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Das N, Khan T, Halder B, Ghosh S, Sen P. Macromolecular crowding effects on protein dynamics. Int J Biol Macromol 2024:136248. [PMID: 39374718 DOI: 10.1016/j.ijbiomac.2024.136248] [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: 06/29/2024] [Revised: 09/30/2024] [Accepted: 09/30/2024] [Indexed: 10/09/2024]
Abstract
Macromolecular crowding experiments bridge the gap between in-vivo and in-vitro studies by mimicking some of the cellular complexities like high viscosity and limited space, while still manageable for experiments and analysis. Macromolecular crowding impacts all biological processes and is a focus of contemporary research. Recent reviews have highlighted the effect of crowding on various protein properties. One of the essential characteristics of protein is its dynamic nature; however, how protein dynamics get modulated in the crowded milieu has been largely ignored. This article discusses how protein translational, rotational, conformational, and solvation dynamics change under crowded conditions, summarizing key observations in the literature. We emphasize our research on microsecond conformational and water dynamics in crowded milieus and their impact on enzymatic activity and stability. Lastly, we provided our outlook on how this field might move forward in the future.
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Affiliation(s)
- Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Tanmoy Khan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Bisal Halder
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Shreya Ghosh
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India.
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2
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Khan T, Halder B, Das N, Sen P. Role of Associated Water Dynamics on Protein Stability and Activity in Crowded Milieu. J Phys Chem B 2024; 128:8672-8686. [PMID: 39224956 DOI: 10.1021/acs.jpcb.4c04337] [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: 09/04/2024]
Abstract
Macromolecular crowding bridges in vivo and in vitro studies by simulating cellular complexities such as high viscosity and limited space while maintaining the experimental feasibility. Over the last two decades, the impact of macromolecular crowding on protein stability and activity has been a significant topic of study and discussion, though still lacking a thorough mechanistic understanding. This article investigates the role of associated water dynamics on protein stability and activity within crowded environments, using bromelain and Ficoll-70 as the model systems. Traditional crowding theory primarily attributes protein stability to entropic effects (excluded volume) and enthalpic interactions. However, our recent findings suggest that water structure modulation plays a crucial role in a crowded environment. In this report, we strengthen the conclusion of our previous study, i.e., rigid-associated water stabilizes proteins via entropy and destabilizes them via enthalpy, while flexible water has the opposite effect. In the process, we addressed previous shortcomings with a systematic concentration-dependent study using a single-domain protein and component analysis of solvation dynamics. More importantly, we analyze bromelain's hydrolytic activity using the Michaelis-Menten model to understand kinetic parameters like maximum velocity (Vmax) achieved by the system and the Michaelis-Menten coefficient (KM). Results indicate that microviscosity (not the bulk viscosity) controls the enzyme-substrate (ES) complex formation, where an increase in the microviscosity makes the ES complex formation less favorable. On the other hand, flexible associated water dynamics were found to favor the rate of product formation significantly from the ES complex, while rigid associated water hinders it. This study improves our understanding of protein stability and activity in crowded environments, highlighting the critical role of associated water dynamics.
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Affiliation(s)
- Tanmoy Khan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Bisal Halder
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
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3
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López-Molina J, Groh S, Dzubiella J, Moncho-Jordá A. Nonequilibrium relaxation of soft responsive colloids. J Chem Phys 2024; 161:094902. [PMID: 39225526 DOI: 10.1063/5.0221903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Accepted: 08/12/2024] [Indexed: 09/04/2024] Open
Abstract
Stimuli-responsive macromolecules display large conformational changes during their dynamics, sometimes switching between states. Such a multi-stability is useful for the development of soft functional materials. Here, we introduce a mean-field dynamical density functional theory for a model of responsive colloids to study the nonequilibrium dynamics of a colloidal dispersion in time-dependent external fields, with a focus on the coupling of translational and conformational dynamics during their relaxation. Specifically, we consider soft Gaussian particles with a bimodal size distribution between two confining walls with time-dependent (switching-on and off) external gravitational and osmotic fields. We find a rich relaxation behavior of the systems in excellent agreement with particle-based Brownian dynamics computer simulations. In particular, we find time-asymmetric relaxations of integrated observables (wall pressures, mean size, and liquid center-of-mass) for activation/deactivation of external potentials, respectively, which are tunable by the ratio of translational and conformational diffusion time scales. Our work thus paves the way for studying the nonequilibrium relaxation dynamics of complex soft matter with multiple degrees of freedom and hierarchical relaxations.
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Affiliation(s)
- José López-Molina
- Department of Applied Physics, University of Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Sebastien Groh
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany
| | - Joachim Dzubiella
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany
- Cluster of Excellence livMatS @ FIT-Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwigs-Universität Freiburg, D-79110 Freiburg, Germany
| | - Arturo Moncho-Jordá
- Department of Applied Physics, University of Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
- Institute Carlos I for Theoretical and Computational Physics, University de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
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4
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Mukherjee P, Mazumder A. Macromolecular crowding has opposite effects on two critical sub-steps of transcription initiation. FEBS Lett 2024; 598:1022-1033. [PMID: 38479985 PMCID: PMC7615953 DOI: 10.1002/1873-3468.14851] [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: 12/23/2023] [Revised: 02/12/2024] [Accepted: 02/19/2024] [Indexed: 04/12/2024]
Abstract
Transcription initiation, the first step in gene expression, has been studied extensively in dilute buffer, a condition which fails to consider the crowded environment in live cells. Recent reports indicate the kinetics of promoter escape is altered in crowded conditions for a consensus bacterial promoter. Here, we use a real-time fluorescence enhancement assay to study the kinetics of unwound bubble formation and promoter escape for three separate promoters. We find that the effect of crowding on transcription initiation is complex, with lower rates of unwound bubble formation, higher rates of promoter escape, and large variations depending on promoter identity. Based on our results, we suggest that altered conditions of crowding inside a live cell can trigger global changes.
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Affiliation(s)
- Pratip Mukherjee
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre, Ghaziabad, India
| | - Abhishek Mazumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
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5
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Cubuk J, Alston J, Incicco JJ, Holehouse A, Hall K, Stuchell-Brereton M, Soranno A. The disordered N-terminal tail of SARS-CoV-2 Nucleocapsid protein forms a dynamic complex with RNA. Nucleic Acids Res 2024; 52:2609-2624. [PMID: 38153183 PMCID: PMC10954482 DOI: 10.1093/nar/gkad1215] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 11/17/2023] [Accepted: 12/11/2023] [Indexed: 12/29/2023] Open
Abstract
The SARS-CoV-2 Nucleocapsid (N) protein is responsible for condensation of the viral genome. Characterizing the mechanisms controlling nucleic acid binding is a key step in understanding how condensation is realized. Here, we focus on the role of the RNA binding domain (RBD) and its flanking disordered N-terminal domain (NTD) tail, using single-molecule Förster Resonance Energy Transfer and coarse-grained simulations. We quantified contact site size and binding affinity for nucleic acids and concomitant conformational changes occurring in the disordered region. We found that the disordered NTD increases the affinity of the RBD for RNA by about 50-fold. Binding of both nonspecific and specific RNA results in a modulation of the tail configurations, which respond in an RNA length-dependent manner. Not only does the disordered NTD increase affinity for RNA, but mutations that occur in the Omicron variant modulate the interactions, indicating a functional role of the disordered tail. Finally, we found that the NTD-RBD preferentially interacts with single-stranded RNA and that the resulting protein:RNA complexes are flexible and dynamic. We speculate that this mechanism of interaction enables the Nucleocapsid protein to search the viral genome for and bind to high-affinity motifs.
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Affiliation(s)
- Jasmine Cubuk
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Jhullian J Alston
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - J Jeremías Incicco
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Kathleen B Hall
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
| | - Melissa D Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
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Jain M, Sahoo A, Matysiak S. Modulation of Aβ 16-22 aggregation by glucose. Phys Chem Chem Phys 2024; 26:5038-5044. [PMID: 38258497 DOI: 10.1039/d3cp04494g] [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: 01/24/2024]
Abstract
The self-assembly of amyloid-beta (Aβ) peptides into fibrillar structures in the brain is a signature of Alzheimer's disease. Recent studies have reported correlations between Alzheimer's disease and type-2 diabetes. Structurally, hyperglycemia induces covalent protein crosslinkings by advanced glycation end products (AGE), which can affect the stability of Aβ oligomers. In this work, we leverage physics-based coarse-grained molecular simulations to probe alternate thermodynamic pathways that affect peptide aggregation propensities at varying concentrations of glucose molecules. Similar to previous experimental reports, our simulations show a glucose concentration-dependent increase in Aβ aggregation rates, without changes in the overall secondary structure content. We discovered that glucose molecules prefer partitioning onto the aggregate-water interface at a specific orientation, resulting in a loss of molecular rotational entropy. This effectively hastens the aggregation rates, as peptide self-assembly can reduce the available surface area for peptide-glucose interactions. This work introduces a new thermodynamic-driven pathway, beyond chemical cross-linking, that can modulate Aβ aggregation.
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Affiliation(s)
- Meenal Jain
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
| | - Abhilash Sahoo
- Center for Computational Biology, Flatiron Institute, New York, NY, USA
- Center for Computational Mathematics, Flatiron Institute, New York, NY, USA
| | - Silvina Matysiak
- Biophysics Program, Institute of Physical Science and Technology, University of Maryland, College Park, MD, USA.
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
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7
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Miyagawa A, Ueda Y, Nakatani K. Molecular crowding effect in Hantzch pyridine synthesis in polyethylene glycol aqueous solution. Phys Chem Chem Phys 2024; 26:5615-5620. [PMID: 38288480 DOI: 10.1039/d3cp06104c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
In a molecular crowding environment, the kinetics and thermodynamics differ from those in a diluted solution. Although the molecular crowding effect has been extensively investigated, its fundamental kinetics and thermodynamics remain unclear. In this study, we investigated the change in the rate constant (k) of the Hantzch pyridine reaction in a molecular crowding environment using polyethylene glycol (PEG). While the k value increased to a PEG concentration (CPEG) of 10 vol%, a decreasing trend was observed for CPEG > 20 vol%. This intriguing behavior was analyzed based on the increase in reactant activity due to volume exclusion and the decrease in water activity due to osmotic pressure. Volume exclusion and osmotic pressure had opposing effects on the reaction, which were positive for volume exclusion and negative for osmotic pressure. We found that k decreased when the negative effect of the osmotic pressure surpassed the volume exclusion effect.
