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Halder K, Sabnam K, Das A, Goswami DK, Dasgupta S. Thin Film Formation of HSA in the Presence of CTAB-Capped Gold Nanorods through Phase Separation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:14847-14862. [PMID: 38952216 DOI: 10.1021/acs.langmuir.4c00694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
Phase behavior in protein-nanoparticle systems in light of protein corona formation has been investigated. We report the formation of HSA thin films following the addition of a solid protein to a solution of CTAB-capped gold nanorods (AuNRs) via phase separation. The phase separation behavior was observed through UV-vis spectroscopy, turbidity assays, and DLS studies. UV-vis spectra for the protein-AuNR solution indicated a possible self-assembly formation by CTAB-HSA complexes and AuNR-HSA conjugates. The turbidity was found to increase linearly up to 30-50% v/v for each component. The growth phase slope is proportional to the concentration of the components, AuNRs, and HSA, with no lag phase. Dynamic light scattering (DLS) shows the formation of larger aggregates with time, implying a segregated phase of AuNR-HSA and a CTAB-HSA-AuNR network. ζ-potential values confirm surface modification, implying protein corona formation on nanorods. The thin films were also characterized using SEM, AFM, SAXS, XPS, FTIR, and TGA studies. SEM images show a smooth surface with a reduced number of pores, indicating the compactness of the deposited structure. AFM shows two different structural pattern formations with the deposition, indicating possible self-assembly of the protein-conjugated nanoparticles. FTIR studies indicate a change in the hydrogen bonding network and confirm the CTAB-HSA-AuNR complex network formation. The XPS studies indicate Au-S bond formation, along with Au-S-S-Au interactions. SAXS studies indicate the formation of aggregates (oligomers), as well as the presence of dominant attractive intermolecular interactions in the thin films.
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Affiliation(s)
- Krishna Halder
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Kabira Sabnam
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Abhirup Das
- Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Dipak K Goswami
- Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Swagata Dasgupta
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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2
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Figueroa GB, D'souza S, Pereira HS, Vasudeva G, Figueroa SB, Robinson ZE, Badmalia MD, Meier-Stephenson V, Corcoran JA, van Marle G, Ni Y, Urban S, Coffin CS, Patel TR. Development of a single-domain antibody to target a G-quadruplex located on the hepatitis B virus covalently closed circular DNA genome. J Med Virol 2024; 96:e29692. [PMID: 38804172 DOI: 10.1002/jmv.29692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/22/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
To achieve a virological cure for hepatitis B virus (HBV), innovative strategies are required to target the covalently closed circular DNA (cccDNA) genome. Guanine-quadruplexes (G4s) are a secondary structure that can be adopted by DNA and play a significant role in regulating viral replication, transcription, and translation. Antibody-based probes and small molecules have been developed to study the role of G4s in the context of the human genome, but none have been specifically made to target G4s in viral infection. Herein, we describe the development of a humanized single-domain antibody (S10) that can target a G4 located in the PreCore (PreC) promoter of the HBV cccDNA genome. MicroScale Thermophoresis demonstrated that S10 has a strong nanomolar affinity to the PreC G4 in its quadruplex form and a structural electron density envelope of the complex was determined using Small-Angle X-ray Scattering. Lentiviral transduction of S10 into HepG2-NTCP cells shows nuclear localization, and chromatin immunoprecipitation coupled with next-generation sequencing demonstrated that S10 can bind to the HBV PreC G4 present on the cccDNA. This research validates the existence of a G4 in HBV cccDNA and demonstrates that this DNA secondary structure can be targeted with high structural and sequence specificity using S10.
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Affiliation(s)
- Gerardo B Figueroa
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Simmone D'souza
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Higor S Pereira
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Gunjan Vasudeva
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Sara B Figueroa
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Zachary E Robinson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Maulik D Badmalia
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
- Li Ka Shing Institute of Virology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Vanessa Meier-Stephenson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
- Li Ka Shing Institute of Virology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jennifer A Corcoran
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Guido van Marle
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Yi Ni
- Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infection Research, Heidelberg University, Heidelberg, Germany
| | - Stephan Urban
- Department of Infectious Diseases, Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infection Research, Heidelberg University, Heidelberg, Germany
| | - Carla S Coffin
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Trushar R Patel
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, Lethbridge, Alberta, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Alberta, Canada
- Li Ka Shing Institute of Virology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
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3
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Hazra R, Roy D. Robustness of heteroaggregates involving hydrophobic cholesterol and its mimetics. Phys Chem Chem Phys 2023; 25:27230-27243. [PMID: 37791397 DOI: 10.1039/d3cp02174b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Exploring the self and cross aggregation affinity of cholesterol (CHL) and some of its lookalikes, e.g., cholesteryl hemisuccinate (CHM), campesterol (CAM) and arjunic acid (ARJ), provides crucial understanding towards the influence of weak forces in inducing mixed micellization through heteroaggregation. Strongly hydrophobic CHL, with a benchmark inclination towards aggregation, often forms detrimental plaques in crucial human organs that are fairly difficult to disintegrate. Traditionally known anti-dyslipidemic agents like CAM and ARJ are known to interact strongly with CHL in the gut when ingested. They further form mixed micelles along with the bile components and interfere with the CHL absorption across the epithelial cell layer of the intestine. Some invariant questions like how robust are the heteroaggregates formed between these mimetics and CHL are very important to appreciate the efficacy of such anti-dyslipidemic agents. In this work using molecular dynamics simulations and varied structural analysis, we characterize the heteroaggregates. Simulations indicate that CHL-CHM mixed assemblies are comparatively bigger and significantly stabilized by strong electrostatic and favourable vdW forces. Small and diffused CHL-ARJ aggregates are observed in our simulations with a not so favourable energetics, indicating a possible attenuation pathway of CHL aggregation in the presence of ARJ.
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Affiliation(s)
- Rituparna Hazra
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Hyderabad, Telangana 500078, India.
| | - Durba Roy
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Jawahar Nagar, Kapra Mandal, Hyderabad, Telangana 500078, India.
