1
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Mensah GAK, Schaefer KG, Roberts AG, King GM, Bartlett MG. Probing the Mechanisms Underlying the Transport of the Vinca Alkaloids by P-glycoprotein. J Pharm Sci 2024; 113:1960-1974. [PMID: 38527618 DOI: 10.1016/j.xphs.2024.03.014] [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: 10/26/2023] [Revised: 03/18/2024] [Accepted: 03/18/2024] [Indexed: 03/27/2024]
Abstract
The efficacy of many cancer drugs is hindered by P-glycoprotein (Pgp), a cellular pump that removes drugs from cells. To improve chemotherapy, drugs capable of evading Pgp must be developed. Despite similarities in structure, vinca alkaloids (VAs) show disparate Pgp-mediated efflux ratios. ATPase activity and binding affinity studies show at least two binding sites for the VAs: high- and low-affinity sites that stimulate and inhibit the ATPase activity rate, respectively. The affinity for ATP from the ATPase kinetics curve for vinblastine (VBL) at the high-affinity site was 2- and 9-fold higher than vinorelbine (VRL) and vincristine (VCR), respectively. Conversely, VBL had the highest Km (ATP) for the low-affinity site. The dissociation constants (KDs) determined by protein fluorescence quenching were in the order VBL < VRL< VCR. The order of the KDs was reversed at higher substrate concentrations. Acrylamide quenching of protein fluorescence indicate that the VAs, either at 10 µM or 150 µM, predominantly maintain Pgp in an open-outward conformation. When 3.2 mM AMPPNP was present, 10 µM of either VBL, VRL, or VCR cause Pgp to shift to an open-outward conformation, while 150 µM of the VAs shifted the conformation of Pgp to an intermediate orientation, between opened inward and open-outward. However, the conformational shift induced by saturating AMPPNP and VCR condition was less than either VBL or VRL in the presence of AMPPNP. At 150 µM, atomic force microscopy (AFM) revealed that the VAs shift Pgp population to a predominantly open-inward conformation. Additionally, STDD NMR studies revealed comparable groups in VBL, VRL, and VCR are in contact with the protein during binding. Our results, when coupled with VAs-microtubule structure-activity relationship studies, could lay the foundation for developing next-generation VAs that are effective as anti-tumor agents. A model that illustrates the intricate process of Pgp-mediated transport of the VAs is presented.
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Affiliation(s)
- Gershon A K Mensah
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA
| | - Katherine G Schaefer
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
| | - Arthur G Roberts
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA.
| | - Gavin M King
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA; Joint with Biochemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA.
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2
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Hernández-Sánchez A, Páez-Pérez ED, Alfaro-Saldaña E, Olivares-Illana V, García-Meza JV. Understanding a Core Pilin of the Type IVa Pili of Acidithiobacillus thiooxidans, PilV. J Microbiol Biotechnol 2024; 34:527-537. [PMID: 38346803 PMCID: PMC11016768 DOI: 10.4014/jmb.2310.10033] [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: 10/25/2023] [Revised: 12/22/2023] [Accepted: 12/29/2023] [Indexed: 04/17/2024]
Abstract
Pilins are protein subunits of pili. The pilins of type IV pili (T4P) in pathogenic bacteria are well characterized, but anything is known about the T4P proteins in acidophilic chemolithoautotrophic microorganisms such as the genus Acidithiobacillus. The interest in T4P of A. thiooxidans is because of their possible role in cell recruitment and bacterial aggregation on the surface of minerals during biooxidation of sulfide minerals. In this study we present a successful ad hoc methodology for the heterologous expression and purification of extracellular proteins such as the minor pilin PilV of the T4P of A. thiooxidans, a pilin exposed to extreme conditions of acidity and high oxidation-reduction potentials, and that interact with metal sulfides in an environment rich in dissolved minerals. Once obtained, the model structure of A. thiooxidans PilV revealed the core basic architecture of T4P pilins. Because of the acidophilic condition, we carried out in silico characterization of the protonation status of acidic and basic residues of PilV in order to calculate the ionization state at specific pH values and evaluated their pH stability. Further biophysical characterization was done using UV-visible and fluorescence spectroscopy and the results showed that PilV remains soluble and stable even after exposure to significant changes of pH. PilV has a unique amino acid composition that exhibits acid stability, with significant biotechnology implications such as biooxidation of sulfide minerals. The biophysics profiles of PilV open new paradigms about resilient proteins and stimulate the study of other pilins from extremophiles.
