1
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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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2
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Wang L, Lin Z, Carli J, Gladala‐Kostarz A, Davies JM, Franklin‐Tong VE, Bosch M. Depletion plays a pivotal role in self-incompatibility, revealing a link between cellular energy status, cytosolic acidification and actin remodelling in pollen tubes. THE NEW PHYTOLOGIST 2022; 236:1691-1707. [PMID: 35775998 PMCID: PMC9796540 DOI: 10.1111/nph.18350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/15/2022] [Indexed: 06/08/2023]
Abstract
Self-incompatibility (SI) involves specific interactions during pollination to reject incompatible ('self') pollen, preventing inbreeding in angiosperms. A key event observed in pollen undergoing the Papaver rhoeas SI response is the formation of punctate F-actin foci. Pollen tube growth is heavily energy-dependent, yet ATP levels in pollen tubes have not been directly measured during SI. Here we used transgenic Arabidopsis lines expressing the Papaver pollen S-determinant to investigate a possible link between ATP levels, cytosolic pH ([pH]cyt ) and alterations to the actin cytoskeleton. We identify for the first time that SI triggers a rapid and significant ATP depletion in pollen tubes. Artificial depletion of ATP triggered cytosolic acidification and formation of actin aggregates. We also identify in vivo, evidence for a threshold [pH]cyt of 5.8 for actin foci formation. Imaging revealed that SI stimulates acidic cytosolic patches adjacent to the plasma membrane. In conclusion, this study provides evidence that ATP depletion plays a pivotal role in SI upstream of programmed cell death and reveals a link between the cellular energy status, cytosolic acidification and alterations to the actin cytoskeleton in regulating Papaver SI in pollen tubes.
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Affiliation(s)
- Ludi Wang
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Zongcheng Lin
- Key Laboratory of Horticultural Plant BiologyHuazhong Agricultural UniversityWuhan430070China
| | - José Carli
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Agnieszka Gladala‐Kostarz
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
| | - Julia M. Davies
- Department of Plant SciencesUniversity of CambridgeCambridgeCB2 3EAUK
| | - Vernonica E. Franklin‐Tong
- School of Biosciences, College of Life and Environmental SciencesUniversity of BirminghamEdgbastonBirminghamB15 2TTUK
| | - Maurice Bosch
- Institute of Biological, Environmental and Rural Sciences (IBERS)Aberystwyth UniversityPlas GogerddanAberystwythSY23 3EEUK
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3
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Alva E, George A, Brancaleon L, Marucho M. In vitro Preparation of Homogenous Actin Filaments for Dynamic and Electrophoretic Light Scattering Measurements. Bio Protoc 2022; 12:e4553. [PMID: 36561921 PMCID: PMC9729858 DOI: 10.21769/bioprotoc.4553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/24/2022] [Accepted: 09/12/2022] [Indexed: 11/19/2022] Open
Abstract
Actin filaments are essential for various biological activities in eukaryotic cellular processes. Available in vitro experimental data on these systems often lack details and information on sample preparation protocols and experimental techniques, leading to unreproducible results. Additionally, different experimental techniques and polymerization buffers provide different, sometimes contradictory results on the properties of these systems, making it substantially difficult to gather meaningful data and conclusive information from them. This article presents a robust, accurate, detailed polymerization protocol to prepare high-quality actin filament samples for light scattering experiments. It has been shown to provide unicity and consistency in preparing stable, dispersed, aggregates-free, homogenous actin filament samples that could benefit many other scientific research groups currently working in the field. To develop the protocol, we used conventional actin buffers in physiological conditions. However, it can easily be adapted to prepare samples using other buffers and biological fluids. This protocol yielded reproducible results on essential actin filament parameters such as the translational diffusion coefficient and electrophoretic mobility. Overall, suitable modifications of the proposed experimental method could generate accurate, reproducible light scattering results on other highly charged anionic filaments commonly found in biological cells (e.g., microtubules, DNAs, RNAs, or filamentous viruses). This protocol was validated in: Polymers (2022), DOI: 10.3390/polym14122438 Graphical abstract.
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Affiliation(s)
- Ernesto Alva
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, USA
| | - Annitta George
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, USA
| | - Lorenzo Brancaleon
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, USA
| | - Marcelo Marucho
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, USA
,
*For correspondence:
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4
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Alva E, George A, Brancaleon L, Marucho M. Hydrodynamic and Polyelectrolyte Properties of Actin Filaments: Theory and Experiments. Polymers (Basel) 2022; 14:polym14122438. [PMID: 35746014 PMCID: PMC9230757 DOI: 10.3390/polym14122438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/07/2022] [Accepted: 06/14/2022] [Indexed: 11/17/2022] Open
Abstract
Actin filament’s polyelectrolyte and hydrodynamic properties, their interactions with the biological environment, and external force fields play an essential role in their biological activities in eukaryotic cellular processes. In this article, we introduce a unique approach that combines dynamics and electrophoresis light-scattering experiments, an extended semiflexible worm-like chain model, and an asymmetric polymer length distribution theory to characterize the polyelectrolyte and hydrodynamic properties of actin filaments in aqueous electrolyte solutions. A fitting approach was used to optimize the theories and filament models for hydrodynamic conditions. We used the same sample and experimental conditions and considered several g-actin and polymerization buffers to elucidate the impact of their chemical composition, reducing agents, pH values, and ionic strengths on the filament translational diffusion coefficient, electrophoretic mobility, structure factor, asymmetric length distribution, effective filament diameter, electric charge, zeta potential, and semiflexibility. Compared to those values obtained from molecular structure models, our results revealed a lower value of the effective G-actin charge and a more significant value of the effective filament diameter due to the formation of the double layer of the electrolyte surrounding the filaments. Contrary to the data usually reported from electron micrographs, the lower values of our results for the persistence length and average contour filament length agree with the significant difference in the association rates at the filament ends that shift to sub-micro lengths, which is the maximum of the length distribution.
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5
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Yang Q, Miao Y, Campanello LJ, Hourwitz MJ, Abubaker-Sharif B, Bull AL, Devreotes PN, Fourkas JT, Losert W. Cortical waves mediate the cellular response to electric fields. eLife 2022; 11:73198. [PMID: 35318938 PMCID: PMC8942472 DOI: 10.7554/elife.73198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 03/08/2022] [Indexed: 11/13/2022] Open
Abstract
Electrotaxis, the directional migration of cells in a constant electric field, is important in regeneration, development, and wound healing. Electrotaxis has a slower response and a smaller dynamic range than guidance by other cues, suggesting that the mechanism of electrotaxis shares both similarities and differences with chemical-gradient-sensing pathways. We examine a mechanism centered on the excitable system consisting of cortical waves of biochemical signals coupled to cytoskeletal reorganization, which has been implicated in random cell motility. We use electro-fused giant Dictyostelium discoideum cells to decouple waves from cell motion and employ nanotopographic surfaces to limit wave dimensions and lifetimes. We demonstrate that wave propagation in these cells is guided by electric fields. The wave area and lifetime gradually increase in the first 10 min after an electric field is turned on, leading to more abundant and wider protrusions in the cell region nearest the cathode. The wave directions display 'U-turn' behavior upon field reversal, and this switch occurs more quickly on nanotopography. Our results suggest that electric fields guide cells by controlling waves of signal transduction and cytoskeletal activity, which underlie cellular protrusions. Whereas surface receptor occupancy triggers both rapid activation and slower polarization of signaling pathways, electric fields appear to act primarily on polarization, explaining why cells respond to electric fields more slowly than to other guidance cues.
