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Zhang M, Zhang Z, Niu X, Ti H, Zhou Y, Gao B, Li Y, Liu J, Chen X, Li H. Interplay Between Intracellular Transport Dynamics and Liquid‒Liquid Phase Separation. Adv Sci (Weinh) 2024; 11:e2308338. [PMID: 38447188 PMCID: PMC11109639 DOI: 10.1002/advs.202308338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/22/2024] [Indexed: 03/08/2024]
Abstract
Liquid‒liquid phase separation (LLPS) is a ubiquitous process in which proteins, RNA, and biomolecules assemble into membrane-less compartments, playing important roles in many biological functions and diseases. The current knowledge on the biophysical and biochemical principles of LLPS is largely from in vitro studies; however, the physiological environment in living cells is complex and not at equilibrium. The characteristics of intracellular dynamics and their roles in physiological LLPS remain to be resolved. Here, by using single-particle tracking of quantum dots and dynamic monitoring of the formation of stress granules (SGs) in single cells, the spatiotemporal dynamics of intracellular transport in cells undergoing LLPS are quantified. It is shown that intracellular diffusion and active transport are both reduced. Furthermore, the formation of SG droplets contributes to increased spatial heterogeneity within the cell. More importantly, the study demonstrated that the LLPS of SGs can be regulated by intracellular dynamics in two stages: the reduced intracellular diffusion promotes SG assembly and the microtubule-associated transport facilitates SG coalescences. The work on intracellular dynamics not only improves the understanding of the mechanism of physiology phase separations occurring in nonequilibrium environments but also reveals an interplay between intracellular dynamics and LLPS.
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Affiliation(s)
- Ming‐Li Zhang
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Ziheng Zhang
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Xue‐Zhi Niu
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Hui‐Ying Ti
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Yu‐Xuan Zhou
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Bo Gao
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Yiwei Li
- The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics – Hubei Bioinformatics and Molecular Imaging Key LaboratoryDepartment of Biomedical EngineeringCollege of Life Science and TechnologyHuazhong University of Science and TechnologyWuhan430074China
| | - Ji‐Long Liu
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Xiaosong Chen
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
| | - Hui Li
- School of Systems Science and Institute of Nonequilibrium SystemsBeijing Normal UniversityBeijing100875China
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2
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Ma XY, Coleman B, Prabhu P, Yang M, Wen F. Engineering Compositionally Uniform Yeast Whole-Cell Biocatalysts with Maximized Surface Enzyme Density for Cellulosic Biofuel Production. ACS Synth Biol 2024; 13:1225-1236. [PMID: 38551819 DOI: 10.1021/acssynbio.3c00669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
In recent decades, whole-cell biocatalysis has played an increasingly important role in the food, pharmaceutical, and energy sector. One promising application is the use of ethanologenic yeast displaying minicellulosomes on the cell surface to combine cellulose hydrolysis and fermentation into a single step for consolidated bioprocessing. However, cellulosic ethanol production using existing yeast whole-cell biocatalysts (yWCBs) has not reached industrial feasibility due to their inefficient cellulose hydrolysis. As prior studies have demonstrated enzyme density on the yWCB surface to be one of the most important parameters for enhancing cellulose hydrolysis, we sought to maximize this parameter at both the population and single-cell levels in yWCBs displaying tetrafunctional minicellulosomes. At the population level, enzyme density is limited by the presence of a nondisplay population constituting 25-50% of all cells. In this study, we identified the cause to be plasmid loss and successfully eliminated the nondisplay population to generate compositionally uniform yWCBs. At the single-cell level, we demonstrate that enzyme density is limited by molecular crowding, which hinders minicellulosome assembly. By adjusting the integrated gene copy number, we obtained yWCBs of tunable enzyme display levels. This tunability allowed us to avoid the crowding-limited regime and achieve a maximum enzyme density per cell. As a result, the best strain showed a cellulose-to-ethanol yield of 4.92 g/g, corresponding to 96% of the theoretical maximum and near-complete conversion (∼96%) of the starting cellulose (1% PASC). Our holistic engineering strategy that combines a population and single-cell level approach is broadly applicable to enhance the WCB performance in other biocatalytic cascade schemes.
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Affiliation(s)
- Xiao Yin Ma
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bryan Coleman
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ponnandy Prabhu
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Margaret Yang
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Fei Wen
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
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3
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Beard JW, Hunt SL, Evans A, Goenner C, Miller BL. Mimicking an in cellulo environment for enzyme-free paper-based nucleic acid tests at the point of care. bioRxiv 2024:2024.02.27.582375. [PMID: 38464301 PMCID: PMC10925243 DOI: 10.1101/2024.02.27.582375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Point of care (PoC) nucleic acid amplification tests (NAATs) are a cornerstone of public health, providing the earliest and most accurate diagnostic method for many communicable diseases, such as HIV, in the same location the patient receives treatment. Communicable diseases disproportionately impact low-resource communities where NAATs are often unobtainable due to the resource intensive enzymes that drive the tests. Enzyme-free nucleic acid detection methods, such as hybridization chain reaction (HCR), use DNA secondary structures for self-driven amplification schemes producing large DNA nanostructures and capable of single molecule detection in cellulo. These thermodynamically driven DNA-based tests have struggled to penetrate the PoC diagnostic field due to their inadequate limits of detection or complex workflows. Here we present a proof-of-concept NAAT that combines HCR-based amplification of a target nucleic acid sequence with paper-based nucleic acid filtration and enrichment capable of detecting sub pM levels of synthetic DNA. We reconstruct the favorable hybridization conditions of an in cellulo reaction in vitro by incubating HCR in an evaporating, microvolume environment containing poly(ethylene glycol) as a crowding agent. We demonstrate that the kinetics and thermodynamics of DNA-DNA and DNA-RNA hybridization is enhanced by the dynamic evaporating environment and inclusion of crowding agents, bringing HCR closer to meeting PoC NAAT needs.
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Affiliation(s)
- Jeffrey W. Beard
- Department of Dermatology, University of Rochester, Rochester, NY 14627, USA
| | - Samuel L. Hunt
- Department of Dermatology, University of Rochester, Rochester, NY 14627, USA
| | - Alexander Evans
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Coleman Goenner
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14627, USA
| | - Benjamin L. Miller
- Department of Dermatology, University of Rochester, Rochester, NY 14627, USA
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14627, USA
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4
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Subramanya AR, Boyd-Shiwarski CR. Molecular Crowding: Physiologic Sensing and Control. Annu Rev Physiol 2024; 86:429-452. [PMID: 37931170 DOI: 10.1146/annurev-physiol-042222-025920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
The cytoplasm is densely packed with molecules that contribute to its nonideal behavior. Cytosolic crowding influences chemical reaction rates, intracellular water mobility, and macromolecular complex formation. Overcrowding is potentially catastrophic; to counteract this problem, cells have evolved acute and chronic homeostatic mechanisms that optimize cellular crowdedness. Here, we provide a physiology-focused overview of molecular crowding, highlighting contemporary advances in our understanding of its sensing and control. Long hypothesized as a form of crowding-induced microcompartmentation, phase separation allows cells to detect and respond to intracellular crowding through the action of biomolecular condensates, as indicated by recent studies. Growing evidence indicates that crowding is closely tied to cell size and fluid volume, homeostatic responses to physical compression and desiccation, tissue architecture, circadian rhythm, aging, transepithelial transport, and total body electrolyte and water balance. Thus, molecular crowding is a fundamental physiologic parameter that impacts diverse functions extending from molecule to organism.
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Affiliation(s)
- Arohan R Subramanya
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; ,
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for Kidney Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- VA Pittsburgh Healthcare System, Pittsburgh, Pennsylvania, USA
| | - Cary R Boyd-Shiwarski
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; ,
- Pittsburgh Center for Kidney Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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5
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Khatri S, Pandey P, Mejia G, Ghimire G, Leng F, He J. Nanoconfinement and Crowding Enhanced Single-Molecule Detection of Small Molecules with Nanopipettes. J Am Chem Soc 2023; 145:28075-28084. [PMID: 37996390 PMCID: PMC11036617 DOI: 10.1021/jacs.3c09311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Glass nanopipettes have gained widespread use as a versatile single-entity detector in chemical and biological sensing, analysis, and imaging. Its advantages include low cost, easy accessibility, simplicity of use, and high versatility. However, conventional nanopipettes based on the volume exclusion mechanism have limitations in detecting small biomolecules due to their small volume and high mobility in aqueous solution. To overcome this challenge, we have employed a novel approach by capitalizing on the strong nanoconfinement effect of nanopipettes. This is achieved by utilizing both the hard confinement provided by the long taper nanopipette tip at the cis side and the soft confinement offered by the hydrogel at the trans side. Through this approach, we have effectively slowed down the exit motion of small molecules, allowing us to enrich and jam them at the nanopipette tip. Consequently, we have achieved high throughput detection of small biomolecules with sizes as small as 1 nm, including nucleoside triphosphates, short peptides, and small proteins with excellent signal-to-noise ratios. Furthermore, molecular complex formation through specific intermolecular interactions, such as hydrogen bonding between closely spaced nucleotides in the jam-packed nanopipette tip, has been detected based on the unique ionic current changes.
