stochastic simulations and kinetic modeling.
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Affiliation(s)
- Carmen Al Masri
- Department of Physics and Astronomy, University of California, Irvine, California
| | - Biao Wan
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, China
| | - Jin Yu
- Department of Physics and Astronomy, University of California, Irvine, California; Department of Physics and Astronomy, Department of Chemistry, NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, California.
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4
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Cintori L, Di Guilmi AM, Canitrot Y, Huet S, Campalans A. Spatio-temporal dynamics of the DNA glycosylase OGG1 in finding and processing 8-oxoguanine. DNA Repair (Amst) 2023; 129:103550. [PMID: 37542751 DOI: 10.1016/j.dnarep.2023.103550] [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: 05/30/2023] [Revised: 07/26/2023] [Accepted: 07/29/2023] [Indexed: 08/07/2023]
Abstract
OGG1 is the DNA glycosylase responsible for the removal of the oxidative lesion 8-oxoguanine (8-oxoG) from DNA. The recognition of this lesion by OGG1 is a complex process that involves scanning the DNA for the presence of 8-oxoG, followed by recognition and lesion removal. Structural data have shown that OGG1 evolves through different stages of conformation onto the DNA, corresponding to elementary steps of the 8-oxoG recognition and extrusion from the double helix. Single-molecule studies of OGG1 on naked DNA have shown that OGG1 slides in persistent contact with the DNA, displaying different binding states probably corresponding to the different conformation stages. However, in cells, the DNA is not naked and OGG1 has to navigate into a complex and highly crowded environment within the nucleus. To ensure rapid detection of 8-oxoG, OGG1 alternates between 3D diffusion and sliding along the DNA. This process is regulated by the local chromatin state but also by protein co-factors that could facilitate the detection of oxidized lesions. We will review here the different methods that have been used over the last years to better understand how OGG1 detects and process 8-oxoG lesions.
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Affiliation(s)
- Luana Cintori
- Molecular, Cellular and Developmental Biology unit, Centre de Biologie Integrative, University of Toulouse, CNRS, F-31062 Toulouse, France
| | - Anne-Marie Di Guilmi
- Université de Paris-Cite, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France; Université Paris-Saclay, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France
| | - Yvan Canitrot
- Molecular, Cellular and Developmental Biology unit, Centre de Biologie Integrative, University of Toulouse, CNRS, F-31062 Toulouse, France
| | - Sebastien Huet
- Université Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, BIOSIT (Biologie, ´ Sante, Innovation Technologique de Rennes) - UMS 3480, US 018, F-35000 Rennes, France; Institut Universitaire de France, Paris, France
| | - Anna Campalans
- Université de Paris-Cite, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France; Université Paris-Saclay, CEA /IBFJ/IRCM. UMR Stabilité Génétique Cellules Souches et Radiations, F-92260 Fontenay-aux-Roses, France.
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5
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Lüking M, van der Spoel D, Elf J, Tribello GA. Can molecular dynamics be used to simulate biomolecular recognition? J Chem Phys 2023; 158:2889489. [PMID: 37158325 DOI: 10.1063/5.0146899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/19/2023] [Indexed: 05/10/2023] Open
Abstract
There are many problems in biochemistry that are difficult to study experimentally. Simulation methods are appealing due to direct availability of atomic coordinates as a function of time. However, direct molecular simulations are challenged by the size of systems and the time scales needed to describe relevant motions. In theory, enhanced sampling algorithms can help to overcome some of the limitations of molecular simulations. Here, we discuss a problem in biochemistry that offers a significant challenge for enhanced sampling methods and that could, therefore, serve as a benchmark for comparing approaches that use machine learning to find suitable collective variables. In particular, we study the transitions LacI undergoes upon moving between being non-specifically and specifically bound to DNA. Many degrees of freedom change during this transition and that the transition does not occur reversibly in simulations if only a subset of these degrees of freedom are biased. We also explain why this problem is so important to biologists and the transformative impact that a simulation of it would have on the understanding of DNA regulation.
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Affiliation(s)
- Malin Lüking
- Department of Cell and Molecular Biology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden
| | - David van der Spoel
- Department of Cell and Molecular Biology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden
| | - Johan Elf
- Department of Cell and Molecular Biology, Uppsala University, Husargatan 3, SE-75124 Uppsala, Sweden
| | - Gareth A Tribello
- Centre for Quantum Materials and Technologies, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
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6
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Jibiki K, Kodama TS, Yasuhara N. Importin alpha family NAAT/IBB domain: Functions of a pleiotropic long chameleon sequence. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:175-209. [PMID: 36858734 DOI: 10.1016/bs.apcsb.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Nuclear transport is essential for eukaryotic cell survival and regulates the movement of functional molecules in and out of the nucleus via the nuclear pore. Transport is facilitated by protein-protein interactions between cargo and transport receptors, which contribute to the expression and regulation of downstream genetic information. This chapter focuses on the molecular basis of the multifunctional nature of the importin α family, the representative transport receptors that bring proteins into the nucleus. Importin α performs multiple functions during the nuclear transport cycle through interactions with multiple molecules by a single domain called the IBB domain. This domain is a long chameleon sequence, which can change its conformation and binding mode depending on the interaction partners. By considering the evolutionarily conserved biochemical/physicochemical propensities of the amino acids constituting the functional complex interfaces, together with their structural properties, the mechanisms of switching between multiple complexes formed via IBB and the regulation of downstream functions are examined in detail. The mechanism of regulation by IBB indicates that the time has come for a paradigm shift in the way we view the molecular mechanisms by which proteins regulate downstream functions through their interactions with other molecules.