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Affiliation(s)
- Qixin Yang
- Department of Physics, University of Maryland, College Park, United States.,Institute for Physical Science and Technology, University of Maryland, College Park, United States
| | - Yuchuan Miao
- Department of Cell Biology, Johns Hopkins University, Baltimore, United States
| | - Leonard J Campanello
- Department of Physics, University of Maryland, College Park, United States.,Institute for Physical Science and Technology, University of Maryland, College Park, United States
| | - Matt J Hourwitz
- Department of Chemistry & Biochemistry, University of Maryland, College Park, United States
| | | | - Abby L Bull
- Department of Physics, University of Maryland, College Park, United States.,Institute for Physical Science and Technology, University of Maryland, College Park, United States
| | - Peter N Devreotes
- Department of Cell Biology, Johns Hopkins University, Baltimore, United States
| | - John T Fourkas
- Institute for Physical Science and Technology, University of Maryland, College Park, United States.,Department of Chemistry & Biochemistry, University of Maryland, College Park, United States
| | - Wolfgang Losert
- Department of Physics, University of Maryland, College Park, United States.,Institute for Physical Science and Technology, University of Maryland, College Park, United States
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6
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Hoyer M, Crevenna AH, Kitel R, Willems K, Czub M, Dubin G, Van Dorpe P, Holak TA, Lamb DC. Analysis tools for single-monomer measurements of self-assembly processes. Sci Rep 2022; 12:4682. [PMID: 35304498 PMCID: PMC8933434 DOI: 10.1038/s41598-022-08245-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/22/2022] [Indexed: 11/29/2022] Open
Abstract
Protein assembly plays an important role throughout all phyla of life, both physiologically and pathologically. In particular, aggregation and polymerization of proteins are key-strategies that regulate cellular function. In recent years, methods to experimentally study the assembly process on a single-molecule level have been developed. This progress concomitantly has triggered the question of how to analyze this type of single-filament data adequately and what experimental conditions are necessary to allow a meaningful interpretation of the analysis. Here, we developed two analysis methods for single-filament data: the visitation analysis and the average-rate analysis. We benchmarked and compared both approaches with the classic dwell-time-analysis frequently used to study microscopic association and dissociation rates. In particular, we tested the limitations of each analysis method along the lines of the signal-to-noise ratio, the sampling rate, and the labeling efficiency and bleaching rate of the fluorescent dyes used in single-molecule fluorescence experiments. Finally, we applied our newly developed methods to study the monomer assembly of actin at the single-molecule-level in the presence of the class II nucleator Cappuccino and the WH2 repeats of Spire. For Cappuccino, our data indicated fast elongation circumventing a nucleation phase whereas, for Spire, we found that the four WH2 motifs are not sufficient to promote de novo nucleation of actin.
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Affiliation(s)
- Maria Hoyer
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany
| | - Alvaro H Crevenna
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany.,Epigenetics and Neurobiology Unit, EMBL Rome, Monterotondo, Italy
| | - Radoslaw Kitel
- Department of Organic Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Krakow, Poland.,Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387, Krakow, Poland
| | | | - Miroslawa Czub
- Department of Organic Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Krakow, Poland
| | - Grzegorz Dubin
- Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387, Krakow, Poland
| | | | - Tad A Holak
- Department of Organic Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Krakow, Poland
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany.
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7
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Structure and function of an atypical homodimeric actin capping protein from the malaria parasite. Cell Mol Life Sci 2022; 79:125. [PMID: 35132495 PMCID: PMC8821504 DOI: 10.1007/s00018-021-04032-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/28/2021] [Accepted: 11/09/2021] [Indexed: 11/27/2022]
Abstract
Apicomplexan parasites, such as Plasmodium spp., rely on an unusual actomyosin motor, termed glideosome, for motility and host cell invasion. The actin filaments are maintained by a small set of essential regulators, which provide control over actin dynamics in the different stages of the parasite life cycle. Actin filament capping proteins (CPs) are indispensable heterodimeric regulators of actin dynamics. CPs have been extensively characterized in higher eukaryotes, but their role and functional mechanism in Apicomplexa remain enigmatic. Here, we present the first crystal structure of a homodimeric CP from the malaria parasite and compare the homo- and heterodimeric CP structures in detail. Despite retaining several characteristics of a canonical CP, the homodimeric Plasmodium berghei (Pb)CP exhibits crucial differences to the canonical heterodimers. Both homo- and heterodimeric PbCPs regulate actin dynamics in an atypical manner, facilitating rapid turnover of parasite actin, without affecting its critical concentration. Homo- and heterodimeric PbCPs show partially redundant activities, possibly to rescue actin filament capping in life cycle stages where the β-subunit is downregulated. Our data suggest that the homodimeric PbCP also influences actin kinetics by recruiting lateral actin dimers. This unusual function could arise from the absence of a β-subunit, as the asymmetric PbCP homodimer lacks structural elements essential for canonical barbed end interactions suggesting a novel CP binding mode. These findings will facilitate further studies aimed at elucidating the precise actin filament capping mechanism in Plasmodium.
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8
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Lussier F, Schröter M, Diercks NJ, Jahnke K, Weber C, Frey C, Platzman I, Spatz JP. pH-Triggered Assembly of Endomembrane Multicompartments in Synthetic Cells. ACS Synth Biol 2022; 11:366-382. [PMID: 34889607 PMCID: PMC8787813 DOI: 10.1021/acssynbio.1c00472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Indexed: 11/29/2022]
Abstract
By using electrostatic interactions as driving force to assemble vesicles, the droplet-stabilized method was recently applied to reconstitute and encapsulate proteins, or compartments, inside giant unilamellar vesicles (GUVs) to act as minimal synthetic cells. However, the droplet-stabilized approach exhibits low production efficiency associated with the troublesome release of the GUVs from the stabilized droplets, corresponding to a major hurdle for the droplet-stabilized approach. Herein, we report the use of pH as a potential trigger to self-assemble droplet-stabilized GUVs (dsGUVs) by either bulk or droplet-based microfluidics. Moreover, pH enables the generation of compartmentalized GUVs with flexibility and robustness. By co-encapsulating pH-sensitive small unilamellar vesicles (SUVs), negatively charged SUVs, and/or proteins, we show that acidification of the droplets efficiently produces dsGUVs while sequestrating the co-encapsulated material. Most importantly, the pH-mediated assembly of dsGUVs significantly improves the production efficiency of free-standing GUVs (i.e., released from the stabilizing-droplets) compared to its previous implementation.
