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Ghosh S, Prabhu NP. Heterogeneous Macromolecular crowding effect on nucleation-independent fibril formation of Lysozyme: Spectroscopic analysis of Structure, Stability, and fibrillation rate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 315:124276. [PMID: 38626673 DOI: 10.1016/j.saa.2024.124276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/18/2024]
Affiliation(s)
- Subhasree Ghosh
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - N Prakash Prabhu
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
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2
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Chang CW, Dargaville BL, Momot KI, Hutmacher DW. An investigation of water status in gelatin methacrylate hydrogels by means of water relaxometry and differential scanning calorimetry. J Mater Chem B 2024; 12:6328-6341. [PMID: 38628083 DOI: 10.1039/d4tb00053f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
The relationship between molecular structure and water dynamics is a fundamental yet often neglected subject in the field of hydrogels for drug delivery, bioprinting, as well as biomaterial science and tissue engineering & regenerative medicine (TE&RM). Water is a fundamental constituent of hydrogel systems and engages via hydrogen bonding with the macromolecular network. The methods and techniques to measure and reveal the phenomena and dynamics of water within hydrogels are still limited. In this work, differential scanning calorimetry (DSC) was used as a quantitative method to analyze freezable (including free and freezable bound) and non-freezable bound water within gelatin methacrylate (GelMA) hydrogels. Nuclear magnetic resonance (NMR) is a complementary method for the study of water behavior and can be used to measure the spin-relaxation of water hydrogen nuclei, which is related to water dynamics. In this research, nuclear magnetic resonance relaxometry was employed to investigate the molecular state of water in GelMA hydrogels using spin-lattice (T1) and spin-spin (T2) spin-relaxation time constants. The data displays a trend of increasing bound water content with increasing GelMA concentration. In addition, T2 values were further applied to calculate microviscosity and translational diffusion coefficients. Water relaxation under various chemical environments, including different media, temperatures, gelatin sources, as well as crosslinking effects, were also examined. These comprehensive physical data sets offer fundamental insight into biomolecule transport within the GelMA hydrogel system, which ultimately are important for drug delivery, bioprinting, as well as biomaterial science and TE&RM communities.
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Affiliation(s)
- Chun-Wei Chang
- Max Planck Queensland Centre on the Materials Science for Extracellular Matrices, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
- School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology (QUT), QLD 4059, Australia
| | - Bronwin L Dargaville
- Max Planck Queensland Centre on the Materials Science for Extracellular Matrices, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
- School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology (QUT), QLD 4059, Australia
| | - Konstantin I Momot
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4001, Australia
| | - Dietmar W Hutmacher
- Max Planck Queensland Centre on the Materials Science for Extracellular Matrices, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
- School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology (QUT), QLD 4059, Australia
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3
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Collette D, Dunlap D, Finzi L. Macromolecular Crowding and DNA: Bridging the Gap between In Vitro and In Vivo. Int J Mol Sci 2023; 24:17502. [PMID: 38139331 PMCID: PMC10744201 DOI: 10.3390/ijms242417502] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/29/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
The cellular environment is highly crowded, with up to 40% of the volume fraction of the cell occupied by various macromolecules. Most laboratory experiments take place in dilute buffer solutions; by adding various synthetic or organic macromolecules, researchers have begun to bridge the gap between in vitro and in vivo measurements. This is a review of the reported effects of macromolecular crowding on the compaction and extension of DNA, the effect of macromolecular crowding on DNA kinetics, and protein-DNA interactions. Theoretical models related to macromolecular crowding and DNA are briefly reviewed. Gaps in the literature, including the use of biologically relevant crowders, simultaneous use of multi-sized crowders, empirical connections between macromolecular crowding and liquid-liquid phase separation of nucleic materials are discussed.
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Affiliation(s)
| | | | - Laura Finzi
- Department of Physics, College of Arts & Sciences, Emory University, Atlanta, GA 30322, USA; (D.C.); (D.D.)
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4
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Kitamura A, Oasa S, Kawaguchi H, Osaka M, Vukojević V, Kinjo M. Increased intracellular crowding during hyperosmotic stress. Sci Rep 2023; 13:11834. [PMID: 37481632 PMCID: PMC10363123 DOI: 10.1038/s41598-023-39090-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/20/2023] [Indexed: 07/24/2023] Open
Abstract
Hyperosmotic stress activates in live cells numerous processes and also promotes intracellular protein/RNA aggregation and phase separation. However, the time course and the extent of these changes remain largely uncharacterized. To investigate dynamic changes in intracellular macromolecular crowding (MMC) induced by hyperosmotic stress in live cells, we used fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy (FCS) to quantify changes in the local environment by measuring the fluorescence lifetime and the diffusion of the monomeric enhanced green fluorescent protein (eGFP), respectively. Real-time monitoring of eGFP fluorescence lifetime showed that a faster response to environmental changes due to MMC is observed than when measuring the acceptor/donor emission ratio using the MMC-sensitive Förster resonance energy transfer sensor (GimRET). This suggests that eGFP molecular electronic states and/or collision frequency are affected by changes in the immediate surroundings due to MMC without requiring conformational changes as is the case for the GimRET sensor. Furthermore, eGFP diffusion assessed by FCS indicated higher intracellular viscosity due to increased MMC during hyperosmotic stress. Our findings reveal that changes in eGFP fluorescence lifetime and diffusion are early indicators of elevated intracellular MMC. Our approach can therefore be used to reveal in live cells short-lived transient states through which MMC builds over time, which could not be observed when measuring changes in other physical properties that occur at slower time scales.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
| | - Sho Oasa
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176, Stockholm, Sweden
| | - Haruka Kawaguchi
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Misato Osaka
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Vladana Vukojević
- Department of Clinical Neuroscience (CNS), Center for Molecular Medicine (CMM), Karolinska Institutet, 17176, Stockholm, Sweden
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
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5
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Demosthene B, Lee M, Marracino RR, Heidings JB, Kang EH. Molecular Basis for Actin Polymerization Kinetics Modulated by Solution Crowding. Biomolecules 2023; 13:biom13050786. [PMID: 37238656 DOI: 10.3390/biom13050786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Actin polymerization drives cell movement and provides cells with structural integrity. Intracellular environments contain high concentrations of solutes, including organic compounds, macromolecules, and proteins. Macromolecular crowding has been shown to affect actin filament stability and bulk polymerization kinetics. However, the molecular mechanisms behind how crowding influences individual actin filament assembly are not well understood. In this study, we investigated how crowding modulates filament assembly kinetics using total internal reflection fluorescence (TIRF) microscopy imaging and pyrene fluorescence assays. The elongation rates of individual actin filaments analyzed from TIRF imaging depended on the type of crowding agent (polyethylene glycol, bovine serum albumin, and sucrose) as well as their concentrations. Further, we utilized all-atom molecular dynamics (MD) simulations to evaluate the effects of crowding molecules on the diffusion of actin monomers during filament assembly. Taken together, our data suggest that solution crowding can regulate actin assembly kinetics at the molecular level.
