1
|
Wu H, Li Z. A new dual-thickness semi-transparent beamstop for small-angle X-ray scattering. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:1197-1208. [PMID: 39182204 PMCID: PMC11371043 DOI: 10.1107/s1600577524007392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2024] [Accepted: 07/24/2024] [Indexed: 08/27/2024]
Abstract
An innovative dual-thickness semi-transparent beamstop designed to enhance the performance of small-angle X-ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher-order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high-precision SAXS experiments.
Collapse
Affiliation(s)
- Haijuan Wu
- Beijing Synchrotron Radiation Facility, Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049People’s Republic of China
- College of Nuclear Science and TechnologyUniversity of Chinese Academy of SciencesBeijing100049People’s Republic of China
| | - Zhihong Li
- Beijing Synchrotron Radiation Facility, Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049People’s Republic of China
| |
Collapse
|
2
|
Lin J, Bjørk PK, Kolte MV, Poulsen E, Dedic E, Drace T, Andersen SU, Nadzieja M, Liu H, Castillo-Michel H, Escudero V, González-Guerrero M, Boesen T, Pedersen JS, Stougaard J, Andersen KR, Reid D. Zinc mediates control of nitrogen fixation via transcription factor filamentation. Nature 2024; 631:164-169. [PMID: 38926580 PMCID: PMC11222152 DOI: 10.1038/s41586-024-07607-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 05/24/2024] [Indexed: 06/28/2024]
Abstract
Plants adapt to fluctuating environmental conditions by adjusting their metabolism and gene expression to maintain fitness1. In legumes, nitrogen homeostasis is maintained by balancing nitrogen acquired from soil resources with nitrogen fixation by symbiotic bacteria in root nodules2-8. Here we show that zinc, an essential plant micronutrient, acts as an intracellular second messenger that connects environmental changes to transcription factor control of metabolic activity in root nodules. We identify a transcriptional regulator, FIXATION UNDER NITRATE (FUN), which acts as a sensor, with zinc controlling the transition between an inactive filamentous megastructure and an active transcriptional regulator. Lower zinc concentrations in the nodule, which we show occur in response to higher levels of soil nitrate, dissociates the filament and activates FUN. FUN then directly targets multiple pathways to initiate breakdown of the nodule. The zinc-dependent filamentation mechanism thus establishes a concentration readout to adapt nodule function to the environmental nitrogen conditions. In a wider perspective, these results have implications for understanding the roles of metal ions in integration of environmental signals with plant development and optimizing delivery of fixed nitrogen in legume crops.
Collapse
Affiliation(s)
- Jieshun Lin
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
| | - Peter K Bjørk
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Marie V Kolte
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Emil Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Emil Dedic
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Taner Drace
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Stig U Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Marcin Nadzieja
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Huijun Liu
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Viviana Escudero
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA/CSIC), Universidad Politécnica de Madrid, Pozuelo de Alarcón, Spain
| | - Manuel González-Guerrero
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA/CSIC), Universidad Politécnica de Madrid, Pozuelo de Alarcón, Spain
- Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas. Universidad Politécnica de Madrid, Madrid, Spain
| | - Thomas Boesen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Jens Stougaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Kasper R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
| | - Dugald Reid
- La Trobe Institute for Sustainable Agriculture and Food (LISAF), La Trobe University, Melbourne, Victoria, Australia.
- Department of Animal, Plant and Soil Sciences, School of Agriculture Bioscience and Environment, La Trobe University, Melbourne, Victoria, Australia.
| |
Collapse
|
3
|
Brodszkij E, Ryberg C, Lyons JA, Juhl DW, Nielsen NC, Sigalas NI, Lyulin AV, Pedersen JS, Städler B. Poly(Sitosterol)-Based Hydrophobic Blocks in Amphiphilic Block Copolymers for the Assembly of Hybrid Vesicles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401934. [PMID: 38860565 DOI: 10.1002/smll.202401934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/19/2024] [Indexed: 06/12/2024]
Abstract
Amphiphilic block copolymer and lipids can be assembled into hybrid vesicles (HVs), which are an alternative to liposomes and polymersomes. Block copolymers that have either poly(sitostryl methacrylate) or statistical copolymers of sitosteryl methacrylate and butyl methacrylate as the hydrophobic part and a poly(carboxyethyl acrylate) hydrophilic segment are synthesized and characterized. These block copolymers assemble into small HVs with soybean L-α-phosphatidylcholine (soyPC), confirmed by electron microscopy and small-angle X-ray scattering. The membrane's hybrid nature is illustrated by fluorescence resonance energy transfer between labeled building blocks. The membrane packing, derived from spectra when using Laurdan as an environmentally sensitive fluorescent probe, is comparable between small HVs and the corresponding liposomes with molecular sitosterol, although the former show indications of transmembrane asymmetry. Giant HVs with homogenous distribution of the block copolymers and soyPC in their membranes are assembled using the electroformation method. The lateral diffusion of both building blocks is slowed down in giant HVs with higher block copolymer content, but their permeability toward (6)-carboxy-X-rhodamine is higher compared to giant vesicles made of soyPC and molecular sitosterol. This fundamental effort contributes to the rapidly expanding understanding of the integration of natural membrane constituents with designed synthetic compounds to form hybrid membranes.