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Affiliation(s)
- Félix Lussier
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Martin Schröter
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Nicolas J. Diercks
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Kevin Jahnke
- Biophysical
Engineering Group, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Department
of Physics and Astronomy, Heidelberg University, D-69120 Heidelberg, Germany
| | - Cornelia Weber
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Christoph Frey
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Ilia Platzman
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
| | - Joachim P. Spatz
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, D-69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, D-69120 Heidelberg, Germany
- Max
Planck School Matter to Life, Jahnstraße 29, D-69120 Heidelberg, Germany
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9
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Abstract
The precise assembly and disassembly of actin filaments is required for several cellular processes, and their regulation has been scrutinized for decades. Twenty years ago, a handful of studies marked the advent of a new type of experiment to study actin dynamics: using optical microscopy to look at individual events, taking place on individual filaments in real time. Here, we summarize the main characteristics of this approach and how it has changed our ability to understand actin assembly dynamics. We also highlight some of its caveats and reflect on what we have learned over the past 20 years, leading us to propose a set of guidelines, which we hope will contribute to a better exploitation of this powerful tool.
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10
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Hoyer M, Crevenna AH, Correia JRC, Quezada AG, Lamb DC. Zero-mode waveguides visualize the first steps during gelsolin-mediated actin filament formation. Biophys J 2022; 121:327-335. [PMID: 34896371 PMCID: PMC8790234 DOI: 10.1016/j.bpj.2021.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 06/29/2021] [Accepted: 12/07/2021] [Indexed: 01/21/2023] Open
Abstract
Actin filament dynamics underlie key cellular processes. Although the elongation of actin filaments has been extensively studied, the mechanism of nucleation remains unclear. The micromolar concentrations needed for filament formation have prevented direct observation of nucleation dynamics on the single molecule level. To overcome this limitation, we have used the attoliter excitation volume of zero-mode waveguides to directly monitor the early steps of filament assembly. Immobilizing single gelsolin molecules as a nucleator at the bottom of the zero-mode waveguide, we could visualize the actin filament nucleation process. The process is surprisingly dynamic, and two distinct populations during gelsolin-mediated nucleation are observed. The two populations are defined by the stability of the actin dimers and determine whether elongation occurs. Furthermore, by using an inhibitor to block flattening, a conformational change in actin associated with filament formation, elongation was prevented. These observations indicate that a conformational transition and pathway competition determine the nucleation of gelsolin-mediated actin filament formation.
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Affiliation(s)
- Maria Hoyer
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany
| | - Alvaro H. Crevenna
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal,Corresponding author
| | - Jose Rafael Cabral Correia
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Andrea G. Quezada
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Don C. Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians University Munich, Munich, Germany,Corresponding author
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11
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Self-assembly of protein superstructures by physical interactions under cytoplasm-like conditions. Biophys J 2021; 120:2701-2709. [PMID: 34022233 DOI: 10.1016/j.bpj.2021.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/20/2021] [Accepted: 05/13/2021] [Indexed: 11/21/2022] Open
Abstract
The structure-driven assembly of multimeric protein complexes and the formation of intracellular phase-like protein condensates have been the subject of intense research. However, the assembly of larger superstructures comprising cellular components, such as protein nanoparticles driven by general physical rather than specific biochemical interactions, remains relatively uncharacterized. Here, we use gas vesicles (GVs)-genetically encoded protein nanoparticles that form ordered intracellular clusters-as a model system to study the forces driving multiparticle assembly under cytoplasm-like conditions. Our calculations and experimental results show that the ordered assembly of GVs can be achieved by screening their mutual electrostatic repulsion with electrolytes and creating a crowding force with dissolved macromolecules. The precise balance of these forces results in different packing configurations. Biomacromolecules such as polylysine and DNA are capable of driving GV clustering. These results provide basic insights into how physically driven interactions affect the formation of protein superstructures, offer guidance for manipulating nanoparticle assembly in cellular environments through synthetic biology methods, and inform research on the biotechnology applications of GVs.
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12
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Díaz-Martín RD, Valencia-Hernández JD, Betancourt-Lozano M, Yáñez-Rivera B. Changes in microtubule stability in zebrafish ( Danio rerio) embryos after glyphosate exposure. Heliyon 2021; 7:e06027. [PMID: 33532646 PMCID: PMC7829154 DOI: 10.1016/j.heliyon.2021.e06027] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 11/09/2020] [Accepted: 01/13/2021] [Indexed: 02/06/2023] Open
Abstract
Glyphosate, the most commonly used pesticide worldwide, blocks aromatic amino acid biosynthetic pathways and inhibits growth in plants. Although the specific mode of action of glyphosate in animals remains unclear, adverse effects during embryonic development have been reported, including epiboly delays, morphological alterations, and changes in central nervous system development and cardiogenesis. In this study, we suggest a possible toxicity mechanism for this herbicide related to changes in microtubule stability, which could alter the distribution and dynamics of cytoskeleton components. Using zebrafish embryos to evaluate in vivo effects of glyphosate exposure (5, 10, and 50 μg/ml), we found significant reductions in the levels of acetylated α-tubulin (50 μg/ml) and in the polymeric tubulin percentage in zebrafish embryos that had been exposed to 10 and 50 μg/ml glyphosate, without any changes in either the expression patterns of α-tubulin or the stability of actin filaments. These results indicate that high concentrations of glyphosate were associated with reduced levels of acetylated α-tubulin and altered microtubule stability, which may explain some of the neurotoxic and cardiotoxic effects that have been attributed to this herbicide.
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Affiliation(s)
- Rubén D Díaz-Martín
- Centro de Investigación en Alimentación y Desarrollo, A. C., Av. Sábalo-Cerritos s/n, Mazatlán, Sinaloa, 82100, Mexico
| | - Jesús D Valencia-Hernández
- Centro de Investigación en Alimentación y Desarrollo, A. C., Av. Sábalo-Cerritos s/n, Mazatlán, Sinaloa, 82100, Mexico
| | - Miguel Betancourt-Lozano
- Centro de Investigación en Alimentación y Desarrollo, A. C., Av. Sábalo-Cerritos s/n, Mazatlán, Sinaloa, 82100, Mexico
| | - Beatriz Yáñez-Rivera
- Centro de Investigación en Alimentación y Desarrollo, A. C., Av. Sábalo-Cerritos s/n, Mazatlán, Sinaloa, 82100, Mexico.,Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Ciudad de México, 03940, Mexico
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13
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Du MT, Zhu GL, Chen HZ, Han R. Actin filaments altered distribution in wheat (Triticum aestivum) "Bending Root" to respond to enhanced Ultraviolet-B radiation. BRAZ J BIOL 2020; 81:684-691. [PMID: 32935819 DOI: 10.1590/1519-6984.229774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/28/2020] [Indexed: 11/22/2022] Open
Abstract
Plants adjust their shoot growth to acclimate to changing environmental factors, such as to enhanced Ultraviolet-B (UV-B) radiation. However, people have ignored that plant roots can also respond to UV-B light. Here, we find the morphology curled wheat roots under UV-B radiation, that we call, "bending roots." The curly region is the transition zone of the root after observed at the cellular level. After exposed to enhanced UV-B radiation for 2 d (10.08 KJ/m2/d), cell size decreased and actin filaments gathered in wheat roots. We also find that H2O2 production increased and that content of the indole-3-acetic acid (IAA) increased remarkably. The pharmacological experiment revealed that actin filaments gathered and polymerized into bundles in the wheat root cells after irrigated H2O2 and IAA. These results indicated that actin filaments changed their distribution and formed the "bending root," which was related to H2O2 production and increase in IAA. Overall, actin filaments in wheat root cells could be a subcellular target of UV-B radiation, and its disruption determines root morphology.