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Affiliation(s)
- Bryan Demosthene
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL 32827, USA
| | - Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA
| | - Ryan R Marracino
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL 32827, USA
| | - James B Heidings
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL 32827, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA
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6
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Role of the Two Flagellar Stators in Swimming Motility of Pseudomonas putida. mBio 2022; 13:e0218222. [PMID: 36409076 PMCID: PMC9765564 DOI: 10.1128/mbio.02182-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In the soil bacterium Pseudomonas putida, the motor torque for flagellar rotation is generated by the two stators MotAB and MotCD. Here, we construct mutant strains in which one or both stators are knocked out and investigate their swimming motility in fluids of different viscosity and in heterogeneous structured environments (semisolid agar). Besides phase-contrast imaging of single-cell trajectories and spreading cultures, dual-color fluorescence microscopy allows us to quantify the role of the stators in enabling P. putida's three different swimming modes, where the flagellar bundle pushes, pulls, or wraps around the cell body. The MotAB stator is essential for swimming motility in liquids, while spreading in semisolid agar is not affected. Moreover, if the MotAB stator is knocked out, wrapped mode formation under low-viscosity conditions is strongly impaired and only partly restored for increased viscosity and in semisolid agar. In contrast, when the MotCD stator is missing, cells are indistinguishable from the wild type in fluid experiments but spread much more slowly in semisolid agar. Analysis of the microscopic trajectories reveals that the MotCD knockout strain forms sessile clusters, thereby reducing the number of motile cells, while the swimming speed is unaffected. Together, both stators ensure a robust wild type that swims efficiently under different environmental conditions. IMPORTANCE Because of its heterogeneous habitat, the soil bacterium Pseudomonas putida needs to swim efficiently under very different environmental conditions. In this paper, we knocked out the stators MotAB and MotCD to investigate their impact on the swimming motility of P. putida. While the MotAB stator is crucial for swimming in fluids, in semisolid agar, both stators are sufficient to sustain a fast-swimming phenotype and increased frequencies of the wrapped mode, which is known to be beneficial for escaping mechanical traps. However, in contrast to the MotAB knockout, a culture of MotCD knockout cells spreads much more slowly in the agar, as it forms nonmotile clusters that reduce the number of motile cells.
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7
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Miescher I, Wolint P, Opelz C, Snedeker JG, Giovanoli P, Calcagni M, Buschmann J. Impact of High-Molecular-Weight Hyaluronic Acid on Gene Expression in Rabbit Achilles Tenocytes In Vitro. Int J Mol Sci 2022; 23:ijms23147926. [PMID: 35887273 PMCID: PMC9320370 DOI: 10.3390/ijms23147926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 11/17/2022] Open
Abstract
(1) Background: Surgical tendon repair often leads to adhesion formation, leading to joint stiffness and a reduced range of motion. Tubular implants set around sutured tendons might help to reduce peritendinous adhesions. The lubricant hyaluronic acid (HA) is a viable option for optimizing such tubes with the goal of further enhancing the anti-adhesive effect. As the implant degrades over time and diffusion is presumed, the impact of HA on tendon cells is important to know. (2) Methods: A culture medium of rabbit Achilles tenocytes was supplemented with high-molecular-weight (HMW) HA and the growth curves of the cells were assessed. Additionally, after 3, 7 and 14 days, the gene expression of several markers was analyzed for matrix assembly, tendon differentiation, fibrosis, proliferation, matrix remodeling, pro-inflammation and resolution. (3) Results: The addition of HA decreased matrix marker genes, downregulated the fibrosis marker α-SMA for a short time and slightly increased the matrix-remodeling gene MMP-2. Of the pro-inflammatory marker genes, only IL-6 was significantly upregulated. IL-6 has to be kept in check, although IL-6 is also needed for a proper initial inflammation and efficient resolution. (4) Conclusions: The observed effects in vitro support the intended anti-adhesion effect and therefore, the use of HMW HA is promising as a biodegradable implant for tendon repair.
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Affiliation(s)
- Iris Miescher
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
| | - Petra Wolint
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
| | - Christine Opelz
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
| | - Jess G. Snedeker
- Orthopaedic Biomechanics, University Clinic Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland;
| | - Pietro Giovanoli
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
| | - Maurizio Calcagni
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
| | - Johanna Buschmann
- Division of Plastic Surgery and Hand Surgery, University Hospital Zurich, Sternwartstrasse 14, 8091 Zurich, Switzerland; (I.M.); (P.W.); (C.O.); (P.G.); (M.C.)
- Correspondence: ; Tel.: +41-44-255-98-95
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8
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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 (BASEL, SWITZERLAND) 2022; 27:molecules27072110. [PMID: 35408509 PMCID: PMC9000840 DOI: 10.3390/molecules27072110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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9
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Basu M, Mishra PP. Kineto-Mechanistic Investigation of Effect of Macromolecular Crowding on the Breathing of DNA Bubble. J Phys Chem B 2022; 126:1375-1387. [PMID: 35143192 DOI: 10.1021/acs.jpcb.1c08206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macromolecular crowding along with hydrogen bonding or stacking interactions and hydration reportedly has enormous repercussions on elementary biochemical processes, such as the folding of proteins or nucleic acids involving the stability of DNA base pairing. By using the mismatch-induced DNA bubble as a mesoscopic model, the complex interplay of macromolecular crowding on the dynamical fluctuations at the bubble region within the thermodynamic limit has been monitored using single-molecule fluorescence resonance energy transfer (sm-FRET). These single-molecule experimental results have been further corroborated using physical models such as "scaled particle theory" (SPT) and "Gaussian cloud model" (GCM), to predict the biological activity of DNA. The two-state fluctuation of the DNA bubble has been visualized as a function of the nature, size, and concentration of the crowder. The influence of crowders on the DNA conformation has been investigated with the help of the m-factor, the eccentricity, and the kinetic and thermodynamic parameters without any prior assumption. The clear effect of crowding on the dynamics of such a simple biomolecular system emphasizes the power of single-molecule methods and the dependency of the radius of gyration of the co-solute as well as the preferential interaction with the crowder on the distinct conformational states adopted by the bubble. This study provides an idea and hypothesizes the preferential propensity of the DNA bubble to adopt a conformation with the single-stranded domains being far apart, independent of the crowder size, that may be beneficial for efficient recognition by proteins for an uninterrupted procession of the biological process of the central dogma.