Collapse
Affiliation(s)
- Edit Brodszkij
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
| | - Cecilie Ryberg
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
| | - Joseph A Lyons
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, Aarhus, 8000, Denmark
| | - Dennis Wilkens Juhl
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
| | - Niels Chr Nielsen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus, 8000, Denmark
| | - Nikolaos I Sigalas
- Soft Matter and Biological Physics Group, Department of Applied Physics, Technische Universiteit Eindhoven, Eindhoven, 5600 MB, The Netherlands
| | - Alexey V Lyulin
- Soft Matter and Biological Physics Group, Department of Applied Physics, Technische Universiteit Eindhoven, Eindhoven, 5600 MB, The Netherlands
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus, 8000, Denmark
| | - Brigitte Städler
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus, 8000, Denmark
| |
Collapse
|
4
|
Fehér B, Wacha A, Jezsó B, Bóta A, Pedersen JS, Varga I. The evolution of equilibrium poly(styrene sulfonate) and dodecyl trimethylammonium bromide supramolecular structure in dilute aqueous solution with increasing surfactant binding. J Colloid Interface Sci 2023; 651:992-1007. [PMID: 37586154 DOI: 10.1016/j.jcis.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/18/2023]
Abstract
HYPOTHESIS In the last 20 years, it has been demonstrated that oppositely charged polyelectrolyte-surfactant (PE-S) mixtures are prone to forming kinetically arrested non-equilibrium aggregates, which are present in the prepared mixtures from rather low surfactant-to-polymer-repeat-unit ratios. Practically, this means that the PE-S mixtures used for the structural investigations of the formed PE-S complexes are typically a mixture of the primary PE-S complexes and large non-equilibrium aggregates of close to charge-neutral complexes. EXPERIMENTS In this work, we present a unique approach that allows the preparation of PE-S mixtures in the equilibrium one-phase region (surfactant binding β, is typically below 80%) without forming non-equilibrium aggregates. We used this method to prepare equilibrium, non-aggregated complexes of sodium poly(styrene sulfonate) (NaPSS, Mw = 17 kDa) and dodecyltrimethylammonium bromide (DTAB) (β = 10 - 70%) both in water and in an inert electrolyte (100 mM NaCl). The evolution of the complex structure was monitored by small-angle X-ray scattering (SAXS) as a function of increasing surfactant binding (β), and the measured scattering data were fitted by suitable structural models on an absolute scale where concentrations, compositions, and scattering contrasts calculated from molecular properties are used as restraints. FINDINGS We could show that at low binding (β < 30%), the system is a mixture of bare polyelectrolyte coils and NaPSS-DTAB complexes containing a closed surfactant associates of low aggregation number wrapped by the polyelectrolyte chain. Once all polymer chains are occupied by a micelle-like surfactant aggregate, the aggregation number increases linearly with increasing surfactant chemical potential. Using the structural insight provided by the SAXS measurements, we could fit the experimental binding isotherm data with a physically coherent, simple thermodynamic model. Finally, we also compared the stoichiometric NaPSS-DTAB precipitate's structure with the equilibrium complexes' structure.
Collapse
Affiliation(s)
- Bence Fehér
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary.
| | - András Wacha
- Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary.
| | - Bálint Jezsó
- Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary.
| | - Attila Bóta
- Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary.
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
| | - Imre Varga
- Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary.
| |
Collapse
|
5
|
Bærentsen RL, Nielsen SV, Skjerning RB, Lyngsø J, Bisiak F, Pedersen JS, Gerdes K, Sørensen MA, Brodersen DE. Structural basis for kinase inhibition in the tripartite E. coli HipBST toxin-antitoxin system. eLife 2023; 12:RP90400. [PMID: 37929938 PMCID: PMC10627512 DOI: 10.7554/elife.90400] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023] Open
Abstract
Many bacteria encode multiple toxin-antitoxin (TA) systems targeting separate, but closely related, cellular functions. The toxin of the Escherichia coli hipBA system, HipA, is a kinase that inhibits translation via phosphorylation of glutamyl-tRNA synthetase. Enteropathogenic E. coli O127:H6 encodes the hipBA-like, tripartite TA system; hipBST, in which the HipT toxin specifically targets the tryptophanyl-tRNA synthetase, TrpS. Notably, in the tripartite system, the function as antitoxin has been taken over by the third protein, HipS, but the molecular details of how activity of HipT is inhibited remain poorly understood. Here, we show that HipBST is structurally different from E. coli HipBA and that the unique HipS protein, which is homologous to the N-terminal subdomain of HipA, inhibits the kinase through insertion of a conserved Trp residue into the active site. We also show how auto-phosphorylation at two conserved sites in the kinase toxin serve different roles and affect the ability of HipS to neutralize HipT. Finally, solution structural studies show how phosphorylation affects overall TA complex flexibility.