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4
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Peesapati S, Roy D. Structural and spectroscopic details of polysaccharide-bile acid composites from molecular dynamics simulations. J Biomol Struct Dyn 2023; 41:8782-8794. [PMID: 36310090 DOI: 10.1080/07391102.2022.2137242] [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: 08/05/2022] [Accepted: 10/11/2022] [Indexed: 10/31/2022]
Abstract
Interactions of a prototypical bile acid (cholic acid, 'Ch') and its corresponding sodium salt (sodium cholate, 'NaCh') with a standard dietary β-glucan (β-G), bearing β-D-glucopyranose units having mixed 1-4/1-3 glycosidic linkages are studied using molecular dynamics simulation and density functional theory (DFT) calculations. Self-aggregation of the biliary components and their interaction with fifteen strands of the decameric mixed linkage β-glucan is elucidated by estimating varieties of physical properties like the coordination number, moment of inertia and shape anisotropy of the biggest cluster formed at different time instants. Small angle scattering profiles indicate formation of compact spheroidal aggregates. The simulated results of small angle scattering and 1H NMR chemical shifts are compared to spectroscopic data, wherever available. Density functional theory calculations and estimation of the 1H NMR chemical shifts of Ch-protons lying close to the β-G chains reveal change in chemical shift values from that in absence of the polysaccharide. Hydrogen bonding and non-bonding interactions, primarily short range van der Waals interactions and some extent of inter-molecular charge transfer are found to play significant role in stabilizing the complex soft assemblies of bile acid aggregates and β-G.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Sruthi Peesapati
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad, India
| | - Durba Roy
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Hyderabad, India
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5
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Murty R, Bera MK, Walton IM, Whetzel C, Prausnitz MR, Walton KS. Interrogating Encapsulated Protein Structure within Metal-Organic Frameworks at Elevated Temperature. J Am Chem Soc 2023; 145:7323-7330. [PMID: 36961883 PMCID: PMC10080685 DOI: 10.1021/jacs.2c13525] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
Encapsulating biomacromolecules within metal-organic frameworks (MOFs) can confer thermostability to entrapped guests. It has been hypothesized that the confinement of guest molecules within a rigid MOF scaffold results in heightened stability of the guests, but no direct evidence of this mechanism has been shown. Here, we present a novel analytical method using small-angle X-ray scattering (SAXS) to solve the structure of bovine serum albumin (BSA) while encapsulated within two zeolitic imidazolate frameworks (ZIF-67 and ZIF-8). Our approach comprises subtracting the scaled SAXS spectrum of the ZIF from that of the biocomposite BSA@ZIF to determine the radius of gyration of encapsulated BSA through Guinier, Kratky, and pair distance distribution function analyses. While native BSA exposed to 70 °C became denatured, in situ SAXS analysis showed that encapsulated BSA retained its size and folded state at 70 °C when encapsulated within a ZIF scaffold, suggesting that entrapment within MOF cavities inhibited protein unfolding and thus denaturation. This method of SAXS analysis not only provides insight into biomolecular stabilization in MOFs but may also offer a new approach to study the structure of other conformationally labile molecules in rigid matrices.
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Affiliation(s)
- Rohan Murty
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Mrinal K Bera
- NSF's ChemMatCARS, Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Ian M Walton
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Christina Whetzel
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Mark R Prausnitz
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Krista S Walton
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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6
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Kämäräinen T, Kadota K, Tse JY, Uchiyama H, Oguchi T, Arima-Osonoi H, Tozuka Y. Tuning the Phytoglycogen Size and Aggregate Structure with Solvent Quality: Influence of Water-Ethanol Mixtures Revealed by X-ray and Light Scattering Techniques. Biomacromolecules 2023; 24:225-237. [PMID: 36484419 DOI: 10.1021/acs.biomac.2c01093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Phytoglycogen (PG) is a hyperbranched polysaccharide with promising properties for biomedical and pharmaceutical applications. Herein, we explore the size and structure of sweet corn PG nanoparticles and their aggregation in water-ethanol mixtures up to the ethanol mole fraction xEtOH = 0.364 in dilute concentrations using small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements. Between 0 ≤ xEtOH ≤ 0.129, the conformation of PG contracts gradually decreasing up to ca. 80% in hydrodynamic volume, when measured shortly after ethanol addition. For equilibrated PG dispersions, SAXS suggests a lower PG volume decrease between 19 and 67% at the corresponding xEtOH range; however, the inflection point of the DLS volume contraction coincides with the onset of reduced colloidal stability observed with SAXS. Up to xEtOH = 0.201, the water-ethanol mixtures yield labile fractal and globular aggregates, as evidenced by their partial breakup under mild ultrasonic treatment, demonstrated by the decrease in their hydrodynamic size. Between 0.235 ≤ xEtOH ≤ 0.364, PG nanoparticles form larger, more cohesive globular aggregates that are less affected by ultrasonic shear forces.
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Affiliation(s)
- Tero Kämäräinen
- Department of Formulation Design and Pharmaceutical Technology, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka569-1094, Japan
| | - Kazunori Kadota
- Department of Formulation Design and Pharmaceutical Technology, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka569-1094, Japan
| | - Jun Y Tse
- Department of Formulation Design and Pharmaceutical Technology, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka569-1094, Japan
| | - Hiromasa Uchiyama
- Department of Formulation Design and Pharmaceutical Technology, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka569-1094, Japan
| | - Toshio Oguchi
- Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi409-3898, Japan
| | - Hiroshi Arima-Osonoi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki319-1106, Japan
| | - Yuichi Tozuka
- Department of Formulation Design and Pharmaceutical Technology, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka569-1094, Japan
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7
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Duarte H, Gummel J, Robles E, Berti D, Fratini E. Ultra-/Small Angle X-ray Scattering (USAXS/SAXS) and Static Light Scattering (SLS) Modeling as a Tool to Determine Structural Changes and Effect on Growth in S. epidermidis. ACS APPLIED BIO MATERIALS 2022; 5:3703-3712. [PMID: 35905477 PMCID: PMC9940853 DOI: 10.1021/acsabm.2c00218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Usually, to characterize bacterial cells' susceptibility to antimicrobials, basic microbiology techniques such as serial dilutions or disk assays are used. In this work, we present an approach focused on combining static light scattering (SLS) and ultra-/small angle X-ray scattering (USAXS/SAXS). This approach was used to support microbiology techniques, with the aim of understanding the structural changes caused to bacteria when they are exposed to different stresses like pH, oxidation, and surfactants. Using USAXS/SAXS and SLS data, we developed a detailed multiscale model for a Gram-positive bacterium, S. epidermidis, and we extracted information regarding changes in the overall size and cell thickness induced by different stresses (i.e., pH and hydrogen peroxide). Increasing the concentration of hydrogen peroxide leads to a progressive reduction in cell wall thickness. Moreover, the concomitant use of pH and hydrogen peroxide provides evidence for a synergy in inhibiting the S. epidermidis growth. These promising results will be used as a starting base to further investigate more complex formulations and improve/refine the data modeling of bacteria in the small angle scattering regime.
