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Thonnekottu D, Chatterjee D. Probing the modulation in facilitated diffusion guided by DNA-protein interactions in target search processes. Phys Chem Chem Phys 2024. [PMID: 38922594 DOI: 10.1039/d4cp01580k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
Many fundamental biophysical processes involving gene regulation and gene editing rely, at the molecular level, on an intricate methodology of searching and locating the precise target base pair sequence on the genome by specific binding proteins. A unique mechanism, known as 'facilitated diffusion', which is a combination of 1D sliding along with 3D movement, is considered to be the key step for such events. This also explains the relatively much shorter timescale of the target searching process, compared to other diffusion-controlled biophysical processes. In this work, we aim to probe the modulation of target search dynamics of a protein moiety by estimating the rate of the target search process, and the statistics of the search rounds and timescales accomplished by the 1D and 3D motions, based on first passage time (FPT) calculations. This is studied with its characteristics getting influenced by various given conditions such as, when the DNA is rigid or flexible, and when the target is placed at different locations on the DNA. The current theoretical framework includes a Brownian dynamics simulation setup adopting a straightforward coarse-grained model for a diffusing protein on DNA. Moreover, this theoretical analysis provides insights into the complex target search dynamics by highlighting the significance of the chain dynamics in the mechanistic details of the facilitated diffusion process.
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Affiliation(s)
- Diljith Thonnekottu
- Department of Physics, Indian Institute of Technology Palakkad, Kerala 678623, India
| | - Debarati Chatterjee
- Department of Chemistry, Indian Institute of Technology Palakkad, Kerala 678623, India.
- Department of Physics, Indian Institute of Technology Palakkad, Kerala 678623, India
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2
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Mersch K, Sokoloski J, Nguyen B, Galletto R, Lohman T. "Helicase" Activity promoted through dynamic interactions between a ssDNA translocase and a diffusing SSB protein. Proc Natl Acad Sci U S A 2023; 120:e2216777120. [PMID: 37011199 PMCID: PMC10104510 DOI: 10.1073/pnas.2216777120] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/06/2023] [Indexed: 04/05/2023] Open
Abstract
Replication protein A (RPA) is a eukaryotic single-stranded (ss) DNA-binding (SSB) protein that is essential for all aspects of genome maintenance. RPA binds ssDNA with high affinity but can also diffuse along ssDNA. By itself, RPA is capable of transiently disrupting short regions of duplex DNA by diffusing from a ssDNA that flanks the duplex DNA. Using single-molecule total internal reflection fluorescence and optical trapping combined with fluorescence approaches, we show that S. cerevisiae Pif1 can use its ATP-dependent 5' to 3' translocase activity to chemomechanically push a single human RPA (hRPA) heterotrimer directionally along ssDNA at rates comparable to those of Pif1 translocation alone. We further show that using its translocation activity, Pif1 can push hRPA from a ssDNA loading site into a duplex DNA causing stable disruption of at least 9 bp of duplex DNA. These results highlight the dynamic nature of hRPA enabling it to be readily reorganized even when bound tightly to ssDNA and demonstrate a mechanism by which directional DNA unwinding can be achieved through the combined action of a ssDNA translocase that pushes an SSB protein. These results highlight the two basic requirements for any processive DNA helicase: transient DNA base pair melting (supplied by hRPA) and ATP-dependent directional ssDNA translocation (supplied by Pif1) and that these functions can be unlinked by using two separate proteins.
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Affiliation(s)
- Kacey N. Mersch
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110-1093
| | - Joshua E. Sokoloski
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110-1093
- Department of Chemistry, Salisbury University, Salisbury, MD21801
| | - Binh Nguyen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110-1093
| | - Roberto Galletto
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110-1093
| | - Timothy M. Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110-1093
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Matozel EK, Parziale S, Price AC. A programmable DNA roadblock system using dCas9 and multivalent target sites. PLoS One 2022; 17:e0268099. [PMID: 35522691 PMCID: PMC9075669 DOI: 10.1371/journal.pone.0268099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/21/2022] [Indexed: 11/19/2022] Open
Abstract
A protein roadblock forms when a protein binds DNA and hinders translocation of other DNA binding proteins. These roadblocks can have significant effects on gene expression and regulation as well as DNA binding. Experimental methods for studying the effects of such roadblocks often target endogenous sites or introduce non-variable specific sites into DNAs to create binding sites for artificially introduced protein roadblocks. In this work, we describe a method to create programmable roadblocks using dCas9, a cleavage deficient mutant of the CRISPR effector nuclease Cas9. The programmability allows us to custom design target sites in a synthetic gene intended for in vitro studies. These target sites can be coded with multivalency-in our case, internal restriction sites which can be used in validation studies to verify complete binding of the roadblock. We provide full protocols and sequences and demonstrate how to use the internal restriction sites to verify complete binding of the roadblock. We also provide example results of the effect of DNA roadblocks on the translocation of the restriction endonuclease NdeI, which searches for its cognate site using one dimensional diffusion along DNA.