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Affiliation(s)
- Akihisa Miyagawa
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Yasuyuki Ueda
- Institute of Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan
| | - Kiyoharu Nakatani
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
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8
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Gemmill DL, Nelson CR, Badmalia MD, Pereira HS, Kerr L, Wolfinger MT, Patel TR. The 3' terminal region of Zika virus RNA contains a conserved G-quadruplex and is unfolded by human DDX17. Biochem Cell Biol 2024; 102:96-105. [PMID: 37774422 DOI: 10.1139/bcb-2023-0036] [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: 10/01/2023] Open
Abstract
Zika virus (ZIKV) infection remains a worldwide concern, and currently no effective treatments or vaccines are available. Novel therapeutics are an avenue of interest that could probe viral RNA-human protein communication to stop viral replication. One specific RNA structure, G-quadruplexes (G4s), possess various roles in viruses and all domains of life, including transcription and translation regulation and genome stability, and serves as nucleation points for RNA liquid-liquid phase separation. Previous G4 studies on ZIKV using a quadruplex forming G-rich sequences Mapper located a potential G-quadruplex sequence in the 3' terminal region (TR) and was validated structurally using a 25-mer oligo. It is currently unknown if this structure is conserved and maintained in a large ZIKV RNA transcript and its specific roles in viral replication. Using bioinformatic analysis and biochemical assays, we demonstrate that the ZIKV 3' TR G4 is conserved across all ZIKV isolates and maintains its structure in a 3' TR full-length transcript. We further established the G4 formation using pyridostatin and the BG4 G4-recognizing antibody binding assays. Our study also demonstrates that the human DEAD-box helicases, DDX3X132-607 and DDX17135-555, bind to the 3' TR and that DDX17135-555 unfolds the G4 present in the 3' TR. These findings provide a path forward in potential therapeutic targeting of DDX3X or DDX17's binding to the 3' TR G4 region for novel treatments against ZIKV.
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Affiliation(s)
- Dannielle L Gemmill
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Corey R Nelson
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Maulik D Badmalia
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Higor S Pereira
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Liam Kerr
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
| | - Michael T Wolfinger
- Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Währinger Strasse 29, 1090, Vienna, Austria
- Department of Theoretical Chemistry, University of Vienna, Währinger Strasse 17, 1090, Vienna, Austria
- RNA Forecast e.U., 1140 Vienna, Austria
| | - Trushar R Patel
- Alberta RNA Research and Training Institute & Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada
- Department of Microbiology, Immunology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
- Li Ka Shing Institute of Virology and Discovery Lab, University of Alberta, Edmonton, AB T6G 2E1, Canada
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9
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Moncho-Jordá A, Groh S, Dzubiella J. External field-driven property localization in liquids of responsive macromolecules. J Chem Phys 2024; 160:024904. [PMID: 38189617 DOI: 10.1063/5.0177933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/14/2023] [Indexed: 01/09/2024] Open
Abstract
We explore theoretically the effects of external potentials on the spatial distribution of particle properties in a liquid of explicitly responsive macromolecules. In particular, we focus on the bistable particle size as a coarse-grained internal degree of freedom (DoF, or "property"), σ, that moves in a bimodal energy landscape, in order to model the response of a state-switching (big-to-small) macromolecular liquid to external stimuli. We employ a mean-field density functional theory (DFT) that provides the full inhomogeneous equilibrium distributions of a one-component model system of responsive colloids (RCs) interacting with a Gaussian pair potential. For systems confined between two parallel hard walls, we observe and rationalize a significant localization of the big particle state close to the walls, with pressures described by an exact RC wall theorem. Application of more complex external potentials, such as linear (gravitational), osmotic, and Hamaker potentials, promotes even stronger particle size segregation, in which macromolecules of different size are localized in different spatial regions. Importantly, we demonstrate how the degree of responsiveness of the particle size and its coupling to the external potential tune the position-dependent size distribution. The DFT predictions are corroborated by Brownian dynamics simulations. Our study highlights the fact that particle responsiveness can be used to localize liquid properties and therefore helps to control the property- and position-dependent function of macromolecules, e.g., in biomedical applications.
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Affiliation(s)
- Arturo Moncho-Jordá
- Department of Applied Physics, University de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
- Institute Carlos I for Theoretical and Computational Physics, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Sebastien Groh
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany
| | - Joachim Dzubiella
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany
- Cluster of Excellence livMatS @ FIT - Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwigs-Universität 6 Freiburg, D-79110 Freiburg, Germany
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10
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Kang B, Park SV, Oh SS. Ionic liquid-caged nucleic acids enable active folding-based molecular recognition with hydrolysis resistance. Nucleic Acids Res 2024; 52:73-86. [PMID: 37994697 PMCID: PMC10783497 DOI: 10.1093/nar/gkad1093] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 11/07/2023] [Indexed: 11/24/2023] Open
Abstract
Beyond storage and transmission of genetic information in cellular life, nucleic acids can perform diverse interesting functions, including specific target recognition and biochemical reaction acceleration; the versatile biopolymers, however, are acutely vulnerable to hydrolysis-driven degradation. Here, we demonstrate that the cage effect of choline dihydrogen phosphate permits active folding of nucleic acids like water, but prevents their phosphodiester hydrolysis unlike water. The choline-based ionic liquid not only serves as a universal inhibitor of nucleases, exceptionally extending half-lives of nucleic acids up to 6 500 000 times, but highly useful tasks of nucleic acids (e.g. mRNA detection of molecular beacons, ligand recognition of aptamers, and transesterification reaction of ribozymes) can be also conducted with well-conserved affinities and specificities. As liberated from the function loss and degradation risk, the presence of undesired and unknown nucleases does not undermine desired molecular functions of nucleic acids without hydrolysis artifacts even in nuclease cocktails and human saliva.
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Affiliation(s)
- Byunghwa Kang
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, South Korea
| | - Soyeon V Park
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, South Korea
| | - Seung Soo Oh
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, South Korea
- Institute for Convergence Research and Education in Advanced Technology (I-CREATE), Yonsei University, Incheon 21983, South Korea
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11
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Aznauryan M, Birkedal V. Dynamics of G-Quadruplex Formation under Molecular Crowding. J Phys Chem Lett 2023; 14:10354-10360. [PMID: 37948600 DOI: 10.1021/acs.jpclett.3c02453] [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: 11/12/2023]
Abstract
G-quadruplex (G4) structures assemble from guanine-rich DNA sequences and are believed to regulate several key cellular processes. G4 formation and conformational interconversions are well-established to occur dynamically in vitro. However, a clear understanding of G4 formation dynamics in cells as well as under conditions mimicking the cellular environment is missing. To fill this gap, we have investigated the G4 dynamics in molecularly crowded solutions, thus replicating the effect of the excluded volume present in cells. The results show that the volume exclusion exerted by large crowding agents accelerates the rate of G4 formation by at least an order of magnitude, leading to significant G4 stabilization. Extrapolation from our experimental data predicts crowding-induced G4 stabilization by more than 3 kcal/mol, under crowding levels found in the cellular environment. Such effects are likely to be important for G4-driven regulatory functions.
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Affiliation(s)
- Mikayel Aznauryan
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
- Univ. Bordeaux, ARNA Laboratory, INSERM U1212, CNRS UMR 5320, Institut Européen de Chimie et Biologie, 33607 Pessac, France
| | - Victoria Birkedal
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
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12
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DasGupta S, Zhang S, Szostak JW. Molecular Crowding Facilitates Ribozyme-Catalyzed RNA Assembly. ACS CENTRAL SCIENCE 2023; 9:1670-1678. [PMID: 37637737 PMCID: PMC10451029 DOI: 10.1021/acscentsci.3c00547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Indexed: 08/29/2023]
Abstract
Catalytic RNAs or ribozymes are considered to be central to primordial biology. Most ribozymes require moderate to high concentrations of divalent cations such as Mg2+ to fold into their catalytically competent structures and perform catalysis. However, undesirable effects of Mg2+ such as hydrolysis of reactive RNA building blocks and degradation of RNA structures are likely to undermine its beneficial roles in ribozyme catalysis. Further, prebiotic cell-like compartments bounded by fatty acid membranes are destabilized in the presence of Mg2+, making ribozyme function inside prebiotically relevant protocells a significant challenge. Therefore, we sought to identify conditions that would enable ribozymes to retain activity at low concentrations of Mg2+. Inspired by the ability of ribozymes to function inside crowded cellular environments with <1 mM free Mg2+, we tested molecular crowding as a potential mechanism to lower the Mg2+ concentration required for ribozyme-catalyzed RNA assembly. Here, we show that the ribozyme-catalyzed ligation of phosphorimidazolide RNA substrates is significantly enhanced in the presence of the artificial crowding agent polyethylene glycol. We also found that molecular crowding preserves ligase activity under denaturing conditions such as alkaline pH and the presence of urea. Additionally, we show that crowding-induced stimulation of RNA-catalyzed RNA assembly is not limited to phosphorimidazolide ligation but extends to the RNA-catalyzed polymerization of nucleoside triphosphates. RNA-catalyzed RNA ligation is also stimulated by the presence of prebiotically relevant small molecules such as ethylene glycol, ribose, and amino acids, consistent with a role for molecular crowding in primordial ribozyme function and more generally in the emergence of RNA-based cellular life.
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Affiliation(s)
- Saurja DasGupta
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Howard
Hughes Medical Institute, Massachusetts General
Hospital, Boston, Massachusetts 02114, United States
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Stephanie Zhang
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Jack W. Szostak
- Department
of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Howard
Hughes Medical Institute, Massachusetts General
Hospital, Boston, Massachusetts 02114, United States
- Department
of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, Cambridge, Massachusetts 02138, United States
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13
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Stringer M, Cubuk J, Incicco JJ, Roy D, Hall KB, Stuchell-Brereton MD, Soranno A. Excluded Volume and Weak Interactions in Crowded Solutions Modulate Conformations and RNA Binding of an Intrinsically Disordered Tail. J Phys Chem B 2023; 127:5837-5849. [PMID: 37348142 PMCID: PMC10331728 DOI: 10.1021/acs.jpcb.3c02356] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 06/08/2023] [Indexed: 06/24/2023]
Abstract
The cellular milieu is a solution crowded with a significant concentration of different components (proteins, nucleic acids, metabolites, etc.). Such a crowded environment affects protein conformations, dynamics, and interactions. Intrinsically disordered proteins and regions are particularly sensitive to these effects. Here, we investigate the impact on an intrinsically disordered tail that flanks a folded domain, the N-terminal domain, and the RNA-binding domain of the SARS-CoV-2 nucleocapsid protein. We mimic the crowded environment of the cell using polyethylene glycol (PEG) and study its impact on protein conformations using single-molecule Förster resonance energy transfer. We found that high-molecular-weight PEG induces a collapse of the disordered N-terminal tail, whereas low-molecular-weight PEG induces a chain expansion. Our data can be explained by accounting for two opposing contributions: favorable interactions between the protein and crowder molecules and screening of excluded volume interactions. We further characterized the interaction between protein and RNA in the presence of crowding agents. While for all PEG molecules tested, we observed an increase in the binding affinity, the trend is not monotonic as a function of the degree of PEG polymerization. This points to the role of nonspecific protein-PEG interactions on binding in addition to the entropic effects due to crowding. To separate the enthalpic and entropic components of the effects, we investigated the temperature dependence of the association constants in the absence and presence of crowders. Finally, we compared the effects of crowding across mutations in the disordered region and found that the threefold difference in association constants for two naturally occurring variants of the SARS-CoV-2 nucleocapsid protein is reduced to almost identical affinities in the presence of crowders. Overall, our data provide new insights into understanding and modeling the contribution of crowding effects on disordered regions, including the impact of interactions between proteins and crowders and their interplay when binding a ligand.