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Affiliation(s)
- Manali Basu
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.,Homi Bhaba National Institute, Mumbai, Maharashtra 400094, India
| | - Padmaja Prasad Mishra
- Single Molecule Biophysics Lab, Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.,Homi Bhaba National Institute, Mumbai, Maharashtra 400094, India
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10
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Dong X, Qin LY, Gong Z, Qin S, Zhou HX, Tang C. Preferential Interactions of a Crowder Protein with the Specific Binding Site of a Native Protein Complex. J Phys Chem Lett 2022; 13:792-800. [PMID: 35044179 PMCID: PMC8852806 DOI: 10.1021/acs.jpclett.1c03794] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nonspecific binding of crowder proteins with functional proteins is likely prevalent in vivo, yet direct quantitative evidence, let alone residue-specific information, is scarce. Here we present nuclear magnetic resonance (NMR) characterization showing that bovine serum albumin weakly but preferentially interacts with the histidine carrier protein (HPr). Notably, the binding interface overlaps with that for HPr's specific partner protein, EIN, leading to competition. The crowder protein thus decreases the EIN-HPr binding affinity and accelerates the dissociation of the native complex. In contrast, Ficoll-70 stabilizes the native complex and slows its dissociation, as one would expect from excluded-volume and microviscosity effects. Our atomistic modeling of macromolecular crowding rationalizes the experimental data and provides quantitative insights into the energetics of protein-crowder interactions. The integrated NMR and modeling study yields benchmarks for the effects of crowded cellular environments on protein-protein specific interactions, with implications for evolution regarding how nonspecific binding can be minimized or exploited.
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Affiliation(s)
- Xu Dong
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Ling-Yun Qin
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhou Gong
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
| | - Sanbo Qin
- Department of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States
| | - Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Chun Tang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
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11
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Park J, Kravchuk P, Krishnaprasad A, Roy T, Kang EH. Graphene Enhances Actin Filament Assembly Kinetics and Modulates NIH-3T3 Fibroblast Cell Spreading. Int J Mol Sci 2022; 23:509. [PMID: 35008935 PMCID: PMC8745492 DOI: 10.3390/ijms23010509] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 01/01/2023] Open
Abstract
Actin plays critical roles in various cellular functions, including cell morphogenesis, differentiation, and movement. The assembly of actin monomers into double-helical filaments is regulated in surrounding microenvironments. Graphene is an attractive nanomaterial that has been used in various biomaterial applications, such as drug delivery cargo and scaffold for cells, due to its unique physical and chemical properties. Although several studies have shown the potential effects of graphene on actin at the cellular level, the direct influence of graphene on actin filament dynamics has not been studied. Here, we investigate the effects of graphene on actin assembly kinetics using spectroscopy and total internal reflection fluorescence microscopy. We demonstrate that graphene enhances the rates of actin filament growth in a concentration-dependent manner. Furthermore, cell morphology and spreading are modulated in mouse embryo fibroblast NIH-3T3 cultured on a graphene surface without significantly affecting cell viability. Taken together, these results suggest that graphene may have a direct impact on actin cytoskeleton remodeling.
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Affiliation(s)
- Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA; (J.P.); (P.K.); (A.K.); (T.R.)
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Pavlo Kravchuk
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA; (J.P.); (P.K.); (A.K.); (T.R.)
| | - Adithi Krishnaprasad
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA; (J.P.); (P.K.); (A.K.); (T.R.)
- Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Tania Roy
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA; (J.P.); (P.K.); (A.K.); (T.R.)
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA
- Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL 32826, USA; (J.P.); (P.K.); (A.K.); (T.R.)
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816, USA
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
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12
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Molecular diffusion in ternary poly(vinyl alcohol) solutions. Front Chem Sci Eng 2021. [DOI: 10.1007/s11705-021-2121-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractThe diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering. We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species. The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration, but significantly slows down the diffusion of rhodamine B above 3.9% (w/v) due to a dominating steric inhibition effect. Furthermore, introducing surfactants (cationic/nonionic/anionic) to the system results in a decreased diffusion coefficient of the molecular probe. In solutions containing nonionic surfactant, this can be explained by an increased crowding effect. For ternary poly(vinyl alcohol) solutions containing cationic or anionic surfactant, surfactant—polymer and surfactant—rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffusivity of rhodamine B. The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds, and highlight the importance of selecting the appropriate additives and surfactants in formulated products.
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13
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It is time to crowd your cell culture media - Physicochemical considerations with biological consequences. Biomaterials 2021; 275:120943. [PMID: 34139505 DOI: 10.1016/j.biomaterials.2021.120943] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 05/24/2021] [Accepted: 05/29/2021] [Indexed: 12/12/2022]
Abstract
In vivo, the interior and exterior of cells is populated by various macromolecules that create an extremely crowded milieu. Yet again, in vitro eukaryotic cell culture is conducted in dilute culture media that hardly imitate the native tissue density. Herein, the concept of macromolecular crowding is discussed in both intracellular and extracellular context. Particular emphasis is given on how the physicochemical properties of the crowding molecules govern and determine kinetics, equilibria and mechanism of action of biochemical and biological reactions, processes and functions. It is evidenced that we are still at the beginning of appreciating, let alone effectively implementing, the potential of macromolecular crowding in permanently differentiated and stem cell culture systems.
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14
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A biomimetic model of 3D fluid extracellular macromolecular crowding microenvironment fine-tunes ovarian cancer cells dissemination phenotype. Biomaterials 2020; 269:120610. [PMID: 33388691 DOI: 10.1016/j.biomaterials.2020.120610] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/21/2020] [Accepted: 12/14/2020] [Indexed: 12/15/2022]
Abstract
An early fundamental step in ovarian cancer progression is the dissemination of cancer cells through liquid environments, one of them being cancer ascites accumulated in the peritoneal cavity. These biological fluids are highly crowded with a high total macromolecule concentration. This biophysical property of fluids is widely used in tissue engineering for a few decades now, yet is largely underrated in cancer biomimetic models. To unravel the role of fluids extracellular macromolecular crowding (MMC), we exposed ovarian cancer cells (OCC) to high molecular weight inert polymer solutions. High macromolecular composition of extracellular liquid presented a differential effect: i) it impeded non-adherent OCC aggregation in suspension and, decreased their adhesion; ii) it promoted adherent OCC migration by decreasing extracellular matrix deposition. Besides, there seemed to be a direct link between the extracellular MMC and intracellular processes, especially the actin cytoskeleton organization and the nucleus morphology. In conclusion, extracellular fluid MMC orients OCC dissemination phenotype. Integrating MMC seems crucial to produce more relevant mimetic 3D in vitro fluid models to study ovarian dissemination but also to screen drugs.