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Affiliation(s)
- Araceli Hernández-Sánchez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, San Luis Potosí, 78210, SLP, México
| | - Edgar D. Páez-Pérez
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, San Luis Potosí, 78210, SLP, México
| | - Elvia Alfaro-Saldaña
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, San Luis Potosí, 78210, SLP, México
| | - Vanesa Olivares-Illana
- Laboratorio de Interacciones Biomoleculares y Cáncer. Instituto de Física, Universidad Autónoma de San Luis Potosí, Av. Parque Chapultepec 1570, Privadas del Pedregal, San Luis Potosí, 78210, SLP, México
| | - J. Viridiana García-Meza
- Geomicrobiología, Metalurgia, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, San Luis Potosí, 78210, SLP, México
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3
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Fossum CJ, Johnson BOV, Golde ST, Kielman AJ, Finke B, Smith MA, Lowater HR, Laatsch BF, Bhattacharyya S, Hati S. Insights into the Mechanism of Tryptophan Fluorescence Quenching due to Synthetic Crowding Agents: A Combined Experimental and Computational Study. ACS OMEGA 2023; 8:44820-44830. [PMID: 38046287 PMCID: PMC10688029 DOI: 10.1021/acsomega.3c06006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/28/2023] [Accepted: 10/31/2023] [Indexed: 12/05/2023]
Abstract
Intrinsic tryptophan fluorescence spectroscopy is an important tool for examining the effects of molecular crowding and confinement on the structure, dynamics, and function of proteins. Synthetic crowders such as dextran, ficoll, polyethylene glycols, polyvinylpyrrolidone, and their respective monomers are used to mimic crowded intracellular environments. Interactions of these synthetic crowders with tryptophan and the subsequent impact on its fluorescence properties are therefore critically important for understanding the possible interference created by these crowders. In the present study, the effects of polymer and monomer crowders on tryptophan fluorescence were assessed by using experimental and computational approaches. The results of this study demonstrated that both polymer and monomer crowders have an impact on the tryptophan fluorescence intensity; however, the molecular mechanisms of quenching were different. Using Stern-Volmer plots and a temperature variation study, a physical basis for the quenching mechanism of commonly used synthetic crowders was established. The quenching of free tryptophan was found to involve static, dynamic, and sphere-of-action mechanisms. In parallel, computational studies employing Kohn-Sham density functional theory provided a deeper insight into the effects of intermolecular interactions and solvation, resulting in differing quenching modes for these crowders. Taken together, the study offers new physical insights into the quenching mechanisms of some commonly used monomer and polymer synthetic crowders.
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Affiliation(s)
| | - Benjamin O. V. Johnson
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Spencer T. Golde
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Alexis J. Kielman
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Brianna Finke
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Macey A. Smith
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Harrison R. Lowater
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Bethany F. Laatsch
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Sudeep Bhattacharyya
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
| | - Sanchita Hati
- Department of Chemistry and
Biochemistry, University of Wisconsin-Eau
Claire, Eau Claire, Wisconsin 54701, United States
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4
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Mensah GAK, Schaefer KG, Bartlett MG, Roberts AG, King GM. Drug-Induced Conformational Dynamics of P-Glycoprotein Underlies the Transport of Camptothecin Analogs. Int J Mol Sci 2023; 24:16058. [PMID: 38003248 PMCID: PMC10671697 DOI: 10.3390/ijms242216058] [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: 10/04/2023] [Revised: 10/24/2023] [Accepted: 10/28/2023] [Indexed: 11/26/2023] Open
Abstract