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Affiliation(s)
- Madison
A. Stringer
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
- Center
for Biomolecular Condensates, Washington
University in St Louis, 1 Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Jasmine Cubuk
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
- Center
for Biomolecular Condensates, Washington
University in St Louis, 1 Brookings Drive, Saint Louis, Missouri 63130, United States
| | - J. Jeremías Incicco
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
| | - Debjit Roy
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
- Center
for Biomolecular Condensates, Washington
University in St Louis, 1 Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Kathleen B. Hall
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
| | - Melissa D. Stuchell-Brereton
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
- Center
for Biomolecular Condensates, Washington
University in St Louis, 1 Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Andrea Soranno
- Department
of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Avenue, Saint
Louis, Missouri 63110, United States
- Center
for Biomolecular Condensates, Washington
University in St Louis, 1 Brookings Drive, Saint Louis, Missouri 63130, United States
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14
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Liang T, Yang C, Song X, Feng Y, Liu Y, Chen H. Quantification of macromolecule crowding at single-molecule level. Phys Rev E 2023; 108:014406. [PMID: 37583195 DOI: 10.1103/physreve.108.014406] [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: 03/24/2023] [Accepted: 06/19/2023] [Indexed: 08/17/2023]
Abstract
Macromolecule crowding has a prominent impact on a series of biochemical processes in the cell. It is also expected to promote macromolecular complexation induced by excluded volume effects, which conflicts with recent advances in the thermodynamic interaction between inert, synthetic polymers, and nucleic acids. Along this line, a method combining high-resolution magnetic tweezers and extended crowder-oxDNA model was applied to resolve these discrepancies by systematically studying the kinetics and thermodynamics of the folding-unfolding transition for an individual DNA hairpin in a crowded environment. More specifically, from the magnetic tweezers-based experiments, the linear dependence of the critical force of the DNA hairpin on the polyethylene glycol (PEG) concentration was demonstrated, which is consistent with the results based on the crowder-oxDNA model in which the Lennard-Jones potential was adopted to express the interaction between the crowders and the DNA hairpin. These consistencies highlight that the excluded volume effects are mainly responsible for the interaction between PEG and the DNA hairpin, which is different from the interaction between dextran and the DNA hairpin. In the meantime, the dependence of the folding rate on the molecule weight of PEG, which was different from fluorescence resonance energy transfer-based results, was identified. The proposed method opens a path to detect the interaction between an inert, synthetic molecule, and the DNA hairpin, which is important to accurately mimic the cytosolic environments using mixtures of different inert molecules.
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Affiliation(s)
- Ting Liang
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Chao Yang
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Xiaoya Song
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Yuyu Feng
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Yanhui Liu
- College of Physics, Guizhou University, Guiyang 550025, China
| | - Hu Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
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15
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Zhang N, Guan W, Cui S, Ai N. Crowded environments tune the fold-switching in metamorphic proteins. Commun Chem 2023; 6:117. [PMID: 37291449 PMCID: PMC10250422 DOI: 10.1038/s42004-023-00909-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/22/2023] [Indexed: 06/10/2023] Open
Abstract
Metamorphic proteins such as circadian clock protein KaiB and human chemokine XCL1 play vital roles in regulating biological processes, including gene expression, circadian clock and innate immune responses, and perform distinct functions in living cell by switching different structures in response to cellular environment stimuli. However, it is unclear how complex and crowded intracellular environments affect conformational rearrangement of metamorphic proteins. Here, the kinetics and thermodynamics of two well-characterized metamorphic proteins, circadian clock protein KaiB and human chemokine XCL1, were quantified in physiologically relevant environments by using NMR spectroscopy, indicating that crowded agents shift equilibrium towards the inactive form (ground-state KaiB and Ltn10-like state XCL1) without disturbing the corresponding structures, and crowded agents have predominantly impact on the exchange rate of XCL1 that switches folds on timescales of seconds, but have slightly impact on the exchange rate of KaiB that switches folds on timescales of hours. Our data shed light on how metamorphic proteins can respond immediately to the changed crowded intracellular conditions that induced by environmental cues and then execute different functions in living cell, and it also enhances our understanding of how environments enrich the sequence-structure-function paradigm.
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Affiliation(s)
- Ning Zhang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
- Shandong Energy Institute, Qingdao, 266101, China.
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China.
| | - Wenyan Guan
- Materials and Biomaterials Science and Engineering, University of California, Merced, CA, 95343, USA
| | - Shouqi Cui
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
- Shandong Energy Institute, Qingdao, 266101, China
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Nana Ai
- Materials and Biomaterials Science and Engineering, University of California, Merced, CA, 95343, USA
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16
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Delgado A, Vera-Villalobos J, Paz JL, Lossada C, Hurtado-León ML, Marrero-Ponce Y, Toro-Mendoza J, Alvarado YJ, González-Paz L. Macromolecular crowding impact on anti-CRISPR AcrIIC3/NmeCas9 complex: Insights from scaled particle theory, molecular dynamics, and elastic networks models. Int J Biol Macromol 2023:125113. [PMID: 37257544 DOI: 10.1016/j.ijbiomac.2023.125113] [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: 02/16/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/02/2023]
Abstract
The coupling of Cas9 and its inhibitor AcrIIC3, both from the bacterium Neisseria meningitidis (Nme), form a homodimer of the (NmeCas9/AcrIIC3)2 type. This coupling was studied to assess the impact of their interaction with the crowders in the following environments: (1) homogeneous crowded, (2) heterogeneous, and (3) microheterogeneous cytoplasmic. For this, statistical thermodynamic models based on the scaled particle theory (SPT) were used, considering the attractive and repulsive protein-crowders contributions and the stability of the formation of spherocylindrical homodimers and the effects of changes in the size of spherical dimers were estimated. Studies based on models of dynamics, elastic networks, and statistical potentials to the formation of complexes NmeCas9/AcrIIC3 using PEG as the crowding agent support the predictions from SPT. Macromolecular crowding stabilizes the formation of the dimers, being more significant when the attractive protein-crowder interactions are weaker and the crowders are smaller. The coupling is favored towards the formation of spherical and compact dimers due to crowding addition (excluded-volume effects) and the thermodynamic stability of the dimers is markedly dependent on the size of the crowders. These results support the experimental mechanistic proposal of inhibition of NmeCas9 mediated by AcrIIC3.
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Affiliation(s)
- Ariana Delgado
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Biomedicina Molecular (CBM), Laboratorio de Química Biofísica Teórica y Experimental (LQBTE), 4001 Maracaibo, Zulia, Venezuela; Universidad del Zulia (LUZ), Facultad Experimental de Ciencias (FEC), Departamento de Química, Laboratorio de Química Teórica y Computacional (LQTC), 4001 Maracaibo, Venezuela
| | - Joan Vera-Villalobos
- Facultad de Ciencias Naturales y Matemáticas, Departamento de Química y Ciencias Ambientales, Laboratorio de Análisis Químico Instrumental (LAQUINS), Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador
| | - José Luis Paz
- Departamento Académico de Química Inorgánica, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Carla Lossada
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Biomedicina Molecular (CBM), Laboratorio de Biocomputación (LB), 4001 Maracaibo, Zulia, Venezuela
| | - María Laura Hurtado-León
- Universidad del Zulia (LUZ), Facultad Experimental de Ciencias (FEC), Departamento de Biología, Laboratorio de Genética y Biología Molecular (LGBM), 4001 Maracaibo, Venezuela
| | - Yovani Marrero-Ponce
- Universidad San Francisco de Quito (USFQ), Grupo de Medicina Molecular y Traslacional (MeM&T), Colegio de Ciencias de la Salud (COCSA), Escuela de Medicina, Edificio de Especialidades Médicas, Quito 170157, Pichincha, Ecuador; Departamento de Ciencias de la Computación, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Baja California 22860, Mexico; Instituto de Simulación Computacional (ISC-USFQ), Diego de Robles y vía Interoceánica, Quito 170157, Pichincha, Ecuador
| | - Jhoan Toro-Mendoza
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Biomedicina Molecular (CBM), Laboratorio de Química Biofísica Teórica y Experimental (LQBTE), 4001 Maracaibo, Zulia, Venezuela
| | - Ysaías J Alvarado
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Biomedicina Molecular (CBM), Laboratorio de Química Biofísica Teórica y Experimental (LQBTE), 4001 Maracaibo, Zulia, Venezuela.
| | - Lenin González-Paz
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Biomedicina Molecular (CBM), Laboratorio de Biocomputación (LB), 4001 Maracaibo, Zulia, Venezuela.
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17
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Moncho-Jordá A, Göth N, Dzubiella J. Liquid structure of bistable responsive macromolecules using mean-field density-functional theory. SOFT MATTER 2023; 19:2832-2846. [PMID: 37000605 DOI: 10.1039/d2sm01523d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Macromolecular crowding typically applies to biomolecular and polymer-based systems in which the individual particles often feature a two-state folded/unfolded or coil-to-globule transition, such as found for proteins and peptides, DNA and RNA, or supramolecular polymers. Here, we employ a mean-field density functional theory (DFT) of a model of soft and bistable responsive colloids (RCs) in which the size of the macromolecule is explicitly resolved as a degree of freedom living in a bimodal 'Landau' energy landscape (exhibiting big and small states), thus directly responding to the crowding environment. Using this RC-DFT we study the effects of self-crowding on the liquid bulk structure and thermodynamics for different energy barriers and softnesses of the bimodal energy landscape, in conditions close to the coil-to-globule transition. We find substantial crowding effects on the internal distributions, a complex polydispersity behavior, and quasi-universal compression curves for increasing (generalized) packing fractions. Moreover, we uncover distinct signatures of bimodal versus unimodal behavior in the particle compression. Finally, the analysis of the pair structure - derived from the test particle route - reveals that the microstructure of the liquid is quite inhomogeneous due to local depletion effects, tuneable by particle softness.
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Affiliation(s)
- Arturo Moncho-Jordá
- Institute Carlos I for Theoretical and Computational Physics, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
- Departamento de Física Aplicada, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Nils Göth
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
| | - Joachim Dzubiella
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
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18
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Yang C, Song X, Feng Y, Zhao G, Liu Y. Stability of DNA and RNA hairpins: a comparative study based on ox-DNA. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:265101. [PMID: 36972608 DOI: 10.1088/1361-648x/acc7eb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/27/2023] [Indexed: 06/18/2023]
Abstract
Advances in single-molecule experiments on macromolecular crowding urgently need an efficient simulation method to resolve their discrepancies quantitatively. Ox-DNA model has been since reworked to treat the thermodynamics and mechanical properties of DNA/RNA hairpin at a stretching force. In hopping experiments, the critical forces of RNA hairpins at different temperatures are greater than those of DNA hairpins, in addition, the Gibbs free energy at a fixed temperature required to convert an RNA hairpin into a single-stranded molecule at zero force is obviously greater than that of DNA hairpin and gradually decreases by increasing the temperature. As far as force-ramping experiments are concerned, the first-rupture forces of RNA/DNA hairpins corresponding to the maximum probability density linearly pertain to the force-loading rate, with those of RNA hairpins being greater. The extended ox-DNA model could potentially identify the interaction between biologically inert polymer and RNA/DNA hairpins in crowded environments.