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Affiliation(s)
- Kazuya Jibiki
- Graduate School of Integrated Basic Sciences, Nihon University, Setagaya-ku, Tokyo, Japan
| | - Takashi S Kodama
- Laboratory of Molecular Biophysics, Institute for Protein Research, Osaka University, Osaka, Japan.
| | - Noriko Yasuhara
- Graduate School of Integrated Basic Sciences, Nihon University, Setagaya-ku, Tokyo, Japan.
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7
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Lüking M, Elf J, Levy Y. Conformational Change of Transcription Factors from Search to Specific Binding: A lac Repressor Case Study. J Phys Chem B 2022; 126:9971-9984. [PMID: 36416228 PMCID: PMC9743208 DOI: 10.1021/acs.jpcb.2c05006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In a process known as facilitated diffusion, DNA-binding proteins find their target sites by combining three-dimensional diffusion and one-dimensional scanning of the DNA. Following the trade-off between speed and stability, agile exploration of DNA requires loose binding, whereas, at the DNA target site, the searching protein needs to establish tight interactions with the DNA. To enable both efficient search and stable binding, DNA-binding proteins and DNA often switch conformations upon recognition. Here, we study the one-dimensional diffusion and DNA binding of the dimeric lac repressor (LacI), which was reported to adopt two different conformations when binding different conformations of DNA. Using coarse-grained molecular dynamic simulations, we studied the diffusion and the sequence-specific binding of these conformations of LacI, as well as their truncated or monomeric variants, with two DNA conformations: straight and bent. The simulations were compared to experimental observables. This study supports that linear diffusion along DNA combines tight rotation-coupled groove tracking and rotation-decoupled hopping, where the protein briefly dissociates and reassociates just a few base pairs away. Tight groove tracking is crucial for target-site recognition, while hopping speeds up the overall search process. We investigated the diffusion of different LacI conformations on DNA and show how the flexibility of LacI's hinge regions ensures agility on DNA as well as faithful groove tracking. If the hinge regions instead form α-helices at the protein-DNA interface, tight groove tracking is not possible. On the contrary, the helical hinge region is essential for tight binding to bent, specific DNA, for the formation of the specific complex. Based on our study of different encounter complexes, we argue that the conformational change in LacI and DNA bending are somewhat coupled. Our findings underline the importance of two distinct protein conformations for facilitated diffusion and specific binding, respectively.
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Affiliation(s)
- Malin Lüking
- Department
of Cell- and Molecular Biology-ICM, Uppsala
University, Uppsala, Uppsala County751 24, Sweden
| | - Johan Elf
- Department
of Cell- and Molecular Biology-ICM, Uppsala
University, Uppsala, Uppsala County751 24, Sweden
| | - Yaakov Levy
- Department
of Chemical and Structural Biology, Weizmann
Institute of Science, Rehovot, Central District76100, Israel,. Tel.: 972-8-9344587
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8
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Soares MAF, Oliveira RA, Castro DS. Function and regulation of transcription factors during mitosis-to-G1 transition. Open Biol 2022; 12:220062. [PMID: 35642493 PMCID: PMC9157305 DOI: 10.1098/rsob.220062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/26/2022] [Indexed: 01/04/2023] Open
Abstract
During cell division, drastic cellular changes characteristic of mitosis result in the inactivation of the transcriptional machinery, and global downregulation of transcription. Sequence-specific transcription factors (TFs) have thus been considered mere bystanders, devoid of any regulatory function during mitosis. This view changed significantly in recent years, upon the conclusion that many TFs associate with condensed chromosomes during cell division, even occupying a fraction of their genomic target sites in mitotic chromatin. This finding was at the origin of the concept of mitotic bookmarking by TFs, proposed as a mechanism to propagate gene regulatory information across cell divisions, by facilitating the reactivation of specific bookmarked genes. While the underlying mechanisms and biological significance of this model remain elusive, recent developments in this fast-moving field have cast new light into TF activity during mitosis, beyond a bookmarking role. Here, we start by reviewing the most recent findings on the complex nature of TF-chromatin interactions during mitosis, and on mechanisms that may regulate them. Next, and in light of recent reports describing how transcription is reinitiated in temporally distinct waves during mitosis-to-G1 transition, we explore how TFs may contribute to defining this hierarchical gene expression process. Finally, we discuss how TF activity during mitotic exit may impact the acquisition of cell identity upon cell division, and propose a model that integrates dynamic changes in TF-chromatin interactions during this cell-cycle period, with the execution of cell-fate decisions.