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Affiliation(s)
- Santosh Khatri
- Physics Department, Florida International University, Miami, Florida, 33199, USA
| | - Popular Pandey
- Physics Department, Florida International University, Miami, Florida, 33199, USA
| | - German Mejia
- Chemistry and Biochemistry Department, Florida International University, Miami, Florida, 33199, USA
- Biomolecular Science Institute, Florida International University, Miami, Florida, 33199, USA
| | - Govinda Ghimire
- Physics Department, Florida International University, Miami, Florida, 33199, USA
| | - Fenfei Leng
- Chemistry and Biochemistry Department, Florida International University, Miami, Florida, 33199, USA
- Biomolecular Science Institute, Florida International University, Miami, Florida, 33199, USA
| | - Jin He
- Physics Department, Florida International University, Miami, Florida, 33199, USA
- Biomolecular Science Institute, Florida International University, Miami, Florida, 33199, USA
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6
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Huang JH, Chen Y, Huang WYC, Tabatabaee S, Ferrell JE. Robust trigger wave speed in Xenopus cytoplasmic extracts. bioRxiv 2023:2023.12.22.573127. [PMID: 38187567 PMCID: PMC10769400 DOI: 10.1101/2023.12.22.573127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Self-regenerating trigger waves can spread rapidly through the crowded cytoplasm without diminishing in amplitude or speed, providing consistent, reliable, long-range communication. The macromolecular concentration of the cytoplasm varies in response to physiological and environmental fluctuations, raising the question of how or if trigger waves can robustly operate in the face of such fluctuations. Using Xenopus extracts, we found that mitotic and apoptotic trigger wave speeds are remarkably invariant. We derived a model that accounts for this robustness and for the eventual slowing at extremely high and low cytoplasmic concentrations. The model implies that the positive and negative effects of cytoplasmic concentration (increased reactant concentration vs. increased viscosity) are nearly precisely balanced. Accordingly, artificially maintaining a constant cytoplasmic viscosity during dilution abrogates this robustness. The robustness in trigger wave speeds may contribute to the reliability of the extremely rapid embryonic cell cycle.
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Affiliation(s)
- Jo-Hsi Huang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
- These authors contributed equally
| | - Yuping Chen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
- These authors contributed equally
| | - William Y C Huang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
| | - Saman Tabatabaee
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 943055307, USA
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7
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Abstract
Life emerges from thousands of biochemical processes occurring within a shared intracellular environment. We have gained deep insights from in vitro reconstitution of isolated biochemical reactions. However, the reaction medium in test tubes is typically simple and diluted. The cell interior is far more complex: macromolecules occupy more than a third of the space, and energy-consuming processes agitate the cell interior. Here, we review how this crowded, active environment impacts the motion and assembly of macromolecules, with an emphasis on mesoscale particles (10-1000 nm diameter). We describe methods to probe and analyze the biophysical properties of cells and highlight how changes in these properties can impact physiology and signaling, and potentially contribute to aging, and diseases, including cancer and neurodegeneration.
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Affiliation(s)
- Martina Bonucci
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA
| | - Tong Shu
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Medical Center, 435 E 30th Street, New York, NY 10016, USA.
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8
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Hirai M, Arai S, Iwase H. Fibrillization Process of Human Amyloid-Beta Protein (1-40) under a Molecular Crowding Environment Mimicking the Interior of Living Cells Using Cell Debris. Molecules 2023; 28:6555. [PMID: 37764331 PMCID: PMC10535490 DOI: 10.3390/molecules28186555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023] Open
Abstract
Molecular crowding environments play a crucial role in understanding the mechanisms of biological reactions. Inside living cells, a diverse array of molecules coexists within a volume fraction ranging from 10% to 30% v/v. However, conventional spectroscopic methods often face difficulties in selectively observing the structures of particular proteins or membranes within such molecularly crowded environments due to the presence of high background signals. Therefore, it is crucial to establish in vitro measurement conditions that closely resemble the intracellular environment. Meanwhile, the neutron scattering method offers a significant advantage in selectively observing target biological components, even within crowded environments. Recently, we have demonstrated a novel scattering method capable of selectively detecting the structures of targeted proteins or membranes in a closely mimicking intracellular milieu achieved utilizing whole-cell contents (deuterated-cell debris). This method relies on the inverse contrast matching technique in neutron scattering. By employing this method, we successfully observed the fibrillization process of human amyloid beta-protein (Aβ 1-40) under a molecular crowding environment (13.1% w/v cell debris, Aβ/cell debris = ~1/25 w/w) that closely mimics the interior of living cells. Aβ protein is well known as a major pathogenic component of Alzheimer's disease. The present results combining model simulation analyses clearly show that the intracellular environment facilitates the potential formation of even more intricate higher-order aggregates of Aβ proteins than those previously reported.
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Affiliation(s)
- Mitsuhiro Hirai
- Graduate School of Science and Technology, Gunma University, 4-2 Aramaki, Maebashi 371-8510, Gunma, Japan
| | - Shigeki Arai
- National Institute for Quantum and Radiological Science and Technology, Tokai 319-1106, Ibaraki, Japan;
| | - Hiroki Iwase
- Comprehensive Research Organization for Science and Society (CROSS), Tokai 319-1106, Ibaraki, Japan;
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9
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Morozov VN, Klimovich MA, Shibaeva AV, Klimovich ON, Koshevaya ED, Kolyvanova MA, Kuzmin VA. Optical Polymorphism of Liquid-Crystalline Dispersions of DNA at High Concentrations of Crowding Polymer. Int J Mol Sci 2023; 24:11365. [PMID: 37511123 PMCID: PMC10379083 DOI: 10.3390/ijms241411365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Optically active liquid-crystalline dispersions (LCD) of nucleic acids, obtained by polymer- and salt-induced (psi-) condensation, e.g., by mixing of aqueous saline solutions of low molecular weight DNA (≤106 Da) and polyethylene glycol (PEG), possess an outstanding circular dichroism (CD) signal (so-called psi-CD) and are of interest for sensor applications. Typically, such CD signals are observed in PEG content from ≈12.5% to ≈22%. However, in the literature, there are very conflicting data on the existence of psi-CD in DNA LCDs at a higher content of crowding polymer up to 30-40%. In the present work, we demonstrate that, in the range of PEG content in the system above ≈24%, optically polymorphic LCDs can be formed, characterized by both negative and positive psi-CD signals, as well as by ones rather slightly differing from the spectrum of isotropic DNA solution. Such a change in the CD signal is determined by the concentration of the stock solution of PEG used for the preparation of LCDs. We assume that various saturation of polymer chains with water molecules may affect the amount of active water, which in turn leads to a change in the hydration of DNA molecules and their transition from B-form to Z-form.
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Affiliation(s)
- Vladimir N Morozov
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
| | - Mikhail A Klimovich
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
- Burnazyan Federal Medical Biophysical Center, Federal Medical Biological Agency of the Russian Federation, 23 Marshala Novikova, 123182 Moscow, Russia
| | - Anna V Shibaeva
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
| | - Olga N Klimovich
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
| | - Ekaterina D Koshevaya
- Burnazyan Federal Medical Biophysical Center, Federal Medical Biological Agency of the Russian Federation, 23 Marshala Novikova, 123182 Moscow, Russia
| | - Maria A Kolyvanova
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
- Burnazyan Federal Medical Biophysical Center, Federal Medical Biological Agency of the Russian Federation, 23 Marshala Novikova, 123182 Moscow, Russia
| | - Vladimir A Kuzmin
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina, 119334 Moscow, Russia
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10
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Chen Y, Huang JH, Phong C, Ferrell JE. Protein homeostasis from diffusion-dependent control of protein synthesis and degradation. bioRxiv 2023:2023.04.24.538146. [PMID: 37162886 PMCID: PMC10168264 DOI: 10.1101/2023.04.24.538146] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
It has been proposed that the concentration of proteins in the cytoplasm maximizes the speed of important biochemical reactions. Here we have used the Xenopus extract system, which can be diluted or concentrated to yield a range of cytoplasmic protein concentrations, to test the effect of cytoplasmic concentration on mRNA translation and protein degradation. We found that protein synthesis rates are maximal in ~1x cytoplasm, whereas protein degradation continues to rise to an optimal concentration of ~1.8x. This can be attributed to the greater sensitivity of translation to cytoplasmic viscosity, perhaps because it involves unusually large macromolecular complexes like polyribosomes. The different concentration optima sets up a negative feedback homeostatic system, where increasing the cytoplasmic protein concentration above the 1x physiological level increases the viscosity of the cytoplasm, which selectively inhibits translation and drives the system back toward the 1x set point.
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Affiliation(s)
- Yuping Chen
- Dept. of Chemical and Systems Biology, Stanford University School of Medicine, Stanford CA 94305
- These authors contributed equally
- Corresponding authors
| | - Jo-Hsi Huang
- Dept. of Chemical and Systems Biology, Stanford University School of Medicine, Stanford CA 94305
- These authors contributed equally
| | - Connie Phong
- Dept. of Chemical and Systems Biology, Stanford University School of Medicine, Stanford CA 94305
| | - James E. Ferrell
- Dept. of Chemical and Systems Biology, Stanford University School of Medicine, Stanford CA 94305
- Dept. of Biochemistry, Stanford University School of Medicine, Stanford CA 94305
- Corresponding authors
- Lead contact
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11
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Maheshwari AJ, Sunol AM, Gonzalez E, Endy D, Zia RN. Colloidal Physics Modeling Reveals How Per-Ribosome Productivity Increases with Growth Rate in Escherichia coli. mBio 2023; 14:e0286522. [PMID: 36537810 DOI: 10.1128/mbio.02865-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Faster-growing cells must synthesize proteins more quickly. Increased ribosome abundance only partly accounts for increases in total protein synthesis rates. The productivity of individual ribosomes must increase too, almost doubling by an unknown mechanism. Prior models point to diffusive transport as a limiting factor but raise a paradox: faster-growing cells are more crowded, yet crowding slows diffusion. We suspected that physical crowding, transport, and stoichiometry, considered together, might reveal a more nuanced explanation. To investigate, we built a first-principles physics-based model of Escherichia coli cytoplasm in which Brownian motion and diffusion arise directly from physical interactions between individual molecules of finite size, density, and physiological abundance. Using our microscopically detailed model, we predicted that physical transport of individual ternary complexes accounts for ~80% of translation elongation latency. We also found that volumetric crowding increases during faster growth even as cytoplasmic mass density remains relatively constant. Despite slowed diffusion, we predicted that improved proximity between ternary complexes and ribosomes wins out, illustrating a simple physics-based mechanism for how individual elongating ribosomes become more productive. We speculate that crowding imposes a physical limit on growth rate and undergirds cellular behavior more broadly. Unfitted colloidal-scale modeling offers systems biology a complementary "physics engine" for exploring how cellular-scale behaviors arise from physical transport and reactions among individual molecules. IMPORTANCE Ribosomes are the factories in cells that synthesize proteins. When cells grow faster, there are not enough ribosomes to keep up with the demand for faster protein synthesis without individual ribosomes becoming more productive. Yet, faster-growing cells are more crowded, seemingly making it harder for each ribosome to do its work. Our computational model of the physics of translation elongation reveals the underlying mechanism for how individual ribosomes become more productive: proximity and stoichiometry of translation molecules overcome crowding. Our model also suggests a universal physical limitation of cell growth rates.