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Affiliation(s)
- M T Du
- Shanxi Normal University, Higher Education Key Laboratory of Plant Molecular and Environment Stress Response, Linfen, Shanxi, China
| | - G L Zhu
- Ministry of Education of China, Yangzhou University, Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou, Jiangsu, China
| | - H Z Chen
- Shanxi Normal University, Higher Education Key Laboratory of Plant Molecular and Environment Stress Response, Linfen, Shanxi, China
| | - R Han
- Shanxi Normal University, Higher Education Key Laboratory of Plant Molecular and Environment Stress Response, Linfen, Shanxi, China
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14
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Alkalinization of the Synaptic Cleft during Excitatory Neurotransmission. J Neurosci 2020; 40:6267-6269. [PMID: 32801127 DOI: 10.1523/jneurosci.0914-20.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/20/2020] [Accepted: 07/05/2020] [Indexed: 11/21/2022] Open
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15
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Subramanian H, Brown J, Gatenby R. Prebiotic competition and evolution in self-replicating polynucleotides can explain the properties of DNA/RNA in modern living systems. BMC Evol Biol 2020; 20:75. [PMID: 32590933 PMCID: PMC7318430 DOI: 10.1186/s12862-020-01641-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 06/17/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We hypothesize prebiotic evolution of self-replicating macro-molecules (Alberts, Molecular biology of the cell, 2015; Orgel, Crit Rev Biochem Mol Biol 39:99-123, 2004; Hud, Nat Commun 9:5171) favoured the constituent nucleotides and biophysical properties observed in the RNA and DNA of modern organisms. Assumed initial conditions are a shallow tide pool, containing a racemic mix of diverse nucleotide monomers (Barks et al., Chembiochem 11:1240-1243, 2010; Krishnamurthy, Nat Commun 9:5175, 2018; Hirao, Curr Opin Chem Biol 10:622-627), subject to day/night thermal fluctuations (Piccirilli et al., Nature 343:33-37, 1990). Self-replication, like Polymerase Chain Reactions, followed as higher daytime thermal energy "melted" inter-strand hydrogen bonds causing strand separation while solar UV radiation increased prebiotic nucleobase formation (Szathmary, Proc Biol Sci 245:91-99, 1991; Materese et al., Astrobiology 17:761-770, 2017; Bera et al., Astrobiology 17:771-785, 2017). Lower night energies allowed free monomers to form hydrogen bonds with their template counterparts leading to daughter strand synthesis (Hirao, Biotechniques 40:711, 2006). RESULTS Evolutionary selection favoured increasing strand length to maximize auto-catalytic function in RNA and polymer stability in double stranded DNA (Krishnamurthy, Chemistry 24:16708-16715, 2018; Szathmary, Nat Rev Genet 4:995-1001, 2003). However, synthesis of the full daughter strand before daytime temperatures produced strand separation, longer polymer length required increased speed of self-replication. Computer simulations demonstrate optimal polynucleotide autocatalytic speed is achieved when the constituent nucleotides possess a left-right asymmetry that decreases the hydrogen bond kinetic barrier for the free nucleotide attachment to the template on one side and increases bond barrier on the other side preventing it from releasing prior to covalent bond formation. This phenomenon is similar to asymmetric kinetics observed during polymerization of the front and the back ends of linear cytoskeletal proteins such as actin and microtubules (Orgel, Nature 343:18-20, 1990; Henry, Curr Opin Chem Biol 7:727-733, 2003; Walker et al., J Cell Biol 108:931-937, 1989; Crevenna et al., J Biol Chem 288:12102-12113, 2013). Since rotation of the nucleotide would disrupt the asymmetry, the optimal nucleotides must form two or more hydrogen bonds with their counterpart on the template strand. All nucleotides in modern RNA and DNA have these predicted properties. Our models demonstrate these constraints on the properties of constituent monomers result in biophysical properties found in modern DNA and RNA including strand directionality, anti-parallel strand orientation, homochirality, quadruplet alphabet, and complementary base pairing. Furthermore, competition between RNA and DNA auto-replicators for 3 nucleotides in common permit states coexistence and possible cooperative interactions that could be incorporated into nascent living systems. CONCLUSION Our findings demonstrate the molecular properties of DNA/RNA could have emerged from Darwinian competition among macromolecular replicators that selected nucleotide monomers that maximized the speed of autocatalysis.
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Affiliation(s)
- Hemachander Subramanian
- Cancer Biology and Evolution Program, Tampa, FL, 33612, USA.,Integrated Mathematical Oncology Department, H. Lee Moffitt Cancer Center, 12902 Magnolia Dr, Tampa, FL, 33612, USA.,Present Address: Department of Physics, National Institute of Technology, Durgapur, West Bengal, India
| | - Joel Brown
- Cancer Biology and Evolution Program, Tampa, FL, 33612, USA.,Integrated Mathematical Oncology Department, H. Lee Moffitt Cancer Center, 12902 Magnolia Dr, Tampa, FL, 33612, USA
| | - Robert Gatenby
- Cancer Biology and Evolution Program, Tampa, FL, 33612, USA. .,Integrated Mathematical Oncology Department, H. Lee Moffitt Cancer Center, 12902 Magnolia Dr, Tampa, FL, 33612, USA.
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16
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Cantero M, Gutierrez BC, Cantiello HF. Actin filaments modulate electrical activity of brain microtubule protein two‐dimensional sheets. Cytoskeleton (Hoboken) 2020; 77:167-177. [DOI: 10.1002/cm.21596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 01/09/2023]
Affiliation(s)
- María Cantero
- Laboratorio de Canales IónicosInstituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD, UNSE‐CONICET) Santiago del Estero Argentina
| | - Brenda C. Gutierrez
- Laboratorio de Canales IónicosInstituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD, UNSE‐CONICET) Santiago del Estero Argentina
| | - Horacio F. Cantiello
- Laboratorio de Canales IónicosInstituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD, UNSE‐CONICET) Santiago del Estero Argentina
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17
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The many implications of actin filament helicity. Semin Cell Dev Biol 2019; 102:65-72. [PMID: 31862222 DOI: 10.1016/j.semcdb.2019.10.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/15/2019] [Accepted: 10/31/2019] [Indexed: 12/17/2022]
Abstract
One of the best known features of actin filaments is their helical structure. A number of essential properties emerge from this molecular arrangement of actin subunits. Here, we give an overview of the mechanical and biochemical implications of filament helicity, at different scales. In particular, a number of recent studies have highlighted the role of filament helicity in the adaptation to and the generation of mechanical torsion, and in the modulation of the filament's interaction with very different actin-binding proteins (such as myosins, cross-linkers, formins, and cofilin). Helicity can thus be seen as a key factor for the regulation of actin assembly, and as a link between biochemical regulators and their mechanical context. In addition, actin filament helicity appears to play an essential role in the establishment of chirality at larger scales, up to the organismal scale. Altogether, helicity appears to be an essential feature contributing to the regulation of actin assembly dynamics, and to actin's ability to organize cells at a larger scale.
