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Ali A, Ganguillet S, Turgay Y, Keys TG, Causa E, Fradique R, Lutz-Bueno V, Chesnov S, Tan-Lin CW, Lentsch V, Kotar J, Cicuta P, Mezzenga R, Slack E, Radiom M. Surface Cross-Linking by Macromolecular Tethers Enhances Virus-like Particles' Resilience to Mucosal Stress Factors. ACS Nano 2024; 18:3382-3396. [PMID: 38237058 PMCID: PMC10832050 DOI: 10.1021/acsnano.3c10339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/31/2024]
Abstract
Virus-like particles (VLPs) are emerging as nanoscaffolds in a variety of biomedical applications including delivery of vaccine antigens and cargo such as mRNA to mucosal surfaces. These soft, colloidal, and proteinaceous structures (capsids) are nevertheless susceptible to mucosal environmental stress factors. We cross-linked multiple capsid surface amino acid residues using homobifunctional polyethylene glycol tethers to improve the persistence and survival of the capsid to model mucosal stressors. Surface cross-linking enhanced the stability of VLPs assembled from Acinetobacter phage AP205 coat proteins in low pH (down to pH 4.0) and high protease concentration conditions (namely, in pig and mouse gastric fluids). Additionally, it increased the stiffness of VLPs under local mechanical indentation applied using an atomic force microscopy cantilever tip. Small angle X-ray scattering revealed an increase in capsid diameter after cross-linking and an increase in capsid shell thickness with the length of the PEG cross-linkers. Moreover, surface cross-linking had no effect on the VLPs' mucus translocation and accumulation on the epithelium of in vitro 3D human nasal epithelial tissues with mucociliary clearance. Finally, it did not compromise VLPs' function as vaccines in mouse subcutaneous vaccination models. Compared to PEGylation without cross-linking, the stiffness of surface cross-linked VLPs were higher for the same length of the PEG molecule, and also the lifetimes of surface cross-linked VLPs were longer in the gastric fluids. Surface cross-linking using macromolecular tethers, but not simple conjugation of these molecules, thus offers a viable means to enhance the resilience and survival of VLPs for mucosal applications.
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Affiliation(s)
- Ahmed Ali
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Suwannee Ganguillet
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Yagmur Turgay
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Timothy G. Keys
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Erika Causa
- Biological
and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
| | - Ricardo Fradique
- Biological
and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
| | - Viviane Lutz-Bueno
- Paul
Scherrer Institute (PSI), Villigen 5232, Switzerland
- Laboratoire
Léon Brillouin, CEA-CNRS (UMR-12), CEA Saclay, Université
Paris-Saclay, Gif-sur-Yvette Cedex 91191, France
| | - Serge Chesnov
- Functional
Genomics Centre Zürich (FGCZ), University of Zürich/ETH
Zürich, Zürich 8057, Switzerland
| | - Chia-Wei Tan-Lin
- Functional
Genomics Centre Zürich (FGCZ), University of Zürich/ETH
Zürich, Zürich 8057, Switzerland
| | - Verena Lentsch
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Jurij Kotar
- Biological
and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
| | - Pietro Cicuta
- Biological
and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
| | - Raffaele Mezzenga
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Emma Slack
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Milad Radiom
- Department
of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
- Biological
and Soft Systems, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
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Radiom M, Keys T, Turgay Y, Ali A, Preet S, Chesnov S, Lutz-Bueno V, Slack E, Mezzenga R. Mechanical tuning of virus-like particles. J Colloid Interface Sci 2023; 634:963-971. [PMID: 36571858 DOI: 10.1016/j.jcis.2022.12.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/18/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
HYPOTHESIS Virus-like particles (VLPs) are promising scaffolds for developing mucosal vaccines. For their optimal performance, in addition to design parameters from an immunological perspective, biophysical properties may need to be considered. EXPERIMENTS We investigated the mechanical properties of VLPs scaffolded on the coat protein of Acinetobacter phage AP205 using atomic force microscopy and small angle X-ray scattering. FINDINGS Investigations showed that AP205 VLP is a tough nanoshell of stiffness 93 ± 23 pN/nm and elastic modulus 0.11 GPa. However, its mechanical properties are modulated by attaching muco-inert polyethylene glycol to 46 ± 10 pN/nm and 0.05 GPa. Addition of antigenic peptides derived from SARS-CoV2 spike protein by genetic fusion increased the stiffness to 146 ± 54 pN/nm although the elastic modulus remained unchanged. These results, which are interpreted in terms of shell thickness and coat protein net charge variations, demonstrate that surface conjugation can induce appreciable changes in the biophysical properties of VLP-scaffolded vaccines.