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Affiliation(s)
- Mário A. F. Soares
- i3S Instituto de Investigação e Inovação em Saúde, IBMC Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal
| | | | - Diogo S. Castro
- i3S Instituto de Investigação e Inovação em Saúde, IBMC Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal
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9
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Chu X, Suo Z, Wang J. Investigating the Conformational Dynamics of a Y-Family DNA Polymerase during Its Folding and Binding to DNA and a Nucleotide. JACS AU 2022; 2:341-356. [PMID: 35252985 PMCID: PMC8889613 DOI: 10.1021/jacsau.1c00368] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Indexed: 06/14/2023]
Abstract
During DNA polymerization, the Y-family DNA polymerases are capable of bypassing various DNA damage, which can stall the replication fork progression. It has been well acknowledged that the structures of the Y-family DNA polymerases have been naturally evolved to undertake this vital task. However, the mechanisms of how these proteins utilize their unique structural and conformational dynamical features to perform the translesion DNA synthesis are less understood. Here, we developed structure-based models to study the precatalytic DNA polymerization process, including DNA and nucleotide binding to DPO4, a paradigmatic Y-family polymerase from Sulfolobus solfataricus. We studied the interplay between the folding and the conformational dynamics of DPO4 and found that DPO4 undergoes first unraveling (unfolding) and then folding for accomplishing the functional "open-to-closed" conformational transition. DNA binding dynamically modulates the conformational equilibrium in DPO4 during the stepwise binding through different types of interactions, leading to different conformational distributions of DPO4 at different DNA binding stages. We observed that nucleotide binding induces modulation of a few contacts surrounding the active site of the DPO4-DNA complex associated with a high free energy barrier. Our simulation results resonate with the experimental evidence that the conformational change at the active site led by nucleotide is the rate-limiting step of nucleotide incorporation. In combination with localized frustration analyses, we underlined the importance of DPO4 conformational dynamics and fluctuations in facilitating DNA and nucleotide binding. Our findings offer mechanistic insights into the processes of DPO4 conformational dynamics associated with the substrate binding and contribute to the understanding of the "structure-dynamics-function" relationship in the Y-family DNA polymerases.
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Affiliation(s)
- Xiakun Chu
- Department
of Chemistry, State University of New York
at Stony Brook, Stony
Brook, New York 11794, United States
| | - Zucai Suo
- Department
of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306, United States
| | - Jin Wang
- Department
of Chemistry, State University of New York
at Stony Brook, Stony
Brook, New York 11794, United States
- Department
of Physics and Astronomy, State University
of New York at Stony Brook, Stony Brook, New York 11794, United States
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10
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Whitford PC. Overview of the Biomolecular Association and Dynamics session at the 20th IUPAB congress, 45th Brazilian congress of SBBF, and the 50th annual meeting of SBBq. Biophys Rev 2022; 13:863-865. [PMID: 35059009 DOI: 10.1007/s12551-021-00884-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 05/31/2023] Open
Abstract
In this session, experts in molecular biophysics described the dynamics of biopolymers across a wide range of length and time scales. This discussion highlighted numerous techniques that span from highly detailed simulations, to coarse-grained theoretical models, as well as high-resolution structural analysis. The topics were equally diverse, where there was discussion of biological processes at small (individual atoms), intermediate (assemblies) and very large scales (phase separation).
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Affiliation(s)
- Paul Charles Whitford
- Department of Physics and Center for Theoretical Biological Physics, Northeastern University, Boston, MA USA
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11
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Leroux M, Soubry N, Reyes-Lamothe R. Dynamics of Proteins and Macromolecular Machines in Escherichia coli. EcoSal Plus 2021; 9:eESP00112020. [PMID: 34060908 PMCID: PMC11163846 DOI: 10.1128/ecosalplus.esp-0011-2020] [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: 01/25/2021] [Accepted: 03/16/2021] [Indexed: 11/20/2022]
Abstract
Proteins are major contributors to the composition and the functions in the cell. They often assemble into larger structures, macromolecular machines, to carry out intricate essential functions. Although huge progress in understanding how macromolecular machines function has been made by reconstituting them in vitro, the role of the intracellular environment is still emerging. The development of fluorescence microscopy techniques in the last 2 decades has allowed us to obtain an increased understanding of proteins and macromolecular machines in cells. Here, we describe how proteins move by diffusion, how they search for their targets, and how they are affected by the intracellular environment. We also describe how proteins assemble into macromolecular machines and provide examples of how frequent subunit turnover is used for them to function and to respond to changes in the intracellular conditions. This review emphasizes the constant movement of molecules in cells, the stochastic nature of reactions, and the dynamic nature of macromolecular machines.