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Affiliation(s)
- Chao Yang
- College of Physics, Guizhou University, Guiyang, Guizhou 550025, People's Republic of China
| | - Xiaoya Song
- College of Physics, Guizhou University, Guiyang, Guizhou 550025, People's Republic of China
| | - Yuyu Feng
- College of Physics, Guizhou University, Guiyang, Guizhou 550025, People's Republic of China
| | - Guangju Zhao
- College of Physics, Guizhou University, Guiyang, Guizhou 550025, People's Republic of China
| | - Yanhui Liu
- College of Physics, Guizhou University, Guiyang, Guizhou 550025, People's Republic of China
- Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education (Guizhou University), Guiyang, Guizhou 550025, People's Republic of China
- State Key Laboratory of Public Big Data, Guizhou University, Guiyang 550025, People's Republic of China
- Kechuang Industrial Development Company Limited,Gui'an New Area, Guiyang 550025, People's Republic of China
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19
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Pradhan S, Rath R, Biswas M. GB1 Dimerization in Crowders: A Multiple Resolution Approach. J Chem Inf Model 2023; 63:1570-1577. [PMID: 36858485 DOI: 10.1021/acs.jcim.3c00012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
In-cell protein-protein association, which is crucial in enzyme catalysis and polymerization, occurs in an environment that is highly heterogeneous and crowded. The crowder molecules exclude the reactant molecules from occupying certain regions of the cell, resulting in changes in the reaction thermodynamics and kinetics. Recent studies, both experiment and simulations, revealed that the nature of the interaction between crowder and protein species, in particular the soft interactions, plays an important role in crowder induced effects on protein association. To this end, from a simulation perspective, it is important to decipher the level of structural resolution in a protein-crowder model that can faithfully capture the influence of crowding on protein association. Here, we investigate the dimerization of model system GB1 in the presence of lysozyme crowders at two structural resolutions. The lower resolution model assumes both protein and crowder species as spherical beads, similar to the analytical scaled particle theory model, whereas the higher resolution model retains residue specific structural details for protein and crowder species. From the higher resolution model, it is found that GB1 dimer formation is destabilized in the presence of lysozyme crowders, and the destabilization is more for the side-by-side dimer compared to the domain-swapped dimer, in qualitative agreement with experimental findings. However, the low resolution CG model predicts stabilization of the dimers in the presence of the lysozyme crowder, similar to the SPT model. Our results indicate a nontrivial role of the choice of model resolution in computer simulation studies investigating crowder induced effects.
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Affiliation(s)
- Sweta Pradhan
- National Institute of Technology Rourkela, Rourkela 769008, India
| | - Rajendra Rath
- National Institute of Technology Rourkela, Rourkela 769008, India
| | - Mithun Biswas
- National Institute of Technology Rourkela, Rourkela 769008, India
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20
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González-Paz L, Lossada C, Hurtado-León ML, Fernández-Materán FV, Paz JL, Parvizi S, Cardenas Castillo RE, Romero F, Alvarado YJ. Intrinsic Dynamics of the ClpXP Proteolytic Machine Using Elastic Network Models. ACS OMEGA 2023; 8:7302-7318. [PMID: 36873006 PMCID: PMC9979342 DOI: 10.1021/acsomega.2c04347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 10/25/2022] [Indexed: 06/18/2023]
Abstract
ClpXP complex is an ATP-dependent mitochondrial matrix protease that binds, unfolds, translocates, and subsequently degrades specific protein substrates. Its mechanisms of operation are still being debated, and several have been proposed, including the sequential translocation of two residues (SC/2R), six residues (SC/6R), and even long-pass probabilistic models. Therefore, it has been suggested to employ biophysical-computational approaches that can determine the kinetics and thermodynamics of the translocation. In this sense, and based on the apparent inconsistency between structural and functional studies, we propose to apply biophysical approaches based on elastic network models (ENM) to study the intrinsic dynamics of the theoretically most probable hydrolysis mechanism. The proposed models ENM suggest that the ClpP region is decisive for the stabilization of the ClpXP complex, contributing to the flexibility of the residues adjacent to the pore, favoring the increase in pore size and, therefore, with the energy of interaction of its residues with a larger portion of the substrate. It is predicted that the complex may undergo a stable configurational change once assembled and that the deformability of the system once assembled is oriented, to increase the rigidity of the domains of each region (ClpP and ClpX) and to gain flexibility of the pore. Our predictions could suggest under the conditions of this study the mechanism of the interaction of the system, of which the substrate passes through the unfolding of the pore in parallel with a folding of the bottleneck. The variations in the distance calculated by molecular dynamics could allow the passage of a substrate with a size equivalent to ∼3 residues. The theoretical behavior of the pore and the stability and energy of binding to the substrate based on ENM models suggest that in this system, there are thermodynamic, structural, and configurational conditions that allow a possible translocation mechanism that is not strictly sequential.
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Affiliation(s)
- Lenin González-Paz
- Facultad
Experimental de Ciencias (FEC), Departamento de Biología, Laboratorio
de Genética y Biología Molecular (LGBM), Universidad del Zulia (LUZ), 4001 Maracaibo, Zulia, República Bolivariana
de Venezuela
- Centro
de Biomedicina Molecular (CBM). Laboratorio de Biocomputación
(LB), Instituto Venezolano de Investigaciones
Científicas (IVIC), 4001 Maracaibo, Zulia, República Bolivariana de Venezuela
| | - Carla Lossada
- Centro
de Biomedicina Molecular (CBM). Laboratorio de Biocomputación
(LB), Instituto Venezolano de Investigaciones
Científicas (IVIC), 4001 Maracaibo, Zulia, República Bolivariana de Venezuela
| | - Maria Laura Hurtado-León
- Facultad
Experimental de Ciencias (FEC), Departamento de Biología, Laboratorio
de Genética y Biología Molecular (LGBM), Universidad del Zulia (LUZ), 4001 Maracaibo, Zulia, República Bolivariana
de Venezuela
| | - Francelys V. Fernández-Materán
- Centro
de Biomedicina Molecular (CBM). Laboratorio de Biocomputación
(LB), Instituto Venezolano de Investigaciones
Científicas (IVIC), 4001 Maracaibo, Zulia, República Bolivariana de Venezuela
| | - José Luis Paz
- Departamento
Académico de Química Inorgánica, Facultad de
Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos, 15081 Lima, Perú
| | - Shayan Parvizi
- Pulmonary,
Critical Care and Sleep Medicine, Baylor
College of Medicine, Houston, Texas 77030, United States
| | | | - Freddy Romero
- Pulmonary,
Critical Care and Sleep Medicine, Baylor
College of Medicine, Houston, Texas 77030, United States
| | - Ysaias J. Alvarado
- Centro
de Biomedicina Molecular (CBM), Laboratorio de Química Biofísica
Teórica y Experimental (LQBTE), Instituto
Venezolano de Investigaciones Cientificas (IVIC), 4001 Maracaibo, Zulia, República Bolivariana de Venezuela
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21
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Banerjee S, Hemmat MA, Shubham S, Gosai A, Devarakonda S, Jiang N, Geekiyanage C, Dillard JA, Maury W, Shrotriya P, Lamm MH, Nilsen-Hamilton M. Structurally Different Yet Functionally Similar: Aptamers Specific for the Ebola Virus Soluble Glycoprotein and GP1,2 and Their Application in Electrochemical Sensing. Int J Mol Sci 2023; 24:4627. [PMID: 36902059 PMCID: PMC10003157 DOI: 10.3390/ijms24054627] [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: 12/31/2022] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 03/04/2023] Open
Abstract
The Ebola virus glycoprotein (GP) gene templates several mRNAs that produce either the virion-associated transmembrane protein or one of two secreted glycoproteins. Soluble glycoprotein (sGP) is the predominant product. GP1 and sGP share an amino terminal sequence of 295 amino acids but differ in quaternary structure, with GP1 being a heterohexamer with GP2 and sGP a homodimer. Two structurally different DNA aptamers were selected against sGP that also bound GP1,2. These DNA aptamers were compared with a 2'FY-RNA aptamer for their interactions with the Ebola GP gene products. The three aptamers have almost identical binding isotherms for sGP and GP1,2 in solution and on the virion. They demonstrated high affinity and selectivity for sGP and GP1,2. Furthermore, one aptamer, used as a sensing element in an electrochemical format, detected GP1,2 on pseudotyped virions and sGP with high sensitivity in the presence of serum, including from an Ebola-virus-infected monkey. Our results suggest that the aptamers interact with sGP across the interface between the monomers, which is different from the sites on the protein bound by most antibodies. The remarkable similarity in functional features of three structurally distinct aptamers suggests that aptamers, like antibodies, have preferred binding sites on proteins.
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Affiliation(s)
- Soma Banerjee
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA
| | - Mahsa Askary Hemmat
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Shambhavi Shubham
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Agnivo Gosai
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | | | - Nianyu Jiang
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | | | - Jacob A. Dillard
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 50011, USA
| | - Wendy Maury
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA 50011, USA
| | - Pranav Shrotriya
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA
| | - Monica H. Lamm
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Marit Nilsen-Hamilton
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
- Aptalogic Inc., Ames, IA 50014, USA
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22
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André AAM, Yewdall NA, Spruijt E. Crowding-induced phase separation and gelling by co-condensation of PEG in NPM1-rRNA condensates. Biophys J 2023; 122:397-407. [PMID: 36463407 PMCID: PMC9892608 DOI: 10.1016/j.bpj.2022.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 11/11/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
The crowdedness of the cell calls for adequate intracellular organization. Biomolecular condensates, formed by liquid-liquid phase separation of intrinsically disordered proteins and nucleic acids, are important organizers of cellular fluids. To underpin the molecular mechanisms of protein condensation, cell-free studies are often used where the role of crowding is not investigated in detail. Here, we investigate the effects of macromolecular crowding on the formation and material properties of a model heterotypic biomolecular condensate, consisting of nucleophosmin (NPM1) and ribosomal RNA (rRNA). We studied the effect of the macromolecular crowding agent poly(ethylene glycol) (PEG), which is often considered an inert crowding agent. We observed that PEG could induce both homotypic and heterotypic phase separation of NPM1 and NPM1-rRNA, respectively. Crowding increases the condensed concentration of NPM1 and decreases its equilibrium dilute phase concentration, although no significant change in the concentration of rRNA in the dilute phase was observed. Interestingly, the crowder itself is concentrated in the condensates, suggesting that co-condensation rather than excluded volume interactions underlie the enhanced phase separation by PEG. Fluorescence recovery after photobleaching measurements indicated that both NPM1 and rRNA become immobile at high PEG concentrations, indicative of a liquid-to-gel transition. Together, these results provide more insight into the role of synthetic crowding agents in phase separation and demonstrate that condensate properties determined in vitro depend strongly on the addition of crowding agents.
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Affiliation(s)
- Alain A M André
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - N Amy Yewdall
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Evan Spruijt
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands.