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Affiliation(s)
- Hugo Duarte
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy,
| | - Jeremie Gummel
- Brussels
Innovation Centre, Temselaan
100, Strombeek-bever B-1853, Belgium
| | - Eric Robles
- Household
Care Analytical, Procter & Gamble Newcastle
Innovation Centre, Newcastle NE12 9TS, United Kingdom
| | - Debora Berti
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy
| | - Emiliano Fratini
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy,
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8
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D'Souza MH, Mrozowich T, Badmalia MD, Geeraert M, Frederickson A, Henrickson A, Demeler B, Wolfinger MT, Patel TR. Biophysical characterisation of human LincRNA-p21 sense and antisense Alu inverted repeats. Nucleic Acids Res 2022; 50:5881-5898. [PMID: 35639511 PMCID: PMC9177966 DOI: 10.1093/nar/gkac414] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/26/2022] [Accepted: 05/09/2022] [Indexed: 12/05/2022] Open
Abstract
Human Long Intergenic Noncoding RNA-p21 (LincRNA-p21) is a regulatory noncoding RNA that plays an important role in promoting apoptosis. LincRNA-p21 is also critical in down-regulating many p53 target genes through its interaction with a p53 repressive complex. The interaction between LincRNA-p21 and the repressive complex is likely dependent on the RNA tertiary structure. Previous studies have determined the two-dimensional secondary structures of the sense and antisense human LincRNA-p21 AluSx1 IRs using SHAPE. However, there were no insights into its three-dimensional structure. Therefore, we in vitro transcribed the sense and antisense regions of LincRNA-p21 AluSx1 Inverted Repeats (IRs) and performed analytical ultracentrifugation, size exclusion chromatography, light scattering, and small angle X-ray scattering (SAXS) studies. Based on these studies, we determined low-resolution, three-dimensional structures of sense and antisense LincRNA-p21. By adapting previously known two-dimensional information, we calculated their sense and antisense high-resolution models and determined that they agree with the low-resolution structures determined using SAXS. Thus, our integrated approach provides insights into the structure of LincRNA-p21 Alu IRs. Our study also offers a viable pipeline for combining the secondary structure information with biophysical and computational studies to obtain high-resolution atomistic models for long noncoding RNAs.
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Affiliation(s)
- Michael H D'Souza
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Tyler Mrozowich
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Maulik D Badmalia
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Mitchell Geeraert
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Angela Frederickson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Borries Demeler
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada.,Department of Chemistry and Biochemistry, University of Montana, Missoula, MT 59812, USA.,NorthWest Biophysics Consortium, University of Lethbridge, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Michael T Wolfinger
- Bioinformatics and Computational Biology, Faculty of Computer Science, Währingerstrasse 29, 1090 Vienna, Austria.,Department of Theoretical Chemistry, University of Vienna, Währingerstrasse 17, 1090 Vienna, Austria
| | - Trushar R Patel
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada.,Department of Microbiology, Immunology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.,Li Ka Shing Institute of Virology and Discovery Lab, University of Alberta, Edmonton, AB T6G 2E1, Canada
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9
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Christiansen MV, Smith GN, Brok ES, Schmiele M, Ahrné L. The relationship between ultra-small-angle X-ray scattering and viscosity measurements of casein micelles in skim milk concentrates. Food Res Int 2021; 147:110451. [PMID: 34399453 DOI: 10.1016/j.foodres.2021.110451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/26/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022]
Abstract
Skim milk concentrates have important applications in the dairy industry, often as intermediate ingredients. Concentration of skim milk by reverse osmosis membrane filtration induces water removal, which reduces the free volume between the colloidal components, in particular the casein micelles. Thermal treatment before or after concentration impacts the morphology of casein micelles. These changes affect the flow behavior and viscosity, but the consequences for supermicellar structure have not been elucidated. In the present study, skim milk concentrates with different total solid contents from 8.7% (control) up to 22.8% (w/w), prepared by reverse osmosis membrane filtration of non-heated and pasteurized skim milk, were heat treated at 75 °C for 18 s, and compared with non-heated concentrates. The structure of the concentrates was studied using Ultra Small Angle X-ray Scattering (USAXS), and the viscosity of concentrates was measured. The USAXS intensity I(q) was fitted at small and intermediate q-regions (0.0005 < q < 0.003 Å-1 and 0.0035 < q < 0.03 Å-1, respectively) with a power law. The value of the power law exponent was used to assess the heat- and concentration-induced aggregation of the milk solids and correlate it with the apparent viscosity. The results showed that increased viscosity of skim milk concentrates, due to water removal and heat-load, can be explained by increased aggregation of the casein micelles into elongated aggregates and increased smoothening of the casein micelle surface.
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Affiliation(s)
- Morten V Christiansen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark
| | - Gregory N Smith
- ISIS Neutron Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Erik S Brok
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Martin Schmiele
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Lilia Ahrné
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.