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Affiliation(s)
- Maxime Leroux
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Nicolas Soubry
- Department of Biology, McGill University, Montreal, QC, Canada
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12
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Lin SN, Dame RT, Wuite GJL. Direct visualization of the effect of DNA structure and ionic conditions on HU-DNA interactions. Sci Rep 2021; 11:18492. [PMID: 34531428 PMCID: PMC8446073 DOI: 10.1038/s41598-021-97763-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/04/2021] [Indexed: 11/17/2022] Open
Abstract
Architectural DNA–binding proteins are involved in many important DNA transactions by virtue of their ability to change DNA conformation. Histone-like protein from E. coli strain U93, HU, is one of the most studied bacterial architectural DNA–binding proteins. Nevertheless, there is still a limited understanding of how the interactions between HU and DNA are affected by ionic conditions and the structure of DNA. Here, using optical tweezers in combination with fluorescent confocal imaging, we investigated how ionic conditions affect the interaction between HU and DNA. We directly visualized the binding and the diffusion of fluorescently labelled HU dimers on DNA. HU binds with high affinity and exhibits low mobility on the DNA in the absence of Mg2+; it moves 30-times faster and stays shorter on the DNA with 8 mM Mg2+ in solution. Additionally, we investigated the effect of DNA tension on HU–DNA complexes. On the one hand, our studies show that binding of HU enhances DNA helix stability. On the other hand, we note that the binding affinity of HU for DNA in the presence of Mg2+ increases at tensions above 50 pN, which we attribute to force-induced structural changes in the DNA. The observation that HU diffuses faster along DNA in presence of Mg2+ compared to without Mg2+ suggests that the free energy barrier for rotational diffusion along DNA is reduced, which can be interpreted in terms of reduced electrostatic interaction between HU and DNA, possibly coinciding with reduced DNA bending.
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Affiliation(s)
- Szu-Ning Lin
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands.,Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands. .,Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands.
| | - Gijs J L Wuite
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. .,LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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13
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Jibiki K, Kodama TS, Suenaga A, Kawase Y, Shibazaki N, Nomoto S, Nagasawa S, Nagashima M, Shimodan S, Kikuchi R, Okayasu M, Takashita R, Mehmood R, Saitoh N, Yoneda Y, Akagi KI, Yasuhara N. Importin α2 association with chromatin: Direct DNA binding via a novel DNA-binding domain. Genes Cells 2021; 26:945-966. [PMID: 34519142 DOI: 10.1111/gtc.12896] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/10/2021] [Accepted: 09/11/2021] [Indexed: 12/18/2022]
Abstract
The nuclear transport of proteins is important for facilitating appropriate nuclear functions. The importin α family proteins play key roles in nuclear transport as transport receptors for copious nuclear proteins. Additionally, these proteins possess other functions, including chromatin association and gene regulation. However, these nontransport functions of importin α are not yet fully understood, especially their molecular-level mechanisms and consequences for functioning with chromatin. Here, we report the novel molecular characteristics of importin α binding to diverse DNA sequences in chromatin. We newly identified and characterized a DNA-binding domain-the Nucleic Acid Associating Trolley pole domain (NAAT domain)-in the N-terminal region of importin α within the conventional importin β binding (IBB) domain that is necessary for nuclear transport of cargo proteins. Furthermore, we found that the DNA binding of importin α synergistically coupled the recruitment of its cargo protein to DNA. This is the first study to delineate the interaction between importin α and chromatin DNA via the NAAT domain, indicating the bifunctionality of the importin α N-terminal region for nuclear transport and chromatin association.