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15
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Park J, Lee M, Lee B, Castaneda N, Tetard L, Kang EH. Crowding tunes the organization and mechanics of actin bundles formed by crosslinking proteins. FEBS Lett 2020; 595:26-40. [PMID: 33020904 DOI: 10.1002/1873-3468.13949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 01/05/2023]
Abstract
Fascin and α-actinin form higher-ordered actin bundles that mediate numerous cellular processes including cell morphogenesis and movement. While it is understood crosslinked bundle formation occurs in crowded cytoplasm, how crowding affects the bundling activities of the two crosslinking proteins is not known. Here, we demonstrate how solution crowding modulates the organization and mechanical properties of fascin- and α-actinin-induced bundles, utilizing total internal reflection fluorescence and atomic force microscopy imaging. Molecular dynamics simulations support the inference that crowding reduces binding interaction between actin filaments and fascin or the calponin homology 1 domain of α-actinin evidenced by interaction energy and hydrogen bonding analysis. Based on our findings, we suggest a mechanism of crosslinked actin bundle assembly and mechanics in crowded intracellular environments.
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Affiliation(s)
- Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA
| | - Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Briana Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
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16
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Tsai RF, Lin NC, Kao TY, Kuo YH, Lo FC, Liaw WF, Chiang YW. Nitrosylation of the Diiron Core Mediated by the N Domain of YtfE. J Phys Chem Lett 2020; 11:8538-8542. [PMID: 32940468 DOI: 10.1021/acs.jpclett.0c02200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The YtfE protein catalyzes the reduction of NO to N2O, protecting iron-sulfur clusters from nitrosylation. The structure of YtfE has a two-domain architecture, with a diiron-containing C-terminal domain linked to an N-terminal domain, in which the function of the latter is enigmatic. Here, by using electron spin resonance (ESR) spectroscopy, we show that YtfE exists in two conformational states, one of which has not been reported. Under high osmotic stress, YtfE adopts a homogeneous conformation (C state) similar to the known crystal structure. In a regular buffer, the N-terminal domain switches between the C state and a previously unidentified conformation (C' state), the latter of which has more space at the domain interface to allow the trafficking of NO molecules and thus is proposed to be a functionally active state. The conformational switch between the C and C' states is pivotal for facilitating NO access to the diiron core.
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Affiliation(s)
- Ruei-Fong Tsai
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Nien-Chen Lin
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Te-Yu Kao
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Yun-Hsuan Kuo
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Feng-Chun Lo
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Wen-Feng Liaw
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
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17
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Micro- and macro-viscosity relations in high concentration antibody solutions. Eur J Pharm Biopharm 2020; 153:211-221. [DOI: 10.1016/j.ejpb.2020.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/11/2020] [Accepted: 06/14/2020] [Indexed: 11/18/2022]
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18
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Zhang Q, Bai Q, Zhu L, Hou T, Zhao J, Liang D. Macromolecular Crowding and Confinement Effect on the Growth of DNA Nanotubes in Dextran and Hyaluronic Acid Media. ACS APPLIED BIO MATERIALS 2019; 3:412-420. [DOI: 10.1021/acsabm.9b00892] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qiufen Zhang
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Qingwen Bai
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Lin Zhu
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Tianhao Hou
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiang Zhao
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Dehai Liang
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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19
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Anderson SJ, Matsuda C, Garamella J, Peddireddy KR, Robertson-Anderson RM, McGorty R. Filament Rigidity Vies with Mesh Size in Determining Anomalous Diffusion in Cytoskeleton. Biomacromolecules 2019; 20:4380-4388. [PMID: 31687803 DOI: 10.1021/acs.biomac.9b01057] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The diffusion of microscopic particles through the cell, important to processes such as viral infection, gene delivery, and vesicle transport, is largely controlled by the complex cytoskeletal network, comprised of semiflexible actin filaments and rigid microtubules, that pervades the cytoplasm. By varying the relative concentrations of actin and microtubules, the cytoskeleton can display a host of different structural and dynamic properties that, in turn, impact the diffusion of particles through the composite network. Here, we couple single-particle tracking with differential dynamic microscopy to characterize the transport of microsphere tracers diffusing through composite in vitro networks with varying ratios of actin and microtubules. We analyze multiple complementary metrics for anomalous transport to show that particles exhibit anomalous subdiffusion in all networks, which our data suggest arises from caging by networks. Further, subdiffusive characteristics are markedly more pronounced in actin-rich networks, which exhibit similarly more prominent viscoelastic properties compared to microtubule-rich composites. While the smaller mesh size of actin-rich composites compared to microtubule-rich composites plays an important role in these results, the rigidity of the filaments comprising the network also influences the anomalous characteristics that we observe. Our results suggest that as microtubules in our composites are replaced with actin filaments, the decreasing filament rigidity competes with increasing network connectivity to drive anomalous transport.
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Affiliation(s)
- Sylas J Anderson
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
| | - Christelle Matsuda
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
| | - Jonathan Garamella
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
| | - Karthik Reddy Peddireddy
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
| | - Rae M Robertson-Anderson
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
| | - Ryan McGorty
- Department of Physics and Biophysics , University of San Diego , San Diego , California 92110 , United States
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20
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Chung S, Lerner E, Jin Y, Kim S, Alhadid Y, Grimaud LW, Zhang IX, Knobler CM, Gelbart WM, Weiss S. The effect of macromolecular crowding on single-round transcription by Escherichia coli RNA polymerase. Nucleic Acids Res 2019; 47:1440-1450. [PMID: 30590739 PMCID: PMC6379708 DOI: 10.1093/nar/gky1277] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 12/01/2018] [Accepted: 12/13/2018] [Indexed: 01/09/2023] Open
Abstract
Previous works have reported significant effects of macromolecular crowding on the structure and behavior of biomolecules. The crowded intracellular environment, in contrast to in vitro buffer solutions, likely imparts similar effects on biomolecules. The enzyme serving as the gatekeeper for the genome, RNA polymerase (RNAP), is among the most regulated enzymes. Although it was previously demonstrated that macromolecular crowding affects association of RNAP to DNA, not much is known about how crowding acts on late initiation and promoter clearance steps, which are considered to be the rate-determining steps for many promoters. Here, we demonstrate that macromolecular crowding enhances the rate of late initiation and promoter clearance using in vitro quenching-based single-molecule kinetics assays. Moreover, the enhancement's dependence on crowder size notably deviates from predictions by the scaled-particle theory, commonly used for description of crowding effects. Our findings shed new light on how enzymatic reactions could be affected by crowded conditions in the cellular milieu.