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23
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Raina N, Hassan MI, Ahmad F, Islam A, Singh AK. PEG mediated destabilization of holo α-lactalbumin probed by in silico and in vitro studies: deviation from excluded volume effect. J Biomol Struct Dyn 2022; 40:13265-13277. [PMID: 34726117 DOI: 10.1080/07391102.2021.1987990] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Crowded and confined macromolecular milieus surround proteins, and both are stabilizing if the nature of the interaction between crowder and proteins are considered hard-core repulsive interactions. However, non-specific chemical interactions between a protein and its surroundings also play a significant role and the sum effect of both hard-core repulsion and soft interaction balances the overall effect of crowding/confinement. Previous studies showing the effect of polyethylene glycol (PEG) on protein and nucleic acid may be interpreted as either primarily excluded volume effect or, in some cases, chemical effect by changing solvent properties. In case of destabilizing interactions, charge-charge and hydrophobic contact have to gain more attention. For instance, in vitro and in vivo studies using protein as crowding agent revealed the destabilization of proteins induced by charge-charge interactions. To investigate the effect of PEG 10 kDa on holo α-lactalbumin (holo α-LA), structure and thermal stability of the protein were measured at different pH values using several techniques. Structural characterization by Trp-fluorescence, near-UV CD and far-UV measurements at different pH values clearly shows perturbation of tertiary and secondary structure of holo α-LA by PEG 10 kDa. Furthermore, the dynamic light scattering measurement shows that the protein is homogeneous under all experimental conditions. Analysis of the heat-induced denaturation profile in the presence of the crowder shows destabilization of the protein in terms of Tm (midpoint of denaturation) and ΔGD0 (Gibbs free energy change at 25 °C). To evaluate the interaction of PEG 10 kDa with holo α-LA and stability of PEG-α-LA complex, docking and molecular dynamic simulation were carried out for 100 ns.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Neha Raina
- Department of Biotechnology, Sharda University, Greater Noida, Uttar Pradesh, India.,Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, Delhi, India
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, Delhi, India
| | - Faizan Ahmad
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, Delhi, India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, Delhi, India
| | - Amit Kumar Singh
- Department of Biotechnology, Sharda University, Greater Noida, Uttar Pradesh, India
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24
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Miyagawa A, Komatsu H, Nagatomo S, Nakatani K. Thermodynamic Complexation Mechanism of Zinc Ion with 8-Hydroxyquinoline-5-Sulfonic Acid in Molecular Crowding Environment. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.121181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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25
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The biophysics of disordered proteins from the point of view of single-molecule fluorescence spectroscopy. Essays Biochem 2022; 66:875-890. [PMID: 36416865 PMCID: PMC9760427 DOI: 10.1042/ebc20220065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/10/2022] [Accepted: 10/11/2022] [Indexed: 11/24/2022]
Abstract
Intrinsically disordered proteins (IDPs) and regions (IDRs) have emerged as key players across many biological functions and diseases. Differently from structured proteins, disordered proteins lack stable structure and are particularly sensitive to changes in the surrounding environment. Investigation of disordered ensembles requires new approaches and concepts for quantifying conformations, dynamics, and interactions. Here, we provide a short description of the fundamental biophysical properties of disordered proteins as understood through the lens of single-molecule fluorescence observations. Single-molecule Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) provides an extensive and versatile toolbox for quantifying the characteristics of conformational distributions and the dynamics of disordered proteins across many different solution conditions, both in vitro and in living cells.
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26
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Quinn SD, Dresser L, Graham S, Conteduca D, Shepherd J, Leake MC. Crowding-induced morphological changes in synthetic lipid vesicles determined using smFRET. Front Bioeng Biotechnol 2022; 10:958026. [PMID: 36394015 PMCID: PMC9650091 DOI: 10.3389/fbioe.2022.958026] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/13/2022] [Indexed: 12/02/2022] Open
Abstract
Lipid vesicles are valuable mesoscale molecular confinement vessels for studying membrane mechanics and lipid-protein interactions, and they have found utility among bio-inspired technologies, including drug delivery vehicles. While vesicle morphology can be modified by changing the lipid composition and introducing fusion or pore-forming proteins and detergents, the influence of extramembrane crowding on vesicle morphology has remained under-explored owing to a lack of experimental tools capable of capturing morphological changes on the nanoscale. Here, we use biocompatible polymers to simulate molecular crowding in vitro, and through combinations of FRET spectroscopy, lifetime analysis, dynamic light scattering, and single-vesicle imaging, we characterize how crowding regulates vesicle morphology. We show that both freely diffusing and surface-tethered vesicles fluorescently tagged with the DiI and DiD FRET pair undergo compaction in response to modest concentrations of sorbitol, polyethylene glycol, and Ficoll. A striking observation is that sorbitol results in irreversible compaction, whereas the influence of high molecular weight PEG-based crowders was found to be reversible. Regulation of molecular crowding allows for precise control of the vesicle architecture in vitro, with vast implications for drug delivery and vesicle trafficking systems. Furthermore, our observations of vesicle compaction may also serve to act as a mechanosensitive readout of extramembrane crowding.
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Affiliation(s)
- Steven D. Quinn
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
| | - Lara Dresser
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Sarah Graham
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Donato Conteduca
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Jack Shepherd
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- Department of Biology, University of York, York, United Kingdom
| | - Mark C. Leake
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
- Department of Biology, University of York, York, United Kingdom
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27
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Yoo H, Davis CM. An in vitro cytomimetic of in-cell RNA folding. Chembiochem 2022; 23:e202200406. [PMID: 35999178 DOI: 10.1002/cbic.202200406] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/21/2022] [Indexed: 11/07/2022]
Abstract
To discover the cytomimetic that accounts for cytoplasmic crowding and sticking on RNA stability, we conducted a two-dimensional scan of mixtures of artificial crowding and sticking agents, PEG10k and M-PERTM. As our model RNA, we investigate the fourU RNA thermometer motif of Salmonella, a hairpin-structured RNA that regulates translation by unfolding and exposing its RBS in response to temperature perturbations. We found that the addition of artificial crowding and sticking agents leads to a stabilization and destabilization of RNA folding, respectively, through the excluded volume effect and surface interactions. FRET-labels were added to the fourU RNA and Fast Relaxation Imaging (FReI), fluorescence microscopy coupled to temperature-jump spectroscopy, probed differences between folding stability of RNA inside single living cells and in vitro. Our results suggest that the cytoplasmic environment affecting RNA folding is comparable to a combination of 20% v/v M-PERTM and 150 g/L PEG10k.
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Affiliation(s)
- Hyejin Yoo
- Yale University, Chemistry, 225 Prospect St, 06511, New Haven, UNITED STATES
| | - Caitlin M Davis
- Yale University, Chemistry, 225 Prospect St., 06511, New Haven, UNITED STATES
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28
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Sung HL, Nesbitt DJ. Synergism in the Molecular Crowding of Ligand-Induced Riboswitch Folding: Kinetic/Thermodynamic Insights from Single-Molecule Spectroscopy. J Phys Chem B 2022; 126:6419-6427. [PMID: 35981263 DOI: 10.1021/acs.jpcb.2c03507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Conformational dynamics in riboswitches involves ligand binding and folding of RNA, each of which can be influenced by excluded volume effects under "crowded" in vivo cellular conditions and thus incompletely characterized by in vitro studies under dilute buffer conditions. In this work, temperature-dependent single-molecule fluorescence resonance energy transfer (FRET) spectroscopy is used to characterize the thermodynamics of (i) cognate ligand and (ii) molecular crowders (PEG, polyethylene glycol) on folding of the B. subtilis LysC lysine riboswitch. With the help of detailed kinetic analysis, we isolate and study the effects of PEG on lysine binding and riboswitch folding steps individually, from which we find that PEG crowding facilitates riboswitch folding primarily via a surprising increase in affinity for the cognate ligand. This is furthermore confirmed by temperature-dependent studies, which reveal that PEG crowding is not purely entropic and instead significantly impacts both enthalpic and entropic contributions to the free energy landscape for folding. The results indicate that PEG molecular crowding/stabilization of the lysine riboswitch is more mechanistically complex and requires extension beyond the conventional picture of purely repulsive solvent-solute steric interactions arising from excluded volume and entropy. Instead, the current experimental FRET data support an alternative multistep mechanism, whereby PEG first entropically crowds the unfolded riboswitch into a "pre-folded" conformation, which in turn greatly increases the ligand binding affinity and thereby enhances the overall equilibrium for riboswitch folding.
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Affiliation(s)
- Hsuan-Lei Sung
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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29
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Zhou Y, Jia E, Sheng Y, Qiao Y, Wang Y, Shi H, Liu Z, Pan M, Tu J, Bai Y, Zhao X, Ge Q, Lu Z. Sensitive and Low-Bias Transcriptome Sequencing Using Agarose PCR. ACS APPLIED MATERIALS & INTERFACES 2022; 14:19154-19167. [PMID: 35446027 DOI: 10.1021/acsami.2c02133] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Transcriptome sequencing has emerged as an important research tool for exploring the mysteries of life at the single-cell level. However, its wide application is limited by the bias associated with the amplification reactions which is essential for library building of trace RNA. In this study, low-melting-point agarose was added to the amplification reactions to take advantage of its molecular crowding effect and polymer cross-linked structure to improve the sensitivity of the reactions and reduce bias. To further evaluate the performance of the method, it was applied to transcriptome sequencing of microregion samples from brain tissue sections of mice with Parkinson's disease at the single cell level. The results showed that agarose PCR had better performance than in-tube PCR. Further application of agarose PCR to transcriptome library sequencing could obtain data closer to that of unamplified. With the addition of low melting point agarose, the sensitivity of the amplification reaction was significantly increased, while homogeneity was increased by approximately 2-fold. Not only that, but this work also provides 11% sensitivity improvement for spatial transcriptomic study on Parkinson's disease-associated gene detection. The agarose PCR provides a new tool for efficient and homogeneous amplification of trace samples and can be widely used for spatial transcriptome library sequencing and studies.
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Affiliation(s)
- Ying Zhou
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Erteng Jia
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yuqi Sheng
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yi Qiao
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Ying Wang
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Huajuan Shi
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Zhiyu Liu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Min Pan
- School of Medicine, Southeast University, Nanjing 210097, China
| | - Jing Tu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yunfei Bai
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xiangwei Zhao
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Qinyu Ge
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Zuhong Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
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30
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Comparative study of SARS-CoV-2 infection in different cell types: Biophysical-computational approach to the role of potential receptors. Comput Biol Med 2022; 142:105245. [PMID: 35077937 PMCID: PMC8770263 DOI: 10.1016/j.compbiomed.2022.105245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/07/2022] [Accepted: 01/16/2022] [Indexed: 12/17/2022]
Abstract
Cellular susceptibility to SARS-CoV-2 infection in the respiratory tract has been associated with the ability of the virus to interact with potential receptors on the host membrane. We have modeled viral dynamics by simulating various cellular systems and artificial conditions, including macromolecular crowding, based on experimental and transcriptomic data to infer parameters associated with viral growth and predict cell susceptibility. We have accomplished this based on the type, number and level of expression of the angiotensin-converting enzyme 2 (ACE2), transmembrane serine 2 (TMPRSS2), basigin2 (CD147), FURIN protease, neuropilin 1 (NRP1) or other less studied candidate receptors such as heat shock protein A5 (HSPA5) and angiotensin II receptor type 2 (AGTR2). In parallel, we studied the effect of simulated artificial environments on the accessibility to said proposed receptors. In addition, viral kinetic behavior dependent on the degree of cellular susceptibility was predicted. The latter was observed to be more influenced by the type of proteins and expression level, than by the number of potential proteins associated with the SARS CoV-2 infection. We predict a greater theoretical propensity to susceptibility in cell lines such as NTERA-2, SCLC-21H, HepG2 and Vero6, and a lower theoretical propensity in lines such as CaLu3, RT4, HEK293, A549 and U-251MG. An important relationship was observed between expression levels, protein diffusivity, and thermodynamically favorable interactions between host proteins and the viral spike, suggesting potential sites of early infection other than the lungs. This research is expected to stimulate future quantitative experiments and promote systematic investigation of the effect of crowding presented here.