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Affiliation(s)
- Kazuya Jibiki
- Graduate School of Integrated Basic Sciences, Nihon University, Tokyo, Japan
| | - Takashi S Kodama
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Atsushi Suenaga
- Graduate School of Integrated Basic Sciences, Nihon University, Tokyo, Japan.,Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Yota Kawase
- Graduate School of Integrated Basic Sciences, Nihon University, Tokyo, Japan
| | - Noriko Shibazaki
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Shin Nomoto
- Graduate School of Integrated Basic Sciences, Nihon University, Tokyo, Japan
| | - Seiya Nagasawa
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Misaki Nagashima
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Shieri Shimodan
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Renan Kikuchi
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Mina Okayasu
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Ruka Takashita
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
| | - Rashid Mehmood
- Department of Life Sciences, College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia
| | - Noriko Saitoh
- Division of Cancer Biology, The Cancer Institute of JFCR, Tokyo, Japan
| | - Yoshihiro Yoneda
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan
| | - Ken-Ichi Akagi
- National Institutes of Biomedical Innovation, Health and Nutrition (NIBIOHN), Osaka, Japan.,Environmental Metabolic Analysis Research Team, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Noriko Yasuhara
- Graduate School of Integrated Basic Sciences, Nihon University, Tokyo, Japan.,Department of Biosciences, College of Humanities and Sciences, Nihon University, Tokyo, Japan
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14
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Kamagata K, Itoh Y, Tan C, Mano E, Wu Y, Mandali S, Takada S, Johnson RC. Testing mechanisms of DNA sliding by architectural DNA-binding proteins: dynamics of single wild-type and mutant protein molecules in vitro and in vivo. Nucleic Acids Res 2021; 49:8642-8664. [PMID: 34352099 PMCID: PMC8421229 DOI: 10.1093/nar/gkab658] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/10/2021] [Accepted: 07/22/2021] [Indexed: 01/06/2023] Open
Abstract
Architectural DNA-binding proteins (ADBPs) are abundant constituents of eukaryotic or bacterial chromosomes that bind DNA promiscuously and function in diverse DNA reactions. They generate large conformational changes in DNA upon binding yet can slide along DNA when searching for functional binding sites. Here we investigate the mechanism by which ADBPs diffuse on DNA by single-molecule analyses of mutant proteins rationally chosen to distinguish between rotation-coupled diffusion and DNA surface sliding after transient unbinding from the groove(s). The properties of yeast Nhp6A mutant proteins, combined with molecular dynamics simulations, suggest Nhp6A switches between two binding modes: a static state, in which the HMGB domain is bound within the minor groove with the DNA highly bent, and a mobile state, where the protein is traveling along the DNA surface by means of its flexible N-terminal basic arm. The behaviors of Fis mutants, a bacterial nucleoid-associated helix-turn-helix dimer, are best explained by mobile proteins unbinding from the major groove and diffusing along the DNA surface. Nhp6A, Fis, and bacterial HU are all near exclusively associated with the chromosome, as packaged within the bacterial nucleoid, and can be modeled by three diffusion modes where HU exhibits the fastest and Fis the slowest diffusion.
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Affiliation(s)
- Kiyoto Kamagata
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Yuji Itoh
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Cheng Tan
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Eriko Mano
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Yining Wu
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Sridhar Mandali
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Reid C Johnson
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
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15
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Negri A, Werbowy O, Wons E, Dersch S, Hinrichs R, Graumann PL, Mruk I. Regulator-dependent temporal dynamics of a restriction-modification system's gene expression upon entering new host cells: single-cell and population studies. Nucleic Acids Res 2021; 49:3826-3840. [PMID: 33744971 PMCID: PMC8053105 DOI: 10.1093/nar/gkab183] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 01/05/2023] Open
Abstract
Restriction-modification (R-M) systems represent a first line of defense against invasive DNAs, such as bacteriophage DNAs, and are widespread among bacteria and archaea. By acquiring a Type II R-M system via horizontal gene transfer, the new hosts generally become more resistant to phage infection, through the action of a restriction endonuclease (REase), which cleaves DNA at or near specific sequences. A modification methyltransferase (MTase) serves to protect the host genome against its cognate REase activity. The production of R-M system components upon entering a new host cell must be finely tuned to confer protective methylation before the REase acts, to avoid host genome damage. Some type II R-M systems rely on a third component, the controller (C) protein, which is a transcription factor that regulates the production of REase and/or MTase. Previous studies have suggested C protein effects on the dynamics of expression of an R-M system during its establishment in a new host cell. Here, we directly examine these effects. By fluorescently labelling REase and MTase, we demonstrate that lack of a C protein reduces the delay of REase production, to the point of being simultaneous with, or even preceding, production of the MTase. Single molecule tracking suggests that a REase and a MTase employ different strategies for their target search within host cells, with the MTase spending much more time diffusing in proximity to the nucleoid than does the REase. This difference may partially ameliorate the toxic effects of premature REase expression.
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Affiliation(s)
- Alessandro Negri
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Olesia Werbowy
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Ewa Wons
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
| | - Simon Dersch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Hans-Meerwein-Strasse 6, 35032 Marburg, Germany
| | - Rebecca Hinrichs
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Hans-Meerwein-Strasse 6, 35032 Marburg, Germany
| | - Peter L Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Hans-Meerwein-Strasse 6, 35032 Marburg, Germany
| | - Iwona Mruk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, Gdansk 80-308, Poland
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16
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Bigman LS, Greenblatt HM, Levy Y. What Are the Molecular Requirements for Protein Sliding along DNA? J Phys Chem B 2021; 125:3119-3131. [PMID: 33754737 PMCID: PMC8041311 DOI: 10.1021/acs.jpcb.1c00757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
DNA-binding proteins rely on linear
diffusion along the longitudinal
DNA axis, supported by their nonspecific electrostatic affinity for
DNA, to search for their target recognition sites. One may therefore
expect that the ability to engage in linear diffusion along DNA is
universal to all DNA-binding proteins, with the detailed biophysical
characteristics of that diffusion differing between proteins depending
on their structures and functions. One key question is whether the
linear diffusion mechanism is defined by translation coupled with
rotation, a mechanism that is often termed sliding. We conduct coarse-grained
and atomistic molecular dynamics simulations to investigate the minimal
requirements for protein sliding along DNA. We show that coupling,
while widespread, is not universal. DNA-binding proteins that slide
along DNA transition to uncoupled translation–rotation (i.e.,
hopping) at higher salt concentrations. Furthermore, and consistently
with experimental reports, we find that the sliding mechanism is the
less dominant mechanism for some DNA-binding proteins, even at low
salt concentrations. In particular, the toroidal PCNA protein is shown
to follow the hopping rather than the sliding mechanism.