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10
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Chauvin A, Sergievskaya A, Fucikova A, Corrêa CA, Vesely J, Cornil J, Cornil D, Dopita M, Konstantinidis S. Insights into the growth of nanoparticles in liquid polyol by thermal annealing. NANOSCALE ADVANCES 2021; 3:4780-4789. [PMID: 36134317 PMCID: PMC9418955 DOI: 10.1039/d1na00222h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/28/2021] [Indexed: 05/20/2023]
Abstract
We report on the growth of metal- and metal-oxide based nanoparticles (NPs) in heated polyol solutions. For this purpose, NPs are produced by the sputtering of a silver, gold, or a copper target to produce either silver, gold, or copper oxide NPs in pentaerythritol ethoxylate (PEEL) which has been annealed up to 200 °C. The objective of the annealing step is the fine modulation of their size. Thus, the evolution of the NP size and shape after thermal annealing is explained according to collision/coalescence kinetics and the affinity between the metal-/metal-oxide and PEEL molecule. Moreover, highlights of few phenomena arising from the annealing step are described such as (i) the reduction of copper oxide into copper by the polyol process and (ii) the effective formation of carbon dots after annealing at 200 °C.
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Affiliation(s)
- Adrien Chauvin
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
- Chimie des Interactions Plasma-Surface (ChIPS), University of Mons Place du Parc 20 7000 Mons Belgium
| | - Anastasiya Sergievskaya
- Chimie des Interactions Plasma-Surface (ChIPS), University of Mons Place du Parc 20 7000 Mons Belgium
| | - Anna Fucikova
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | - Cinthia Antunes Corrêa
- Institute of Physics of the Czech Academy of Sciences Cukrovarnická 10/112 162 00 Prague 6 Czech Republic
- Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | - Jozef Vesely
- Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials (CMN), University of Mons Place du Parc 20 Mons 7000 Belgium
| | - David Cornil
- Laboratory for Chemistry of Novel Materials (CMN), University of Mons Place du Parc 20 Mons 7000 Belgium
| | - Milan Dopita
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5 121 16 Praha 2 Czech Republic
| | - Stephanos Konstantinidis
- Chimie des Interactions Plasma-Surface (ChIPS), University of Mons Place du Parc 20 7000 Mons Belgium
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11
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Wetzel O, Hosseini S, Loza K, Heggen M, Prymak O, Bayer P, Beuck C, Schaller T, Niemeyer F, Weidenthaler C, Epple M. Metal-Ligand Interface and Internal Structure of Ultrasmall Silver Nanoparticles (2 nm). J Phys Chem B 2021; 125:5645-5659. [PMID: 34029093 DOI: 10.1021/acs.jpcb.1c02512] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ultrasmall silver nanoparticles were prepared by reduction with NaBH4 and surface-terminated with glutathione (GSH). The particles had a solid core diameter of 2 nm as shown by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). NMR-DOSY gave a hydrodynamic diameter of 2 to 2.8 nm. X-ray photoelectron spectroscopy (XPS) showed that silver is bound to the thiol group of the central cysteine in glutathione under partial oxidation to silver(+I). In turn, the thiol group is deprotonated to thiolate. X-ray powder diffraction (XRD) together with Rietveld refinement confirmed a twinned (polycrystalline) fcc structure of ultrasmall silver nanoparticles with a lattice compression of about 0.9% compared to bulk silver metal. By NMR spectroscopy, the interaction between the glutathione ligand and the silver surface was analyzed, also with 13C-labeled glutathione. The adsorbed glutathione is fully intact and binds to the silver surface via cysteine. In situ 1H NMR spectroscopy up to 85 °C in dispersion showed that the glutathione ligand did not detach from the surface of the silver nanoparticle, i.e. the silver-sulfur bond is remarkably strong. The ultrasmall nanoparticles had a higher cytotoxicity than bigger particles in in vitro cell culture with HeLa cells with a cytotoxic concentration of about 1 μg mL-1 after 24 h incubation. The overall stoichiometry of the nanoparticles was about Ag∼250GSH∼155.
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Affiliation(s)
- Oliver Wetzel
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Shabnam Hosseini
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Kateryna Loza
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Marc Heggen
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Oleg Prymak
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Peter Bayer
- Department of Structural and Medicinal Biochemistry, Centre for Medical Biotechnology (ZMB), University of Duisburg-Essen, 45117 Essen, Germany
| | - Christine Beuck
- Department of Structural and Medicinal Biochemistry, Centre for Medical Biotechnology (ZMB), University of Duisburg-Essen, 45117 Essen, Germany
| | - Torsten Schaller
- Organic Chemistry, University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Felix Niemeyer
- Organic Chemistry, University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
| | - Claudia Weidenthaler
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Matthias Epple
- Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstrasse 5-7, 45117 Essen, Germany
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12
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Torabi SF, Chen YL, Zhang K, Wang J, DeGregorio SJ, Vaidya AT, Su Z, Pabit SA, Chiu W, Pollack L, Steitz JA. Structural analyses of an RNA stability element interacting with poly(A). Proc Natl Acad Sci U S A 2021; 118:e2026656118. [PMID: 33785601 PMCID: PMC8040590 DOI: 10.1073/pnas.2026656118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cis-acting RNA elements are crucial for the regulation of polyadenylated RNA stability. The element for nuclear expression (ENE) contains a U-rich internal loop flanked by short helices. An ENE stabilizes RNA by sequestering the poly(A) tail via formation of a triplex structure that inhibits a rapid deadenylation-dependent decay pathway. Structure-based bioinformatic studies identified numerous ENE-like elements in evolutionarily diverse genomes, including a subclass containing two ENE motifs separated by a short double-helical region (double ENEs [dENEs]). Here, the structure of a dENE derived from a rice transposable element (TWIFB1) before and after poly(A) binding (∼24 kDa and ∼33 kDa, respectively) is investigated. We combine biochemical structure probing, small angle X-ray scattering (SAXS), and cryo-electron microscopy (cryo-EM) to investigate the dENE structure and its local and global structural changes upon poly(A) binding. Our data reveal 1) the directionality of poly(A) binding to the dENE, and 2) that the dENE-poly(A) interaction involves a motif that protects the 3'-most seven adenylates of the poly(A). Furthermore, we demonstrate that the dENE does not undergo a dramatic global conformational change upon poly(A) binding. These findings are consistent with the recently solved crystal structure of a dENE+poly(A) complex [S.-F. Torabi et al., Science 371, eabe6523 (2021)]. Identification of additional modes of poly(A)-RNA interaction opens new venues for better understanding of poly(A) tail biology.