Collapse
Affiliation(s)
- René L Bærentsen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Stine V Nielsen
- Department of Biology, University of CopenhagenCopenhagenDenmark
| | | | - Jeppe Lyngsø
- Department of Chemistry and Interdisciplinary Nanoscience Centre (iNANO)AarhusDenmark
| | - Francesco Bisiak
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Centre (iNANO)AarhusDenmark
| | | | | | - Ditlev E Brodersen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| |
Collapse
|
6
|
Rusbjerg-Weberskov C, Johansen ML, Nowak JS, Otzen DE, Pedersen JS, Enghild JJ, Nielsen NS. Periostin C-Terminal Is Intrinsically Disordered and Interacts with 143 Proteins in an In Vitro Epidermal Model of Atopic Dermatitis. Biochemistry 2023; 62:2803-2815. [PMID: 37704583 PMCID: PMC10552548 DOI: 10.1021/acs.biochem.3c00176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/18/2023] [Indexed: 09/15/2023]
Abstract
Human periostin is a 78-91 kDa matricellular protein implicated in extracellular matrix remodeling, tumor development, metastasis, and inflammatory diseases like atopic dermatitis, psoriasis, and asthma. The protein consists of six domains, including an N-terminal Cys-rich CROPT domain, four fasciclin-1 domains, and a C-terminal domain. The exons encoding the C-terminal domain may be alternatively spliced by shuffling four exons, generating ten variants of unknown function. Here, we investigate the structure and interactome of the full-length variant of the C-terminal domain with no exons spliced out. The structural analysis showed that the C-terminal domain lacked a tertiary structure and was intrinsically disordered. In addition, we show that the motif responsible for heparin-binding is in the conserved very C-terminal part of periostin. Pull-down confirmed three known interaction partners and identified an additional 140 proteins, among which nine previously have been implicated in atopic dermatitis. Based on our findings, we suggest that the C-terminal domain of periostin facilitates interactions between connective tissue components in concert with the four fasciclin domains.
Collapse
Affiliation(s)
| | - Mette Liere Johansen
- Department
of Molecular Biology and Genetics, Aarhus
University, Aarhus
C 8000, Denmark
| | - Jan S. Nowak
- Department
of Molecular Biology and Genetics, Aarhus
University, Aarhus
C 8000, Denmark
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark
| | - Daniel E. Otzen
- Department
of Molecular Biology and Genetics, Aarhus
University, Aarhus
C 8000, Denmark
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark
| | - Jan Skov Pedersen
- Department
of Chemistry, Aarhus University, Aarhus C 8000, Denmark
- Interdisciplinary
Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark
| | - Jan J. Enghild
- Department
of Molecular Biology and Genetics, Aarhus
University, Aarhus
C 8000, Denmark
| | - Nadia Sukusu Nielsen
- Department
of Molecular Biology and Genetics, Aarhus
University, Aarhus
C 8000, Denmark
| |
Collapse
|
7
|
Rasmussen HØ, Nielsen J, de Poli A, Otzen DE, Pedersen JS. Tau Fibrillation Induced by Heparin or a Lysophospholipid Show Different Initial Oligomer Formation. J Mol Biol 2023; 435:168194. [PMID: 37437877 DOI: 10.1016/j.jmb.2023.168194] [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: 04/18/2023] [Revised: 06/18/2023] [Accepted: 07/05/2023] [Indexed: 07/14/2023]
Abstract
The protein tau is involved in several neurogenerative diseases such as Alzheimer's Disease, where tau content and fibrillation have been linked to disease progression. Tau colocalizes with phospholipids and glycosaminoglycans in vivo. We investigated if and how tau fibrillation can be induced by two lysophospholipids, namely the zwitterionic 1-myristoyl-2-hydroxy-sn-glycero-3-phosphocholine (LPC) and the anionic 1-myristoyl-2-hydroxy-sn-glycero-3-phospho-(1'-rac-glycerol) (LPG) as well as the glycosaminoglycan heparin. We used a range of biophysical techniques including small-angle X-ray scattering, Thioflavin T fluorescence, and SDS-PAGE, collecting data at various time points to obtain structural information on each phase of the fibrillation. We find that LPC does not induce fibrillation or interact with tau. Low concentrations of LPG induce fibrillation by formation of small hydrophobic clusters with monomeric tau. At higher LPG concentrations, a core-shell complex is formed where tau wraps around LPG micelles with regions extending away from the micelles. For heparin, loosely associated oligomers are formed rapidly with around ten tau molecules. Fibrils formed with either LPG or heparin show similar final cross-section dimensions. Furthermore, SDS-resistant oligomers are observed for both LPG and heparin. Our study demonstrates that tau fibrillation can be induced by two different biologically relevant cofactors leading to structurally different initial states but similar cross-sectional dimensions for the fibrils. Structural information about initial states prior to fibril formation is important both to gain a better understanding of the onset of fibrillation in vivo, and for the development of targeted drugs that can reduce or abolish tau fibrillation.