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Affiliation(s)
- Milad Radiom
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland; Laboratory of Food and Soft Materials, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland.
| | - Tim Keys
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland
| | - Yagmur Turgay
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland
| | - Ahmed Ali
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland
| | - Swapan Preet
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland
| | - Serge Chesnov
- University of Zürich/ETH Zürich, Functional Genomics Centre Zürich, Zürich, Switzerland
| | | | - Emma Slack
- Laboratory of Food Immunology, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland.
| | - Raffaele Mezzenga
- Laboratory of Food and Soft Materials, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland.
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Podvalnyy NM, Chesnov S, Nanni P, Gut M, Holland JP, Hennet T. Synthesis of photoactivable oligosaccharide derivatives from 1,2-cyclic carbamate building blocks and study of their interaction with carbohydrate-binding proteins. Carbohydr Res 2021; 508:108399. [PMID: 34298358 DOI: 10.1016/j.carres.2021.108399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/09/2021] [Accepted: 07/09/2021] [Indexed: 11/24/2022]
Abstract
Despite the broad occurrence of carbohydrate-protein interactions in biology, the low binding affinities of such interactions hamper the characterization of carbohydrate binding sites in the absence of three-dimensional structural models. To allow the identification of proteins interacting with specific carbohydrate epitopes, we have developed new photoactivable oligosaccharide probes. Oligosaccharides containing the 1,2-cyclic carbamate group were attached to building blocks with a primary amino group to yield the corresponding urea derivatives. Cyclic carbamates of lactose, and 3- and 2'-fucosyl lactose, were used for the conjugation with building blocks containing photoactivable diazirine, benzophenone or aryl azido groups. The resulting oligosaccharide derivatives were tested for binding to Erythrina cristagalli lectin (ECL), Aleuria aurantia lectin (AAL) and Ulex europaeus agglutinin-I (UEA I). We found that ligands containing an aryl azido photoactivable group were successfully attached to lectins. The photoactivation reaction preserved lectin integrity, as no sign of protein degradation was visible. Mass spectrometric analysis confirmed the covalent binding of between one to three oligosaccharide probes, which matched with the expected carbohydrate-binding properties of the lectins tested. The conjugation of cyclic carbamate-derivatized oligosaccharides with photoactivable aryl azido groups thus represents a convenient approach to study protein-carbohydrate interactions.