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12
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Sanjeev BS, Chitara D, Madhumalar A. Physiological models to study the effect of molecular crowding on multi-drug bound proteins: insights from SARS-CoV-2 main protease. J Biomol Struct Dyn 2022; 40:13564-13580. [PMID: 34699337 DOI: 10.1080/07391102.2021.1993342] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Molecular Dynamics simulations are often used in drug design. However, such simulations do not account for the physiological environment of the receptor; hence overlook its impact on biomolecular interactions. To address this lacuna, we identified three objectives to pursue - develop models of physiological environment, study a drug-receptor complex in such environments, and identify methods to analyze these complicated simulations. Two novel physiological models were developed and studied. The first, called 'm10', comprises of 10 of the most abundant cytoplasmic metabolites at physiological concentrations. The second, called 'phy', supplements m10 with an additional crowder protein to elicit macromolecular crowding effect. The main protease (Mpro) of SARS-CoV-2, being essential for viral replication, is an attractive drug target for COVID-19. Hence, we chose Mpro docked with multiple drugs as our model drug-receptor system. With a plethora of compounds, physiological systems can be exceedingly large and complex. A novel Spark-based software (SparkTraj) was developed to rapidly analyze non-specific contacts and water interactions. Our study shows that crowding enhances the difference in the dynamics of apo- vs drug-bound complexes. Metabolites, at times as a cluster, were seen interacting with the protease, drugs, and binding sites in drug-free receptor. Except one that crawled to an adjacent pocket in phy, the drugs remained in their respective pockets in all simulations. Given these observations, we hope that the models and approach presented here would help the optimization, evaluation, and selection of potential drugs. Generic biomolecular dynamics could also benefit from such models and tools.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- B S Sanjeev
- Department of Applied Sciences, Indian Institute of Information Technology, Allahabad, India
| | - Dheeraj Chitara
- Department of Applied Sciences, Indian Institute of Information Technology, Allahabad, India
| | - Arumugam Madhumalar
- Multidisciplinary Centre for Advanced Research and Studies, Jamia Millia Islamia, New Delhi, India
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13
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Lecinski S, Shepherd JW, Bunting K, Dresser L, Quinn SD, MacDonald C, Leake MC. Correlating viscosity and molecular crowding with fluorescent nanobeads and molecular probes: in vitro and in vivo. Interface Focus 2022; 12:20220042. [PMID: 36330320 PMCID: PMC9560789 DOI: 10.1098/rsfs.2022.0042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/05/2022] [Indexed: 02/02/2023] Open
Abstract
In eukaryotes, intracellular physico-chemical properties like macromolecular crowding and cytoplasmic viscoelasticity influence key processes such as metabolic activities, molecular diffusion and protein folding. However, mapping crowding and viscoelasticity in living cells remains challenging. One approach uses passive rheology in which diffusion of exogenous fluorescent particles internalized in cells is tracked and physico-chemical properties inferred from derived mean square displacement relations. Recently, the crGE2.3 Förster resonance energy transfer biosensor was developed to quantify crowding in cells, though it is unclear how this readout depends on viscoelasticity and the molecular weight of the crowder. Here, we present correlative, multi-dimensional data to explore diffusion and molecular crowding characteristics of molecular crowding agents using super-resolved fluorescence microscopy and ensemble time-resolved spectroscopy. We firstly characterize in vitro and then apply these insights to live cells of budding yeast Saccharomyces cerevisiae. It is to our knowledge the first time this has been attempted. We demonstrate that these are usable both in vitro and in the case of endogenously expressed sensors in live cells. Finally, we present a method to internalize fluorescent beads as in situ viscoelasticity markers in the cytoplasm of live yeast cells and discuss limitations of this approach including impairment of cellular function.
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Affiliation(s)
- Sarah Lecinski
- Department of Physics, University of York, York YO10 5DD, UK
| | - Jack W. Shepherd
- Department of Physics, University of York, York YO10 5DD, UK
- Department of Biology, University of York, York YO10 5DD, UK
| | - Kate Bunting
- Department of Biology, University of York, York YO10 5DD, UK
| | - Lara Dresser
- Department of Physics, University of York, York YO10 5DD, UK
| | - Steven D. Quinn
- Department of Physics, University of York, York YO10 5DD, UK
| | - Chris MacDonald
- Department of Biology, University of York, York YO10 5DD, UK
| | - Mark C. Leake
- Department of Physics, University of York, York YO10 5DD, UK
- Department of Biology, University of York, York YO10 5DD, UK
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14
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Pastore A, Temussi PA. Crowding revisited: Open questions and future perspectives. Trends Biochem Sci 2022; 47:1048-1058. [PMID: 35691783 DOI: 10.1016/j.tibs.2022.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 05/12/2022] [Accepted: 05/24/2022] [Indexed: 12/24/2022]
Abstract
Although biophysical studies have traditionally been performed in diluted solutions, it was pointed out in the late 1990s that the cellular milieu contains several other macromolecules, creating a condition of molecular crowding. How crowding affects protein stability is an important question heatedly discussed over the past 20 years. Theoretical estimations have suggested a 5-20°C effect of fold stabilisation. This estimate, however, is at variance with what has been verified experimentally that proposes only a limited increase of stability, opening the question whether some of the assumptions taken for granted should be reconsidered. The present review critically analyses the causes of this discrepancy and discusses the limitations and implications of the current concept of crowding.
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Affiliation(s)
- Annalisa Pastore
- UK Dementia Research Institute at the Maurice Wohl Institute of King's College London, London, SE5 9RT, UK.
| | - Piero Andrea Temussi
- UK Dementia Research Institute at the Maurice Wohl Institute of King's College London, London, SE5 9RT, UK.
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15
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Pandey S, Jonchhe S, Mishra S, Emura T, Sugiyama H, Endo M, Mao H. Zeptoliter DNA Origami Reactor to Reveal Cosolute Effects on Nanoconfined G-Quadruplexes. J Phys Chem Lett 2022; 13:8692-8698. [PMID: 36094396 PMCID: PMC10323737 DOI: 10.1021/acs.jpclett.2c02253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Cellular environments such as nanoconfinement and molecular crowding can change biomolecular properties. However, in nanoconfinement, it is extremely challenging to investigate effects of crowding cosolutes on macromolecules. By using optical tweezers, here, we elucidated the effects of hexaethylene glycol (HEG) on the mechanical stability of a telomeric G-quadruplex (GQ) in a zeptoliter DNA origami reactor (zepto-reactor). When HEG molecules were introduced in the GQ-containing zepto-reactor at different positions, we found that the GQ species split into two equilibrated populations, reflecting diverse effects of the oligoethylene glycol on the GQ via either a long-range dehydration effect or direct interactions. When the number of HEG molecules was increased, the stability of the GQ unexpectedly decreased, suggesting that the direct destabilizing interaction between the GQ and HEG is dominating over the long-range stabilizing dehydration effects of the HEG in hydrophilic nanocavities. These findings indicate that a nanoconfined environment can alter regular effects of cosolutes on biomacromolecules.
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Affiliation(s)
- Shankar Pandey
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Sagun Jonchhe
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
| | - Shubham Mishra
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Tomoko Emura
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Hiroshi Sugiyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
- Institute for Integrated Cell–Material Sciences (iCeMS), Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Masayuki Endo
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
- Institute for Integrated Cell–Material Sciences (iCeMS), Kyoto University, Sakyo, Kyoto 606-8501, Japan
- Organization for Research and Development of Innovative Science and Technology, Kansai University, Suita, Osaka 564-8680, Japan1
| | - Hanbin Mao
- Department of Chemistry & Biochemistry, Kent State University, Kent, OH 44242, USA
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16
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Spukti FF, Schnauß J. Large and stable: actin aster networks formed via entropic forces. Front Chem 2022; 10:899478. [PMID: 36118308 PMCID: PMC9481034 DOI: 10.3389/fchem.2022.899478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/13/2022] [Indexed: 12/04/2022] Open
Abstract
Biopolymer networks play a major role as part of the cytoskeleton. They provide stable structures and act as a medium for signal transport. These features encourage the application of such networks as organic computation devices. While research on this topic is not advanced yet, previous results are very promising. The protein actin in particular appears advantageous. It can be arranged to various stable structures and transmit several signals. In this study aster shaped networks were self-assembled via entropic forces by the crowding agent methyl cellulose. These networks are characterised by a regular and uniquely thick bundle structure, but have so far only been accounted in droplets of 100 μm diameter. We report now regular asters in an area of a few mm2 that could be observed even after months. Such stability outside of an organism is striking and underlines the great potential actin aster networks display.
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Affiliation(s)
| | - Jörg Schnauß
- Peter Debye Institute for Soft Matter Physics, University of Leipzig, Leipzig, Germany.,Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany.,Unconventional Computing Laboratory, Department of Computer Science, University of the West of England, Bristol, United Kingdom
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17
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Strobl K, Selivanovitch E, Ibáñez-Freire P, Moreno-Madrid F, Schaap IAT, Delgado-Buscalioni R, Douglas T, de Pablo PJ. Electromechanical Photophysics of GFP Packed Inside Viral Protein Cages Probed by Force-Fluorescence Hybrid Single-Molecule Microscopy. Small 2022; 18:e2200059. [PMID: 35718881 PMCID: PMC9528512 DOI: 10.1002/smll.202200059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/29/2022] [Indexed: 06/15/2023]
Abstract
Packing biomolecules inside virus capsids has opened new avenues for the study of molecular function in confined environments. These systems not only mimic the highly crowded conditions in nature, but also allow their manipulation at the nanoscale for technological applications. Here, green fluorescent proteins are packed in virus-like particles derived from P22 bacteriophage procapsids. The authors explore individual virus cages to monitor their emission signal with total internal reflection fluorescence microscopy while simultaneously changing the microenvironment with the stylus of atomic force microscopy. The mechanical and electronic quenching can be decoupled by ≈10% each using insulator and conductive tips, respectively. While with conductive tips the fluorescence quenches and recovers regardless of the structural integrity of the capsid, with the insulator tips quenching only occurs if the green fluorescent proteins remain organized inside the capsid. The electronic quenching is associated with the coupling of the protein fluorescence emission with the tip surface plasmon resonance. In turn, the mechanical quenching is a consequence of the unfolding of the aggregated proteins during the mechanical disruption of the capsid.