Collapse
Affiliation(s)
- Helena Østergaard Rasmussen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Janni Nielsen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Angela de Poli
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark; Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
| |
Collapse
|
8
|
McRae EKS, Rasmussen HØ, Liu J, Bøggild A, Nguyen MTA, Sampedro Vallina N, Boesen T, Pedersen JS, Ren G, Geary C, Andersen ES. Structure, folding and flexibility of co-transcriptional RNA origami. NATURE NANOTECHNOLOGY 2023; 18:808-817. [PMID: 36849548 PMCID: PMC10566746 DOI: 10.1038/s41565-023-01321-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
RNA origami is a method for designing RNA nanostructures that can self-assemble through co-transcriptional folding with applications in nanomedicine and synthetic biology. However, to advance the method further, an improved understanding of RNA structural properties and folding principles is required. Here we use cryogenic electron microscopy to study RNA origami sheets and bundles at sub-nanometre resolution revealing structural parameters of kissing-loop and crossover motifs, which are used to improve designs. In RNA bundle designs, we discover a kinetic folding trap that forms during folding and is only released after 10 h. Exploration of the conformational landscape of several RNA designs reveal the flexibility of helices and structural motifs. Finally, sheets and bundles are combined to construct a multidomain satellite shape, which is characterized by individual-particle cryo-electron tomography to reveal the domain flexibility. Together, the study provides a structural basis for future improvements to the design cycle of genetically encoded RNA nanodevices.
Collapse
Affiliation(s)
- Ewan K S McRae
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Helena Østergaard Rasmussen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Andreas Bøggild
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Michael T A Nguyen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | | | - Thomas Boesen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Cody Geary
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Ebbe Sloth Andersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
| |
Collapse
|
9
|
Allen AJ. Selected advances in small-angle scattering and applications they serve in manufacturing, energy and climate change. J Appl Crystallogr 2023; 56:787-800. [PMID: 37284276 PMCID: PMC10241057 DOI: 10.1107/s1600576723003898] [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] [Received: 02/23/2023] [Accepted: 05/02/2023] [Indexed: 06/08/2023] Open
Abstract
Innovations in small-angle X-ray and neutron scattering (SAXS and SANS) at major X-ray and neutron facilities offer new characterization tools for researching materials phenomena relevant to advanced applications. For SAXS, the new generation of diffraction-limited storage rings, incorporating multi-bend achromat concepts, dramatically decrease electron beam emittance and significantly increase X-ray brilliance over previous third-generation sources. This results in intense X-ray incident beams that are more compact in the horizontal plane, allowing significantly improved spatial resolution, better time resolution, and a new era for coherent-beam SAXS methods such as X-ray photon correlation spectroscopy. Elsewhere, X-ray free-electron laser sources provide extremely bright, fully coherent, X-ray pulses of <100 fs and can support SAXS studies of material processes where entire SAXS data sets are collected in a single pulse train. Meanwhile, SANS at both steady-state reactor and pulsed spallation neutron sources has significantly evolved. Developments in neutron optics and multiple detector carriages now enable data collection in a few minutes for materials characterization over nanometre-to-micrometre scale ranges, opening up real-time studies of multi-scale materials phenomena. SANS at pulsed neutron sources is becoming more integrated with neutron diffraction methods for simultaneous structure characterization of complex materials. In this paper, selected developments are highlighted and some recent state-of-the-art studies discussed, relevant to hard matter applications in advanced manufacturing, energy and climate change.
Collapse
Affiliation(s)
- Andrew J. Allen
- Materials Measurement Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA
| |
Collapse
|
10
|
Kumar A, Vadas O, Dos Santos Pacheco N, Zhang X, Chao K, Darvill N, Rasmussen HØ, Xu Y, Lin GMH, Stylianou FA, Pedersen JS, Rouse SL, Morgan ML, Soldati-Favre D, Matthews S. Structural and regulatory insights into the glideosome-associated connector from Toxoplasma gondii. eLife 2023; 12:e86049. [PMID: 37014051 PMCID: PMC10125020 DOI: 10.7554/elife.86049] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/03/2023] [Indexed: 04/05/2023] Open
Abstract
The phylum of Apicomplexa groups intracellular parasites that employ substrate-dependent gliding motility to invade host cells, egress from the infected cells, and cross biological barriers. The glideosome-associated connector (GAC) is a conserved protein essential to this process. GAC facilitates the association of actin filaments with surface transmembrane adhesins and the efficient transmission of the force generated by myosin translocation of actin to the cell surface substrate. Here, we present the crystal structure of Toxoplasma gondii GAC and reveal a unique, supercoiled armadillo repeat region that adopts a closed ring conformation. Characterisation of the solution properties together with membrane and F-actin binding interfaces suggests that GAC adopts several conformations from closed to open and extended. A multi-conformational model for assembly and regulation of GAC within the glideosome is proposed.