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Affiliation(s)
| | - Serge Chesnov
- Functional Genomics Center Zurich, ETH Zurich / University of Zurich, Zurich, Switzerland
| | - Paolo Nanni
- Functional Genomics Center Zurich, ETH Zurich / University of Zurich, Zurich, Switzerland
| | - Melanie Gut
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Jason P Holland
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Thierry Hennet
- Institute of Physiology, University of Zurich, Zurich, Switzerland
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Salim A, Chesnov S, Freisinger E. Metallation pathway of a plant metallothionein: Cicer arietinum MT2. J Inorg Biochem 2020; 210:111157. [PMID: 32622214 DOI: 10.1016/j.jinorgbio.2020.111157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 06/18/2020] [Accepted: 06/21/2020] [Indexed: 11/25/2022]
Abstract
The plant metallothionein 2 protein from Cicer arietinum (cicMT2) is a typical member of the plant MT subfamily p2 that is characterized by an N- and C-terminal cysteine- (Cys-)rich, metal binding sequence connected by a long cysteine-free linker region. cicMT2 coordinates up to five ZnII or CdII ions by its 14 cysteine thiolate groups forming a single metal-thiolate cluster. While MTs from other phyla are considerably well-studied, many details about plant MTs are missing. In this study the metallation pathway of cicMT2 is investigated using mass spectrometry. To evaluate the influence of the linker region as well as the interplay of the two Cys-rich stretches, the full-length cicMT2 protein as well as the individual Cys-rich domains with and without the linker region were analysed. Up to three CdII ions can be coordinated by the eight Cys residues of the N-terminal part and up to two CdII ions by the six Cys residues of the C-terminal sequence. However, no preferential binding to either of the two sequences is observed, which is in-line with the closely similar apparent binding constants of the individual domains obtained from competition reactions with the chelator 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid. The combination of limited proteolytic digestion, mass spectrometry, dynamic light scattering, size-exclusion chromatography, and 19F NMR spectroscopy enables us to draw conclusions about the overall protein-fold and the cluster formation process.
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Affiliation(s)
- Alma Salim
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Serge Chesnov
- University of Zurich/ETH Zurich, Functional Genomics Centre Zurich, Zurich, Switzerland
| | - Eva Freisinger
- Department of Chemistry, University of Zurich, Zurich, Switzerland.
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5
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Habjanič J, Chesnov S, Zerbe O, Freisinger E. Impact of naturally occurring serine/cysteine variations on the structure and function of Pseudomonas metallothioneins. Metallomics 2020; 12:23-33. [DOI: 10.1039/c9mt00213h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Naturally occurring Ser/Cys variations in Pseudomonas metallothioneinss affect intra-cluster dynamics rather than binding capacity.
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Affiliation(s)
- Jelena Habjanič
- Department of Chemistry
- University of Zurich
- Zurich
- Switzerland
| | - Serge Chesnov
- University of Zurich/ETH Zurich
- Functional Genomics Centre Zurich
- Zurich
- Switzerland
| | - Oliver Zerbe
- Department of Chemistry
- University of Zurich
- Zurich
- Switzerland
| | - Eva Freisinger
- Department of Chemistry
- University of Zurich
- Zurich
- Switzerland
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Canonica F, Klose D, Ledermann R, Sauer MM, Abicht HK, Quade N, Gossert AD, Chesnov S, Fischer HM, Jeschke G, Hennecke H, Glockshuber R. Structural basis and mechanism for metallochaperone-assisted assembly of the Cu A center in cytochrome oxidase. Sci Adv 2019; 5:eaaw8478. [PMID: 31392273 PMCID: PMC6669012 DOI: 10.1126/sciadv.aaw8478] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
The mechanisms underlying the biogenesis of the structurally unique, binuclear Cu1.5+•Cu1.5+ redox center (CuA) on subunit II (CoxB) of cytochrome oxidases have been a long-standing mystery. Here, we reconstituted the CoxB•CuA center in vitro from apo-CoxB and the holo-forms of the copper transfer chaperones ScoI and PcuC. A previously unknown, highly stable ScoI•Cu2+•CoxB complex was shown to be rapidly formed as the first intermediate in the pathway. Moreover, our structural data revealed that PcuC has two copper-binding sites, one each for Cu1+ and Cu2+, and that only PcuC•Cu1+•Cu2+ can release CoxB•Cu2+ from the ScoI•Cu2+•CoxB complex. The CoxB•CuA center was then formed quantitatively by transfer of Cu1+ from a second equivalent of PcuC•Cu1+•Cu2+ to CoxB•Cu2+. This metalation pathway is consistent with all available in vivo data and identifies the sources of the Cu ions required for CuA center formation and the order of their delivery to CoxB.