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Affiliation(s)
- Lavi S Bigman
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Harry M Greenblatt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yaakov Levy
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Iwahara J, Kolomeisky AB. Discrete-state stochastic kinetic models for target DNA search by proteins: Theory and experimental applications. Biophys Chem 2021; 269:106521. [PMID: 33338872 PMCID: PMC7855466 DOI: 10.1016/j.bpc.2020.106521] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022]
Abstract
To perform their functions, transcription factors and DNA-repair/modifying enzymes randomly search DNA in order to locate their specific targets on DNA. Discrete-state stochastic kinetic models have been developed to explain how the efficiency of the search process is influenced by the molecular properties of proteins and DNA as well as by other factors such as molecular crowding. These theoretical models not only offer explanations on the relation of microscopic processes to macroscopic behavior of proteins, but also facilitate the analysis and interpretation of experimental data. In this review article, we provide an overview on discrete-state stochastic kinetic models and explain how these models can be applied to experimental investigations using stopped-flow, single-molecule, nuclear magnetic resonance (NMR), and other biophysical and biochemical methods.
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Affiliation(s)
- Junji Iwahara
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Anatoly B Kolomeisky
- Department of Chemistry, Department of Chemical and Biomolecular Engineering, Department of Physics and Astronomy and Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
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18
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D'Acunto M. Protein-DNA target search relies on quantum walk. Biosystems 2020; 201:104340. [PMID: 33387562 DOI: 10.1016/j.biosystems.2020.104340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 01/25/2023]
Abstract
Protein-DNA interactions play a fundamental role in all life systems. A critical issue of such interactions is given by the strategy of protein search for specific targets on DNA. The mechanisms by which the protein are able to find relatively small cognate sequences, typically 15-20 base pairs (bps) for repressors, and 4-6 bps for restriction enzymes among the millions of bp of non-specific chromosomal DNA have hardly engaged researchers for decades. Recent experimental studies have generated new insights on the basic processes of protein-DNA interactions evidencing the underlying complex dynamic phenomena involved, which combine three-dimensional and one-dimensional motion along the DNA chain. It has been demonstrated that protein molecules have an extraordinary ability to find the target very quickly on the DNA chain, in some cases, with two orders of magnitude faster than the diffusion limit. This unique property of protein-DNA search mechanism is known as facilitated diffusion. Several theoretical mechanisms have been suggested to describe the origin of facilitated diffusion. However, none of such models currently has the ability to fully describe the protein search strategy. In this paper, we suggest that the ability of proteins to identify consensus sequences on DNA is based on the entanglement of π-π electrons between DNA nucleotides and protein amino acids. The π-π entanglement is based on Quantum Walk (QW), through Coin-position entanglement (CPE). First, the protein identifies a dimer belonging to the consensus sequence, and localize a π on such dimer, hence, the other π electron scans the DNA chain until the sequence is identified. Focusing on the example of recognition of consensus sequences of EcoRV or EcoRI, we will describe the quantum features of QW on protein-DNA complexes during the search strategy, such as walker quadratic spreading on a coherent superposition of different vertices and environment-supported long-time survival probability of the walker. We will employ both discrete- or continuous-time versions of QW. Biased and unbiased classical Random Walk (CRW) have been used for a long time to describe the Protein-DNA search strategy. QW, the quantum version of CRW, has been widely studied for its applications in quantum information applications. In our biological application, the walker (the protein) resides at a vertex in a graph (the DNA structural topology). Differently to CRW, where the walker moves randomly, the quantum walker can hop along the edges in the graph to reach other vertices entering coherently a superposition across different vertices spreading quadratically faster than CRW analogous evidencing the typical speed up features of the QW. When applied to a protein-DNA target search problem, QW gives the possibility to achieve the experimental diffusional motion of proteins over diffusion classical limits experienced along DNA chains exploiting quantum features such as CPE and long-time survival probability supported by the environment. In turn, we come to the conclusion that, under quantum picture, the protein search strategy does not distinguish between one-dimensional (1D) and three-dimensional (3D) cases.
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Affiliation(s)
- Mario D'Acunto
- CNR-IBF, Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Via Moruzzi 1, 56124, Pisa, Italy.