Collapse
Affiliation(s)
- Amit Kumar
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Oscar Vadas
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of GenevaGenevaSwitzerland
| | - Nicolas Dos Santos Pacheco
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of GenevaGenevaSwitzerland
| | - Xu Zhang
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Kin Chao
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Nicolas Darvill
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Helena Ø Rasmussen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus UniversityAarhusDenmark
| | - Yingqi Xu
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Gloria Meng-Hsuan Lin
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of GenevaGenevaSwitzerland
| | | | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus UniversityAarhusDenmark
| | - Sarah L Rouse
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Marc L Morgan
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of GenevaGenevaSwitzerland
| | - Stephen Matthews
- Department of Life Sciences, Imperial College LondonLondonUnited Kingdom
| |
Collapse
|
11
|
Rasmussen HØ, Kumar A, Shin B, Stylianou F, Sewell L, Xu Y, Otzen DE, Pedersen JS, Matthews SJ. FapA is an Intrinsically Disordered Chaperone for Pseudomonas Functional Amyloid FapC. J Mol Biol 2023; 435:167878. [PMID: 36368411 DOI: 10.1016/j.jmb.2022.167878] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/18/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
Bacterial functional amyloids contribute to biofilm development by bacteria and provide protection from the immune system and prevent antibiotic treatment. Strategies to target amyloid formation and interrupt biofilm formation have attracted recent interest due to their antimicrobial potential. Functional amyloid in Pseudomonas (Fap) includes FapC as the major component of the fibril while FapB is a minor component suggested to function as a nucleator of FapC. The system also includes the small periplasmic protein FapA, which has been shown to regulate fibril composition and morphology. The interplay between these three components is central in Fap fibril biogenesis. Here we present a comprehensive biophysical and spectroscopy analysis of FapA, FapB and FapC and provide insight into their molecular interactions. We show that all three proteins are primarily disordered with some regions with structural propensities for α-helix and β-sheet. FapA inhibits FapC fibrillation by targeting the nucleation step, whereas for FapB the elongation step is modulated. Furthermore, FapA alters the morphology of FapC (more than FapB) fibrils. Complex formation is observed between FapA and FapC, but not between FapA and FapB, and likely involves the N-terminus of FapA. We conclude that FapA is an intrinsically disordered chaperone for FapC that guards against fibrillation within the periplasm. This new understanding of a natural protective mechanism of Pseudomonas against amyloid formations can serve as inspiration for strategies blocking biofilm formation in infections.
Collapse
Affiliation(s)
- Helena Ø Rasmussen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Amit Kumar
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom
| | - Ben Shin
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom
| | - Fisentzos Stylianou
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom
| | - Lee Sewell
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom
| | - Yingqi Xu
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom
| | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Steve J Matthews
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, United Kingdom.
| |
Collapse
|
12
|
He J, Steffen JH, Thulstrup PW, Pedersen JN, Sauerland MB, Otzen DE, Hawkins CL, Gourdon P, Davies MJ, Hägglund P. Anastellin impacts on the processing of extracellular matrix fibronectin and stimulates release of cytokines from coronary artery smooth muscle cells. Sci Rep 2022; 12:22051. [PMID: 36543832 PMCID: PMC9772232 DOI: 10.1038/s41598-022-26359-9] [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] [Received: 06/17/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Anastellin, a recombinant protein fragment from the first type III module of fibronectin, mimics a partially unfolded intermediate implicated in the assembly of fibronectin fibrils. Anastellin influences the structure of fibronectin and initiates in vitro fibrillation, yielding "superfibronectin", a polymer with enhanced cell-adhesive properties. This ability is absent in an anastellin double mutant, L37AY40A. Here we demonstrate that both wild-type and L37AY40A anastellin affect fibronectin processing within the extracellular matrix (ECM) of smooth muscle cells. Fibronectin fibrils are diminished in the ECM from cells treated with anastellin, but are partially rescued by supplementation with plasma fibronectin in cell media. Proteomic analyses reveal that anastellin also impacts on the processing of other ECM proteins, with increased collagen and decreased laminin detected in media from cells exposed to wild-type anastellin. Moreover, both anastellin forms stimulate release of inflammatory cytokines, including interleukin 6. At the molecular level, L37AY40A does not exhibit major perturbations of structural features relative to wild-type anastellin, though the mutant showed differences in heparin binding characteristics. These findings indicate that wild-type and L37AY40A anastellin share similar molecular features but elicit slightly different, but partially overlapping, responses in smooth muscle cells resulting in altered secretion of cytokines and proteins involved in ECM processing.