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Affiliation(s)
- Fabia Canonica
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Daniel Klose
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | | | - Maximilian M. Sauer
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Helge K. Abicht
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Nick Quade
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Alvar D. Gossert
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Serge Chesnov
- Functional Genomics Center Zurich, University of Zurich/ETH Zurich, Zurich, Switzerland
| | | | - Gunnar Jeschke
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | - Hauke Hennecke
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Rudi Glockshuber
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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7
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Tarasava K, Chesnov S, Freisinger E. Oxidation of the N-terminal domain of the wheat metallothionein Ec -1 leads to the formation of three distinct disulfide bridges. Biopolymers 2016; 106:295-308. [PMID: 27061576 DOI: 10.1002/bip.22849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 04/05/2016] [Indexed: 01/15/2023]
Abstract
Metallothioneins (MTs) are low molecular weight proteins, characterized by a high cysteine content and the ability to coordinate large amounts of d(10) metal ions, for example, Zn(II), Cd(II), and Cu(I), in form of metal-thiolate clusters. Depending on intracellular conditions such as redox potential or metal ion concentrations, MTs can occur in various states ranging from the fully metal-loaded holo- to the metal-free apo-form. The Cys thiolate groups in the apo-form can be either reduced or be involved in disulfide bridges. Although oxidation-mediated Zn(II) release might be a possible mechanism for the regulation of Zn(II) availability by MTs, no concise information regarding the associated pathways and the structure of oxidized apo-MT forms is available. Using the well-studied Zn2 γ-Ec -1 domain of the wheat Zn6 Ec -1 MT we attempt here to answer several question regarding the structure and biophysical properties of oxidized MT forms, such as: (1) does disulfide bond formation increase the stability against proteolysis, (2) is the overall peptide backbone fold similar for the holo- and the oxidized apo-MT form, and (3) are disulfide bridges specifically or randomly formed? Our investigations show that oxidation leads to three distinct disulfide bridges independently of the applied oxidation conditions and of the initial species used for oxidation, that is, the apo- or the holo-form. In addition, the oxidized apo-form is as stable against proteolysis as Zn2 γ-Ec -1, rendering the currently assumed degradation of oxidized MTs unlikely and suggesting a role of the oxidation process for the extension of protein lifetime in absence of sufficient amounts of metal ions. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 295-308, 2016.
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Affiliation(s)
- Katsiaryna Tarasava
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
| | - Serge Chesnov
- University of Zurich/ETH Zurich, Functional Genomics Center Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
| | - Eva Freisinger
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland
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Tzouros M, Chesnov S, Bigler L, Bienz S. A template approach for the characterization of linear polyamines and derivatives in spider venom. Eur J Mass Spectrom (Chichester) 2013; 19:57-69. [PMID: 23841226 DOI: 10.1255/ejms.1213] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A combination of high-performance liquid chromatography (HPLC) and atmospheric-pressure chemical ionization mass spectrometry (APCI-MS and APCI-MS/MS) was used to detect and characterize linear polyamine derivatives in the venom of the spiders Agelenopsis aperta, Hololena curta and Paracoelotes birulai. The compounds were identified with a template approach, by which the collision-induced dissociation (CID) spectra of known compounds are directly compared and correlated with those of the analytes. To facilitate the perception of the spectra and the recognition of the structural features of the analytes, an ion nomenclature closely leaned on the accepted nomenclature for fragment ions of peptides or nucleic acids is introduced. The structure identification of polyamine derivatives by direct correlation of MS spectra is possible because such compounds show very distinctive fragmentation behavior. Of particular relevance is the fact that the signal patterns that are observed with analytes possessing different polyamine backbones are not only distinct with regard to mass distributions but also with regard to relative signal intensities, resulting in fingerprint-like signal patterns. The direct correlation of these patterns--more than the correlation of the ion distributions--was found to be of key significance. With this, the new approach is fundamentally different from the sequencing of peptides or nucleic acids, which are largely based on mass distributions. The method is more efficient and more reliable than the de novo interpretation of the MS data and it even allows the identification of polyamine portions in compounds that are analyzed within mixtures.