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31
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Basu M, Mishra PP. Kineto-Mechanistic Investigation of Effect of Macromolecular Crowding on the Breathing of DNA Bubble. J Phys Chem B 2022; 126:1375-1387. [PMID: 35143192 DOI: 10.1021/acs.jpcb.1c08206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macromolecular crowding along with hydrogen bonding or stacking interactions and hydration reportedly has enormous repercussions on elementary biochemical processes, such as the folding of proteins or nucleic acids involving the stability of DNA base pairing. By using the mismatch-induced DNA bubble as a mesoscopic model, the complex interplay of macromolecular crowding on the dynamical fluctuations at the bubble region within the thermodynamic limit has been monitored using single-molecule fluorescence resonance energy transfer (sm-FRET). These single-molecule experimental results have been further corroborated using physical models such as "scaled particle theory" (SPT) and "Gaussian cloud model" (GCM), to predict the biological activity of DNA. The two-state fluctuation of the DNA bubble has been visualized as a function of the nature, size, and concentration of the crowder. The influence of crowders on the DNA conformation has been investigated with the help of the m-factor, the eccentricity, and the kinetic and thermodynamic parameters without any prior assumption. The clear effect of crowding on the dynamics of such a simple biomolecular system emphasizes the power of single-molecule methods and the dependency of the radius of gyration of the co-solute as well as the preferential interaction with the crowder on the distinct conformational states adopted by the bubble. This study provides an idea and hypothesizes the preferential propensity of the DNA bubble to adopt a conformation with the single-stranded domains being far apart, independent of the crowder size, that may be beneficial for efficient recognition by proteins for an uninterrupted procession of the biological process of the central dogma.
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Affiliation(s)
- Manali Basu
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.,Homi Bhaba National Institute, Mumbai, Maharashtra 400094, India
| | - 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, Maharashtra 400094, India
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32
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Surmeier G, Paulus M, Schneider E, Dogan S, Tolan M, Nase J. A pressure-jump study on the interaction of osmolytes and crowders with cubic monoolein structures. SOFT MATTER 2022; 18:990-998. [PMID: 35015016 DOI: 10.1039/d1sm01425k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Many vital processes that take place in biological cells involve remodeling of lipid membranes. These processes take place in a milieu that is packed with various solutes, ranging from ions and small organic osmolytes to proteins and other macromolecules, occupying about 30% of the available volume. In this work, we investigated how molecular crowding, simulated with the polymer polyethylene glycol (PEG), and the osmolytes urea and trimethylamine-N-oxide (TMAO) affect the equilibration of cubic monoolein structures after a phase transition from a lamellar state induced by an abrupt pressure reduction. In absence of additives, swollen cubic crystallites form after the transition, releasing excess water over several hours. This process is reflected in a decreasing lattice constant and was monitored with small angle X-ray scattering. We found that the osmotic pressure exerted by PEG and TMAO, which are displaced from narrow inter-bilayer spaces, accelerates the equilibration. When the radius of gyration of the added PEG was smaller than the radius of the water channels of the cubic phase, the effect became more pronounced with increasing molecular weight of the polymers. As the release of hydration water from the cubic structures is accompanied by an increasing membrane curvature and a reduction of the interface between lipids and aqueous phase, urea, which has a slight affinity to reside near membrane surfaces, stabilized the swollen crystallites and slowed down the equilibration dynamics. Our results support the view that cellular solutes are important contributors to dynamic membrane processes, as they can accelerate dehydration of inter-bilayer spaces and promote or counteract membrane curvature.
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Affiliation(s)
- Göran Surmeier
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
| | - Michael Paulus
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
| | - Eric Schneider
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
| | - Susanne Dogan
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
| | - Metin Tolan
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
| | - Julia Nase
- Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.
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33
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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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34
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Peng H, Lelievre A, Landenfeld K, Müller S, Chen IA. Vesicle encapsulation stabilizes intermolecular association and structure formation of functional RNA and DNA. Curr Biol 2022; 32:86-96.e6. [PMID: 34762821 PMCID: PMC8752491 DOI: 10.1016/j.cub.2021.10.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/02/2021] [Accepted: 10/21/2021] [Indexed: 01/12/2023]
Abstract
During the origin of life, encapsulation of RNA inside vesicles is believed to have been a defining feature of the earliest cells (protocells). The confined biophysical environment provided by membrane encapsulation differs from that of bulk solution and has been shown to increase activity as well as evolutionary rate for functional RNA. However, the structural basis of the effect on RNA has not been clear. Here, we studied how encapsulation of the hairpin ribozyme inside model protocells affects ribozyme kinetics, ribozyme folding into the active conformation, and cleavage and ligation activities. We further examined the effect of encapsulation on the folding of a stem-loop RNA structure and on the formation of a triplex structure in a pH-sensitive DNA switch. The results indicate that encapsulation promotes RNA-RNA association, both intermolecular and intramolecular, and also stabilizes tertiary folding, including the docked conformation characteristic of the active hairpin ribozyme and the triplex structure. The effects of encapsulation were sufficient to rescue the activity of folding-deficient mutants of the hairpin ribozyme. Stabilization of multiple modes of nucleic acid folding and interaction thus enhanced the activity of encapsulated nucleic acids. Increased association between RNA molecules may facilitate the formation of more complex structures and cooperative interactions. These effects could promote the emergence of biological functions in an "RNA world" and may have utility in the construction of minimal synthetic cells.
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Affiliation(s)
- Huan Peng
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
| | - Amandine Lelievre
- Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | | | - Sabine Müller
- Institute of Biochemistry, University of Greifswald, 17487 Greifswald, Germany
| | - Irene A. Chen
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA,Lead Contact:
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35
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Baul U, Göth N, Bley M, Dzubiella J. Modulating internal transition kinetics of responsive macromolecules by collective crowding. J Chem Phys 2021; 155:244902. [PMID: 34972378 DOI: 10.1063/5.0076139] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Packing and crowding are used in biology as mechanisms to (self-)regulate internal molecular or cellular processes based on collective signaling. Here, we study how the transition kinetics of an internal "switch" of responsive macromolecules is modified collectively by their spatial packing. We employ Brownian dynamics simulations of a model of Responsive Colloids, in which an explicit internal degree of freedom-here, the particle size-moving in a bimodal energy landscape self-consistently responds to the density fluctuations of the crowded environment. We demonstrate that populations and transition times for the two-state switching kinetics can be tuned over one order of magnitude by "self-crowding." An exponential scaling law derived from a combination of Kramers' and liquid state perturbation theory is in very good agreement with the simulations.
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Affiliation(s)
- Upayan Baul
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
| | - Nils Göth
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
| | - Michael Bley
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
| | - Joachim Dzubiella
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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36
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Sung HL, Nesbitt DJ. Effects of Molecular Crowders on Single-Molecule Nucleic Acid Folding: Temperature-Dependent Studies Reveal True Crowding vs Enthalpic Interactions. J Phys Chem B 2021; 125:13147-13157. [PMID: 34813337 DOI: 10.1021/acs.jpcb.1c07852] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Biomolecular folding in cells can be strongly influenced by spatial overlap/excluded volume interactions (i.e., "crowding") with intracellular solutes. As a result, traditional in vitro experiments with dilute buffers may not accurately recapitulate biomolecule folding behavior in vivo. In order to account for such ubiquitous excluded volume effects, biologically inert polyethylene glycol (PEG) and polysaccharides (dextran and Ficoll) are often used as in vitro crowding agents to mimic in vivo crowding conditions, with a common observation that high concentrations of these polymers stabilize the more compact biomolecule conformation. However, such an analysis can be distorted by differences in polymer interactions with the folded vs unfolded conformers, requiring temperature-dependent analysis of the thermodynamics to reliably assess competing enthalpic vs entropic contributions and thus the explicit role of excluded volume. In this work, temperature-controlled single-molecule fluorescence resonance energy transfer (smFRET) is used to characterize the thermodynamic interaction between nucleic acids and common polymer crowders PEG, dextran, and Ficoll. The results reveal that PEG promotes secondary and tertiary nucleic acid folding by simultaneously increasing the folding rate while decreasing the unfolding rate, with temperature-dependent studies confirming that the source of PEG stabilization is predominantly entropic and consistent with a true excluded volume crowding mechanism. By way of contrast, neither dextran nor Ficoll induces any significant concentration-dependent change in nucleic acid folding stability at room temperature, but instead, stabilization effects gradually appear with a temperature increase. Such a thermal response indicates that both folding enthalpies and entropies are impacted by dextran and Ficoll. A detailed thermodynamic analysis of the kinetics suggests that, instead of true entropic molecular crowding, dextran and Ficoll associate preferentially with the unfolded vs folded nucleic acid conformer as a result of larger solvent accessible surface area, thereby skewing the free energy landscapes through both significant entropic/enthalpic contributions that compete and fortuitously cancel near room temperature.
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Affiliation(s)
- Hsuan-Lei Sung
- JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- JILA, National Institute of Standards and Technology, University of Colorado, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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37
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Liu T, Pyle AM. Discovery of highly reactive self-splicing group II introns within the mitochondrial genomes of human pathogenic fungi. Nucleic Acids Res 2021; 49:12422-12432. [PMID: 34850132 PMCID: PMC8643640 DOI: 10.1093/nar/gkab1077] [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: 06/30/2021] [Revised: 09/27/2021] [Accepted: 10/20/2021] [Indexed: 11/25/2022] Open
Abstract
Fungal pathogens represent an expanding global health threat for which treatment options are limited. Self-splicing group II introns have emerged as promising drug targets, but their development has been limited by a lack of information on their distribution and architecture in pathogenic fungi. To meet this challenge, we developed a bioinformatic workflow for scanning sequence data to identify unique RNA structural signatures within group II introns. Using this approach, we discovered a set of ubiquitous introns within thermally dimorphic fungi (genera of Blastomyces, Coccidioides and Histoplasma). These introns are the most biochemically reactive group II introns ever reported, and they self-splice rapidly under near-physiological conditions without protein cofactors. Moreover, we demonstrated the small molecule targetability of these introns by showing that they can be inhibited by the FDA-approved drug mitoxantrone in vitro. Taken together, our results highlight the utility of structure-based informatic searches for identifying riboregulatory elements in pathogens, revealing a striking diversity of reactive self-splicing introns with great promise as antifungal drug targets.