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Affiliation(s)
- Seyed-Fakhreddin Torabi
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536
- HHMI, Yale University School of Medicine, New Haven, CT 06536
| | - Yen-Lin Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Kaiming Zhang
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- James H. Clark Center, Stanford University, Stanford, CA 94305
| | - Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536
| | - Suzanne J DeGregorio
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536
- HHMI, Yale University School of Medicine, New Haven, CT 06536
| | - Anand T Vaidya
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536
- HHMI, Yale University School of Medicine, New Haven, CT 06536
- Tata Institute of Fundamental Research Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 10 500046 Hyderabad, India
| | - Zhaoming Su
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- James H. Clark Center, Stanford University, Stanford, CA 94305
| | - Suzette A Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Wah Chiu
- Department of Bioengineering, Stanford University, Stanford, CA 94305;
- James H. Clark Center, Stanford University, Stanford, CA 94305
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Lightsource, Stanford Linear Accelerator Center National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853;
| | - Joan A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536;
- HHMI, Yale University School of Medicine, New Haven, CT 06536
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13
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Small angle X-ray scattering analysis of ligand-bound forms of tetrameric apolipoprotein-D. Biosci Rep 2021; 41:227100. [PMID: 33399852 PMCID: PMC7786332 DOI: 10.1042/bsr20201423] [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: 05/16/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 11/17/2022] Open
Abstract
Human apolipoprotein-D (apoD) is a glycosylated lipocalin that plays a protective role in Alzheimer's disease due to its antioxidant function. Native apoD from human body fluids forms oligomers, predominantly a stable tetramer. As a lipocalin, apoD binds and transports small hydrophobic molecules such as progesterone, palmitic acid and sphingomyelin. Oligomerisation is a common trait in the lipocalin family and is affected by ligand binding in other lipocalins. The crystal structure of monomeric apoD shows no major changes upon progesterone binding. Here, we used small-angle X-ray scattering (SAXS) to investigate the influence of ligand binding and oxidation on apoD oligomerisation and conformation. As a solution-based technique, SAXS is well suited to detect changes in oligomeric state and conformation in response to ligand binding. Our results show no change in oligomeric state of apoD and no major conformational changes or subunit rearrangements in response to binding of ligands or protein oxidation. This highlights the highly stable structure of the native apoD tetramer under various physiologically relevant experimental conditions.
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14
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Narvekar A, Gawali SL, Hassan PA, Jain R, Dandekar P. pH dependent aggregation and conformation changes of rituximab using SAXS and its comparison with the standard regulatory approach of biophysical characterization. Int J Biol Macromol 2020; 164:3084-3097. [PMID: 32835797 DOI: 10.1016/j.ijbiomac.2020.08.148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/10/2020] [Accepted: 08/19/2020] [Indexed: 10/23/2022]
Abstract
Development of biologics and biosimilars involves extensive physical and structural characterization, which underlines the further course of its implementation. These characterization techniques require considerable standardization and are labor intensive. It is therefore, important to have an immediate, independent and affordable characterization strategy that may meet the regulatory guidelines. In this study, we have compared the standard biophysical characterization of an anti-CD 20 antibody with characterization by small angle x ray scattering (SAXS). Aggregation of this mAb was analyzed using standard techniques like size exclusion HPLC, dynamic light scattering and sedimentation velocity - analytical ultracentrifugation, whereas structure analysis was conducted using mass spectrometry, circular dichroism spectroscopy and fluorescence spectroscopy. Our results demonstrated that the inferences about the state of mAb aggregation and its structure deduced using the standard approaches were comparable to the data interpreted using SAXS. The radius of gyration and the P(r) distribution plot obtained using the SAXS scattering data allowed analysis of aggregation and conformation of mAb via a single experiment. Thus, SAXS can be used as an independent technique to complement orthogonal analysis for determining the aggregation profile and structure of mAbs.
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Affiliation(s)
- Aditya Narvekar
- Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Matunga, Mumbai 400019, India
| | - Santosh L Gawali
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Puthusserickal A Hassan
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Ratnesh Jain
- Department of Chemical Engineering, Institute of Chemical Technology, Matunga, Mumbai 400019, India.
| | - Prajakta Dandekar
- Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Matunga, Mumbai 400019, India.
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15
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Yan Y, Tao H, He J, Huang SY. The HDOCK server for integrated protein–protein docking. Nat Protoc 2020; 15:1829-1852. [DOI: 10.1038/s41596-020-0312-x] [Citation(s) in RCA: 288] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 02/03/2020] [Indexed: 12/27/2022]
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16
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Brosey CA, Tainer JA. Evolving SAXS versatility: solution X-ray scattering for macromolecular architecture, functional landscapes, and integrative structural biology. Curr Opin Struct Biol 2019; 58:197-213. [PMID: 31204190 PMCID: PMC6778498 DOI: 10.1016/j.sbi.2019.04.004] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 11/27/2022]
Abstract
Small-angle X-ray scattering (SAXS) has emerged as an enabling integrative technique for comprehensive analyses of macromolecular structures and interactions in solution. Over the past two decades, SAXS has become a mainstay of the structural biologist's toolbox, supplying multiplexed measurements of molecular shape and dynamics that unveil biological function. Here, we discuss evolving SAXS theory, methods, and applications that extend the field of small-angle scattering beyond simple shape characterization. SAXS, coupled with size-exclusion chromatography (SEC-SAXS) and time-resolved (TR-SAXS) methods, is now providing high-resolution insight into macromolecular flexibility and ensembles, delineating biophysical landscapes, and facilitating high-throughput library screening to assess macromolecular properties and to create opportunities for drug discovery. Looking forward, we consider SAXS in the integrative era of hybrid structural biology methods, its potential for illuminating cellular supramolecular and mesoscale structures, and its capacity to complement high-throughput bioinformatics sequencing data. As advances in the field continue, we look forward to proliferating uses of SAXS based upon its abilities to robustly produce mechanistic insights for biology and medicine.