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Affiliation(s)
- Klara Strobl
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | | | - Pablo Ibáñez-Freire
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Francisco Moreno-Madrid
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | | | - Rafael Delgado-Buscalioni
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Institute of Condensed Matter Physics (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Trevor Douglas
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Pedro J de Pablo
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Institute of Condensed Matter Physics (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
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18
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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 Appl Mater Interfaces 2022; 14:19154-19167. [PMID: 35446027 DOI: 10.1021/acsami.2c02133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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Liu D, Qiu Y, Li Q, Zhang H. Atomistic Simulation of Lysozyme in Solutions Crowded by Tetraethylene Glycol: Force Field Dependence. Molecules 2022; 27:molecules27072110. [PMID: 35408509 PMCID: PMC9000840 DOI: 10.3390/molecules27072110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 11/16/2022]
Abstract
The behavior of biomolecules in crowded environments remains largely unknown due to the accuracy of simulation models and the limited experimental data for comparison. Here we chose a small crowder of tetraethylene glycol (PEG-4) to investigate the self-crowding of PEG-4 solutions and molecular crowding effects on the structure and diffusion of lysozyme at varied concentrations from dilute water to pure PEG-4 liquid. Two Amber-like force fields of Amber14SB and a99SB-disp were examined with TIP3P (fast diffusivity and low viscosity) and a99SB-disp (slow diffusivity and high viscosity) water models, respectively. Compared to the Amber14SB protein simulations, the a99SB-disp model yields more coordinated water and less PEG-4 molecules, less intramolecular hydrogen bonds (HBs), more protein-water HBs, and less protein-PEG HBs as well as stronger interactions and more hydrophilic and less hydrophobic contacts with solvent molecules. The a99SB-disp model offers comparable protein-solvent interactions in concentrated PEG-4 solutions to that in pure water. The PEG-4 crowding leads to a slow-down in the diffusivity of water, PEG-4, and protein, and the decline in the diffusion from atomistic simulations is close to or faster than the hard sphere model that neglects attractive interactions. Despite these differences, the overall structure of lysozyme appears to be maintained well at different PEG-4 concentrations for both force fields, except a slightly large deviation at 370 K at low concentrations with the a99SB-disp model. This is mainly attributed to the strong intramolecular interactions of the protein in the Amber14SB force field and to the large viscosity of the a99SB-disp water model. The results indicate that the protein force fields and the viscosity of crowder solutions affect the simulation of biomolecules under crowding conditions.
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20
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Simončič M, Lukšič M. Modulating Role of Co-Solutes in Complexation between Bovine Serum Albumin and Sodium Polystyrene Sulfonate. Polymers (Basel) 2022; 14. [PMID: 35335575 DOI: 10.3390/polym14061245] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/12/2022] [Accepted: 03/18/2022] [Indexed: 11/28/2022] Open
Abstract
The action of three types of co-solutes: (i) salts (NaCl, NaBr, NaI), (ii) polymer (polyethylene glycol; PEG-400, PEG-3000, PEG-20000), and (iii) sugars (sucrose, sucralose) on the complexation between bovine serum albumin (BSA) and sodium polystyrene sulfonate (NaPSS) was studied. Three critical pH parameters were extracted from the pH dependence of the solution’s turbidity: pHc corresponding to the formation of the soluble complexes, pHΦ corresponding to the formation of the insoluble complexes, and pHopt corresponding to the charge neutralization of the complexes. In the presence of salts, the formation of soluble and insoluble complexes as well as the charge neutralization of complexes was hindered, which is a consequence of the electrostatic screening of attractive interactions between BSA and NaPSS. Distinct anion-specific trends were observed in which the stabilizing effect of the salt increased in the order: NaCl < NaBr < NaI. The presence of PEG, regardless of its molecular weight, showed no measurable effect on the formation of soluble complexes. PEG-400 and PEG-3000 showed no effect on the formation of insoluble complexes, but PEG-20000 in high concentrations promoted their formation due to the molecular crowding effect. The presence of sugar molecules had little effect on BSA-NaPSS complexation. Sucralose showed a minor stabilizing effect with respect to the onset of complex formation, which was due to its propensity to the protein surface. This was confirmed by the fluorescence quenching assay (Stern-Volmer relationship) and all-atom MD simulations. This study highlights that when evaluating the modulatory effect of co-solutes on protein-polyelectrolyte interactions, (co-solute)-protein interactions and their subsequent impact on protein aggregation must also be considered.
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21
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Pack CG. Application of quantitative cell imaging using label-free optical diffraction tomography. Biophys Physicobiol 2021; 18:244-253. [PMID: 34745809 PMCID: PMC8550874 DOI: 10.2142/biophysico.bppb-v18.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/11/2021] [Indexed: 12/01/2022] Open
Abstract
The cell is three-dimensionally and dynamically organized into cellular compartments, including the endoplasmic reticulum, mitochondria, vesicles, and nucleus, which have high relative molecular density. The structure and functions of these compartments and organelles may be deduced from the diffusion and interaction of related biomolecules. Among these cellular components, various protein molecules can freely access the nucleolus or mitotic chromosome through Brownian diffusion, even though they have a densely packed structure. However, physicochemical properties of the nucleolus and chromosomes, such as molecular density and volume, are not yet fully understood under changing cellular conditions. Many studies have been conducted based on high-resolution imaging and analysis techniques using fluorescence. However, there are limitations in imaging only fluorescently labeled molecules, and cytotoxicity occurs during three-dimensional imaging. Alternatively, the recently developed label-free three-dimensional optical diffraction tomography (ODT) imaging technique can divide various organelles in cells into volumes and analyze them by refractive index, although specific molecules cannot be observed. A previous study established an analytical method that provides comprehensive insights into the physical properties of the nucleolus and mitotic chromosome by utilizing the advantages of ODT and fluorescence techniques, such as fluorescence correlation spectroscopy and confocal laser scanning microscopy. This review article summarizes a recent study and discusses the future aspects of the ODT for cellular compartments.
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Affiliation(s)
- Chan-Gi Pack
- Convergence Medicine Research Center (CREDIT), Asan Institute for Life Sciences, Asan Medical Center, Seoul 05505, Republic of Korea.,Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Zannino L, Casali C, Siciliani S, Biggiogera M. The dynamics of the nuclear environment and their impact on gene function. J Biochem 2021; 169:259-264. [PMID: 32745171 DOI: 10.1093/jb/mvaa091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/15/2020] [Indexed: 01/04/2023] Open
Abstract
In the last decades, it has become increasingly clear how the modulation of spatial organization of chromatin over time and through the cell cycle is closely connected to gene function regulation. Different physicochemical stimuli contribute to the realization of specific transcriptional programs and finally to a specific cellular phenotype. In this review, we aim to describe the current knowledge about the dynamics regulating the movements and the interactions of molecules within the nucleus and their impact on gene functions. In particular, taking into account that these forces exert their effect in a nuclear environment characterized by a high concentration of molecules, we will discuss the role of proteins and structures that regulate these movements and transduce physicochemical signals acting on the cell to the nucleus.
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Affiliation(s)
- Lorena Zannino
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | | | - Stella Siciliani
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
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24
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Guihur A, Fauvet B, Finka A, Quadroni M, Goloubinoff P. Quantitative proteomic analysis to capture the role of heat-accumulated proteins in moss plant acquired thermotolerance. Plant Cell Environ 2021; 44:2117-2133. [PMID: 33314263 PMCID: PMC8359368 DOI: 10.1111/pce.13975] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 05/08/2023]
Abstract
At dawn of a scorching summer day, land plants must anticipate upcoming extreme midday temperatures by timely establishing molecular defences that can keep heat-labile membranes and proteins functional. A gradual morning pre-exposure to increasing sub-damaging temperatures induces heat-shock proteins (HSPs) that are central to the onset of plant acquired thermotolerance (AT). To gain knowledge on the mechanisms of AT in the model land plant Physcomitrium patens, we used label-free LC-MS/MS proteomics to quantify the accumulated and depleted proteins before and following a mild heat-priming treatment. High protein crowding is thought to promote protein aggregation, whereas molecular chaperones prevent and actively revert aggregation. Yet, we found that heat priming (HP) did not accumulate HSP chaperones in chloroplasts, although protein crowding was six times higher than in the cytosol. In contrast, several HSP20s strongly accumulated in the cytosol, yet contributing merely 4% of the net mass increase of heat-accumulated proteins. This is in poor concordance with their presumed role at preventing the aggregation of heat-labile proteins. The data suggests that under mild HP unlikely to affect protein stability. Accumulating HSP20s leading to AT, regulate the activity of rare and specific signalling proteins, thereby preventing cell death under noxious heat stress.