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Affiliation(s)
- SangYoon Chung
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
| | - Eitan Lerner
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yan Jin
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
| | - Soohong Kim
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yazan Alhadid
- Interdepartmental Program in Molecular, Cellular, and Integrative Physiology, University of California, Los Angeles, CA 90095, USA
| | - Logan Wilson Grimaud
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
| | - Irina X Zhang
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
- Present address: Irina X. Zhang, Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Charles M Knobler
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
| | - William M Gelbart
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
- Interdepartmental Program in Molecular, Cellular, and Integrative Physiology, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute (MBI), University of California Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California Los Angeles, CA 90095, USA
- Correspondence may also be addressed to William M. Gelbart. Tel: +1 310 825 2005; Fax: +1 310 206 4038;
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA 90095, USA
- Interdepartmental Program in Molecular, Cellular, and Integrative Physiology, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute (MBI), University of California Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California Los Angeles, CA 90095, USA
- Department of Physiology, University of California Los Angeles, CA 90095, USA
- Department of Physics, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
- To whom correspondence should be addressed. Tel: +1 310 794 0093; Fax: +1 310 267 4672;
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21
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Gupta A, Sankaran J, Wohland T. Fluorescence correlation spectroscopy: The technique and its applications in soft matter. PHYSICAL SCIENCES REVIEWS 2019. [DOI: 10.1515/psr-2017-0104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abstract
Fluorescence correlation spectroscopy (FCS) is a well-established single-molecule method used for the quantitative spatiotemporal analysis of dynamic processes in a wide range of samples. It possesses single-molecule sensitivity but provides ensemble averaged molecular parameters such as mobility, concentration, chemical reaction kinetics, photophysical properties and interaction properties. These parameters have been utilized to characterize a variety of soft matter systems. This review provides an overview of the basic principles of various FCS modalities, their instrumentation, data analysis, and the applications of FCS to soft matter systems.
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22
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Castaneda N, Lee M, Rivera-Jacquez HJ, Marracino RR, Merlino TR, Kang H. Actin Filament Mechanics and Structure in Crowded Environments. J Phys Chem B 2019; 123:2770-2779. [PMID: 30817154 DOI: 10.1021/acs.jpcb.8b12320] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cellular environment is crowded with high concentrations of macromolecules that significantly reduce accessible volume for biomolecular interactions. Reductions in cellular volume can generate depletion forces that affect protein assembly and stability. The mechanical and structural properties of actin filaments play critical roles in various cellular functions, including structural support, cell movement, division, and intracellular transport. Although the effects of molecular crowding on actin polymerization have been shown, how crowded environments affect filament mechanics and structure is unknown. In this study, we investigate the effects of solution crowding on the modulations of actin filament bending stiffness and conformations both in vitro and in silico. Direct visualization of thermally fluctuating filaments in the presence of crowding agents is achieved by fluorescence microscopy imaging. Biophysical analysis indicates that molecular crowding enhances filament's effective bending stiffness and reduces average filament lengths. Utilizing the all-atom molecular dynamics simulations, we demonstrate that molecular crowding alters filament conformations and intersubunit contacts that are directly coupled to the mechanical properties of filaments. Taken together, our study suggests that the interplay between excluded volume effects and nonspecific interactions raised from molecular crowding may modulate actin filament mechanics and structure.
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Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States.,Burnett School of Biomedical Sciences, College of Medicine , University of Central Florida , Orlando , Florida 32827 , United States
| | - Myeongsang Lee
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Hector J Rivera-Jacquez
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Ryan R Marracino
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States.,Burnett School of Biomedical Sciences, College of Medicine , University of Central Florida , Orlando , Florida 32827 , United States
| | - Theresa R Merlino
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Hyeran Kang
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
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23
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Regan K, Wulstein D, Rasmussen H, McGorty R, Robertson-Anderson RM. Bridging the spatiotemporal scales of macromolecular transport in crowded biomimetic systems. SOFT MATTER 2019; 15:1200-1209. [PMID: 30543245 PMCID: PMC6365203 DOI: 10.1039/c8sm02023j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Crowding plays a key role in the transport and conformations of biological macromolecules. Gene therapy, viral infection, and transfection require DNA to traverse the crowded cytoplasm, including the cytoskeletal network of filamentous proteins. Given the complexity of cellular crowding, the dynamics of biological molecules can be highly dependent on the spatiotemporal scale probed. We present a powerful platform that spans molecular and cellular scales by coupling single-molecule conformational tracking (SMCT) and selective-plane illumination differential dynamic microscopy (SPIDDM). We elucidate the transport and conformational properties of large DNA, crowded by custom-designed networks of actin and microtubules, to link single-molecule conformations with ensemble DNA transport and cytoskeleton structure. We show that actin crowding leads to DNA compaction and suppression of fluctuations, combined with subdiffusion and heterogeneous transport, whereas microtubules have much more subdued impact across all scales. In composite networks of both filaments, scale-dependent effects emerge such that actin dictates ensemble DNA transport while microtubules influence single-molecule dynamics. We show that these intriguing results arise from a complex interplay between network rigidity, mesh size, filament concentration, and DNA size.
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Affiliation(s)
- Kathryn Regan
- Department of Physics and Biophysics, University of San Diego, 5998 Alcala Park, San Diego, CA 92110, USA.