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18
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Bandyopadhyay P, Gupta-Bhaya P. A comparative evaluation of pair correlation functions for a highly asymmetric electrolyte with mono and divalent counterions from integral equation theory in hypernetted chain (HNC) approximation and Monte Carlo simulation. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.136664] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Abstract
Brownian dynamics (BD) is a technique for carrying out computer simulations of physical systems that are driven by thermal fluctuations. Biological systems at the macromolecular and cellular level, while falling in the gap between well-established atomic-level models and continuum models, are especially suitable for such simulations. We present a brief history, examples of important biological processes that are driven by thermal motion, and those that have been profitably studied by BD. We also present some of the challenges facing developers of algorithms and software, especially in the attempt to simulate larger systems more accurately and for longer times.
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Affiliation(s)
- Gary A Huber
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0340, USA.,Department of Pharmocology, University of California San Diego, La Jolla, CA 92093-0636, USA
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0340, USA.,Department of Pharmocology, University of California San Diego, La Jolla, CA 92093-0636, USA
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20
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Oheim M, Salomon A, Weissman A, Brunstein M, Becherer U. Calibrating Evanescent-Wave Penetration Depths for Biological TIRF Microscopy. Biophys J 2019; 117:795-809. [PMID: 31439287 DOI: 10.1016/j.bpj.2019.07.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 07/08/2019] [Accepted: 07/23/2019] [Indexed: 11/28/2022] Open
Abstract
Roughly half of a cell's proteins are located at or near the plasma membrane. In this restricted space, the cell senses its environment, signals to its neighbors, and exchanges cargo through exo- and endocytotic mechanisms. Ligands bind to receptors, ions flow across channel pores, and transmitters and metabolites are transported against concentration gradients. Receptors, ion channels, pumps, and transporters are the molecular substrates of these biological processes, and they constitute important targets for drug discovery. Total internal reflection fluorescence (TIRF) microscopy suppresses the background from the cell's deeper layers and provides contrast for selectively imaging dynamic processes near the basal membrane of live cells. The optical sectioning of TIRF is based on the excitation confinement of the evanescent wave generated at the glass/cell interface. How deep the excitation light actually penetrates the sample is difficult to know, making the quantitative interpretation of TIRF data problematic. Nevertheless, many applications like superresolution microscopy, colocalization, Förster resonance energy transfer, near-membrane fluorescence recovery after photobleaching, uncaging or photoactivation/switching as well as single-particle tracking require the quantitative interpretation of evanescent-wave-excited images. Here, we review existing techniques for characterizing evanescent fields, and we provide a roadmap for comparing TIRF data across images, experiments, and laboratories.
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Affiliation(s)
- Martin Oheim
- Université de Paris, CNRS, Saints-Pères Paris Institute for the Neurosciences (SPPIN), Paris, France.
| | - Adi Salomon
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel
| | - Adam Weissman
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel
| | - Maia Brunstein
- Université de Paris, CNRS, Saints-Pères Paris Institute for the Neurosciences (SPPIN), Paris, France; Chaire d'Excellence Junior, Université Sorbonne Paris Cité, Paris, France
| | - Ute Becherer
- Saarland University, Department of Physiology, CIPMM, Homburg/Saar, Germany
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21
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Actin stabilizing compounds show specific biological effects due to their binding mode. Sci Rep 2019; 9:9731. [PMID: 31278311 PMCID: PMC6611809 DOI: 10.1038/s41598-019-46282-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/26/2019] [Indexed: 11/08/2022] Open
Abstract
Actin binding compounds are widely used tools in cell biology. We compare the biological and biochemical effects of miuraenamide A and jasplakinolide, a structurally related prototypic actin stabilizer. Though both compounds have similar effects on cytoskeletal morphology and proliferation, they affect migration and transcription in a distinctive manner, as shown by a transcriptome approach in endothelial cells. In vitro, miuraenamide A acts as an actin nucleating, F-actin polymerizing and stabilizing compound, just like described for jasplakinolide. However, in contrast to jasplakinolide, miuraenamide A competes with cofilin, but not gelsolin or Arp2/3 for binding to F-actin. We propose a binding mode of miuraenamide A, explaining both its similarities and its differences to jasplakinolide. Molecular dynamics simulations suggest that the bromophenol group of miurenamide A interacts with residues Tyr133, Tyr143, and Phe352 of actin. This shifts the D-loop of the neighboring actin, creating tighter packing of the monomers, and occluding the binding site of cofilin. Since relatively small changes in the molecular structure give rise to this selectivity, actin binding compounds surprisingly are promising scaffolds for creating actin binders with specific functionality instead of just "stabilizers".
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22
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Glausier JR, Konanur A, Lewis DA. Factors Affecting Ultrastructural Quality in the Prefrontal Cortex of the Postmortem Human Brain. J Histochem Cytochem 2019; 67:185-202. [PMID: 30562121 PMCID: PMC6393839 DOI: 10.1369/0022155418819481] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 11/19/2018] [Indexed: 12/13/2022] Open
Abstract
Electron microscopy (EM) studies of the postmortem human brain provide a level of resolution essential for understanding brain function in both normal and disease states. However, processes associated with death can impair the cellular and organelle ultrastructural preservation required for quantitative EM studies. Although postmortem interval (PMI), the time between death and preservation of tissue, is thought to be the most influential factor of ultrastructural quality, numerous other factors may also influence tissue preservation. The goal of the present study was to assess the effects of pre- and postmortem factors on multiple components of ultrastructure in the postmortem human prefrontal cortex. Tissue samples from 30 subjects were processed using standard EM histochemistry. The primary dependent measure was number of identifiable neuronal profiles, and secondary measures included presence and/or integrity of synapses, mitochondria, and myelinated axonal fibers. Number of identifiable neuronal profiles was most strongly affected by the interaction of PMI and pH, such that short PMIs and neutral pH values predicted the best preservation. Secondary measures were largely unaffected by pre- and postmortem factors. Together, these data indicate that distinct components of the neuropil are differentially affected by PMI and pH in postmortem human brain.
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Affiliation(s)
| | - Anisha Konanur
- The Dietrich School of Arts & Sciences, University of Pittsburgh
| | - David A. Lewis
- Department of Psychiatry, University of Pittsburgh
- Department of Neuroscience, University of Pittsburgh
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23
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Wioland H, Jegou A, Romet-Lemonne G. Quantitative Variations with pH of Actin Depolymerizing Factor/Cofilin's Multiple Actions on Actin Filaments. Biochemistry 2018; 58:40-47. [PMID: 30499293 PMCID: PMC6358128 DOI: 10.1021/acs.biochem.8b01001] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
![]()
Actin
depolymerizing factor (ADF)/cofilin is the main protein family
promoting the disassembly of actin filaments, which is essential for
numerous cellular functions. ADF/cofilin proteins disassemble actin
filaments through different reactions, as they bind to their sides,
sever them, and promote the depolymerization of the resulting ADF/cofilin-saturated
filaments. Moreover, the efficiency of ADF/cofilin is known to be
very sensitive to pH. ADF/cofilin thus illustrates two challenges
in actin biochemistry: separating the different regulatory actions
of a single protein and characterizing them as a function of specific
biochemical conditions. Here, we investigate the different reactions
of ADF/cofilin on actin filaments, at four different pH values ranging
from 6.6 to 7.8, using single-filament microfluidics techniques. We
show that decreasing the pH decreases the effective filament severing
rate by increasing the rate at which filaments become saturated by
ADF/cofilin, thereby reducing the number of ADF/cofilin domain boundaries,
where severing can occur. The severing rate per domain boundary, however,
remains unchanged at different pH values. The ADF/cofilin-decorated
filaments (“cofilactin” filaments) depolymerize from
both ends. We show here that, at physiological pH (7.0–7.4),
the pointed end depolymerization of cofilactin filaments is barely
faster than that of bare filaments. In contrast, cofilactin barbed
ends undergo an “unstoppable” depolymerization (depolymerizing
for minutes despite the presence of free actin monomers and capping
protein in solution), throughout our pH range. We thus show that,
at physiological pH, the main contribution of ADF/cofilin to filament
depolymerization is at the barbed end.