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Affiliation(s)
- Anthony Guihur
- Department of Plant Molecular Biology, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
| | - Bruno Fauvet
- Department of Plant Molecular Biology, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
| | - Andrija Finka
- Department of Ecology, Agronomy and AquacultureUniversity of ZadarZadarCroatia
| | | | - Pierre Goloubinoff
- Department of Plant Molecular Biology, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
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25
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Zhao Q, Fujimiya R, Kubo S, Marshall CB, Ikura M, Shimada I, Nishida N. Real-Time In-Cell NMR Reveals the Intracellular Modulation of GTP-Bound Levels of RAS. Cell Rep 2021; 32:108074. [PMID: 32846131 DOI: 10.1016/j.celrep.2020.108074] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/03/2020] [Accepted: 08/05/2020] [Indexed: 02/07/2023] Open
Abstract
The small guanosine triphosphatase (GTPase) RAS serves as a molecular switch in signal transduction, and its mutation and aberrant activation are implicated in tumorigenesis. Here, we perform real-time, in-cell nuclear magnetic resonance (NMR) analyses of non-farnesylated RAS to measure time courses of the fraction of the active GTP-bound form (fGTP) within cytosol of live mammalian cells. The observed intracellular fGTP is significantly lower than that measured in vitro for wild-type RAS as well as oncogenic mutants, due to both decrease of the guanosine diphosphate (GDP)-GTP exchange rate (kex) and increase of GTP hydrolysis rate (khy). In vitro reconstitution experiments show that highly viscous environments promote a reduction of kex, whereas the increase of khy is stimulated by unidentified cytosolic proteins. This study demonstrates the power of in-cell NMR to directly detect the GTP-bound levels of RAS in mammalian cells, thereby revealing that the khy and kex of RAS are modulated by various intracellular factors.
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Affiliation(s)
- Qingci Zhao
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ryu Fujimiya
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Satoshi Kubo
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Christopher B Marshall
- Princess Margaret Cancer Centre, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Centre, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
| | - Noritaka Nishida
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
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26
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Kobayashi R, Inaba H, Matsuura K. Fluorescence Correlation Spectroscopy Analysis of Effect of Molecular Crowding on Self-Assembly of β-Annulus Peptide into Artificial Viral Capsid. Int J Mol Sci 2021; 22:ijms22094754. [PMID: 33946174 PMCID: PMC8125178 DOI: 10.3390/ijms22094754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022] Open
Abstract
Recent progress in the de novo design of self-assembling peptides has enabled the construction of peptide-based viral capsids. Previously, we demonstrated that 24-mer β-annulus peptides from tomato bushy stunt virus spontaneously self-assemble into an artificial viral capsid. Here we propose to use the artificial viral capsid through the self-assembly of β-annulus peptide as a simple model to analyze the effect of molecular crowding environment on the formation process of viral capsid. Artificial viral capsids formed by co-assembly of fluorescent-labelled and unmodified β-annulus peptides in dilute aqueous solutions and under molecular crowding conditions were analyzed using fluorescence correlation spectroscopy (FCS). The apparent particle size and the dissociation constant (Kd) of the assemblies decreased with increasing concentration of the molecular crowding agent, i.e., polyethylene glycol (PEG). This is the first successful in situ analysis of self-assembling process of artificial viral capsid under molecular crowding conditions.
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Affiliation(s)
- Risako Kobayashi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan; (R.K.); (H.I.)
| | - Hiroshi Inaba
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan; (R.K.); (H.I.)
- Centre for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
| | - Kazunori Matsuura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan; (R.K.); (H.I.)
- Centre for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
- Correspondence: ; Tel.: +81-857-31-5262
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Tsuruta M, Sugitani Y, Sugimoto N, Miyoshi D. Combined Effects of Methylated Cytosine and Molecular Crowding on the Thermodynamic Stability of DNA Duplexes. Int J Mol Sci 2021; 22:ijms22020947. [PMID: 33477917 PMCID: PMC7833394 DOI: 10.3390/ijms22020947] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/31/2022] Open
Abstract
Methylated cytosine within CpG dinucleotides is a key factor for epigenetic gene regulation. It has been revealed that methylated cytosine decreases DNA backbone flexibility and increases the thermal stability of DNA. Although the molecular environment is an important factor for the structure, thermodynamics, and function of biomolecules, there are few reports on the effects of methylated cytosine under a cell-mimicking molecular environment. Here, we systematically investigated the effects of methylated cytosine on the thermodynamics of DNA duplexes under molecular crowding conditions, which is a critical difference between the molecular environment in cells and test tubes. Thermodynamic parameters quantitatively demonstrated that the methylation effect and molecular crowding effect on DNA duplexes are independent and additive, in which the degree of the stabilization is the sum of the methylation effect and molecular crowding effect. Furthermore, the effects of methylation and molecular crowding correlate with the hydration states of DNA duplexes. The stabilization effect of methylation was due to the favorable enthalpic contribution, suggesting that direct interactions of the methyl group with adjacent bases and adjacent methyl groups play a role in determining the flexibility and thermodynamics of DNA duplexes. These results are useful to predict the properties of DNA duplexes with methylation in cell-mimicking conditions.
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Affiliation(s)
- Mitsuki Tsuruta
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
| | - Yui Sugitani
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
| | - Naoki Sugimoto
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, Kobe 650-0047, Japan
| | - Daisuke Miyoshi
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe 650-0047, Japan; (M.T.); (Y.S.); (N.S.)
- Correspondence: ; Tel.: +81-(07)-8303-1426
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28
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Zhang W, Watanabe R, Konishi HA, Fujiwara T, Yoshimura SH, Kumeta M. Redox-Sensitive Cysteines Confer Proximal Control of the Molecular Crowding Barrier in the Nuclear Pore. Cell Rep 2020; 33:108484. [PMID: 33326779 DOI: 10.1016/j.celrep.2020.108484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 09/01/2020] [Accepted: 11/13/2020] [Indexed: 10/22/2022] Open
Abstract
The nuclear pore complex forms a highly crowded selective barrier with intrinsically disordered regions at the nuclear membrane to coordinate nucleocytoplasmic molecular communications. Although oxidative stress is known to alter the barrier function, the molecular mechanism underlying this adaptive control of the nuclear pore complex remains unknown. Here we uncover a systematic control of the crowding barrier within the nuclear pore in response to various redox environments. Direct measurements of the crowding states using a crowding-sensitive FRET (Förster resonance energy transfer) probe reveal specific roles of the nuclear pore subunits that adjust the degree of crowding in response to different redox conditions, by adaptively forming or disrupting redox-sensitive disulfide bonds. Relationships between crowding control and the barrier function of the nuclear pore are investigated by single-molecular fluorescence measurements of nuclear transport. Based on these findings, we propose a proximal control model of molecular crowding in vivo that is dynamically regulated at the molecular level.
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Affiliation(s)
- Wanzhen Zhang
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Ryuji Watanabe
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hide A Konishi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan; Laboratory of Chromosome and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Takahiro Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
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29
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Li Y, Chen M, Hu J, Sheng R, Lin Q, He X, Guo M. Volumetric Compression Induces Intracellular Crowding to Control Intestinal Organoid Growth via Wnt/β-Catenin Signaling. Cell Stem Cell 2020; 28:63-78.e7. [PMID: 33053374 DOI: 10.1016/j.stem.2020.09.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 02/26/2020] [Accepted: 09/14/2020] [Indexed: 12/14/2022]
Abstract
Enormous amounts of essential intracellular events are crowdedly packed inside picoliter-sized cellular space. However, the significance of the physical properties of cells remains underappreciated because of a lack of evidence of how they affect cellular functionalities. Here, we show that volumetric compression regulates the growth of intestinal organoids by modifying intracellular crowding and elevating Wnt/β-catenin signaling. Intracellular crowding varies upon stimulation by different types of extracellular physical/mechanical cues and leads to significant enhancement of Wnt/β-catenin signaling by stabilizing the LRP6 signalosome. By enhancing intracellular crowding using osmotic and mechanical compression, we show that expansion of intestinal organoids was facilitated through elevated Wnt/β-catenin signaling and greater intestinal stem cell (ISC) self-renewal. Our results provide an entry point for understanding how intracellular crowdedness functions as a physical regulator linking extracellular physical cues with intracellular signaling and potentially facilitate the design of engineering approaches for expansion of stem cells and organoids.
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Affiliation(s)
- Yiwei Li
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maorong Chen
- F. M. Kirby Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jiliang Hu
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ren Sheng
- F. M. Kirby Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110004, China
| | - Qirong Lin
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xi He
- F. M. Kirby Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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30
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Jalihal AP, Pitchiaya S, Xiao L, Bawa P, Jiang X, Bedi K, Parolia A, Cieslik M, Ljungman M, Chinnaiyan AM, Walter NG. Multivalent Proteins Rapidly and Reversibly Phase-Separate upon Osmotic Cell Volume Change. Mol Cell 2020; 79:978-990.e5. [PMID: 32857953 PMCID: PMC7502480 DOI: 10.1016/j.molcel.2020.08.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 06/11/2020] [Accepted: 08/05/2020] [Indexed: 12/12/2022]
Abstract
Processing bodies (PBs) and stress granules (SGs) are prominent examples of subcellular, membraneless compartments that are observed under physiological and stress conditions, respectively. We observe that the trimeric PB protein DCP1A rapidly (within ∼10 s) phase-separates in mammalian cells during hyperosmotic stress and dissolves upon isosmotic rescue (over ∼100 s) with minimal effect on cell viability even after multiple cycles of osmotic perturbation. Strikingly, this rapid intracellular hyperosmotic phase separation (HOPS) correlates with the degree of cell volume compression, distinct from SG assembly, and is exhibited broadly by homo-multimeric (valency ≥ 2) proteins across several cell types. Notably, HOPS sequesters pre-mRNA cleavage factor components from actively transcribing genomic loci, providing a mechanism for hyperosmolarity-induced global impairment of transcription termination. Our data suggest that the multimeric proteome rapidly responds to changes in hydration and molecular crowding, revealing an unexpected mode of globally programmed phase separation and sequestration.
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Affiliation(s)
- Ameya P Jalihal
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Cell and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sethuramasundaram Pitchiaya
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Lanbo Xiao
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Pushpinder Bawa
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Xia Jiang
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Karan Bedi
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Abhijit Parolia
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Marcin Cieslik
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Mats Ljungman
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA; Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI 48109, USA
| | - Arul M Chinnaiyan
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Urology, University of Michigan, Ann Arbor, MI 48109, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA; Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI 48109, USA.