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19
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Pal A, Greenblatt HM, Levy Y. Prerecognition Diffusion Mechanism of Human DNA Mismatch Repair Proteins along DNA: Msh2-Msh3 versus Msh2-Msh6. Biochemistry 2020; 59:4822-4832. [PMID: 33319999 PMCID: PMC7872316 DOI: 10.1021/acs.biochem.0c00669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
DNA
mismatch repair (MMR) is an important postreplication process
that eliminates mispaired or unpaired nucleotides to ensure genomic
replication fidelity. In humans, Msh2-Msh6 and Msh2-Msh3 are the two
mismatch repair initiation factors that recognize DNA lesions. While
X-ray crystal structures exist for these proteins in complex with
DNA lesions, little is known about their structures during the initial
search along nonspecific double-stranded DNA, because they are short-lived
and difficult to determine experimentally. In this study, various
computational approaches were used to sidestep these difficulties.
All-atom and coarse-grained simulations based on the crystal structures
of Msh2-Msh3 and Msh2-Msh6 showed no translation along the DNA, suggesting
that the initial search conformation differs from the lesion-bound
crystal structure. We modeled probable search-mode structures of MSH
proteins and showed, using coarse-grained molecular dynamics simulations,
that they can perform rotation-coupled diffusion on DNA, which is
a suitable and efficient search mechanism for their function and one
predicted earlier by fluorescence resonance energy transfer and fluorescence
microscopy studies. This search mechanism is implemented by electrostatic
interactions among the mismatch-binding domain (MBD), the clamp domains,
and the DNA backbone. During simulations, their diffusion rate did
not change significantly with an increasing salt concentration, which
is consistent with observations from experimental studies. When the
gap between their DNA-binding clamps was increased, Msh2-Msh3 diffused
mostly via the clamp domains while Msh2-Msh6 still diffused using
the MBD, reproducing the experimentally measured lower diffusion coefficient
of Msh2-Msh6. Interestingly, Msh2-Msh3 was capable of dissociating
from the DNA, whereas Msh2-Msh6 always diffused on the DNA duplex.
This is consistent with the experimental observation that Msh2-Msh3,
unlike Msh2-Msh6, can overcome obstacles such as nucleosomes. Our
models provide a molecular picture of the different mismatch search
mechanisms undertaken by Msh2-Msh6 and Msh2-Msh3, despite the similarity
of their structures.
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Affiliation(s)
- Arumay Pal
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Harry M Greenblatt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yaakov Levy
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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20
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Murugan R. A lattice model on the rate of in vivo site-specific DNA-protein interactions. Phys Biol 2020; 18:016005. [PMID: 33022664 DOI: 10.1088/1478-3975/abbe9a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We develop a lattice model of site-specific DNA-protein interactions under in vivo conditions where DNA is modelled as a self-avoiding random walk that is embedded in a cubic lattice box resembling the living cell. The protein molecule searches for its cognate site on DNA via a combination of three dimensional (3D) and one dimensional (1D) random walks. Hopping and intersegmental transfers occur depending on the conformational state of DNA. Results show that the search acceleration ratio (= search time in pure 3D route/search time in 3D and 1D routes) asymptotically increases towards a limiting value as the dilution factor of DNA (= volume of the cell/the volume of DNA) tends towards infinity. When the dilution ratio is low, then hopping and intersegmental transfers significantly enhance the search efficiency over pure sliding. At high dilution ratio, hopping does not enhance the search efficiency much since under such situation DNA will be in a relaxed conformation that favors only sliding. In the absence of hopping and intersegmental transfers, there exists an optimum sliding time at which the search acceleration ratio attains a maximum in line with the current theoretical results. However, existence of such optimum sliding length disappears in the presence of hopping. When the DNA is confined in a small volume inside the cell resembling a natural cell system, then there exists an optimum dilution and compression ratios (= total cell volume/volume in which DNA is confined) at which the search acceleration factor attains a maximum especially in the presence of hopping and intersegmental transfers. These optimum values are consistent with the values observed in the Escherichia coli cell system. In the absence of confinement of DNA, position of the specific binding site on the genomic DNA significantly influences the search acceleration. However, such position dependent changes in the search acceleration ratio will be nullified in the presence of hopping and intersegmental transfers especially when the DNA is confined in a small volume that is embedded in an outer cell.