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24
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Blaffert J, Haeri HH, Blech M, Hinderberger D, Garidel P. Spectroscopic methods for assessing the molecular origins of macroscopic solution properties of highly concentrated liquid protein solutions. Anal Biochem 2018; 561-562:70-88. [PMID: 30243977 DOI: 10.1016/j.ab.2018.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 09/08/2018] [Accepted: 09/17/2018] [Indexed: 01/14/2023]
Abstract
In cases of subcutaneous injection of therapeutic monoclonal antibodies, high protein concentrations (>50 mg/ml) are often required. During the development of these high concentration liquid formulations (HCLF), challenges such as aggregation, gelation, opalescence, phase separation, and high solution viscosities are more prone compared to low concentrated protein formulations. These properties can impair manufacturing processes, as well as protein stability and shelf life. To avoid such unfavourable solution properties, a detailed understanding about the nature of these properties and their driving forces are required. However, the fundamental mechanisms that lead to macroscopic solution properties, as above mentioned, are complex and not fully understood, yet. Established analytical methods for assessing the colloidal stability, i.e. the ability of a native protein to remain dispersed in solution, are restricted to dilute conditions and provide parameters such as the second osmotic virial coefficient, B22, and the diffusion interaction coefficient, kD. These parameters are routinely applied for qualitative estimations and identifications of proteins with challenging solution behaviours, such as high viscosities and aggregation, although the assays are prepared for low protein concentration conditions, typically between 0.1 and 20 mg/ml ("ideal" solution conditions). Quantitative analysis of samples of high protein concentration is difficult and it is hard to obtain information about the driving forces of such solution properties and corresponding protein-protein self-interactions. An advantage of using specific spectroscopic methods is the potential of directly analysing highly concentrated protein solutions at different solution conditions. This allows for collecting/gaining valuable information about the fundamental mechanisms of solution properties of the high protein concentration regime. In addition, the derived parameters might be more predictive as compared to the parameters originating from assays which are optimized for the low protein concentration range. The provided information includes structural data, molecular dynamics at various timescales and protein-solvent interactions, which can be obtained at molecular resolution. Herein, we provide an overview about spectroscopic techniques for analysing the origins of macroscopic solution behaviours in general, with a specific focus on pharmaceutically relevant high protein concentration and formulation conditions.
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Affiliation(s)
- Jacob Blaffert
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle/Saale, Germany
| | - Haleh Hashemi Haeri
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle/Saale, Germany
| | - Michaela Blech
- Boehringer Ingelheim Pharma GmbH & Co. KG, Protein Science, Birkerndorfer Str. 65, 88397, Biberach/Riß, Germany
| | - Dariush Hinderberger
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle/Saale, Germany
| | - Patrick Garidel
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle/Saale, Germany; Boehringer Ingelheim Pharma GmbH & Co. KG, Protein Science, Birkerndorfer Str. 65, 88397, Biberach/Riß, Germany.
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25
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Chambers JE, Kubánková M, Huber RG, López-Duarte I, Avezov E, Bond PJ, Marciniak SJ, Kuimova MK. An Optical Technique for Mapping Microviscosity Dynamics in Cellular Organelles. ACS NANO 2018; 12:4398-4407. [PMID: 29648785 DOI: 10.1021/acsnano.8b00177] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Microscopic viscosity (microviscosity) is a key determinant of diffusion in the cell and defines the rate of biological processes occurring at the nanoscale, including enzyme-driven metabolism and protein folding. Here we establish a rotor-based organelle viscosity imaging (ROVI) methodology that enables real-time quantitative mapping of cell microviscosity. This approach uses environment-sensitive dyes termed molecular rotors, covalently linked to genetically encoded probes to provide compartment-specific microviscosity measurements via fluorescence lifetime imaging. ROVI visualized spatial and temporal dynamics of microviscosity with suborganellar resolution, reporting on a microviscosity difference of nearly an order of magnitude between subcellular compartments. In the mitochondrial matrix, ROVI revealed several striking findings: a broad heterogeneity of microviscosity among individual mitochondria, unparalleled resilience to osmotic stress, and real-time changes in microviscosity during mitochondrial depolarization. These findings demonstrate the use of ROVI to explore the biophysical mechanisms underlying cell biological processes.
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Affiliation(s)
- Joseph E Chambers
- Cambridge Institute for Medical Research (CIMR), Department of Medicine , University of Cambridge , Wellcome Trust/MRC Building, Hills Road , Cambridge , CB2 0XY , United Kingdom
| | - Markéta Kubánková
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
| | - Roland G Huber
- Bioinformatics Institute (BII) , Agency for Science, Technology, and Research (A*STAR) , Matrix 07-01, 30 Biopolis Street , 138671 Singapore
| | - Ismael López-Duarte
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge , Cambridge Biomedical Campus, Cambridge CB2 0AH , United Kingdom
| | - Peter J Bond
- Bioinformatics Institute (BII) , Agency for Science, Technology, and Research (A*STAR) , Matrix 07-01, 30 Biopolis Street , 138671 Singapore
- Department of Biological Sciences , National University of Singapore , 14 Science Drive 4 , 117543 Singapore
| | - Stefan J Marciniak
- Cambridge Institute for Medical Research (CIMR), Department of Medicine , University of Cambridge , Wellcome Trust/MRC Building, Hills Road , Cambridge , CB2 0XY , United Kingdom
| | - Marina K Kuimova
- Department of Chemistry , Imperial College London , South Kensington , London , SW7 2AZ , United Kingdom
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26
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Miller H, Cosgrove J, Wollman AJM, Taylor E, Zhou Z, O'Toole PJ, Coles MC, Leake MC. High-Speed Single-Molecule Tracking of CXCL13 in the B-Follicle. Front Immunol 2018; 9:1073. [PMID: 29872430 PMCID: PMC5972203 DOI: 10.3389/fimmu.2018.01073] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/30/2018] [Indexed: 12/12/2022] Open
Abstract
Soluble factors are an essential means of communication between cells and their environment. However, many molecules readily interact with extracellular matrix components, giving rise to multiple modes of diffusion. The molecular quantification of diffusion in situ is thus a challenging imaging frontier, requiring very high spatial and temporal resolution. Overcoming this methodological barrier is key to understanding the precise spatial patterning of the extracellular factors that regulate immune function. To address this, we have developed a high-speed light microscopy system capable of millisecond sampling in ex vivo tissue samples and submillisecond sampling in controlled in vitro samples to characterize molecular diffusion in a range of complex microenvironments. We demonstrate that this method outperforms competing tools for determining molecular mobility of fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) for evaluation of diffusion. We then apply this approach to study the chemokine CXCL13, a key determinant of lymphoid tissue architecture, and B-cell-mediated immunity. Super-resolution single-molecule tracking of fluorescently labeled CCL19 and CXCL13 in collagen matrix was used to assess the heterogeneity of chemokine mobility behaviors, with results indicating an immobile fraction and a mobile fraction for both molecules, with distinct diffusion rates of 8.4 ± 0.2 and 6.2 ± 0.3 µm2s−1, respectively. To better understand mobility behaviors in situ, we analyzed CXCL13-AF647 diffusion in murine lymph node tissue sections and observed both an immobile fraction and a mobile fraction with an example diffusion coefficient of 6.6 ± 0.4 µm2s−1, suggesting that mobility within the follicle is also multimodal. In quantitatively studying mobility behaviors at the molecular level, we have obtained an increased understanding of CXCL13 bioavailability within the follicle. Our high-speed single-molecule tracking approach affords a novel perspective from which to understand the mobility of soluble factors relevant to the immune system.