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31
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Takahashi S, Herdwijn P, Sugimoto N. Effect of Molecular Crowding on DNA Polymerase Reactions along Unnatural DNA Templates. Molecules 2020; 25:E4120. [PMID: 32927591 PMCID: PMC7571040 DOI: 10.3390/molecules25184120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/08/2020] [Accepted: 09/08/2020] [Indexed: 11/17/2022] Open
Abstract
Unnatural nucleic acids are promising materials to expand genetic information beyond the natural bases. During replication, substrate nucleotide incorporation should be strictly controlled for optimal base pairing with template strand bases. Base-pairing interactions occur via hydrogen bonding and base stacking, which could be perturbed by the chemical environment. Although unnatural nucleobases and sugar moieties have undergone extensive structural improvement for intended polymerization, the chemical environmental effect on the reaction is less understood. In this study, we investigated how molecular crowding could affect native DNA polymerization along various templates comprising unnatural nucleobases and sugars. Under non-crowding conditions, the preferred incorporation efficiency of pyrimidine deoxynucleotide triphosphates (dNTPs) by the Klenow fragment (KF) was generally high with low fidelity, whereas that of purine dNTPs was the opposite. However, under crowding conditions, the efficiency remained almost unchanged with varying preferences in each case. These results suggest that hydrogen bonding and base-stacking interactions could be perturbed by crowding conditions in the bulk solution and polymerase active center during transient base pairing before polymerization. This study highlights that unintended dNTP incorporation against unnatural nucleosides could be differentiated in cases of intracellular reactions.
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Affiliation(s)
- Shuntaro Takahashi
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan;
| | - Piet Herdwijn
- Medicinal Chemistry, KU Leuven, Rega Institute for Medical Research, Herestraat 49-box 1041, 3000 Leuven, Belgium;
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan;
- Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 7-1-20 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
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32
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Palermo G, Bonvin AMJJ, Dal Peraro M, Amaro RE, Tozzini V. Editorial: Multiscale Modeling From Macromolecules to Cell: Opportunities and Challenges of Biomolecular Simulations. Front Mol Biosci 2020; 7:194. [PMID: 33005628 PMCID: PMC7484804 DOI: 10.3389/fmolb.2020.00194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 07/21/2020] [Indexed: 01/29/2023] Open
Affiliation(s)
- Giulia Palermo
- Departments of Bioengineering and Chemistry, University of California, Riverside, Riverside, CA, United States
| | - Alexandre M. J. J. Bonvin
- Faculty of Science - Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Matteo Dal Peraro
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fdédérale de Lausanne, Lausanne, Switzerland
| | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Valentina Tozzini
- Istituto Nanoscienze, CNR, Pisa, Italy
- Lab NEST, Scuola Normale Superiore, Pisa, Italy
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33
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Nolan V, Collin A, Rodriguez C, Perillo MA. Effect of Polyethylene Glycol-Induced Molecular Crowding on the Enzymatic Activity and Thermal Stability of β-Galactosidase from Kluyveromyces lactis. J Agric Food Chem 2020; 68:8875-8882. [PMID: 32686401 DOI: 10.1021/acs.jafc.0c02316] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Here, we report the effect of polyethylene glycol (PEG6000)-induced molecular crowding (MC) on the catalytic activity and thermal stability of Kluyveromyces lactis β-galactosidase (β-Gal). The β-Gal-catalyzed hydrolysis of o-nitrophenyl-β-d-galactopyranoside followed a Michaelian kinetics at [PEG6000] ≤ 25% w/v and positive cooperativity at higher concentrations (35% w/v PEG6000). Compared with dilute solutions, in the MC media, β-Gal exhibited stronger thermal stability, as shown by the increase in the residual activity recovered after preincubation at high temperatures (e.g., 45 °C) and by the slower inactivation kinetics. Considering the effects of water thermodynamic activity on the reaction kinetics and protein structure and the effect of the exclusion volume on protein conformation, we suggest that changes in the protein oligomerization state and hydration could be the responsible for the behavior observed at the highest MC levels assayed. These results could be relevant and should be taken into account in industrial food processes applying β-Gal from K. lactis.
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Affiliation(s)
- Verónica Nolan
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Fı́sicas y Naturales. ICTA and Departamento de Quı́mica, Cátedra de Quı́mica Biológica, Avenue Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET-Universidad Nacional de Córdoba, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), 5016 Córdoba, Argentina
| | - Alejandro Collin
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Fı́sicas y Naturales. ICTA and Departamento de Quı́mica, Cátedra de Quı́mica Biológica, Avenue Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET-Universidad Nacional de Córdoba, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), 5016 Córdoba, Argentina
| | - Carolina Rodriguez
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Fı́sicas y Naturales. ICTA and Departamento de Quı́mica, Cátedra de Quı́mica Biológica, Avenue Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET-Universidad Nacional de Córdoba, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), 5016 Córdoba, Argentina
| | - María A Perillo
- Universidad Nacional de Córdoba, Facultad de Ciencias Exactas, Fı́sicas y Naturales. ICTA and Departamento de Quı́mica, Cátedra de Quı́mica Biológica, Avenue Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET-Universidad Nacional de Córdoba, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), 5016 Córdoba, Argentina
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34
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Chitara D, Anand R, Sanjeev BS. Molecular crowding and conserved interface interactions of human argonaute protein-miRNA-target mRNA complex. J Biomol Struct Dyn 2020; 39:6370-6383. [PMID: 32752954 DOI: 10.1080/07391102.2020.1800511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
RNA interference (RNAi) has been of interest given its role in genetic interference. More significantly, recent studies provided evidence of it being one of the antiviral response mechanisms in humans. Argonaute (Ago) protein plays a central role in the RNA-induced silencing complex (RISC) that cleaves mRNA. Molecular crowding in cellular systems is known to impact dynamics and interactions of biomolecules. We present here the results from our molecular dynamics simulations based study on the interfaces between Ago, miRNA and Target RNA in presence of molecular crowders. 6 simulations at 3 crowder concentrations, including the aqueous condition, were performed. Our results indicate that crowding changes the dynamics, makes the complex stabler and aids binding free energy. More importantly, features conserved across the three systems and amino acid residues with crowding resilient interactions with RNA are identified.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Dheeraj Chitara
- Department of Applied Sciences, Indian Institute of Information Technology, Allahabad, India
| | - Richa Anand
- Department of Applied Sciences, Indian Institute of Information Technology, Allahabad, India
| | - B S Sanjeev
- Department of Applied Sciences, Indian Institute of Information Technology, Allahabad, India
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35
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Chakraborty S, Mahamid J, Baumeister W. Cryoelectron Tomography Reveals Nanoscale Organization of the Cytoskeleton and Its Relation to Microtubule Curvature Inside Cells. Structure 2020; 28:991-1003.e4. [PMID: 32579947 DOI: 10.1016/j.str.2020.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 04/24/2020] [Accepted: 05/27/2020] [Indexed: 11/19/2022]
Abstract
Microtubules (MTs) are the most rigid elements of the cytoskeleton with in vitro persistence lengths (Lp) in the range of 1-6 mm. In cellular environments, however, MTs often appear strongly curved. This has been attributed to the forces acting upon them in situ where they are embedded in composite networks of different cytoskeletal elements. Hitherto, the nanoscale organization of these networks has remained largely uncharacterized. Cryo-electron tomography (cryo-ET) allowed to visualize and analyze the in situ structure of cytoskeletal networks in pristinely preserved cellular environments and at high resolution. Here, we studied the molecular organization of MTs and their interactions with the composite cytoskeleton in frozen-hydrated HeLa and P19 cells at different cell-cycle stages. We describe modulation of MT curvature correlated with the surrounding molecular architecture, and show that nanoscale defects occur in curved MTs. The data presented here contribute to constructing realistic models of cytoskeletal biomechanics.
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Affiliation(s)
- Saikat Chakraborty
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Julia Mahamid
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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36
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Ghosh S, Takahashi S, Ohyama T, Endoh T, Tateishi-Karimata H, Sugimoto N. Nearest-neighbor parameters for predicting DNA duplex stability in diverse molecular crowding conditions. Proc Natl Acad Sci U S A 2020; 117:14194-201. [PMID: 32522884 DOI: 10.1073/pnas.1920886117] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The intracellular environment is crowded and heterogeneous. Although the thermodynamic stability of nucleic acid duplexes is predictable in dilute solutions, methods of predicting such stability under specific intracellular conditions are not yet available. We recently showed that the nearest-neighbor model for self-complementary DNA is valid under molecular crowding condition of 40% polyethylene glycol with an average molecular weight of 200 (PEG 200) in 100 mM NaCl. Here, we determined nearest-neighbor parameters for DNA duplex formation under the same crowding condition to predict the thermodynamics of DNA duplexes in the intracellular environment. Preferential hydration of the nucleotides was found to be the key factor for nearest-neighbor parameters in the crowding condition. The determined parameters were shown to predict the thermodynamic parameters (∆H°, ∆S°, and ∆G°37) and melting temperatures (T m) of the DNA duplexes in the crowding condition with significant accuracy. Moreover, we proposed a general method for predicting the stability of short DNA duplexes in different cosolutes based on the relationship between duplex stability and the water activity of the cosolute solution. The method described herein would be valuable for investigating biological processes that occur under specific intracellular crowded conditions and for the application of DNA-based biotechnologies in crowded environments.
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37
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Rahman MS, Gulshan MA, Matsumura S, Ikawa Y. Polyethylene glycol molecular crowders enhance the catalytic ability of bimolecular bacterial RNase P ribozymes. Nucleosides Nucleotides Nucleic Acids 2020; 39:715-729. [PMID: 32039645 DOI: 10.1080/15257770.2019.1687909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The modular structure of bacterial ribonuclease P (RNase P) ribozymes, which recognize tertiary structures of precursor tRNAs (pre-tRNAs) to cleave their 5' leader sequence, can be dissected physically into the two structured domain RNAs (S-domain and C-domain). Separately prepared S-domain RNA and C-domain RNA assemble to form bimolecular forms of RNase P ribozymes. We analyzed the effects of polyethylene glycols (PEGs) on pre-tRNA cleavage catalyzed by bimolecular RNase P ribozymes to examine the effects of molecular crowding on the reaction. PEG molecular crowders significantly enhanced the activities of bimolecular RNase P ribozymes, some of which were hardly active without PEGs.