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Affiliation(s)
- Hugo Wioland
- Institut Jacques Monod, CNRS, Université Paris-Diderot , 75013 Paris , France
| | - Antoine Jegou
- Institut Jacques Monod, CNRS, Université Paris-Diderot , 75013 Paris , France
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24
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Zhou HX, Pang X. Electrostatic Interactions in Protein Structure, Folding, Binding, and Condensation. Chem Rev 2018; 118:1691-1741. [PMID: 29319301 DOI: 10.1021/acs.chemrev.7b00305] [Citation(s) in RCA: 454] [Impact Index Per Article: 75.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Charged and polar groups, through forming ion pairs, hydrogen bonds, and other less specific electrostatic interactions, impart important properties to proteins. Modulation of the charges on the amino acids, e.g., by pH and by phosphorylation and dephosphorylation, have significant effects such as protein denaturation and switch-like response of signal transduction networks. This review aims to present a unifying theme among the various effects of protein charges and polar groups. Simple models will be used to illustrate basic ideas about electrostatic interactions in proteins, and these ideas in turn will be used to elucidate the roles of electrostatic interactions in protein structure, folding, binding, condensation, and related biological functions. In particular, we will examine how charged side chains are spatially distributed in various types of proteins and how electrostatic interactions affect thermodynamic and kinetic properties of proteins. Our hope is to capture both important historical developments and recent experimental and theoretical advances in quantifying electrostatic contributions of proteins.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.,Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
| | - Xiaodong Pang
- Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
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25
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Kedrov A, Wickles S, Crevenna AH, van der Sluis EO, Buschauer R, Berninghausen O, Lamb DC, Beckmann R. Structural Dynamics of the YidC:Ribosome Complex during Membrane Protein Biogenesis. Cell Rep 2017; 17:2943-2954. [PMID: 27974208 PMCID: PMC5186731 DOI: 10.1016/j.celrep.2016.11.059] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 10/26/2016] [Accepted: 11/20/2016] [Indexed: 01/30/2023] Open
Abstract
Members of the YidC/Oxa1/Alb3 family universally facilitate membrane protein biogenesis, via mechanisms that have thus far remained unclear. Here, we investigated two crucial functional aspects: the interaction of YidC with ribosome:nascent chain complexes (RNCs) and the structural dynamics of RNC-bound YidC in nanodiscs. We observed that a fully exposed nascent transmembrane domain (TMD) is required for high-affinity YidC:RNC interactions, while weaker binding may already occur at earlier stages of translation. YidC efficiently catalyzed the membrane insertion of nascent TMDs in both fluid and gel phase membranes. Cryo-electron microscopy and fluorescence analysis revealed a conformational change in YidC upon nascent chain insertion: the essential TMDs 2 and 3 of YidC were tilted, while the amphipathic helix EH1 relocated into the hydrophobic core of the membrane. We suggest that EH1 serves as a mechanical lever, facilitating a coordinated movement of YidC TMDs to trigger the release of nascent chains into the membrane.
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Affiliation(s)
- Alexej Kedrov
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany.
| | - Stephan Wickles
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany
| | - Alvaro H Crevenna
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), the NanoSystems Initiative Munich (NIM), Ludwig-Maximilians-University Munich, Butenandtstrasse 11, Munich 81377, Germany
| | - Eli O van der Sluis
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany
| | - Robert Buschauer
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany
| | - Otto Berninghausen
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), the NanoSystems Initiative Munich (NIM), Ludwig-Maximilians-University Munich, Butenandtstrasse 11, Munich 81377, Germany; Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-University, Butenandtstrasse 5-13, Munich 81377, Germany
| | - Roland Beckmann
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich 81377, Germany; Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilians-University, Butenandtstrasse 5-13, Munich 81377, Germany.
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26
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O’Dea S, Annibaldi V, Gallagher L, Mulholland J, Molloy EL, Breen CJ, Gilbert JL, Martin DS, Maguire M, Curry FR. Vector-free intracellular delivery by reversible permeabilization. PLoS One 2017; 12:e0174779. [PMID: 28358921 PMCID: PMC5373627 DOI: 10.1371/journal.pone.0174779] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/15/2017] [Indexed: 02/06/2023] Open
Abstract
Despite advances in intracellular delivery technologies, efficient methods are still required that are vector-free, can address a wide range of cargo types and can be applied to cells that are difficult to transfect whilst maintaining cell viability. We have developed a novel vector-free method that uses reversible permeabilization to achieve rapid intracellular delivery of cargos with varying composition, properties and size. A permeabilizing delivery solution was developed that contains a low level of ethanol as the permeabilizing agent. Reversal of cell permeabilization is achieved by temporally and volumetrically controlling the contact of the target cells with this solution. Cells are seeded in conventional multi-well plates. Following removal of the supernatant, the cargo is mixed with the delivery solution and applied directly to the cells using an atomizer. After a short incubation period, permeabilization is halted by incubating the cells in a phosphate buffer saline solution that dilutes the ethanol and is non-toxic to the permeabilized cells. Normal culture medium is then added. The procedure lasts less than 5 min. With this method, proteins, mRNA, plasmid DNA and other molecules have been delivered to a variety of cell types, including primary cells, with low toxicity and cargo functionality has been confirmed in proof-of-principle studies. Co-delivery of different cargo types has also been demonstrated. Importantly, delivery occurs by diffusion directly into the cytoplasm in an endocytic-independent manner. Unlike some other vector-free methods, adherent cells are addressed in situ without the need for detachment from their substratum. The method has also been adapted to address suspension cells. This delivery method is gentle yet highly reproducible, compatible with high throughput and automated cell-based assays and has the potential to enable a broad range of research, drug discovery and clinical applications.
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Affiliation(s)
- Shirley O’Dea
- Avectas Ltd., Maynooth, Co. Kildare, Ireland
- * E-mail:
| | | | | | | | | | | | | | | | | | - Fitz-Roy Curry
- Avectas Ltd., Maynooth, Co. Kildare, Ireland
- Department of Physiology & Membrane Biology, University of California, Davis, California, United States of America
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27
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Oda T, Aihara T, Wakabayashi K. Early nucleation events in the polymerization of actin, probed by time-resolved small-angle x-ray scattering. Sci Rep 2016; 6:34539. [PMID: 27775032 PMCID: PMC5075782 DOI: 10.1038/srep34539] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/15/2016] [Indexed: 11/30/2022] Open
Abstract
Nucleators generating new F-actin filaments play important roles in cell activities. Detailed information concerning the events involved in nucleation of actin alone in vitro is fundamental to understanding these processes, but such information has been hard to come by. We addressed the early process of salt-induced polymerization of actin using the time-resolved synchrotron small-angle X-ray scattering (SAXS). Actin molecules in low salt solution maintain a monomeric state by an electrostatic repulsive force between molecules. On mixing with salts, the repulsive force was rapidly screened, causing an immediate formation of many of non-polymerizable dimers. SAXS kinetic analysis revealed that tetramerization gives the highest energetic barrier to further polymerization, and the major nucleation is the formation of helical tetramers. Filaments start to grow rapidly with the formation of pentamers. These findings suggest an acceleration mechanism of actin assembly by a variety of nucleators in cells.