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Affiliation(s)
- Tianshuo Liu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520, USA
| | - Anna M Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520, USA.,Department of Chemistry, Yale University, New Haven, CT, 06520, USA.,Howard Hughes Medical Institute, Yale University, New Haven, CT, 06520, USA
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38
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Hohmann KF, Blümler A, Heckel A, Fürtig B. The RNA chaperone StpA enables fast RNA refolding by destabilization of mutually exclusive base pairs within competing secondary structure elements. Nucleic Acids Res 2021; 49:11337-11349. [PMID: 34614185 PMCID: PMC8565331 DOI: 10.1093/nar/gkab876] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/13/2021] [Accepted: 09/17/2021] [Indexed: 11/14/2022] Open
Abstract
In bacteria RNA gene regulatory elements refold dependent on environmental clues between two or more long-lived conformational states each associated with a distinct regulatory state. The refolding kinetics are strongly temperature-dependent and especially at lower temperatures they reach timescales that are biologically not accessible. To overcome this problem, RNA chaperones have evolved. However, the precise molecular mechanism of how these proteins accelerate RNA refolding reactions remains enigmatic. Here we show how the RNA chaperone StpA of Escherichia coli leads to an acceleration of a bistable RNA's refolding kinetics through the selective destabilization of key base pairing interactions. We find in laser assisted real-time NMR experiments on photocaged bistable RNAs that the RNA chaperone leads to a two-fold increase in refolding rates at low temperatures due to reduced stability of ground state conformations. Further, we can show that upon interaction with StpA, base pairing interactions in the bistable RNA are modulated to favor refolding through the dominant pseudoknotted transition pathway. Our results shed light on the molecular mechanism of the interaction between RNA chaperones and bistable RNAs and are the first step into a functional classification of chaperones dependent on their biophysical mode of operation.
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Affiliation(s)
- Katharina F Hohmann
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance BMRZ, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
| | - Anja Blümler
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance BMRZ, Goethe University Frankfurt am Main, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main, Germany
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39
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González-Paz L, Hurtado-León ML, Lossada C, Fernández-Materán FV, Vera-Villalobos J, Loroño M, Paz JL, Jeffreys L, Alvarado YJ. Comparative study of the interaction of ivermectin with proteins of interest associated with SARS-CoV-2: A computational and biophysical approach. Biophys Chem 2021; 278:106677. [PMID: 34428682 PMCID: PMC8373590 DOI: 10.1016/j.bpc.2021.106677] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 01/18/2023]
Abstract
The SARS-CoV-2 pandemic has accelerated the study of existing drugs. The mixture of homologs called ivermectin (avermectin-B1a [HB1a] + avermectin-B1b [HB1b]) has shown antiviral activity against SARS-CoV-2 in vitro. However, there are few reports on the behavior of each homolog. We investigated the interaction of each homolog with promising targets of interest associated with SARS-CoV-2 infection from a biophysical and computational-chemistry perspective using docking and molecular dynamics. We observed a differential behavior for each homolog, with an affinity of HB1b for viral structures, and of HB1a for host structures considered. The induced disturbances were differential and influenced by the hydrophobicity of each homolog and of the binding pockets. We present the first comparative analysis of the potential theoretical inhibitory effect of both avermectins on biomolecules associated with COVID-19, and suggest that ivermectin through its homologs, has a multiobjective behavior.
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Affiliation(s)
- Lenin González-Paz
- Universidad del Zulia (LUZ), Facultad Experimental de Ciencias (FEC), Departamento de Biología, Laboratorio de Genética y Biología Molecular (LGBM), 4001 Maracaibo, Venezuela; Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Estudios Botánicos y Agroforestales (CEBA), Laboratorio de Protección Vegetal (LPV), 4001 Maracaibo, Venezuela.
| | - María Laura Hurtado-León
- Universidad del Zulia (LUZ), Facultad Experimental de Ciencias (FEC), Departamento de Biología, Laboratorio de Genética y Biología Molecular (LGBM), 4001 Maracaibo, Venezuela
| | - Carla Lossada
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Investigación y Tecnología de Materiales (CITeMA), Laboratorio de Caracterización Molecular y Biomolecular, 4001 Maracaibo, Venezuela
| | - Francelys V Fernández-Materán
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Investigación y Tecnología de Materiales (CITeMA), Laboratorio de Caracterización Molecular y Biomolecular, 4001 Maracaibo, Venezuela
| | - Joan Vera-Villalobos
- Facultad de Ciencias Naturales y Matemáticas, Departamento de Química y Ciencias Ambientales, Laboratorio de Análisis Químico Instrumental (LAQUINS), Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador
| | - Marcos Loroño
- Departamento Académico de Química Analítica e Instrumental, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - J L Paz
- Departamento Académico de Química Inorgánica, Facultad de Química e Ingeniería Química, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Laura Jeffreys
- Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Ysaias J Alvarado
- Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Investigación y Tecnología de Materiales (CITeMA), Laboratorio de Caracterización Molecular y Biomolecular, 4001 Maracaibo, Venezuela.
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40
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Zhao T, Beckwith JS, Amin MJ, Pálmai M, Snee PT, Tien M, Yang H. Leveraging lifetime information to perform real-time 3D single-particle tracking in noisy environments. J Chem Phys 2021; 155:164201. [PMID: 34717352 DOI: 10.1063/5.0063634] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A microscopy platform that leverages the arrival time of individual photons to enable 3D single-particle tracking of fast-moving (translational diffusion coefficient of ≃3.3 µm2/s) particles in high-background environments is reported here. It combines a hardware-based time-gating module, which enables the rate of photon processing to be as high as 100 MHz, with a two-photon-excited 3D single-particle tracking confocal microscope to enable high sample penetration depth. Proof-of-principle experiments where single quantum dots are tracked in solutions containing dye-stained cellulose, are shown with tracking performance markedly improved using the hardware-based time-gating module. Such a microscope design is anticipated to be of use to a variety of communities who wish to track single particles in cellular environments, which commonly have high fluorescence and scattering background.
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Affiliation(s)
- Tian Zhao
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Joseph S Beckwith
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - M Junaid Amin
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Marcell Pálmai
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061, USA
| | - Preston T Snee
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061, USA
| | - Ming Tien
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Haw Yang
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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41
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Welte H, Sinn P, Kovermann M. Fluorine NMR Spectroscopy Enables to Quantify the Affinity Between DNA and Proteins in Cell Lysate. Chembiochem 2021; 22:2973-2980. [PMID: 34390111 PMCID: PMC8596521 DOI: 10.1002/cbic.202100304] [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: 06/19/2021] [Revised: 07/30/2021] [Indexed: 11/12/2022]
Abstract
The determination of the binding affinity quantifying the interaction between proteins and nucleic acids is of crucial interest in biological and chemical research. Here, we have made use of site-specific fluorine labeling of the cold shock protein from Bacillus subtilis, BsCspB, enabling to directly monitor the interaction with single stranded DNA molecules in cell lysate. High-resolution 19 F NMR spectroscopy has been applied to exclusively report on resonance signals arising from the protein under study. We have found that this experimental approach advances the reliable determination of the binding affinity between single stranded DNA molecules and its target protein in this complex biological environment by intertwining analyses based on NMR chemical shifts, signal heights, line shapes and simulations. We propose that the developed experimental platform offers a potent approach for the identification of binding affinities characterizing intermolecular interactions in native surroundings covering the nano-to-micromolar range that can be even expanded to in cell applications in future studies.
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Affiliation(s)
- Hannah Welte
- Department of ChemistryUniversity of KonstanzUniversitätsstrasse 1078467KonstanzGermany
| | - Pia Sinn
- Department of ChemistryUniversity of KonstanzUniversitätsstrasse 1078467KonstanzGermany
| | - Michael Kovermann
- Department of ChemistryUniversity of KonstanzUniversitätsstrasse 1078467KonstanzGermany
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42
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Miyagawa A, Komatsu H, Nagatomo S, Nakatani K. Effect of Molecular Crowding on Complexation of Metal Ions and 8-Quinolinol-5-Sulfonic Acid. J Phys Chem B 2021; 125:9853-9859. [PMID: 34410719 DOI: 10.1021/acs.jpcb.1c05851] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effect of molecular crowding on macromolecular reactions has been revealed by many researchers. In this study, we investigate the complexation of metal ions (Zn, Co, and Cd) with 8-quinolinol-5-sulfonic acid as a model of small-molecular reactions in molecular crowding. The complexation constants for 1:1, 1:2, and total complexation in the presence of polyethylene glycol (PEG, a molecular crowding reagent) are evaluated based on the increase in the reactant activity by volume exclusion and the decrease in the water activity due to the change in osmotic pressure. All complexation constants are enhanced by increasing the concentration of PEG. Its mechanisms differ for 1:1, 1:2, and total complexation. The 1:1 complexation is promoted only by the influence of the water activity, while the reactant and water activities influence the increase in the 1:2 complexation constant. Increasing the molecular weight of PEG further increases the complexation constants, as dehydration of the complex is promoted by a higher hydration number of PEG. Because this study gives the fundamental knowledge for the protein-metal interaction, in which solvation is an important factor, in molecular crowding, it provides new insights into molecular crowding studies and should attract the attention of a broad spectrum of biochemistry researchers.
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Affiliation(s)
- Akihisa Miyagawa
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Hiroyuki Komatsu
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Shigenori Nagatomo
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Kiyoharu Nakatani
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
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43
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Dobirul Islam M, Motiar Rahman M, Matsumura S, Ikawa Y. Effects of chain length of polyethylene glycol molecular crowders on a mutant Tetrahymena group I ribozyme lacking large peripheral module. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2021; 40:867-883. [PMID: 34402751 DOI: 10.1080/15257770.2021.1956531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
While current group I ribozymes use several distinct strategies to function under conditions of low Mg2+ concentration (≤ 3 mM), a deletion mutant of the Tetrahymena ribozyme (ΔP5 ribozyme) is virtually inactive with 3 mM Mg2+ due to removal of the large peripheral module, P5abc, supporting the active conformation of the core module. We investigated the molecular crowding effects of synthetic polyethylene glycols (PEGs) on the activity of the ΔP5 ribozyme. Among PEG molecules with different chain lengths, PEG600 improved the activity of the ΔP5 ribozyme most effectively in the presence of 3 mM Mg2+.
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Affiliation(s)
- Md Dobirul Islam
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan
| | - Md Motiar Rahman
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan
| | - Shigeyoshi Matsumura
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan.,Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
| | - Yoshiya Ikawa
- Graduate School of Innovative Life Science, University of Toyama, Toyama, Japan.,Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama, Japan
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44
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Nesterov SV, Ilyinsky NS, Uversky VN. Liquid-liquid phase separation as a common organizing principle of intracellular space and biomembranes providing dynamic adaptive responses. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119102. [PMID: 34293345 DOI: 10.1016/j.bbamcr.2021.119102] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/13/2021] [Accepted: 07/18/2021] [Indexed: 02/07/2023]
Abstract
This work is devoted to the phenomenon of liquid-liquid phase separation (LLPS), which has come to be recognized as fundamental organizing principle of living cells. We distinguish separation processes with different dimensions. Well-known 3D-condensation occurs in aqueous solution and leads to membraneless organelle (MLOs) formation. 2D-films may be formed near membrane surfaces and lateral phase separation (membrane rafts) occurs within the membranes themselves. LLPS may also occur on 1D structures like DNA and the cyto- and nucleoskeleton. Phase separation provides efficient transport and sorting of proteins and metabolites, accelerates the assembly of metabolic and signaling complexes, and mediates stress responses. In this work, we propose a model in which the processes of polymerization (1D structures), phase separation in membranes (2D structures), and LLPS in the volume (3D structures) influence each other. Disordered proteins and whole condensates may provide membrane raft separation or polymerization of specific proteins. On the other hand, 1D and 2D structures with special composition or embedded IDRs can nucleate condensates. We hypothesized that environmental change may trigger a LLPS which can propagate within the cell interior moving along the cytoskeleton or as an autowave. New phase propagation quickly and using a low amount of energy adjusts cell signaling and metabolic systems to new demands. Cumulatively, the interconnected phase separation phenomena in different dimensions represent a previously unexplored system of intracellular communication and regulation which cannot be ignored when considering both physiological and pathological cell processes.