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Affiliation(s)
- Md Sohanur Rahman
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Mst Ara Gulshan
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Shigeyoshi Matsumura
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Yoshiya Ikawa
- Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.,Graduate School of Innovative Life Science, University of Toyama, Gofuku 3190, Toyama, Japan
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38
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Abstract
Cell density shows very little variation within a given cell type. For example, in humans variability in cell density among cells of a given cell type is 100 times smaller than variation in cell mass. This tight control indicates that maintenance of a cell type-specific cell density is important for cell function. Indeed, pathological conditions such as cellular senescence are accompanied by changes in cell density. Despite the apparent importance of cell-type-specific density, we know little about how cell density affects cell function, how it is controlled, and how it sometimes changes as part of a developmental process or in response to changes in the environment. The recent development of new technologies to accurately measure the cell density of single cells in suspension and in tissues is likely to provide answers to these important questions.
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39
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Teng Y, Tateishi-Karimata H, Ohyama T, Sugimoto N. Effect of Potassium Concentration on Triplex Stability under Molecular Crowding Conditions. Molecules 2020; 25:E387. [PMID: 31963464 DOI: 10.3390/molecules25020387] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 11/30/2022] Open
Abstract
The properties of non-canonical DNA structures, like G-quadruplexes and triplexes, change under cell-mimicking molecular crowding conditions relative to dilute aqueous solutions. The analysis of environmental effects on their stability is crucial since they play important roles in gene expression and regulation. In this study, three intramolecular and intermolecular triplex-forming sequences of different C+*G-C triplet content (*: Hoogsteen base pair; - : Watson–Crick base pair) were designed and their stability measured in the absence and presence of a crowding agent with different K+ concentrations. In dilute solution, the stability of the triplexes was reduced by decreasing the concentration of KCl. This reduction became smaller as the number of C+*G-C triplets increased. Under molecular crowding conditions, Watson–Crick base pairs and Hoogsteen base pairs were destabilized and stabilized, respectively. Interestingly, with lower KCl concentrations (≤1 M), the destabilization of the triplexes due to reduction of KCl concentration was significantly smaller than in dilute solutions. In addition, the C+*G-C content had greater influence on triplex stability under molecular crowding conditions. Our work provides quantitative information about the effects of K+ concentration on triplex stability under molecular crowding conditions and should further our understanding of the function and regulation of triplexes in bioprocesses.
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Garenne D, Libchaber A, Noireaux V. Membrane molecular crowding enhances MreB polymerization to shape synthetic cells from spheres to rods. Proc Natl Acad Sci U S A 2020; 117:1902-9. [PMID: 31932440 DOI: 10.1073/pnas.1914656117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Executing gene circuits by cell-free transcription-translation into cell-sized compartments, such as liposomes, is one of the major bottom-up approaches to building minimal cells. The dynamic synthesis and proper self-assembly of macromolecular structures inside liposomes, the cytoskeleton in particular, stands as a central limitation to the development of cell analogs genetically programmed. In this work, we express the Escherichia coli gene mreB inside vesicles with bilayers made of lipid-polyethylene glycol (PEG). We demonstrate that two-dimensional molecular crowding, emulated by the PEG molecules at the lipid bilayer, is enough to promote the polymerization of the protein MreB at the inner membrane into a sturdy cytoskeleton capable of transforming spherical liposomes into elongated shapes, such as rod-like compartments. We quantitatively describe this mechanism with respect to the size of liposomes, lipid composition of the membrane, crowding at the membrane, and strength of MreB synthesis. So far unexplored, molecular crowding at the surface of synthetic cells emerges as an additional development with potential broad applications. The symmetry breaking observed could be an important step toward compartment self-reproduction.
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41
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Ge X, Xu J. Macro molecular crowding effects on transcription and translation are regulated by free magnesium ion. Biotechnol Appl Biochem 2019; 67:117-122. [PMID: 31576614 DOI: 10.1002/bab.1827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/28/2019] [Indexed: 12/21/2022]
Abstract
Cell-free metabolic engineering is an emerging and promising alternative platform for the production of fuels and chemicals. In recent years, macromolecular crowding effect, which is an important function in living cells but ignored in cell-free systems, has been transferred to cell-free protein synthesis (CFPS). However, inhibitory effects of crowding agents on CFPS were frequently observed, and the mechanism is unclear. In this study, free Mg2+ was found to be a key factor that can regulate the macromolecular crowding effect on in vitro transcription, in vitro translation, and coupled transcript/translation. Addition of crowding agents (20% of Ficoll-70 or Ficoll-400) enhanced in vitro transcription at an index of free Mg2+ concentration (IFMC) below 2 mM but inhibited the transcription when the IFMC was higher than 2 mM. Similarly, Ficoll-400 enhanced in vitro translation and coupled transcription/translation at a lower IFMC (0.1-2 mM) and inhibited the reactions at higher IFMC (>2 mM). Based on the results, CFPS systems could be further optimized by adjusting the content of crowding agents and the IFMC. Besides, the results also indicate that macromolecular crowding effect is important for maintaining the efficiency of in vivo transcription and translation which occur at a low intracellular IFMC (<1 mM).
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Affiliation(s)
- Xumeng Ge
- Arkansas Biosciences Institute and College of Agriculture and Technology, Arkansas State University, Jonesboro, AR, USA.,Quasar Energy Group, Independence, OH, USA
| | - Jianfeng Xu
- Arkansas Biosciences Institute and College of Agriculture and Technology, Arkansas State University, Jonesboro, AR, USA
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42
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Stalla D, Akkaladevi N, White TA, Hazelbauer GL. Spatial Restrictions in Chemotaxis Signaling Arrays: A Role for Chemoreceptor Flexible Hinges across Bacterial Diversity. Int J Mol Sci 2019; 20:ijms20122989. [PMID: 31248079 PMCID: PMC6628036 DOI: 10.3390/ijms20122989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 06/15/2019] [Accepted: 06/17/2019] [Indexed: 01/02/2023] Open
Abstract
The chemotactic sensory system enables motile bacteria to move toward favorable environments. Throughout bacterial diversity, the chemoreceptors that mediate chemotaxis are clustered into densely packed arrays of signaling complexes. In these arrays, rod-shaped receptors are in close proximity, resulting in limited options for orientations. A recent geometric analysis of these limitations in Escherichia coli, using published dimensions and angles, revealed that in this species, straight chemoreceptors would not fit into the available space, but receptors bent at one or both of the recently-documented flexible hinges would fit, albeit over a narrow window of shallow bend angles. We have now expanded our geometric analysis to consider variations in receptor length, orientation and placement, and thus to species in which those parameters are known to be, or might be, different, as well as to the possibility of dynamic variation in those parameters. The results identified significant limitations on the allowed combinations of chemoreceptor dimensions, orientations and placement. For most combinations, these limitations excluded straight chemoreceptors, but allowed receptors bent at a flexible hinge. Thus, our analysis identifies across bacterial diversity a crucial role for chemoreceptor flexible hinges, in accommodating the limitations of molecular crowding in chemotaxis core signaling complexes and their arrays.
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Affiliation(s)
- David Stalla
- Electron Microscopy Core Facility, W117 Veterinary Medicine Building, 1600 East Rollins St., University of Missouri, Columbia, MO 65211, USA.
| | - Narahari Akkaladevi
- Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, MO 65211, USA.
| | - Tommi A White
- Electron Microscopy Core Facility, W117 Veterinary Medicine Building, 1600 East Rollins St., University of Missouri, Columbia, MO 65211, USA.
- Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, MO 65211, USA.
| | - Gerald L Hazelbauer
- Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, MO 65211, USA.
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Arrabito G, Cavaleri F, Porchetta A, Ricci F, Vetri V, Leone M, Pignataro B. Printing Life-Inspired Subcellular Scale Compartments with Autonomous Molecularly Crowded Confinement. ACTA ACUST UNITED AC 2019; 3:e1900023. [PMID: 32648672 DOI: 10.1002/adbi.201900023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/03/2019] [Indexed: 12/16/2022]
Abstract
A simple, rapid, and highly controlled platform to prepare life-inspired subcellular scale compartments by inkjet printing has been developed. These compartments consist of fL-scale aqueous droplets (few µm in diameter) incorporating biologically relevant molecular entities with programmed composition and concentration. These droplets are ink-jetted in nL mineral oil drop arrays allowing for lab-on-chip studies by fluorescence microscopy and fluorescence life time imaging. Once formed, fL-droplets are stable for several hours, thus giving the possibility of readily analyze molecular reactions and their kinetics and to verify molecular behavior and intermolecular interactions. Here, this platform is exploited to unravel the behavior of different molecular probes and biomolecular systems (DNA hairpins, enzymatic cascades, protein-ligand couples) within the compartments. The fL-scale size induces the formation of molecularly crowded confined shell structures (hundreds of nanometers in thickness) at the droplet surface, allowing discovery of specific features (e.g., heterogeneity, responsivity to molecular triggers) that are mediated by the intermolecular interactions in these peculiar environments. The presented results indicate the possibility of using this platform for designing nature-inspired confined reactors allowing for a deepened understanding of molecular confinement effects in living subcellular compartments.