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Affiliation(s)
- Toshiro Oda
- X-ray Structural Analysis Research Team, RIKEN SPring-8 Center, RIKEN Harima Institute, Kouto 1-1, Sayo, Hyogo 679-5148, Japan
| | - Tomoki Aihara
- X-ray Structural Analysis Research Team, RIKEN SPring-8 Center, RIKEN Harima Institute, Kouto 1-1, Sayo, Hyogo 679-5148, Japan
| | - Katsuzo Wakabayashi
- X-ray Structural Analysis Research Team, RIKEN SPring-8 Center, RIKEN Harima Institute, Kouto 1-1, Sayo, Hyogo 679-5148, Japan.,Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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28
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Functional and Proteomic Investigations Reveal Major Royal Jelly Protein 1 Associated with Anti-hypertension Activity in Mouse Vascular Smooth Muscle Cells. Sci Rep 2016; 6:30230. [PMID: 27444336 PMCID: PMC4957218 DOI: 10.1038/srep30230] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/01/2016] [Indexed: 12/14/2022] Open
Abstract
Vascular smooth muscle cells (VSMCs) are a major cell type of the arterial wall and their functionality is associated with blood pressure regulation. Although royal jelly (RJ) has reported effects on anti-hypertension, the mechanism of blood pressure regulation by major royal jelly protein 1 (MRJP1), the most abundant RJ protein, is still unknown. The mrjp1 gene was inserted into mouse VSMCs to investigate how MRJP1 influences VSMC functionality by functional and proteomic analysis. The expression of MRJP1 in VSMCs significantly reduced cell contraction, migration, and proliferation, suggesting a potential role in decreasing hypertension via action on VSMCs. These anti-hypertension activities were further observed in the changes of the proteome setting of mouse VSMCs. Among 675 different proteins after MRJP1 expression, 646 were down-regulated and significantly enriched in pathways implicated in VSMC contraction and migration, which suggest MRJP1 lowers VSMC contraction and migration by inhibiting muscle filament movement. The down-regulated proteins also enriched pathways in proliferation, indicating that MRJP1 hinders VSMC proliferation by reducing the supply of energy and genetic material. This is the first report integrating MRJP1 into VSMC, revealing the function and mechanism correlated with anti-hypertensive activity. This offers a therapeutic potential to control hypertension by gene-therapy using bee-products.
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Characterization of Actin Filament Dynamics during Mitosis in Wheat Protoplasts under UV-B Radiation. Sci Rep 2016; 6:20115. [PMID: 26823006 PMCID: PMC4731756 DOI: 10.1038/srep20115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 12/24/2015] [Indexed: 12/26/2022] Open
Abstract
Enhanced ultraviolet-B (UV-B) radiation is caused by the thinning ozone and affects photosynthesis and crop yield. Recently, UV-B radiation has been considered as an environmental signal that regulates plant growth. Elucidating the downstream effectors in UV-B-triggered pathways is of particular interest. Previous studies have shown that actin filaments (AFs) play many roles during cell physiological processes. However, the underlying response of AFs to UV-B radiation remains unclear. In this study, wheat protoplasts were isolated from 7-d-old leaves. The dynamics of AFs during mitosis were observed under different treatments. The protoplasts were treated with UV-B radiation, cytochalasin B (CB) and jasplakinolide (JAS). Ph-FITC labelling results revealed typical actin filament structures in the control group; AFs were rearranged under UV-B radiation. AFs polymerized into bundles during interphase, the preprophase band (PPB) structure was destroyed during prophase, and the AFs gathered into plaques during metaphase in response to UV-B radiation. During anaphase and telophase, the distribution of AFs was dispersed. Pharmacologic experiments revealed that CB induced apoptosis and JAS induced nuclear division without cytokinesis in wheat protoplasts. These results indicated that AFs respond to UV-B radiation during mitosis, supplying evidence of UV-B signal transduction in plants.
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Yigit C, Heyda J, Dzubiella J. Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions. J Chem Phys 2015; 143:064904. [DOI: 10.1063/1.4928077] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Cemil Yigit
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
- Helmholtz Virtual Institute “Multifunctional Biomaterials for Medicine,” 14513 Teltow, Germany
- Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Jan Heyda
- Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6, Czech Republic
| | - Joachim Dzubiella
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
- Helmholtz Virtual Institute “Multifunctional Biomaterials for Medicine,” 14513 Teltow, Germany
- Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
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Geng Y, Kedrov A, Caumanns JJ, Crevenna AH, Lamb DC, Beckmann R, Driessen AJM. Role of the Cytosolic Loop C2 and the C Terminus of YidC in Ribosome Binding and Insertion Activity. J Biol Chem 2015; 290:17250-61. [PMID: 26023232 DOI: 10.1074/jbc.m115.650309] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Indexed: 11/06/2022] Open
Abstract
Members of the YidC/Oxa1/Alb3 protein family mediate membrane protein insertion, and this process is initiated by the assembly of YidC·ribosome nascent chain complexes at the inner leaflet of the lipid bilayer. The positively charged C terminus of Escherichia coli YidC plays a significant role in ribosome binding but is not the sole determinant because deletion does not completely abrogate ribosome binding. The positively charged cytosolic loops C1 and C2 of YidC may provide additional docking sites. We performed systematic sequential deletions within these cytosolic domains and studied their effect on the YidC insertase activity and interaction with translation-stalled (programmed) ribosome. Deletions within loop C1 strongly affected the activity of YidC in vivo but did not influence ribosome binding or substrate insertion, whereas loop C2 appeared to be involved in ribosome binding. Combining the latter deletion with the removal of the C terminus of YidC abolished YidC-mediated insertion. We propose that these two regions play an crucial role in the formation and stabilization of an active YidC·ribosome nascent chain complex, allowing for co-translational membrane insertion, whereas loop C1 may be involved in the downstream chaperone activity of YidC or in other protein-protein interactions.