Collapse
Affiliation(s)
- Jianfei He
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas Hyld Steffen
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Waaben Thulstrup
- grid.5254.60000 0001 0674 042XDepartment of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Jannik Nedergaard Pedersen
- grid.7048.b0000 0001 1956 2722Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark ,grid.432104.0Present Address: Arla Foods Ingredients Group P/S, Sønderupvej 26, 6920 Videbæk, Denmark
| | - Max B. Sauerland
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Daniel E. Otzen
- grid.7048.b0000 0001 1956 2722Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Clare L. Hawkins
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pontus Gourdon
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael J. Davies
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Hägglund
- grid.5254.60000 0001 0674 042XDepartment of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
13
|
Spanjers JM, Brodszkij E, Gal N, Skov Pedersen J, Städler B. On the assembly of zwitterionic block copolymers with phospholipids. Eur Polym J 2022. [DOI: 10.1016/j.eurpolymj.2022.111612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
14
|
Köber M, Illa-Tuset S, Ferrer-Tasies L, Moreno-Calvo E, Tatkiewicz WI, Grimaldi N, Piña D, Pérez Pérez A, Lloveras V, Vidal-Gancedo J, Bulone D, Ratera I, Skov Pedersenc J, Danino D, Veciana J, Faraudo J, Ventosa N. Stable nanovesicles formed by intrinsically planar bilayers. J Colloid Interface Sci 2022; 631:202-211. [DOI: 10.1016/j.jcis.2022.10.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/16/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
|
15
|
Hansen J, Pedersen JN, Pedersen JS, Egelhaaf SU, Platten F. Universal effective interactions of globular proteins close to liquid–liquid phase separation: Corresponding-states behavior reflected in the structure factor. J Chem Phys 2022; 156:244903. [DOI: 10.1063/5.0088601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Intermolecular interactions in protein solutions, in general, contain many contributions. If short-range attractions dominate, the state diagram exhibits liquid–liquid phase separation (LLPS) that is metastable with respect to crystallization. In this case, the extended law of corresponding states (ELCS) suggests that thermodynamic properties are insensitive to details of the underlying interaction potential. Using lysozyme solutions, we investigate the applicability of the ELCS to the static structure factor and how far effective colloidal interaction models can help to rationalize the phase behavior and interactions of protein solutions in the vicinity of the LLPS binodal. The (effective) structure factor has been determined by small-angle x-ray scattering. It can be described by Baxter’s adhesive hard-sphere model, which implies a single fit parameter from which the normalized second virial coefficient b2 is inferred and found to quantitatively agree with previous results from static light scattering. The b2 values are independent of protein concentration but systematically vary with temperature and solution composition, i.e., salt and additive content. If plotted as a function of temperature normalized by the critical temperature, the values of b2 follow a universal behavior. These findings validate the applicability of the ELCS to globular protein solutions and indicate that the ELCS can also be reflected in the structure factor.
Collapse
Affiliation(s)
- Jan Hansen
- Heinrich Heine University, Condensed Matter Physics Laboratory, Düsseldorf, Germany
| | - Jannik N. Pedersen
- iNANO Interdisciplinary Nanoscience Center and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jan Skov Pedersen
- iNANO Interdisciplinary Nanoscience Center and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Stefan U. Egelhaaf
- Heinrich Heine University, Condensed Matter Physics Laboratory, Düsseldorf, Germany
| | - Florian Platten
- Heinrich Heine University, Condensed Matter Physics Laboratory, Düsseldorf, Germany
- Forschungszentrum Jülich, Institute of Biological Information Processing IBI-4, Biomacromolecular Systems and Processes, Jülich, Germany
| |
Collapse
|
16
|
Bregnhøj M, Roeters SJ, Chatterley AS, Madzharova F, Mertig R, Pedersen JS, Weidner T. Structure and Orientation of the SARS-Coronavirus-2 Spike Protein at Air-Water Interfaces. J Phys Chem B 2022; 126:3425-3430. [PMID: 35477296 PMCID: PMC9063992 DOI: 10.1021/acs.jpcb.2c01272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/06/2022] [Indexed: 11/28/2022]
Abstract
The SARS coronavirus 2 (SARS-CoV-2) spike protein is located at the outermost perimeter of the viral envelope and is the first component of the virus to make contact with surrounding interfaces. The stability of the spike protein when in contact with surfaces plays a deciding role for infection pathways and for the viability of the virus after surface contact. While cryo-EM structures of the spike protein have been solved with high resolution and structural studies in solution have provided information about the secondary and tertiary structures, only little is known about the folding when adsorbed to surfaces. We here report on the secondary structure and orientation of the S1 segment of the spike protein, which is often used as a model protein for in vitro studies of SARS-CoV-2, at the air-water interface using surface-sensitive vibrational sum-frequency generation (SFG) spectroscopy. The air-water interface plays an important role for SARS-CoV-2 when suspended in aerosol droplets, and it serves as a model system for hydrophobic surfaces in general. The SFG experiments show that the S1 segment of the spike protein remains folded at the air-water interface and predominantly binds in its monomeric state, while the combination of small-angle X-ray scattering and two-dimensional infrared spectroscopy measurements indicate that it forms hexamers with the same secondary structure in aqueous solution.