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Affiliation(s)
- Giuseppe Arrabito
- Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Parco d'Orleans II, 90128, Palermo, Italy
| | - Felicia Cavaleri
- Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Parco d'Orleans II, 90128, Palermo, Italy
| | - Alessandro Porchetta
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Francesco Ricci
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Valeria Vetri
- Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Parco d'Orleans II, 90128, Palermo, Italy
| | - Maurizio Leone
- Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Parco d'Orleans II, 90128, Palermo, Italy
| | - Bruno Pignataro
- Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Parco d'Orleans II, 90128, Palermo, Italy
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Abstract
Molecular crowding is receiving great attention in cell-free synthetic biology because molecular crowding is a critical feature of natural cell discrimination from artificial cells. Further, it has significant and generic influences on biomolecular functions. Although there are reports on how the macromolecular crowder reagents affect cell-free systems such as transcription and translation, the second class of molecular crowder reagents with low molecular weight, osmolyte, was much less studied in cell-free systems. In the present study, we focused on trimethylamine- N-oxide (TMAO) and betaine, methylamine osmolytes, and investigated the effectiveness of these osmolytes on gene expression activity of reconstituted cell-free protein synthesis. The gene expression activity of the fluorescent proteins Venus and tdTomato and the enzymes β-galactosidase and dihydrofolate reductase were tested. At 37 °C, 0.4 M TMAO showed the highest enhancement of translational activity by a factor of 1.6-3.8, regardless of protein type. In contrast, betaine showed only a moderate effect that was limited to fluorescent proteins. Excess amounts of osmolytes suppressed gene expression activity. An mRNA-start assay and SDS-PAGE quantitative analysis provided firm evidence that TMAO enhances the translation process, instead of transcription, folding, or the maturation of fluorescent proteins. Interestingly, at 26 °C, TMAO and betaine showed the highest enhancement of protein synthesis activity at lower concentrations than at 37 °C. These findings provide implications on how osmolytes assist translation in natural cells. Further, they provide guidelines for modulation of protein synthesis activity in artificial cells through osmolyte addition.
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Affiliation(s)
- Yoshiki Moriizumi
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kazuhito V. Tabata
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Daisuke Miyoshi
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST) and Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 7-1-20 minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Hiroyuki Noji
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Abstract
In all intracellular processes, protein structure and dynamics are subject to the influence of macromolecular crowding (MC). Here, the impact of MC agents of different types and sizes on the model protein Bacillus subtilis Cold shock protein B (BsCspB) during both thermal and chemical denaturation have been comprehensively investigated. We consistently reveal a distinct stabilization of BsCspB in a manner dependent on the MC concentration but not on viscosity, polarity, or size of the MC agent used. This general stabilization has been decoded by use of NMR spectroscopy, through monitoring of chemical shift (CS) perturbations and the intramolecular hydrogen‐bonding networks, as well as local protection of amide protons against exchange with solvent protons. Whereas CSs and hydrogen‐bonding networks are not systematically affected in the presence of MC, we detected a pronounced reduction in exchange in loop regions of BsCspB. We conclude that this reduced accessibility of solvent protons is a key parameter for the increases in protein stability seen under MC.
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Affiliation(s)
- Birgit Köhn
- Fachbereich Chemie, Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.,Research School Chemical Biology (KoRS-CB), Universität Konstanz, Universitätsstrassee 10, 78457, Konstanz, Germany
| | - Michael Kovermann
- Fachbereich Chemie, Universität Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.,Research School Chemical Biology (KoRS-CB), Universität Konstanz, Universitätsstrassee 10, 78457, Konstanz, Germany
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Kai L, Schwille P. Cell-Free Protein Synthesis and Its Perspectives for Assembling Cells from the Bottom-Up. ACTA ACUST UNITED AC 2019; 3:e1800322. [PMID: 32648712 DOI: 10.1002/adbi.201800322] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/14/2019] [Indexed: 12/20/2022]
Abstract
The underlying idea of synthetic biology is that biological reactions/modules/systems can be precisely engineered and controlled toward desired products. Numerous efforts in the past decades in deciphering the complexity of biological systems in vivo have led to a variety of tools for synthetic biology, especially based on recombinant DNA. However, one generic limitation of all living systems is that the vast majority of energy input is dedicated to maintain the system as a whole, rather than the small part of interest. Cell-free synthetic biology is aiming at exactly this fundamental limitation, providing the next level of flexibility for engineering and designing biological systems in vitro. New technology has continuously inspired cell-free biology and extended its applications, including gene circuits, spatiotemporally controlled pathways, coactivated catalysts systems, and rationally designed multienzyme pathways, in particular, minimal cell construction. In the context of this special issue, discussing work being carried out in the "MaxSynBio" consortium, the advances in characterizing stochasticity and dynamics of cell-free protein synthesis within cell-sized compartments, as well as the molecular crowding effect, are discussed. The organization of spatial heterogeneity is the key prerequisite for achieving hierarchy and stepwise assembly of minimal cells from the bottom-up.
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Affiliation(s)
- Lei Kai
- School of Life Sciences, Jiangsu Normal University, Shanghai Road 101, 221116, Xuzhou, P. R. China.,Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152, Martinsried, Germany
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152, Martinsried, Germany
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Kojima T, Lin CC, Takayama S, Fan SK. Determination of Aqueous Two-Phase System Binodals and Tie-Lines by Electrowetting-on-Dielectric Droplet Manipulation. Chembiochem 2019; 20:270-275. [PMID: 30394637 DOI: 10.1002/cbic.201800553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Indexed: 01/12/2023]
Abstract
Handling the aqueous two-phase systems (ATPSs) formed by liquid-liquid phase separation (LLPS) relies on the accurate construction of binodal curves and tie-lines, which delineate the polymer concentrations required for phase separation and depict the properties of the resulting phases, respectively. Various techniques to determine the binodal curves and tie-lines of ATPSs exist, but most rely on manually pipetting relatively large volumes of fluids in a slow and tedious manner. We describe a method to determine ATPS binodals and tie-lines that overcomes these disadvantages: microscale droplet manipulation by electrowetting-on-dielectric (EWOD). EWOD enables automated handling of droplets in an optically transparent platform that allows for in situ droplet observation. Separated phases are clearly visible, and the volumes of each phase are readily determined. Additionally, in considering the molecular crowding present in living cells, this work examines the role of a macromolecule in prompting LLPS. These results show that EWOD-driven droplet manipulation effectively interrogates the phase dynamics of ATPSs and macromolecular crowding in LLPS.
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Affiliation(s)
- Taisuke Kojima
- The Wallace H. Coulter Department of Biomedical Engineering and, Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology and Emory School of Medicine, 950 Atlantic Drive, Atalanta, NW, 30332, USA
| | - Chu-Chi Lin
- Department of Mechanical Engineering, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
| | - Shuichi Takayama
- The Wallace H. Coulter Department of Biomedical Engineering and, Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology and Emory School of Medicine, 950 Atlantic Drive, Atalanta, NW, 30332, USA
| | - Shih-Kang Fan
- Department of Mechanical Engineering, National Taiwan University, No.1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
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48
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Abstract
Unlike in vivo conditions, group II intron ribozymes are known to require high magnesium(II) concentrations ([Mg2+]) and high temperatures (42 °C) for folding and catalysis in vitro. A possible explanation for this difference is the highly crowded cellular environment, which can be mimicked in vitro by macromolecular crowding agents. Here, we combined bulk activity assays and single-molecule Förster Resonance Energy Transfer (smFRET) to study the influence of polyethylene glycol (PEG) on catalysis and folding of the ribozyme. Our activity studies reveal that PEG reduces the [Mg2+] required, and we found an "optimum" [PEG] that yields maximum activity. smFRET experiments show that the most compact state population, the putative active state, increases with increasing [PEG]. Dynamic transitions between folded states also increase. Therefore, this study shows that optimal molecular crowding concentrations help the ribozyme not only to reach the native fold but also to increase its in vitro activity to approach that in physiological conditions.
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Affiliation(s)
- Bishnu P Paudel
- Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
- Single Molecule Imaging, Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
| | - Erica Fiorini
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Richard Börner
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - David S Rueda
- Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom;
- Single Molecule Imaging, Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
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49
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Ding Y, Contreras-Llano LE, Morris E, Mao M, Tan C. Minimizing Context Dependency of Gene Networks Using Artificial Cells. ACS Appl Mater Interfaces 2018; 10:30137-30146. [PMID: 30113814 DOI: 10.1021/acsami.8b10029] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The functioning of synthetic gene circuits depends on their local chemical context defined by the types and concentrations of biomolecules in the surrounding milieu that influences gene transcription and translation. This chemical-context dependence of synthetic gene circuits arises from significant yet unknown cross talk between engineered components, host cells, and environmental factors and has been a persistent challenge for synthetic biology. Here, we show that the sensitivity of synthetic gene networks to their extracellular chemical contexts can be minimized, and their designed functions rendered robust using artificial cells, which are synthetic biomolecular compartments engineered from the bottom-up using liposomes that encapsulate the gene networks. Our artificial cells detect, interact with, and kill bacteria in simulated external environments with different chemical complexity. Our work enables the engineering of synthetic gene networks with minimal dependency on their extracellular chemical context and creates a new frontier in controlling robustness of synthetic biological systems using bioinspired mechanisms.
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Affiliation(s)
- Yunfeng Ding
- Department of Biomedical Engineering , University of California Davis , Davis 95616 , California , United States
| | - Luis E Contreras-Llano
- Department of Biomedical Engineering , University of California Davis , Davis 95616 , California , United States
| | - Eliza Morris
- Department of Biomedical Engineering , University of California Davis , Davis 95616 , California , United States
| | - Michelle Mao
- Department of Biomedical Engineering , University of California Davis , Davis 95616 , California , United States
| | - Cheemeng Tan
- Department of Biomedical Engineering , University of California Davis , Davis 95616 , California , United States
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50
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Leake MC. Transcription factors in eukaryotic cells can functionally regulate gene expression by acting in oligomeric assemblies formed from an intrinsically disordered protein phase transition enabled by molecular crowding. Transcription 2018; 9:298-306. [PMID: 29895219 PMCID: PMC6150617 DOI: 10.1080/21541264.2018.1475806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
High-speed single-molecule fluorescence microscopy in vivo shows that transcription factors in eukaryotes can act in oligomeric clusters mediated by molecular crowding and intrinsically disordered protein. This finding impacts on the longstanding puzzle of how transcription factors find their gene targets so efficiently in the complex, heterogeneous environment of the cell. Abbreviations CDF - cumulative distribution function; FRAP - fluorescence recovery after photobleaching; GFP - Green fluorescent protein; STORM - stochastic optical reconstruction microscopy; TF - Transcription factor; YFP - Yellow fluorescent protein
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Affiliation(s)
- Mark C Leake
- a Departments of Physics and Biology , Biological Physical Sciences Institute, University of York , York , UK
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