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Affiliation(s)
- Chris A Brosey
- Molecular and Cellular Oncology and Cancer Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
| | - John A Tainer
- Molecular and Cellular Oncology and Cancer Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA; MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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17
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Efficacy of aldose reductase inhibitors is affected by oxidative stress induced under X-ray irradiation. Sci Rep 2019; 9:3177. [PMID: 30816220 PMCID: PMC6395642 DOI: 10.1038/s41598-019-39722-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/29/2019] [Indexed: 01/01/2023] Open
Abstract
Human aldose reductase (hAR, AKR1B1) has been explored as drug target since the 1980s for its implication in diabetic complications. An activated form of hAR was found in cells from diabetic patients, showing a reduced sensitivity to inhibitors in clinical trials, which may prevent its pharmacological use. Here we report the conversion of native hAR to its activated form by X-ray irradiation simulating oxidative stress conditions. Upon irradiation, the enzyme activity increases moderately and the potency of several hAR inhibitors decay before global protein radiation damage appears. The catalytic behavior of activated hAR is also reproduced as the KM increases dramatically while the kcat is not much affected. Consistently, the catalytic tetrad is not showing any modification. The only catalytically-relevant structural difference observed is the conversion of residue Cys298 to serine and alanine. A mechanism involving electron capture is suggested for the hAR activation. We propose that hAR inhibitors should not be designed against the native protein but against the activated form as obtained from X-ray irradiation. Furthermore, since the reactive species produced under irradiation conditions are the same as those produced under oxidative stress, the described irradiation method can be applied to other relevant proteins under oxidative stress environments.
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18
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Clifton LA, Hall SCL, Mahmoudi N, Knowles TJ, Heinrich F, Lakey JH. Structural Investigations of Protein-Lipid Complexes Using Neutron Scattering. Methods Mol Biol 2019; 2003:201-251. [PMID: 31218621 DOI: 10.1007/978-1-4939-9512-7_11] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Neutron scattering has significant benefits for examining the structure of protein-lipid complexes. Cold (slow) neutrons are nondamaging and predominantly interact with the atomic nucleus, meaning that neutron beams can penetrate deeply into samples, which allows for flexibility in the design of samples studied. Most importantly, there is a strong difference in neutron scattering length (i.e., scattering power) between protium ([Formula: see text], 99.98% natural abundance) and deuterium ([Formula: see text] or D, 0.015%). Through the mixing of H2O and D2O in the samples and in some cases the deuterium labeling of the biomolecules, components within a complex can be hidden or enhanced in the scattering signal. This enables both the overall structure and the relative distribution of components within a complex to be resolved. Lipid-protein complexes are most commonly studied using neutron reflectometry (NR) and small angle neutron scattering (SANS). In this review the methodologies to produce and examine a variety of model biological membrane systems using SANS and NR are detailed. These systems include supported lipid bilayers derived from vesicle dispersions or Langmuir-Blodgett deposition, tethered bilayer systems, membrane protein-lipid complexes and polymer wrapped lipid nanodiscs. The three key stages of any SANS/NR study on model membrane systems-sample preparation, data collection, and analysis-are described together with some background on the techniques themselves.
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Affiliation(s)
- Luke A Clifton
- Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, Oxfordshire, UK.
| | - Stephen C L Hall
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Najet Mahmoudi
- Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, Oxfordshire, UK
| | - Timothy J Knowles
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA
- National Institute of Standards and Technology Centre for Neutron Research, Gaithersburg, MD, USA
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, UK.
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19
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Larsen AH, Arleth L, Hansen S. Analysis of small-angle scattering data using model fitting and Bayesian regularization. J Appl Crystallogr 2018. [DOI: 10.1107/s1600576718008956] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The structure of macromolecules can be studied by small-angle scattering (SAS), but as this is an ill-posed problem, prior knowledge about the sample must be included in the analysis. Regularization methods are used for this purpose, as already implemented in indirect Fourier transformation and bead-modeling-based analysis of SAS data, but not yet in the analysis of SAS data with analytical form factors. To fill this gap, a Bayesian regularization method was implemented, where the prior information was quantified as probability distributions for the model parameters and included via a functional S. The quantity Q = χ2 + αS was then minimized and the value of the regularization parameter α determined by probability maximization. The method was tested on small-angle X-ray scattering data from a sample of nanodiscs and a sample of micelles. The parameters refined with the Bayesian regularization method were closer to the prior values as compared with conventional χ2 minimization. Moreover, the errors on the refined parameters were generally smaller, owing to the inclusion of prior information. The Bayesian method stabilized the refined values of the fitted model upon addition of noise and can thus be used to retrieve information from data with low signal-to-noise ratio without risk of overfitting. Finally, the method provides a measure for the information content in data, N
g, which represents the effective number of retrievable parameters, taking into account the imposed prior knowledge as well as the noise level in data.
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20
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Bailey DC, Alexander E, Rice MR, Drake EJ, Mydy LS, Aldrich CC, Gulick AM. Structural and functional delineation of aerobactin biosynthesis in hypervirulent Klebsiella pneumoniae. J Biol Chem 2018; 293:7841-7852. [PMID: 29618511 DOI: 10.1074/jbc.ra118.002798] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 03/30/2018] [Indexed: 12/17/2022] Open
Abstract
Aerobactin, a citryl-hydroxamate siderophore, is produced by a number of pathogenic Gram-negative bacteria to aid in iron assimilation. Interest in this well-known siderophore was reignited by recent investigations suggesting that it plays a key role in mediating the enhanced virulence of a hypervirulent pathotype of Klebsiella pneumoniae (hvKP). In contrast to classical opportunistic strains of K. pneumoniae, hvKP causes serious life-threatening infections in previously healthy individuals in the community. Multiple contemporary reports have confirmed fears that the convergence of multidrug-resistant and hvKP pathotypes has led to the evolution of a highly transmissible, drug-resistant, and virulent "super bug." Despite hvKP harboring four distinct siderophore operons, knocking out production of only aerobactin led to a significant attenuation of virulence. Herein, we continue our structural and functional studies on the biosynthesis of this crucial virulence factor. In vivo heterologous production and in vitro reconstitution of aerobactin biosynthesis from hvKP was carried out, demonstrating the specificity, stereoselectivity, and kinetic throughput of the complete pathway. Additionally, we present a steady-state kinetic analysis and the X-ray crystal structure of the second aerobactin synthetase IucC, as well as describe a surface entropy reduction strategy that was employed for structure determination. Finally, we show solution X-ray scattering data that support a unique dimeric quaternary structure for IucC. These new insights into aerobactin assembly will help inform potential antivirulence strategies and advance our understanding of siderophore biosynthesis.