P-glycoprotein (Pgp) plays a pivotal role in drug bioavailability and multi-drug resistance development. Understanding the protein's activity and designing effective drugs require insight into the mechanisms underlying Pgp-mediated transport of xenobiotics. In this study, we investigated the drug-induced conformational changes in Pgp and adopted a conformationally-gated model to elucidate the Pgp-mediated transport of camptothecin analogs (CPTs). While Pgp displays a wide range of conformations, we simplified it into three model states: 'open-inward', 'open-outward', and 'intermediate'. Utilizing acrylamide quenching of Pgp fluorescence as a tool to examine the protein's tertiary structure, we observed that topotecan (TPT), SN-38, and irinotecan (IRT) induced distinct conformational shifts in the protein. TPT caused a substantial shift akin to AMPPNP, suggesting ATP-independent 'open-outward' conformation. IRT and SN-38 had relatively moderate effects on the conformation of Pgp. Experimental atomic force microscopy (AFM) imaging supports these findings. Further, the rate of ATPase hydrolysis was correlated with ligand-induced Pgp conformational changes. We hypothesize that the separation between the nucleotide-binding domains (NBDs) creates a conformational barrier for substrate transport. Substrates that reduce the conformational barrier, like TPT, are better transported. The affinity for ATP extracted from Pgp-mediated ATP hydrolysis kinetics curves for TPT was about 2-fold and 3-fold higher than SN-38 and IRT, respectively. On the contrary, the dissociation constants (KD) determined by fluorescence quenching for these drugs were not significantly different. Saturation transfer double difference (STDD) NMR of TPT and IRT with Pgp revealed that similar functional groups of the CPTs are accountable for Pgp-CPTs interactions. Efforts aimed at modifying these functional groups, guided by available structure-activity relationship data for CPTs and DNA-Topoisomerase-I complexes, could pave the way for the development of more potent next-generation CPTs.
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Affiliation(s)
- Gershon A. K. Mensah
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA; (G.A.K.M.)
| | - Katherine G. Schaefer
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA;
| | - Michael G. Bartlett
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA; (G.A.K.M.)
| | - Arthur G. Roberts
- Department of Pharmaceutical and Biomedical Science, University of Georgia, Athens, GA 30602, USA; (G.A.K.M.)
| | - Gavin M. King
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA;
- Joint with Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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5
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Ghadami SA, Ahmadi Z, Moosavi-Nejad Z. The albumin-based nanoparticle formation in relation to protein aggregation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 252:119489. [PMID: 33524819 DOI: 10.1016/j.saa.2021.119489] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Albumin is an attractive protein for the preparation of nanoparticle with possible therapeutic applications, due to its biodegradable, nontoxic, non-immunogenic, and metabolizable properties. Many studies have investigated the formation of albumin nanoparticles, generally by the desolvation or coacervation approaches. One of the most important parameters that should be considered in the formation of nanoparticles is their morphology (size and shape). There are many proposals to control the nanoparticle size, but it remains a challenge for researchers yet. In this study, we showed that control of BSA-based nanoparticles/microparticles size could be achieved by varying the temperature and pH and therefore controlling the rate of aggregation. The aggregation behavior was monitored by UV-Vis spectroscopy, SEM, and dye-binding assay. Our results provide more options for the size and shape control of BSA-based nanoparticle in natural buffer systems. The aggregation of BSA at different temperatures within the range of 50-80 °C were studied under the effect of different pHs in the range of 4.7-6.2. In this research, we found that protein aggregation under extreme conditions of pH and temperature, or at the pH near to pI appears to be amorphous, and at the pH above the pI seems to be the amyloid fibril structure. In some instances where the aggregation is neither too fast nor too slow, in the initial phase of the aggregation process, nanoparticle structures can be identified and separated by mechanistic approaches. This observation suggests that the best condition for monitoring the formation of albumin-based nanoparticles could be pH 5.7, 70 °C. Satisfactory rationalization of all aspects of our experimental observation requires further and more detailed study.
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Affiliation(s)
| | - Zahra Ahmadi
- Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Zahra Moosavi-Nejad
- Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran.