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Affiliation(s)
- Yanping Geng
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | | | - Joseph J Caumanns
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Alvaro H Crevenna
- the Physical Chemistry, Department for Chemistry, Center for Nanoscience, the NanoSystems Initiative Munich and the Center for Integrated Protein Science Munich, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Don C Lamb
- the Physical Chemistry, Department for Chemistry, Center for Nanoscience, the NanoSystems Initiative Munich and the Center for Integrated Protein Science Munich, Ludwig-Maximilians-University, 81377 Munich, Germany
| | | | - Arnold J M Driessen
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands,
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Crevenna AH, Arciniega M, Dupont A, Mizuno N, Kowalska K, Lange OF, Wedlich-Söldner R, Lamb DC. Side-binding proteins modulate actin filament dynamics. eLife 2015; 4. [PMID: 25706231 PMCID: PMC4375888 DOI: 10.7554/elife.04599] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 02/20/2015] [Indexed: 01/10/2023] Open
Abstract
Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of filaments to polymerize and depolymerize at their ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. In this study, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by the binding of proteins to the lateral filament surface. We also show that the pointed-end has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of flexibility as well as effects on fragmentation and growth suggest that the observed kinetic diversity arises from structural alteration. Tuning elongation kinetics by exploiting the malleability of the filament structure may be a ubiquitous mechanism to generate a rich variety of cellular actin dynamics. DOI:http://dx.doi.org/10.7554/eLife.04599.001 Actin is one of the most abundant proteins in cells. It forms networks of filaments that provide structural support and generate the forces needed for cell movement, division, and many other processes in cells. Filaments of actin continuously change in length as actin molecules are added or removed at the ends. One end of an actin filament—called the barbed-end—grows much faster than the other, known as the pointed-end. Many other proteins also help the actin filaments to form. Some of these proteins bind to the ends of the filaments, where they directly control the growth of the filaments. Other proteins bind along the length of the filaments, but how these ‘side-binding’ proteins influence the growth of filaments is not clear. In this study, Crevenna et al. used a technique called ‘total internal reflection fluorescence (TIRF) microscopy’ to study how several side-binding proteins affect the growth of actin filaments in an artificial system. The growth of the barbed-ends was strongly influenced by which side-binding protein was interacting with the filament. For example, the barbed-end grew rapidly when a protein called VASP was present but grew more slowly in the presence of the protein α-actinin. Although the growth at the pointed-end was generally slow and sporadic, the side-binding proteins also had noticeable effects. Crevenna et al. found that when the side-binding proteins were present at low levels, filament growth was similar for all proteins studied. It was only when the proteins were present at higher levels that the growth of the actin filaments was altered depending on the specific side-binding protein present. One side-binding protein called α-actinin also altered the shape of the actin filament so that when it was present at high levels, the filaments curved in a particular direction. Together, these results suggest that the growth, structure, and flexibility of actin filaments can be strongly influenced by the various proteins that bind along the length of the filaments. The next challenges are to understand the precise details of how these side-binding proteins are able to alter the growth and shape of actin and investigate how they influence other processes that control the structure of actin networks in cells. DOI:http://dx.doi.org/10.7554/eLife.04599.002
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Affiliation(s)
- Alvaro H Crevenna
- Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.,Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Marcelino Arciniega
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Chemistry, Technische Universität München, Garching, Germany
| | - Aurélie Dupont
- Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.,NanoSystems Initiative Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Naoko Mizuno
- Cellular and Membrane Trafficking, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Kaja Kowalska
- Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Oliver F Lange
- Department of Chemistry, Technische Universität München, Garching, Germany.,Biomolecular NMR and Munich Center for Integrated Protein Science, Technische Universität München, Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Roland Wedlich-Söldner
- Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany.,Institute of Cell Dynamics and Imaging, Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Münster, Germany
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.,NanoSystems Initiative Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
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Affiliation(s)
- Fred Chang
- Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, New York 10032;
| | - Nicolas Minc
- Institut Jacques Monod, UMR7592 CNRS, 75205 Paris cedex 13, France;
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Venter G, Oerlemans FTJJ, Wijers M, Willemse M, Fransen JAM, Wieringa B. Glucose controls morphodynamics of LPS-stimulated macrophages. PLoS One 2014; 9:e96786. [PMID: 24796786 PMCID: PMC4010488 DOI: 10.1371/journal.pone.0096786] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 04/11/2014] [Indexed: 12/12/2022] Open
Abstract
Macrophages constantly undergo morphological changes when quiescently surveying the tissue milieu for signs of microbial infection or damage, or after activation when they are phagocytosing cellular debris or foreign material. These morphofunctional alterations require active actin cytoskeleton remodeling and metabolic adaptation. Here we analyzed RAW 264.7 and Maf-DKO macrophages as models to study whether there is a specific association between aspects of carbohydrate metabolism and actin-based processes in LPS-stimulated macrophages. We demonstrate that the capacity to undergo LPS-induced cell shape changes and to phagocytose complement-opsonized zymosan (COZ) particles does not depend on oxidative phosphorylation activity but is fueled by glycolysis. Different macrophage activities like spreading, formation of cell protrusions, as well as phagocytosis of COZ, were thereby strongly reliant on the presence of low levels of extracellular glucose. Since global ATP production was not affected by rewiring of glucose catabolism and inhibition of glycolysis by 2-deoxy-D-glucose and glucose deprivation had differential effects, our observations suggest a non-metabolic role for glucose in actin cytoskeletal remodeling in macrophages, e.g. via posttranslational modification of receptors or signaling molecules, or other effects on the machinery that drives actin cytoskeletal changes. Our findings impute a decisive role for the nutrient state of the tissue microenvironment in macrophage morphodynamics.
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Affiliation(s)
- Gerda Venter
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Frank T. J. J. Oerlemans
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mietske Wijers
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Marieke Willemse
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Jack A. M. Fransen
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Bé Wieringa
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
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Heath G, Johnson B, Olmsted P, Connell S, Evans S. Actin assembly at model-supported lipid bilayers. Biophys J 2013; 105:2355-65. [PMID: 24268147 PMCID: PMC3838754 DOI: 10.1016/j.bpj.2013.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/25/2013] [Accepted: 10/08/2013] [Indexed: 01/07/2023] Open
Abstract
We report on the use of supported lipid bilayers to reveal dynamics of actin polymerization from a nonpolymerizing subphase via cationic phospholipids. Using varying fractions of charged lipid, lipid mobility, and buffer conditions, we show that dynamics at the nanoscale can be used to control the self-assembly of these structures. In the case of fluid-phase lipid bilayers, the actin adsorbs to form a uniform two-dimensional layer with complete surface coverage whereas gel-phase bilayers induce a network of randomly oriented actin filaments, of lower coverage. Reducing the pH increased the polymerization rate, the number of nucleation events, and the total coverage of actin. A model of the adsorption/diffusion process is developed to provide a description of the experimental data and shows that, in the case of fluid-phase bilayers, polymerization arises equally due to the adsorption and diffusion of surface-bound monomers and the addition of monomers directly from the solution phase. In contrast, in the case of gel-phase bilayers, polymerization is dominated by the addition of monomers from solution. In both cases, the filaments are stable for long times even when the G-actin is removed from the supernatant-making this a practical approach for creating stable lipid-actin systems via self-assembly.
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Affiliation(s)
| | | | | | | | - Stephen D. Evans
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom
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37
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Carlier MF, Pernier J, Avvaru BS. Control of actin filament dynamics at barbed ends by WH2 domains: From capping to permissive and processive assembly. Cytoskeleton (Hoboken) 2013; 70:540-9. [DOI: 10.1002/cm.21124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/27/2013] [Accepted: 07/01/2013] [Indexed: 01/01/2023]
Affiliation(s)
| | - Julien Pernier
- Cytoskeleton Dynamics and Motility Team; LEBS; CNRS; Gif-Sur-Yvette France
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