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Affiliation(s)
- Daniel C Bailey
- From the Department of Structural Biology, The Jacobs School of Medicine & Biomedical Sciences, State University of New York, Buffalo, New York 14203.,the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203, and
| | - Evan Alexander
- the Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Matthew R Rice
- the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203, and
| | - Eric J Drake
- From the Department of Structural Biology, The Jacobs School of Medicine & Biomedical Sciences, State University of New York, Buffalo, New York 14203.,the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203, and
| | - Lisa S Mydy
- From the Department of Structural Biology, The Jacobs School of Medicine & Biomedical Sciences, State University of New York, Buffalo, New York 14203.,the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203, and
| | - Courtney C Aldrich
- the Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Andrew M Gulick
- From the Department of Structural Biology, The Jacobs School of Medicine & Biomedical Sciences, State University of New York, Buffalo, New York 14203, .,the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203, and
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21
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Ksenofontov AL, Dobrov EN, Fedorova NV, Serebryakova MV, Prusov AN, Baratova LA, Paalme V, Järvekülg L, Shtykova EV. Isolated Potato Virus A coat protein possesses unusual properties and forms different short virus-like particles. J Biomol Struct Dyn 2017; 36:1728-1738. [DOI: 10.1080/07391102.2017.1333457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Alexander L. Ksenofontov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Eugeny N. Dobrov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Natalia V. Fedorova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Marina V. Serebryakova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Andrei N. Prusov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Ludmila A. Baratova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
| | - Viiu Paalme
- Department of Chemistry and Biotechnology, Tallinn University of Technology , Akadeemia tee 15, Tallinn 12618, Estonia
| | - Lilian Järvekülg
- Department of Chemistry and Biotechnology, Tallinn University of Technology , Akadeemia tee 15, Tallinn 12618, Estonia
| | - Eleonora V. Shtykova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow 119234, Russia
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences , Moscow, Russia
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22
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Prischi F, Pastore A. Hybrid Methods in Iron-Sulfur Cluster Biogenesis. Front Mol Biosci 2017; 4:12. [PMID: 28349052 PMCID: PMC5346568 DOI: 10.3389/fmolb.2017.00012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/23/2017] [Indexed: 11/13/2022] Open
Abstract
Hybrid methods, which combine and integrate several biochemical and biophysical techniques, have rapidly caught up in the last twenty years to provide a way to obtain a fuller description of proteins and molecular complexes with sizes and complexity otherwise not easily affordable. Here, we review the use of a robust hybrid methodology based on a mixture of NMR, SAXS, site directed mutagenesis and molecular docking which we have developed to determine the structure of weakly interacting molecular complexes. We applied this technique to gain insights into the structure of complexes formed amongst proteins involved in the molecular machine, which produces the essential iron-sulfur cluster prosthetic groups. Our results were validated both by X-ray structures and by other groups who adopted the same approach. We discuss the advantages and the limitations of our methodology and propose new avenues, which could improve it.
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Affiliation(s)
- Filippo Prischi
- School of Biological Sciences, University of Essex Colchester, UK
| | - Annalisa Pastore
- Maurice Wohl Institute, King's College LondonLondon, UK; Molecular Medicine Department, University of PaviaPavia, Italy
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23
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Brooks-Bartlett JC, Batters RA, Bury CS, Lowe ED, Ginn HM, Round A, Garman EF. Development of tools to automate quantitative analysis of radiation damage in SAXS experiments. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:63-72. [PMID: 28009547 PMCID: PMC5182020 DOI: 10.1107/s1600577516015083] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 09/23/2016] [Indexed: 05/09/2023]
Abstract
Biological small-angle X-ray scattering (SAXS) is an increasingly popular technique used to obtain nanoscale structural information on macromolecules in solution. However, radiation damage to the samples limits the amount of useful data that can be collected from a single sample. In contrast to the extensive analytical resources available for macromolecular crystallography (MX), there are relatively few tools to quantitate radiation damage for SAXS, some of which require a significant level of manual characterization, with the potential of leading to conflicting results from different studies. Here, computational tools have been developed to automate and standardize radiation damage analysis for SAXS data. RADDOSE-3D, a dose calculation software utility originally written for MX experiments, has been extended to account for the cylindrical geometry of the capillary tube, the liquid composition of the sample and the attenuation of the beam by the capillary material to allow doses to be calculated for many SAXS experiments. Furthermore, a library has been written to visualize and explore the pairwise similarity of frames. The calculated dose for the frame at which three subsequent frames are determined to be dissimilar is defined as the radiation damage onset threshold (RDOT). Analysis of RDOTs has been used to compare the efficacy of radioprotectant compounds to extend the useful lifetime of SAXS samples. Comparison of the RDOTs shows that, for radioprotectant compounds at 5 and 10 mM concentration, glycerol is the most effective compound. However, at 1 and 2 mM concentrations, dithiothreitol (DTT) appears to be most effective. Our newly developed visualization library contains methods that highlight the unusual radiation damage results given by SAXS data collected using higher concentrations of DTT: these observations should pave the way to the development of more sophisticated frame merging strategies.