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Affiliation(s)
- R Murugan
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
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21
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Lost in the Crowd: How Does Human 8-Oxoguanine DNA Glycosylase 1 (OGG1) Find 8-Oxoguanine in the Genome? Int J Mol Sci 2020; 21:ijms21218360. [PMID: 33171795 PMCID: PMC7664663 DOI: 10.3390/ijms21218360] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 12/11/2022] Open
Abstract
The most frequent DNA lesion resulting from an oxidative stress is 7,8-dihydro-8-oxoguanine (8-oxoG). 8-oxoG is a premutagenic base modification due to its capacity to pair with adenine. Thus, the repair of 8-oxoG is critical for the preservation of the genetic information. Nowadays, 8-oxoG is also considered as an oxidative stress-sensor with a putative role in transcription regulation. In mammalian cells, the modified base is excised by the 8-oxoguanine DNA glycosylase (OGG1), initiating the base excision repair (BER) pathway. OGG1 confronts the massive challenge that is finding rare occurrences of 8-oxoG among a million-fold excess of normal guanines. Here, we review the current knowledge on the search and discrimination mechanisms employed by OGG1 to find its substrate in the genome. While there is considerable data from in vitro experiments, much less is known on how OGG1 is recruited to chromatin and scans the genome within the cellular nucleus. Based on what is known of the strategies used by proteins searching for rare genomic targets, we discuss the possible scenarios allowing the efficient detection of 8-oxoG by OGG1.
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22
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Ma P, Elber R, Makarov DE. Value of Temporal Information When Analyzing Reaction Coordinates. J Chem Theory Comput 2020; 16:6077-6090. [PMID: 32841001 PMCID: PMC7881391 DOI: 10.1021/acs.jctc.0c00678] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Reaction coordinates chart pathways from reactants to products of chemical reactions. Determination of reaction coordinates from ensembles of molecular trajectories has thus been the focus of many studies. A widely used and insightful choice of a reaction coordinate is the committor function, defined as the probability that a trajectory will reach the product before the reactant. Here, we consider alternatives to the committor function that add useful mechanistic information, the mean first passage time, and the exit time to the product. We further derive a simple relationship between the functions of the committor, the mean first passage time, and the exit time. We illustrate the diversity of mechanisms predicted by alternative reaction coordinates with several toy problems and with a simple model of protein searching for a specific DNA motif.
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Affiliation(s)
- Piao Ma
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
- Oden Institute for Computational Engineering and Sciences, Austin, Texas 78712, United States
| | - Dmitrii E Makarov
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
- Oden Institute for Computational Engineering and Sciences, Austin, Texas 78712, United States
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23
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Chen J, Qi Y, Duan Y, Duan M, Yang M. C1188D mutation abolishes specific recognition between MLL1-CXXC domain and CpG site by inducing conformational switch of flexible N-terminal. Proteins 2020; 88:1401-1412. [PMID: 32519403 DOI: 10.1002/prot.25960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 05/22/2020] [Accepted: 06/06/2020] [Indexed: 01/19/2023]
Abstract
Mixed lineage leukemia protein (MLL1 protein) recognizes the CpG site via its CXXC domain and is frequently associated with leukemia. The specific recognition is abolished by C1188D mutation, which also prevents MLL-related leukemia. In this paper, multiple molecular dynamic (MD) simulations were performed to investigate the mechanism of recognition and influences of C1188D mutation. Started from fully dissociated DNA and MLL1-CXXC domain, remarkably, the center of mass (COM) of MLL1-CXXC domain quickly concentrates on the vicinity of the CpG site in all 53 short MD simulations. Extended simulations of the wild type showed that the native complex formed in 500 ns among 4 of 53 simulations. In contrast, the C1188D mutant COM distributed broadly around the DNA and the native complex was not observed in any of the extended simulations. Simulations on the apo MLL1-CXXC domain further suggest that the wild type protein remained predominantly in an open form that closely resembles its structure in the native complex whereas C1188D mutant formed predominantly compact structures in which the N- terminal bends to D1188. This conformational switch hinders the formation of encounter complex, thus abolishes the recognition. Our study also provides clues to the study mechanism of recognition, by the CXXC domain from proteins like DNA methyltransferase and ten-eleven translocation enzymes.
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Affiliation(s)
- Jiawen Chen
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonances in Wuhan, State Key laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Yanping Qi
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonances in Wuhan, State Key laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China.,College of Physical Science and Technology, Central China Normal University, Wuhan, China
| | - Yong Duan
- Department of Biomedical Engineering and UC Davis Genome Center, University of California at Davis, Davis, California, USA
| | - Mojie Duan
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonances in Wuhan, State Key laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China
| | - Minghui Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonances in Wuhan, State Key laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, China.,Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China
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24
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Suter DM. Transcription Factors and DNA Play Hide and Seek. Trends Cell Biol 2020; 30:491-500. [PMID: 32413318 DOI: 10.1016/j.tcb.2020.03.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 01/12/2023]
Abstract
Transcription factors (TFs) bind to specific DNA motifs to regulate the expression of target genes. To reach their binding sites, TFs diffuse in 3D and perform local motions such as 1D sliding, hopping, or intersegmental transfer. TF-DNA interactions depend on multiple parameters, such as the chromatin environment, TF partitioning into distinct subcellular regions, and cooperativity with other DNA-binding proteins. In this review, how current understanding of the search process has initially been shaped by prokaryotic studies is discussed, as well as what is known about the parameters regulating TF search efficiency in the context of the complex eukaryotic chromatin landscape.
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Affiliation(s)
- David M Suter
- Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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