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6
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Transthyretin Misfolding, A Fatal Structural Pathogenesis Mechanism. Int J Mol Sci 2021; 22:ijms22094429. [PMID: 33922648 PMCID: PMC8122960 DOI: 10.3390/ijms22094429] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/18/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Transthyretin (TTR) is an essential transporter of a thyroid hormone and a holo-retinol binding protein, found abundantly in human plasma and cerebrospinal fluid. In addition, this protein is infamous for its amyloidogenic propensity, causing various amyloidoses in humans, such as senile systemic amyloidosis, familial amyloid polyneuropathy, and familial amyloid cardiomyopathy. It has been known for over two decades that decreased stability of the native tetrameric conformation of TTR is the main cause of these diseases. Yet, mechanistic details on the amyloidogenic transformation of TTR were not clear until recent multidisciplinary investigations on various structural states of TTR. In this review, we discuss recent advancements in the structural understanding of TTR misfolding and amyloidosis processes. Special emphasis has been laid on the observations of novel structural features in various amyloidogenic species of TTR. In addition, proteolysis-induced fragmentation of TTR, a recently proposed mechanism facilitating TTR amyloidosis, has been discussed in light of its structural consequences and relevance to acknowledge the amyloidogenicity of TTR.
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7
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Codescu MA, Weiß M, Brehm M, Kornilov O, Sebastiani D, Nibbering ETJ. Switching between Proton Vacancy and Excess Proton Transfer Pathways in the Reaction between 7-Hydroxyquinoline and Formate. J Phys Chem A 2021; 125:1845-1859. [PMID: 33651619 PMCID: PMC7957860 DOI: 10.1021/acs.jpca.0c10191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Bifunctional or amphoteric
photoacids simultaneously present donor
(acidic) and acceptor (basic) properties making them useful tools
to analyze proton transfer reactions. In protic solvents, the proton
exchange between the acid and the base is controlled by the acidity
or basicity strength and typically occurs on two different pathways
known as protolysis and hydrolysis. We report here how the addition
of a formate base will alter the relative importance of the possible
reaction pathways of the bifunctional photoacid 7-hydroxyquinoline
(7HQ), which has been recently understood to predominantly involve
a hydroxide/methoxide transport mechanism between the basic proton-accepting
quinoline nitrogen site toward the proton-donating OH group with a
time constant of 360 ps in deuterated methanol (CD3OD).
We follow the reaction dynamics by probing the IR-active marker modes
of the different charged forms of photoexcited 7HQ, and of formic
acid (HCOOD) in CD3OD solution. A comparison of the transient
IR spectra as a function of formate concentration, and classical molecular
dynamics simulations enables us to identify distinct contributions
of “tight” (meaning “contact”) and “loose”
(i.e., “solvent-separated”) 7HQ–formate reaction
pairs in our data. Our results suggest that depending on the orientation
of the OH group with respect to the quinoline aromatic ring system,
the presence of the formate molecule in a proton relay pathway facilitates
a net proton transfer from the proton-donating OH group of 7HQ-N*
via the methanol/formate bridge toward the quinoline N site.
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Affiliation(s)
- Marius-Andrei Codescu
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Moritz Weiß
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Daniel Sebastiani
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
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8
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Pauk JN, Raju Palanisamy J, Kager J, Koczka K, Berghammer G, Herwig C, Veiter L. Advances in monitoring and control of refolding kinetics combining PAT and modeling. Appl Microbiol Biotechnol 2021; 105:2243-2260. [PMID: 33598720 PMCID: PMC7954745 DOI: 10.1007/s00253-021-11151-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 01/19/2021] [Accepted: 01/27/2021] [Indexed: 12/21/2022]
Abstract
Overexpression of recombinant proteins in Escherichia coli results in misfolded and non-active protein aggregates in the cytoplasm, so-called inclusion bodies (IB). In recent years, a change in the mindset regarding IBs could be observed: IBs are no longer considered an unwanted waste product, but a valid alternative to produce a product with high yield, purity, and stability in short process times. However, solubilization of IBs and subsequent refolding is necessary to obtain a correctly folded and active product. This protein refolding process is a crucial downstream unit operation-commonly done as a dilution in batch or fed-batch mode. Drawbacks of the state-of-the-art include the following: the large volume of buffers and capacities of refolding tanks, issues with uniform mixing, challenging analytics at low protein concentrations, reaction kinetics in non-usable aggregates, and generally low re-folding yields. There is no generic platform procedure available and a lack of robust control strategies. The introduction of Quality by Design (QbD) is the method-of-choice to provide a controlled and reproducible refolding environment. However, reliable online monitoring techniques to describe the refolding kinetics in real-time are scarce. In our view, only monitoring and control of re-folding kinetics can ensure a productive, scalable, and versatile platform technology for re-folding processes. For this review, we screened the current literature for a combination of online process analytical technology (PAT) and modeling techniques to ensure a controlled refolding process. Based on our research, we propose an integrated approach based on the idea that all aspects that cannot be monitored directly are estimated via digital twins and used in real-time for process control. KEY POINTS: • Monitoring and a thorough understanding of refolding kinetics are essential for model-based control of refolding processes. • The introduction of Quality by Design combining Process Analytical Technology and modeling ensures a robust platform for inclusion body refolding.