Collapse
Affiliation(s)
- Mikkel Bregnhøj
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Steven J. Roeters
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Adam S. Chatterley
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Fani Madzharova
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Rolf Mertig
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Jan Skov Pedersen
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus
University, Langelandsgade 140, 8000 Aarhus C,
Denmark
| |
Collapse
|
17
|
An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles. NANOMATERIALS 2022; 12:nano12030342. [PMID: 35159685 PMCID: PMC8839642 DOI: 10.3390/nano12030342] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 02/04/2023]
Abstract
Calcium silicate hydrate (C-S-H) is the main binding phase in Portland cement. The addition of C-S-H nanoparticles as nucleation seeds has successfully been used to accelerate the hydration process and the precipitation of binding phases either in conventional Portland cement or in alternative binders. Indeed, the modulation of the hydration kinetics during the early-stage dissolution-precipitation reactions, by acting on the nucleation and growth of binding phases, improves the early strength development. The fine-tuning of concrete properties in terms of compressive strength and durability by designed structural modifications can be achieved through the detailed description of the reaction products at the atomic scale. The nano-sized, chemically complex and structurally disordered nature of these phases hamper their thorough structural characterization. To this aim, we implement a novel multi-scale approach by combining forefront small-angle X-ray scattering (SAXS) and synchrotron wide-angle X-ray total scattering (WAXTS) analyses for the characterization of Cu-doped C-S-H nanoparticles dispersed in a colloidal suspension, used as hardening accelerator. SAXS and WAXTS data were analyzed under a unified modeling approach by developing suitable atomistic models for C-S-H nanoparticles to be used to simulate the experimental X-ray scattering pattern through the Debye scattering equation. The optimization of atomistic models against the experimental pattern, together with complementary information on the structural local order from 29Si solid-state nuclear magnetic resonance and X-ray absorption spectroscopy, provided a comprehensive description of the structure, size and morphology of C-S-H nanoparticles from the atomic to the nanometer scale. C-S-H nanoparticles were modeled as an assembly of layers composed of 7-fold coordinated Ca atoms and decorated by silicate dimers and chains. The structural layers are a few tens of nanometers in length and width, with a crystal structure resembling that of a defective tobermorite, but lacking any ordering between stacking layers.
Collapse
|
18
|
Trewhella J. Recent advances in small-angle scattering and its expanding impact in structural biology. Structure 2022; 30:15-23. [PMID: 34995477 DOI: 10.1016/j.str.2021.09.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/23/2021] [Accepted: 09/20/2021] [Indexed: 10/19/2022]
Abstract
Applications of small-angle scattering (SAS) in structural biology have benefited from continuing developments in instrumentation, tools for data analysis, modeling capabilities, standards for data and model presentation, and data archiving. The interplay of these capabilities has enabled SAS to contribute to advances in structural biology as the field pushes the boundaries in studies of biomolecular complexes and assemblies as large as whole cells, membrane proteins in lipid environments, and dynamic systems on time scales ranging from femtoseconds to hours. This review covers some of the important advances in biomolecular SAS capabilities for structural biology focused on over the last 5 years and presents highlights of recent applications that demonstrate how the technique is exploring new territories.
Collapse
Affiliation(s)
- Jill Trewhella
- School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW 2006, Australia.