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Affiliation(s)
- Helen Miller
- Department of Physics, University of York, York, United Kingdom.,Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Jason Cosgrove
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom.,Department of Electronics, University of York, York, United Kingdom
| | - Adam J M Wollman
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Emily Taylor
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Zhaokun Zhou
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Peter J O'Toole
- Department of Biology, University of York, York, United Kingdom.,Bioscience Technology Facility, University of York, York, United Kingdom
| | - Mark C Coles
- Centre of Immunology and Infection, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, United Kingdom
| | - Mark C Leake
- Department of Physics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
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27
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Biswas S, Kundu J, Mukherjee SK, Chowdhury PK. Mixed Macromolecular Crowding: A Protein and Solvent Perspective. ACS OMEGA 2018; 3:4316-4330. [PMID: 30023892 PMCID: PMC6044960 DOI: 10.1021/acsomega.7b01864] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/16/2018] [Indexed: 06/08/2023]
Abstract
In the living cell, biomolecules perform their respective functions in the presence of not only one type of macromolecules but rather in the presence of various macromolecules with different shapes and sizes. In this study, we have investigated the effects of five single macromolecular crowding agents, Dextran 6, Dextran 40, Dextran 70, Ficoll 70, and PEG 8000 and their binary mixtures on the modulation in the domain separation of human serum albumin using a Förster resonance energy transfer-based approach and the translational mobility of a small fluorescent probe fluorescein isothiocyanate (FITC) using fluorescence correlation spectroscopy (FCS). Our observations suggest that mixed crowding induces greater cooperativity in the domain movement as compared to the components of the mixtures. Thermodynamic analyses of the same provide evidence of crossovers from enthalpy-based interactions to effects dominated by hard-sphere potential. When compared with those obtained for individual crowders, both domain movements and FITC diffusion studies show significant deviations from ideality, with an ideal solution being considered to be that arising from the sum of the contributions of those obtained in the presence of individual crowding agents. Considering the fact that domain movements are local (on the order of a few angstroms) in nature while translational movements span much larger lengthscales, our results imply that the observed deviation from simple additivity exists at several possible levels or lengthscales in such mixtures. Moreover, the nature and the type of deviation not only depend on the identities of the components of the crowder mixtures but are also influenced by the particular face of the serum protein (either the domain I-II or the domain II-III face) that the crowders interact with, thus providing further insights into the possible existence of microheterogeneities in such solutions.
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Bachand GD, Jain R, Ko R, Bouxsein NF, VanDelinder V. Inhibition of Microtubule Depolymerization by Osmolytes. Biomacromolecules 2018; 19:2401-2408. [PMID: 29689154 DOI: 10.1021/acs.biomac.7b01799] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microtubule dynamics play a critical role in the normal physiology of eukaryotic cells as well as a number of cancers and neurodegenerative disorders. The polymerization/depolymerization of microtubules is regulated by a variety of stabilizing and destabilizing factors, including microtubule-associated proteins and therapeutic agents (e.g., paclitaxel, nocodazole). Here we describe the ability of the osmolytes polyethylene glycol (PEG) and trimethylamine- N-oxide (TMAO) to inhibit the depolymerization of individual microtubule filaments for extended periods of time (up to 30 days). We further show that PEG stabilizes microtubules against both temperature- and calcium-induced depolymerization. Our results collectively suggest that the observed inhibition may be related to combination of the kosmotropic behavior and excluded volume/osmotic pressure effects associated with PEG and TMAO. Taken together with prior studies, our data suggest that the physiochemical properties of the local environment can regulate microtubule depolymerization and may potentially play an important role in in vivo microtubule dynamics.
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Affiliation(s)
- George D Bachand
- Center for Integrated Nanotechnologies , Sandia National Laboratories , P.O. Box 5800, MS 1303, Albuquerque , New Mexico 87185 , United States
| | - Rishi Jain
- Center for Integrated Nanotechnologies , Sandia National Laboratories , P.O. Box 5800, MS 1303, Albuquerque , New Mexico 87185 , United States
| | - Randy Ko
- Center for Integrated Nanotechnologies , Sandia National Laboratories , P.O. Box 5800, MS 1303, Albuquerque , New Mexico 87185 , United States
| | - Nathan F Bouxsein
- Center for Integrated Nanotechnologies , Sandia National Laboratories , P.O. Box 5800, MS 1303, Albuquerque , New Mexico 87185 , United States
| | - Virginia VanDelinder
- Center for Integrated Nanotechnologies , Sandia National Laboratories , P.O. Box 5800, MS 1303, Albuquerque , New Mexico 87185 , United States
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Benny P, Raghunath M. Making microenvironments: A look into incorporating macromolecular crowding into in vitro experiments, to generate biomimetic microenvironments which are capable of directing cell function for tissue engineering applications. J Tissue Eng 2017; 8:2041731417730467. [PMID: 29051808 PMCID: PMC5638150 DOI: 10.1177/2041731417730467] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/09/2017] [Indexed: 01/07/2023] Open
Abstract
Biomimetic microenvironments are key components to successful cell culture and tissue engineering in vitro. One of the most accurate biomimetic microenvironments is that made by the cells themselves. Cell-made microenvironments are most similar to the in vivo state as they are cell-specific and produced by the actual cells which reside in that specific microenvironment. However, cell-made microenvironments have been challenging to re-create in vitro due to the lack of extracellular matrix composition, volume and complexity which are required. By applying macromolecular crowding to current cell culture protocols, cell-made microenvironments, or cell-derived matrices, can be generated at significant rates in vitro. In this review, we will examine the causes and effects of macromolecular crowding and how it has been applied in several in vitro systems including tissue engineering.