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Affiliation(s)
- Jan Niklas Pauk
- Research Area Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Gumpendorferstrasse 1a/166, 1060, Vienna, Austria
- Competence Center CHASE GmbH, Altenbergerstraße 69, 4040, Linz, Austria
| | - Janani Raju Palanisamy
- Research Area Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Gumpendorferstrasse 1a/166, 1060, Vienna, Austria
| | - Julian Kager
- Research Area Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Gumpendorferstrasse 1a/166, 1060, Vienna, Austria
| | - Krisztina Koczka
- Bilfinger Industrietechnik Salzburg GmbH, Mooslackengasse 17, 1190, Vienna, Austria
| | - Gerald Berghammer
- Bilfinger Industrietechnik Salzburg GmbH, Mooslackengasse 17, 1190, Vienna, Austria
| | - Christoph Herwig
- Research Area Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Gumpendorferstrasse 1a/166, 1060, Vienna, Austria.
| | - Lukas Veiter
- Research Area Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Vienna University of Technology, Gumpendorferstrasse 1a/166, 1060, Vienna, Austria
- Competence Center CHASE GmbH, Altenbergerstraße 69, 4040, Linz, Austria
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9
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Real-Hohn A, Groznica M, Löffler N, Blaas D, Kowalski H. nanoDSF: In vitro Label-Free Method to Monitor Picornavirus Uncoating and Test Compounds Affecting Particle Stability. Front Microbiol 2020; 11:1442. [PMID: 32676065 PMCID: PMC7333345 DOI: 10.3389/fmicb.2020.01442] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/04/2020] [Indexed: 12/30/2022] Open
Abstract
Thermal shift assays measure the stability of macromolecules and macromolecular assemblies as a function of temperature. The Particle Stability Thermal Release Assay (PaSTRy) of picornaviruses is based on probes becoming strongly fluorescent upon binding to hydrophobic patches of the protein capsid (e.g., SYPRO Orange) or to the viral RNA genome (e.g., SYTO-82) that become exposed upon heating virus particles. PaSTRy has been exploited for studying the stability of viral mutants, viral uncoating, and the effect of capsid-stabilizing compounds. While the results were usually robust, the thermal shift assay with SYPRO Orange is sensitive to surfactants and EDTA and failed at least to correctly report the effect of excipients on an inactivated poliovirus 3 vaccine. Furthermore, interactions between the probe and capsid-binding antivirals as well as mutual competition for binding sites cannot be excluded. To overcome these caveats, we assessed differential scanning fluorimetry with a nanoDSF device as a label-free alternative. NanoDSF monitors the changes in the intrinsic tryptophan fluorescence (ITF) resulting from alterations of the 3D-structure of proteins as a function of the temperature. Using rhinovirus A2 as a model, we demonstrate that nanoDFS is well suited for recording the temperature-dependence of conformational changes associated with viral uncoating with minute amounts of sample. We compare it with orthogonal methods and correlate the increase in viral RNA exposure with PaSTRy measurements. Importantly, nanoDSF correctly identified the thermal stabilization of RV-A2 by pleconaril, a prototypic pocket-binding antiviral compound. NanoDFS is thus a label-free, high throughput-customizable, attractive alternative for the discovery of capsid-binding compounds impacting on viral stability.