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Affiliation(s)
- Emily K. Matozel
- Department of Biology, Emmanuel College, Boston, United States of America
| | - Stephen Parziale
- Department of Mathematics, Emmanuel College, Boston, United States of America
| | - Allen C. Price
- Department of Chemistry and Physics, Emmanuel College, Boston, United States of America
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Chen ZP, Zhang HM, Yang P, Yuan R, Li Y, Liang WB. No-nonspecific recognition-based amplification strategy for endonuclease activity screening with dual-color DNA nano-clew. Biosens Bioelectron 2021; 190:113446. [PMID: 34166945 DOI: 10.1016/j.bios.2021.113446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 06/09/2021] [Accepted: 06/15/2021] [Indexed: 10/21/2022]
Abstract
The inevitable nonspecific recognition severely restricted widely used nucleic acid amplification strategies, which has become an urgent problem in current scientific research. Herein, we developed a novel no-nonspecific recognition-based amplification strategy to construct dual-color dye loaded nano-clew as ultrabright illuminant for screening endonuclease activity with Escherichia coliRY13 I (EcoR I) as a model, which overcame some major drawbacks such as nonspecific recognition and photobleaching. Typically, the target endonuclease induces cleavage of the customized dumbbell-shape substrate (DSS) to generate two same triggers that can initiate the rolling circle amplification (RCA) to prepare long single-strand DNA (lssDNA), which could self-assemble into irregular DNA nano-clew based on the electrostatic interactions with Mg2+ to furtherly capture the donor and accepter fluorophore proximately, constructing the dye loaded nano-clew with dual-color fluorescence (FL) emission to resist photobleaching. Importantly, in absence of EcoR I, even if the DSS could combine with circular template a little, the reaction system performed hardly RCA reaction due to no cohesive terminus, resulting an extremely low background fluorescence signal because of the prevention of nonspecific RCA reaction. As expected, the proposed sensing platform with a low limit of detection (LOD) of 3.4 × 10-7 U/μL was demonstrated to work well for endonuclease inhibitors screening also. Furthermore, the proposed no-nonspecific recognition strategy could be readily extended to various DNA or RNA enzymes such as DNA methyltransferase, DNA repair-related enzymes and polynucleotide kinase just by simply changing the recognition sequence in the DNA substrate, performing great potential of endonucleases-related clinical diagnosis and drugs discovery.
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Affiliation(s)
- Zhao-Peng Chen
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Hao-Min Zhang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Peng Yang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Ruo Yuan
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China
| | - Yan Li
- Department of Clinical and Military Laboratory Medicine, College of Medical Laboratory Science, Army Medical University, Chongqing, 400038, China.
| | - Wen-Bin Liang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715, China.
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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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Ferreira RM, Ware AD, Matozel E, Price AC. Salt concentration modulates the DNA target search strategy of NdeI. Biochem Biophys Res Commun 2020; 534:1059-1063. [PMID: 33121681 DOI: 10.1016/j.bbrc.2020.10.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 10/14/2020] [Indexed: 11/29/2022]
Abstract
DNA target search is a key step in cellular transactions that access genomic information. How DNA binding proteins combine 3D diffusion, sliding and hopping into an overall search strategy remains poorly understood. Here we report the use of a single molecule DNA tethering method to characterize the target search kinetics of the type II restriction endonuclease NdeI. The measured search rate depends strongly on DNA length as well as salt concentration. Using roadblocks, we show that there are significant changes in the DNA sliding length over the salt concentrations in our study. To explain our results, we propose a model including cycles of 3D and 1D search in which salt concentration modulates the strategy by varying the length of DNA probed per 1D scan. At low salt NdeI makes a single non-specific encounter with DNA followed by an effective and complete 1D scan. At higher salt, NdeI must execute multiple cycles of target search due to the reduced efficacy of 1D search.
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Affiliation(s)
- Raquel M Ferreira
- Department of Biology, Emmanuel College, 400 the Fenway, Boston, MA, 02115, United States
| | - Anna D Ware
- Department of Biology, Emmanuel College, 400 the Fenway, Boston, MA, 02115, United States
| | - Emily Matozel
- Department of Biology, Emmanuel College, 400 the Fenway, Boston, MA, 02115, United States
| | - Allen C Price
- Department of Chemistry and Physics, Emmanuel College, 400 the Fenway, Boston, MA, 02115, United States.
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Schneider TD, Jejjala V. Restriction enzymes use a 24 dimensional coding space to recognize 6 base long DNA sequences. PLoS One 2019; 14:e0222419. [PMID: 31671158 PMCID: PMC6822723 DOI: 10.1371/journal.pone.0222419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/29/2019] [Indexed: 11/19/2022] Open
Abstract
Restriction enzymes recognize and bind to specific sequences on invading bacteriophage DNA. Like a key in a lock, these proteins require many contacts to specify the correct DNA sequence. Using information theory we develop an equation that defines the number of independent contacts, which is the dimensionality of the binding. We show that EcoRI, which binds to the sequence GAATTC, functions in 24 dimensions. Information theory represents messages as spheres in high dimensional spaces. Better sphere packing leads to better communications systems. The densest known packing of hyperspheres occurs on the Leech lattice in 24 dimensions. We suggest that the single protein EcoRI molecule employs a Leech lattice in its operation. Optimizing density of sphere packing explains why 6 base restriction enzymes are so common.
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Affiliation(s)
- Thomas D. Schneider
- National Institutes of Health, National Cancer Institute, Center for Cancer Research, RNA Biology Laboratory, Frederick, Maryland, United States of America
| | - Vishnu Jejjala
- Mandelstam Institute for Theoretical Physics, School of Physics, NITheP, and CoE-MaSS, University of the Witwatersrand, Johannesburg, South Africa
- David Rittenhouse Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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