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Affiliation(s)
- Paula Benny
- Department of Biochemistry, National University of Singapore, Singapore
| | - Michael Raghunath
- Department of Biochemistry, National University of Singapore, Singapore.,Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences, Wädenswil, Switzerland
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Palit S, He L, Hamilton WA, Yethiraj A, Yethiraj A. The effect of crowder charge in a model polymer–colloid system for macromolecular crowding: Polymer structure and dynamics. J Chem Phys 2017; 147:114902. [DOI: 10.1063/1.4986353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Swomitra Palit
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador A1B3X7, Canada
| | - Lilin He
- Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - William A. Hamilton
- Instrument and Source Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Anand Yethiraj
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador A1B3X7, Canada
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Erwin N, Patra S, Dwivedi M, Weise K, Winter R. Influence of isoform-specific Ras lipidation motifs on protein partitioning and dynamics in model membrane systems of various complexity. Biol Chem 2017; 398:547-563. [PMID: 27977396 DOI: 10.1515/hsz-2016-0289] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 12/07/2016] [Indexed: 12/17/2022]
Abstract
The partitioning of the lipidated signaling proteins N-Ras and K-Ras4B into various membrane systems, ranging from single-component fluid bilayers, binary fluid mixtures, heterogeneous raft model membranes up to complex native-like lipid mixtures (GPMVs) in the absence and presence of integral membrane proteins have been explored in the last decade in a combined chemical-biological and biophysical approach. These studies have revealed pronounced isoform-specific differences regarding the lateral distribution in membranes and formation of protein-rich membrane domains. In this context, we will also discuss the effects of lipid head group structure and charge density on the partitioning behavior of the lipoproteins. Moreover, the dynamic properties of N-Ras and K-Ras4B have been studied in different model membrane systems and native-like crowded milieus. Addition of crowding agents such as Ficoll and its monomeric unit, sucrose, gradually favors clustering of Ras proteins in forming small oligomers in the bulk; only at very high crowder concentrations association is disfavored.
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Affiliation(s)
- Nelli Erwin
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, Dortmund Technical University, Otto-Hahn-Strasse 4a, D-44227 Dortmund
| | - Satyajit Patra
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, Dortmund Technical University, Otto-Hahn-Strasse 4a, D-44227 Dortmund
| | - Mridula Dwivedi
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, Dortmund Technical University, Otto-Hahn-Strasse 4a, D-44227 Dortmund
| | - Katrin Weise
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, Dortmund Technical University, Otto-Hahn-Strasse 4a, D-44227 Dortmund
| | - Roland Winter
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, Dortmund Technical University, Otto-Hahn-Strasse 4a, D-44227 Dortmund
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Reorganization of Lipid Diffusion by Myelin Basic Protein as Revealed by STED Nanoscopy. Biophys J 2017; 110:2441-2450. [PMID: 27276262 PMCID: PMC4906378 DOI: 10.1016/j.bpj.2016.04.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 03/30/2016] [Accepted: 04/25/2016] [Indexed: 12/13/2022] Open
Abstract
Myelin is a multilayered membrane that ensheathes axonal fibers in the vertebrate nervous system, allowing fast propagation of nerve action potentials. It contains densely packed lipids, lacks an actin-based cytocortex, and requires myelin basic protein (MBP) as its major structural component. This protein is the basic constituent of the proteinaceous meshwork that is localized between adjacent cytoplasmic membranes of the myelin sheath. Yet, it is not clear how MBP influences the organization and dynamics of the lipid constituents of myelin. Here, we used optical stimulated emission depletion super-resolution microscopy in combination with fluorescence correlation spectroscopy to assess the characteristics of diffusion of different fluorescent lipid analogs in myelin membrane sheets of cultured oligodendrocytes and in micrometer-sized domains that were induced by MBP in live epithelial PtK2 cells. Lipid diffusion was significantly faster and less anomalous both in oligodendrocytes and inside the MBP-rich domains of PtK2 cells compared with undisturbed live PtK2 cells. Our data show that MBP reorganizes lipid diffusion, possibly by preventing the buildup of an actin-based cytocortex and by preventing most membrane proteins from entering the myelin sheath region. Yet, in contrast to myelin sheets in oligodendrocytes, the MBP-induced domains in epithelial PtK2 cells demonstrate no change in lipid order, indicating that segregation of long-chain lipids into myelin sheets is a process specific to oligodendrocytes.
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Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps. Proc Natl Acad Sci U S A 2017; 114:6340-6345. [PMID: 28559324 DOI: 10.1073/pnas.1701644114] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.
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Patra S, Erwin N, Winter R. Translational Dynamics of Lipidated Ras Proteins in the Presence of Crowding Agents and Compatible Osmolytes. Chemphyschem 2016; 17:2164-9. [PMID: 27028423 DOI: 10.1002/cphc.201600179] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Indexed: 11/07/2022]
Abstract
Ras proteins are small GTPases and are involved in transmitting signals that control cell growth, differentiation, and proliferation. Since the cell cytoplasm is crowded with different macromolecules, understanding the translational dynamics of Ras proteins in crowded environments is crucial to yielding deeper insight into their reactivity and function. Herein, the translational dynamics of lipidated N-Ras and K-Ras4B is studied in the bulk and in the presence of a macromolecular crowder (Ficoll) and the compatible osmolyte and microcrowder sucrose by fluorescence correlation spectroscopy. The results reveal that N-Ras forms dimers due to the presence of its lipid moiety in the hypervariable region, whereas K-Ras4B remains in its monomeric form in the bulk. Addition of a macromolecular crowding agent gradually favors clustering of the Ras proteins. In 20 wt % Ficoll N-Ras forms trimers and K-Ras4B dimers. Concentrations of sucrose up to 10 wt % foster formation of N-Ras trimers and K-Ras dimers as well. The results can be rationalized in terms of the excluded-volume effect, which enhances the association of the proteins, and, for the higher concentrations, by limited-hydration conditions. The results of this study shed new light on the association state of these proteins in a crowded environment. This is of particular interest for the Ras proteins, because their solution state-monomeric or clustered-influences their membrane-partitioning behavior and their interplay with cytosolic interaction partners.
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Affiliation(s)
- Satyajit Patra
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Nelli Erwin
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany.
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Paul SS, Sil P, Chakraborty R, Haldar S, Chattopadhyay K. Molecular Crowding Affects the Conformational Fluctuations, Peroxidase Activity, and Folding Landscape of Yeast Cytochrome c. Biochemistry 2016; 55:2332-43. [DOI: 10.1021/acs.biochem.6b00053] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Simanta Sarani Paul
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Pallabi Sil
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Ritobrita Chakraborty
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Shubhasis Haldar
- Department
of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz
18, 82152 Martinsried, Germany
| | - Krishnananda Chattopadhyay
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
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