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Affiliation(s)
- Antonio Real-Hohn
- Center for Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Martin Groznica
- Center for Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Nadine Löffler
- Center for Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Dieter Blaas
- Center for Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
| | - Heinrich Kowalski
- Center for Medical Biochemistry, Max Perutz Labs, Vienna Biocenter, Medical University of Vienna, Vienna, Austria
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10
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Ghadami SA, Chia S, Ruggeri FS, Meisl G, Bemporad F, Habchi J, Cascella R, Dobson CM, Vendruscolo M, Knowles TPJ, Chiti F. Transthyretin Inhibits Primary and Secondary Nucleations of Amyloid-β Peptide Aggregation and Reduces the Toxicity of Its Oligomers. Biomacromolecules 2020; 21:1112-1125. [PMID: 32011129 PMCID: PMC7997117 DOI: 10.1021/acs.biomac.9b01475] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
![]()
Alzheimer’s
disease is associated with the deposition of
the amyloid-β peptide (Aβ) into extracellular senile plaques
in the brain. In vitro and in vivo observations have indicated that
transthyretin (TTR) acts as an Aβ scavenger in the brain, but
the mechanism has not been fully resolved. We have monitored the aggregation
process of Aβ40 by thioflavin T fluorescence, in
the presence or absence of different concentrations of preformed seed
aggregates of Aβ40, of wild-type tetrameric TTR (WT-TTR),
and of a variant engineered to be stable as a monomer (M-TTR). Both
WT-TTR and M-TTR were found to inhibit specific steps of the process
of Aβ40 fibril formation, which are primary and secondary
nucleations, without affecting the elongation of the resulting fibrils.
Moreover, the analysis shows that both WT-TTR and M-TTR bind to Aβ40 oligomers formed in the aggregation reaction and inhibit
their conversion into the shortest fibrils able to elongate. Using
biophysical methods, TTR was found to change some aspects of its overall
structure following such interactions with Aβ40 oligomers,
as well as with oligomers of Aβ42, while maintaining
its overall topology. Hence, it is likely that the predominant mechanism
by which TTR exerts its protective role lies in the binding of TTR
to the Aβ oligomers and in inhibiting primary and secondary
nucleation processes, which limits both the toxicity of Aβ oligomers
and the ability of the fibrils to proliferate.
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Affiliation(s)
- Seyyed Abolghasem Ghadami
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Sean Chia
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Francesco Simone Ruggeri
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Georg Meisl
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Francesco Bemporad
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Johnny Habchi
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Roberta Cascella
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Christopher M Dobson
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Michele Vendruscolo
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Tuomas P J Knowles
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, U.K.,Department of Physics, Cavendish Laboratory, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Fabrizio Chiti
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Section of Biochemistry, University of Florence, 50134 Florence, Italy
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Exploration of the Misfolding Mechanism of Transthyretin Monomer: Insights from Hybrid-Resolution Simulations and Markov State Model Analysis. Biomolecules 2019; 9:biom9120889. [PMID: 31861226 PMCID: PMC6995605 DOI: 10.3390/biom9120889] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/13/2019] [Accepted: 12/15/2019] [Indexed: 01/08/2023] Open
Abstract
Misfolding and aggregation of transthyretin (TTR) is widely known to be responsible for a progressive systemic disorder called amyloid transthyretin (ATTR) amyloidosis. Studies suggest that TTR aggregation is initiated by a rate-limiting dissociation of the homo-tetramer into its monomers, which can rapidly misfold and self-assemble into amyloid fibril. Thus, exploring conformational change involved in TTR monomer misfolding is of vital importance for understanding the pathogenesis of ATTR amyloidosis. In this work, microsecond timescale hybrid-resolution molecular dynamics (MD) simulations combined with Markov state model (MSM) analysis were performed to investigate the misfolding mechanism of the TTR monomer. The results indicate that a macrostate with partially unfolded conformations may serve as the misfolded state of the TTR monomer. This misfolded state was extremely stable with a very large equilibrium probability of about 85.28%. With secondary structure analysis, we found the DAGH sheet in this state to be significantly destroyed. The CBEF sheet was relatively stable and sheet structure was maintained. However, the F-strand in this sheet was likely to move away from E-strand and reform a new β-sheet with the H-strand. This observation is consistent with experimental finding that F and H strands in the outer edge drive the misfolding of TTR. Finally, transition pathways from a near native state to this misfolded macrostate showed that the conformational transition can occur either through a native-like β-sheet intermediates or through partially unfolded intermediates, while the later appears to be the main pathway. As a whole, we identified a potential misfolded state of the TTR monomer and elucidated the misfolding pathway for its conformational transition. This work can provide a valuable theoretical basis for understanding of TTR aggregation and the pathogenesis of ATTR amyloidosis at the atomic level.
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