| |
Collapse
|
19
|
Folding Steps in the Fibrillation of Functional Amyloid: Denaturant Sensitivity Reveals Common Features in Nucleation and Elongation. J Mol Biol 2021; 434:167337. [PMID: 34748745 DOI: 10.1016/j.jmb.2021.167337] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 01/09/2023]
Abstract
Functional bacterial amyloids (FuBA) are intrinsically disordered proteins (IDPs) which rapidly and efficiently aggregate, forming extremely stable fibrils. The conversion from IDP to amyloid is evolutionarily optimized and likely couples folding to association. Many FuBA contain several imperfect repeat sequences which contribute to the stability of mature FuBA fibrils. Aggregation can be considered an intermolecular extension of the process of intramolecular protein folding which has traditionally been studied using chemical denaturants. Here we employ denaturants to investigate folding steps during fibrillation of CsgA and FapC. We quantify protein compactification (i.e. the extent of burial of otherwise exposed surface area upon association of proteins) during different stages of fibrillation based on the dependence of fibrillation rate constants on the denaturant concentration (m-values) determined from fibrillation curves. For both proteins, urea mainly affects nucleation and elongation (not fragmentation), consistent with the fact that these steps involve both intra- and intermolecular association. The two steps have similar m-values, indicating that activation steps in nucleation and elongation involve the same level of folding. Surprisingly, deletion of two or three repeats from FapC leads to larger m-values (i.e. higher compactification) during the activation step of fibril growth. This observation is extended by SAXS analysis of the fibrils which indicates that weakening of the amyloidogenic core caused by repeat deletions causes a larger portion of normally unstructured regions of the protein to be included into the amyloid backbone. We conclude that the sensitivity of fibrillation to denaturants can provide useful insight into molecular mechanisms of aggregation.
Collapse
|
20
|
Self-assembling properties of ionisable amphiphilic drugs in aqueous solution. J Colloid Interface Sci 2021; 600:701-710. [PMID: 34049025 DOI: 10.1016/j.jcis.2021.05.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/06/2021] [Accepted: 05/08/2021] [Indexed: 11/22/2022]
Abstract
HYPOTHESIS Common amphiphilic drug molecules often have a more rigid nonpolar part than conventional surfactants. The rigidity is expected to influence the self-assembling properties and possibly give rise to aggregation patterns different from that of regular surfactants. EXPERIMENTS We have investigated self-assembling properties of the hydrochloride salts of adiphenine (ADP), pavatrine (PVT), and amitriptyline (AMT) at concentrations up to 50 wt% using small-angle x-ray scattering, dynamic light scattering, cryo-transmission electron microscopy, and surface tension measurements. FINDINGS All drugs form small micelles of oblate spheroidal shape at concentrations above the critical micelle concentrations (CMC). The micelles grow weakly in size up to about 20 wt%, where the aggregation number reaches a maximum followed by a slight decrease in size at higher drug concentrations. We observe a correlation between the decrease in micelle size at high concentrations and an increasing charge of the micelles, as the degree of ionization increases with increasing drug concentration and decreasing pH. In contrast to what has previously been reported, the aggregation behavior of all studied drugs resembles the closed association behavior of conventional surfactants with a short aliphatic chain as hydrophobic tail group i.e. the micelles are always small in size and lack a second CMC. CMC values were determined with surface tension measurements, including also lidocaine hydrochloride (LDC) and chlorpromazine hydrochloride (CHL).
Collapse
|
21
|
Hansen J, Uthayakumar R, Pedersen JS, Egelhaaf SU, Platten F. Interactions in protein solutions close to liquid-liquid phase separation: ethanol reduces attractions via changes of the dielectric solution properties. Phys Chem Chem Phys 2021; 23:22384-22394. [PMID: 34608908 DOI: 10.1039/d1cp03210k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ethanol is a common protein crystallization agent, precipitant, and denaturant, but also alters the dielectric properties of solutions. While ethanol-induced unfolding is largely ascribed to its hydrophobic parts, its effect on protein phase separation and inter-protein interactions remains poorly understood. Here, the effects of ethanol and NaCl on the phase behavior and interactions of protein solutions are studied in terms of the metastable liquid-liquid phase separation (LLPS) and the second virial coefficient B2 using lysozyme solutions. Determination of the phase diagrams shows that the cloud-point temperatures are reduced and raised by the addition of ethanol and salt, respectively. The observed trends can be explained using the extended law of corresponding states as changes of B2. The results for B2 agree quantitatively with those of static light scattering and small-angle X-ray scattering experiments. Furthermore, B2 values calculated based on inter-protein interactions described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) potential and considering the dielectric solution properties and electrostatic screening due to the ethanol and salt content quantitatively agree with the experimentally observed B2 values.
Collapse
Affiliation(s)
- Jan Hansen
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Rajeevann Uthayakumar
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Jan Skov Pedersen
- iNANO Interdisciplinary Nanoscience Center and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Stefan U Egelhaaf
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Florian Platten
- Condensed Matter Physics Laboratory, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany. .,Institute of Biological Information Processing (IBI-4: Biomacromolecular Systems and Processes), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52428 Jülich, Germany
| |
Collapse
|
22
|
Mortensen HG, Otzen DE, Pedersen JS. Ubiquitin forms conventional decorated micelle structures with sodium dodecyl sulfate at saturation. J Colloid Interface Sci 2021; 596:233-244. [DOI: 10.1016/j.jcis.2021.03.110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/10/2021] [Accepted: 03/19/2021] [Indexed: 12/20/2022]
|