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Affiliation(s)
- Semen V Nesterov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia; Kurchatov Complex of NBICS-Technologies, National Research Center Kurchatov Institute, Moscow 123182, Russia.
| | - Nikolay S Ilyinsky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia
| | - Vladimir N Uversky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny 141700, Russia; Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC07, Tampa, FL 33612, USA.
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45
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Modeling protein association from homogeneous to mixed environments: A reaction-diffusion dynamics approach. J Mol Graph Model 2021; 107:107936. [PMID: 34139641 DOI: 10.1016/j.jmgm.2021.107936] [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: 01/06/2021] [Revised: 03/30/2021] [Accepted: 04/26/2021] [Indexed: 11/21/2022]
Abstract
Protein-protein association in vivo occur in a crowded and complex environment. Theoretical models based on hard-core repulsion predict stabilization of the product under crowded conditions. Soft interactions, on the contrary, can either stabilize or destabilize the product formation. Here we modeled protein association in presence of crowders of varying size, shape, interaction potential and used different mixing parameters for constituent crowders to study the influence on the association reaction. It was found that size is a more dominant factor in crowder-induced stabilization than the shape. Furthermore, in a mixture of crowders having different sizes but identical interaction potential, the change of free energy is additive of the free energy changes produced by individual crowders. However, the free energy change is not additive if two crowders of same size interact via different interaction potentials. These findings provide a systematic understanding of crowding influences in heterogeneous medium.
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46
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Zhang B, Lei T, Zhao N. Comparative study of polymer looping kinetics in passive and active environments. Phys Chem Chem Phys 2021; 23:12171-12190. [PMID: 34008649 DOI: 10.1039/d1cp00591j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intra-chain looping in complex environments is significant in advancing our understanding of biological processes in life. We adopt Langevin dynamics simulations to perform a comparative study of polymer looping kinetics in passive and active environments. From the analysis of looping quantities, including looping-unlooping times and looping probabilities, we unraveled the intriguing effects of active crowder size, activity and crowding. Firstly, we figured out the phase diagram involving a novel facilitation-inhibition transition in the parameter space of active crowder size and active force, and the two-fold roles of activity are clarified. In particular, we find that active particles of a size comparable to the polymer monomer are most favorable for facilitated looping, while those with a similar size to the polymer gyration radius impede the looping most seriously. Secondly, the underlying looping mechanisms in different active crowder size regimes are rationalized by the interplay among diffusion, polymer conformational change and the free-energy barrier. For small active crowders, activity significantly promotes end-to-end distance diffusion, which dominantly facilitates both looping and unlooping processes. In the case of moderate active crowders, the polymer chain suffers from prominent swelling, and thus inevitable inhibited looping will occur. For large active crowders, activity induces a counterintuitive non-cage effect on the looping kinetics, through yielding a higher effective temperature and larger unlooping free-energy barrier. This is in sharp contrast to the caging phenomena observed in passive media. Lastly, the volume-fraction dependence of the looping quantities in an active bath demonstrates dramatic discrepancies from that in a passive bath, which highlights the contrasting effects of activity and crowding.
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Affiliation(s)
- Bingjie Zhang
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Ting Lei
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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47
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Tao P, Wang E, Xiao Y. Pathway regulation mechanism revealed by cotranslational folding of villin headpiece subdomain HP35. Phys Rev E 2021; 101:052403. [PMID: 32575289 DOI: 10.1103/physreve.101.052403] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 04/13/2020] [Indexed: 01/07/2023]
Abstract
Cotranslational folding is one of the most important features of protein folding in vivo. Although many studies have shown that the folding pathways of cotranslational folding are different from free folding in vitro, the detailed mechanism of folding dynamics is lacking. Here we combine all-atom molecular simulations with an ideal ribosome tunnel model to investigate the cotranslational folding of villin headpiece subdomain HP35. By comparing the folding dynamics between cotranslational folding and free folding, we found that cotranslational folding tends to fold along the pathway that is easier to fold into native state in the latter. In addition, the roles of the ribosome tunnel and sequential folding are analyzed separately. Our results show that the ribosome can prevent the untimely folding of the C segment of HP35 to reduce the non-native interactions, while the translation speed can regulate the amounts of native and non-native interactions and the balance between them. Overall, these results give insights into the general mechanisms of cotranslational protein folding.
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Affiliation(s)
- Peng Tao
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
| | - Ercheng Wang
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China.,College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Yi Xiao
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
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48
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Sung HL, Sengupta A, Nesbitt D. Smaller molecules crowd better: Crowder size dependence revealed by single-molecule FRET studies and depletion force modeling analysis. J Chem Phys 2021; 154:155101. [PMID: 33887926 DOI: 10.1063/5.0045492] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The cell is an extremely crowded environment, which is known to have a profound impact on the thermodynamics, functionality, and conformational stability of biomolecules. Speculations from recent theoretical molecular dynamics studies suggest an intriguing size dependence to such purely entropic crowding effects, whereby small molecular weight crowders under constant enthalpy conditions are more effective than larger crowders on a per volume basis. If experimentally confirmed, this would be profoundly significant, as the cellular cytoplasm is also quite concentrated in smaller molecular weight solutes such as inorganic ions, amino acids, and various metabolites. The challenge is to perform such studies isolating entropic effects under isoenthalpic conditions. In this work, we first present results from single-molecule FRET spectroscopy (smFRET) on the molecular size-dependent crowding stabilization of a simple RNA tertiary motif (the GAAA tetraloop-tetraloop receptor), indeed providing evidence in support of the surprising notion in the crowding literature that "smaller is better." Specifically, systematic smFRET studies as a function of crowder solute size reveal that smaller molecules both significantly increase the RNA tertiary folding rate and, yet, simultaneously decrease the unfolding rate, predicting strongly size-dependent stabilization of RNA tertiary structures under crowded cellular conditions. The size dependence of these effects has been explored via systematic variation of crowder size over a broad range of molecular weights (90-3000 amu). Furthermore, corresponding temperature dependent studies indicate the systematic changes in the folding equilibrium to be predominantly entropic in origin, i.e., consistent with a fundamental picture of entropic molecular crowding without additional enthalpic interactions. Most importantly, all trends in the single-molecule crowding data can be quantitatively recapitulated by a simple analytic depletion force model, whereby excluded volume interactions represent the major thermodynamic driving force toward folding. Our study, thus, not only provides experimental evidence and theoretical support for small molecule crowding but also predicts further enhancement of crowding effects for even smaller molecules on a per volume basis.
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Affiliation(s)
- Hsuan-Lei Sung
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - Abhigyan Sengupta
- Biophysics Department, Technical University of Munich, Garching, Germany
| | - David Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
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Li L, Wang H, Xiong C, Luo D, Chen H, Liu Y. Quantify the combined effects of temperature and force on the stability of DNA hairpin. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:185102. [PMID: 33711825 DOI: 10.1088/1361-648x/abee38] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
OxDNA, as a successful coarse-grain model, has been applied to reproduce the thermodynamic and mechanical properties of both single- and double-stranded DNA. In current simulation, oxDNA is extended to explore the combined effects of temperature and force on the stability of DNA hairpin and its free energy landscape. Simulations were carried out at different forces and temperatures, at each temperature, a 18-base-pair DNA hairpin dynamically transited between folded state and unfolded state, and the separation between two states is consistent with the full contour length of single-stranded DNA in the unfolded state. Two methods were used to identify the critical force of DNA hairpin at each temperature and the critical forces obtained from two methods were consistent with each other and gradually decreased with the increasing temperature from 300 K to 326 K. The critical force at 300 K is reasonably consistent with the single molecule result of DNA hairpin with the same stem length. The two-state free energy landscape can be elucidated from the probability distribution of DNA hairpin extension and its dependence on the force and temperature is totally different. The increasing temperature not only reduces the free energy barrier, but also alters the position of transition point along the extension coordinate, resulting in the reduction of folding distance and the extension of unfolding distance, but their sum is not obviously dependent on the temperature. Generally, an assumption that the location of transition state in two-state energy landscape is independent of the stretching force is used to analyze the data of the single molecule experiment, but current simulation results indicate that effects of stretching forces on the location of transition state in two-state energy landscape are dependent on temperature. At relatively high temperature, stretching force can also change the location of transition state in the free energy landscape.
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Affiliation(s)
- Lin Li
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
| | - Hongchang Wang
- School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550025, People's Republic of China
| | - Caiyun Xiong
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
| | - Di Luo
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
| | - Hu Chen
- Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Lab for Soft Functional Materials Research, Department of Physics, Xiamen University, Xiamen, People's Republic of China
| | - Yanhui Liu
- College of Physics, Guizhou University, Guiyang 550025, People's Republic of China
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50
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Feng C, Tan YL, Cheng YX, Shi YZ, Tan ZJ. Salt-Dependent RNA Pseudoknot Stability: Effect of Spatial Confinement. Front Mol Biosci 2021; 8:666369. [PMID: 33928126 PMCID: PMC8078894 DOI: 10.3389/fmolb.2021.666369] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 12/27/2022] Open
Abstract
Macromolecules, such as RNAs, reside in crowded cell environments, which could strongly affect the folded structures and stability of RNAs. The emergence of RNA-driven phase separation in biology further stresses the potential functional roles of molecular crowding. In this work, we employed the coarse-grained model that was previously developed by us to predict 3D structures and stability of the mouse mammary tumor virus (MMTV) pseudoknot under different spatial confinements over a wide range of salt concentrations. The results show that spatial confinements can not only enhance the compactness and stability of MMTV pseudoknot structures but also weaken the dependence of the RNA structure compactness and stability on salt concentration. Based on our microscopic analyses, we found that the effect of spatial confinement on the salt-dependent RNA pseudoknot stability mainly comes through the spatial suppression of extended conformations, which are prevalent in the partially/fully unfolded states, especially at low ion concentrations. Furthermore, our comprehensive analyses revealed that the thermally unfolding pathway of the pseudoknot can be significantly modulated by spatial confinements, since the intermediate states with more extended conformations would loss favor when spatial confinements are introduced.
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Affiliation(s)
- Chenjie Feng
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Lan Tan
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Yu-Xuan Cheng
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Ya-Zhou Shi
- Research Center of Nonlinear Science, School of Mathematics and Computer Science, Wuhan Textile University, Wuhan, China
| | - Zhi-Jie Tan
- Key Laboratory of Artificial Micro and Nano-structures of Ministry of Education, Center for Theoretical Physics, School of Physics and Technology, Wuhan University, Wuhan, China
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