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Affiliation(s)
| | | | - Charles S. Bury
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Edward D. Lowe
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Helen Mary Ginn
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Adam Round
- European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, CS 90181, 38042 Grenoble, France
- SPB/SFX European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
- Faculty of Natural Sciences, Keele University, Staffordshire ST5 5BG, UK
| | - Elspeth F. Garman
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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Putnam CD. Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data. J Appl Crystallogr 2016; 49:1412-1419. [PMID: 27738411 PMCID: PMC5045725 DOI: 10.1107/s1600576716010906] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/05/2016] [Indexed: 01/12/2023] Open
Abstract
The Guinier region in small-angle X-ray scattering (SAXS) defines the radius of gyration, Rg, and the forward scattering intensity, I(0). In Guinier peak analysis (GPA), the plot of qI(q) versus q2 transforms the Guinier region into a characteristic peak for visual and automated inspection of data. Deviations of the peak position from the theoretical position in dimensionless GPA plots can suggest parameter errors, problematic low-resolution data, some kinds of intermolecular interactions or elongated scatters. To facilitate automated analysis by GPA, the elongation ratio (ER), which is the ratio of the areas in the pair-distribution function P(r) after and before the P(r) maximum, was characterized; symmetric samples have ER values around 1, and samples with ER values greater than 5 tend to be outliers in GPA analysis. Use of GPA+ER can be a helpful addition to SAXS data analysis pipelines.
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Affiliation(s)
- Christopher D. Putnam
- Ludwig Institute for Cancer Research, Department of Medicine, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
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Bailey DC, Drake EJ, Grant TD, Gulick AM. Structural and Functional Characterization of Aerobactin Synthetase IucA from a Hypervirulent Pathotype of Klebsiella pneumoniae. Biochemistry 2016; 55:3559-70. [PMID: 27253399 PMCID: PMC4928626 DOI: 10.1021/acs.biochem.6b00409] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Iron is a vital mineral nutrient required by virtually all life forms to prosper; pathogenic bacteria are no exception. Despite the abundance of iron within the human host, highly regulated iron physiology can result in exceedingly low levels of iron bioavailable to prospective invading bacteria. To combat this scarcity of iron, many pathogenic bacteria have acquired specific and efficient iron acquisition systems, which allow them to thrive in iron-deficient host environments. One of the more prominent bacterial iron acquisition systems involves the synthesis, secretion, and reuptake of small-molecule iron chelators known as siderophores. Aerobactin, a citrate-hydroxamate siderophore originally isolated nearly 50 years ago, is produced by a number of pathogenic Gram-negative bacteria. Aerobactin has recently been demonstrated to play a pivotal role in mediating the enhanced virulence of a particularly invasive pathotype of Klebsiella pneumoniae (hvKP). Toward further understanding of this key virulence factor, we report the structural and functional characterization of aerobactin synthetase IucA from a strain of hvKP. The X-ray crystal structures of unliganded and ATP-bound forms of IucA were solved, forming the foundation of our structural analysis. Small angle X-ray scattering (SAXS) data suggest that, unlike its closest structurally characterized homologues, IucA adopts a tetrameric assembly in solution. Finally, we employed activity assays to investigate the substrate specificity and determine the apparent steady-state kinetic parameters of IucA.
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Affiliation(s)
- Daniel C Bailey
- The Hauptman-Woodward Medical Research Institute , Buffalo, New York, United States
| | - Eric J Drake
- The Hauptman-Woodward Medical Research Institute , Buffalo, New York, United States
| | - Thomas D Grant
- The Hauptman-Woodward Medical Research Institute , Buffalo, New York, United States
| | - Andrew M Gulick
- The Hauptman-Woodward Medical Research Institute , Buffalo, New York, United States
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26
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Venditti V, Egner TK, Clore GM. Hybrid Approaches to Structural Characterization of Conformational Ensembles of Complex Macromolecular Systems Combining NMR Residual Dipolar Couplings and Solution X-ray Scattering. Chem Rev 2016; 116:6305-22. [PMID: 26739383 PMCID: PMC5590664 DOI: 10.1021/acs.chemrev.5b00592] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Solving structures or structural ensembles of large macromolecular systems in solution poses a challenging problem. While NMR provides structural information at atomic resolution, increased spectral complexity, chemical shift overlap, and short transverse relaxation times (associated with slow tumbling) render application of the usual techniques that have been so successful for medium sized systems (<50 kDa) difficult. Solution X-ray scattering, on the other hand, is not limited by molecular weight but only provides low resolution structural information related to the overall shape and size of the system under investigation. Here we review how combining atomic resolution structures of smaller domains with sparse experimental data afforded by NMR residual dipolar couplings (which yield both orientational and shape information) and solution X-ray scattering data in rigid-body simulated annealing calculations provides a powerful approach for investigating the structural aspects of conformational dynamics in large multidomain proteins. The application of this hybrid methodology is illustrated for the 128 kDa dimer of bacterial Enzyme I which exists in a variety of open and closed states that are sampled at various points in the catalytic cycles, and for the capsid protein of the human immunodeficiency virus.
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Affiliation(s)
- Vincenzo Venditti
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Timothy K. Egner
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - G. Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
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27
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Hopkins JB, Thorne RE. Quantifying radiation damage in biomolecular small-angle X-ray scattering. J Appl Crystallogr 2016; 49:880-890. [PMID: 27275138 PMCID: PMC4886981 DOI: 10.1107/s1600576716005136] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/25/2016] [Indexed: 11/10/2022] Open
Abstract
Small-angle X-ray scattering (SAXS) is an increasingly popular technique that provides low-resolution structural information about biological macromolecules in solution. Many of the practical limitations of the technique, such as minimum required sample volume, and of experimental design, such as sample flow cells, are necessary because the biological samples are sensitive to damage from the X-rays. Radiation damage typically manifests as aggregation of the sample, which makes the collected data unreliable. However, there has been little systematic investigation of the most effective methods to reduce damage rates, and results from previous damage studies are not easily compared with results from other beamlines. Here a methodology is provided for quantifying radiation damage in SAXS to provide consistent results between different experiments, experimenters and beamlines. These methods are demonstrated on radiation damage data collected from lysozyme, glucose isomerase and xylanase, and it is found that no single metric is sufficient to describe radiation damage in SAXS for all samples. The radius of gyration, molecular weight and integrated SAXS profile intensity constitute a minimal set of parameters that capture all types of observed behavior. Radiation sensitivities derived from these parameters show a large protein dependence, varying by up to six orders of magnitude between the different proteins tested. This work should enable consistent reporting of radiation damage effects, allowing more systematic studies of the most effective minimization strategies.
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Affiliation(s)
| | - Robert E. Thorne
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
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