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Affiliation(s)
- Manuel Tzouros
- Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Singer D, Camargo SMR, Huggel K, Romeo E, Danilczyk U, Kuba K, Chesnov S, Caron MG, Penninger JM, Verrey F. Orphan transporter SLC6A18 is renal neutral amino acid transporter B0AT3. J Biol Chem 2009; 284:19953-60. [PMID: 19478081 DOI: 10.1074/jbc.m109.011171] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The orphan transporter Slc6a18 (XT2) is highly expressed at the luminal membrane of kidney proximal tubules and displays approximately 50% identity with Slc6a19 (B(0)AT1), which is the main neutral amino acid transporter in both kidney and small intestine. As yet, the amino acid transport function of XT2 has only been experimentally supported by the urinary glycine loss observed in xt2 null mice. We report here that in Xenopus laevis oocytes, co-expressed ACE2 (angiotensin-converting enzyme 2) associates with XT2 and reveals its function as a Na(+)- and Cl(-)-de pend ent neutral amino acid transporter. In contrast to its association with ACE2 observed in Xenopus laevis oocytes, our experiments with ace2 and collectrin null mice demonstrate that in vivo it is Collectrin, a smaller homologue of ACE2, that is required for functional expression of XT2 in kidney. To assess the function of XT2 in vivo, we reanalyzed its knock-out mouse model after more than 10 generations of backcrossing into C57BL/6 background. In addition to the previously published glycinuria, we observed a urinary loss of several other amino acids, in particular beta-branched and small neutral ones. Using telemetry, we confirmed the previously described link of XT2 absence with hypertension but only in physically restrained animals. Taken together, our data indicate that the formerly orphan transporter XT2 functions as a sodium and chloride-de pend ent neutral amino acid transporter that we propose to rename B(0)AT3.
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Affiliation(s)
- Dustin Singer
- Institute of Physiology and Center for Integrative Human Physiology, University of Zürich, 8057 Zürich, Switzerland
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Knipp M, Karotki AV, Chesnov S, Natile G, Sadler PJ, Brabec V, Vasák M. Reaction of Zn7metallothionein with cis- and trans-[Pt(N-donor)2Cl2] anticancer complexes: trans-Pt(II) complexes retain their N-donor ligands. J Med Chem 2007; 50:4075-86. [PMID: 17665893 DOI: 10.1021/jm070271l] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intrinsic and acquired resistance are major drawbacks of platinum-based cancer therapy. The protein superfamily of cysteine- and ZnII-rich proteins, metallothioneins (MT), efficiently inactivate these antitumor drugs because of the strong reactivity of platinum compounds with S-donor molecules. In this study the reactions of human Zn7MT-2 with twelve cis/trans-[Pt(N-donor)2Cl2] compounds and [Pt(dien)Cl]Cl, including new generation drugs, were investigated and the products characterized. A comparison of reaction kinetics revealed that trans-PtII compounds react faster with Zn7MT-2 than cis-PtII compounds. The characterization of the products showed that while all ligands in cis-PtII compounds were replaced by cysteine thiolates, trans-PtII compounds retained their N-donor ligands, thus remaining in a potentially active form. These results provide an increased understanding of the role of MT in the acquired resistance to platinum-based anticancer drugs.
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Affiliation(s)
- Markus Knipp
- Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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11
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Braun O, Knipp M, Chesnov S, Vasák M. Specific reactions of S-nitrosothiols with cysteine hydrolases: A comparative study between dimethylargininase-1 and CTP synthetase. Protein Sci 2007; 16:1522-34. [PMID: 17600152 PMCID: PMC2203367 DOI: 10.1110/ps.062718507] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
S-Transnitrosation is an important bioregulatory process whereby NO(+) equivalents are transferred between S-nitrosothiols and Cys of target proteins. This reaction proceeds through a common intermediate R-S-N(O(-))-S-R' and it has been proposed that products different from S-nitrosothiols may be formed in protein cavities. Recently, we have reported on the formation of such a product, an N-thiosulfoximide, at the active site of the Cys hydrolase dimethylargininase-1 (DDAH-1) upon reaction with S-nitroso-l-homocysteine (HcyNO). Here we have addressed the question of whether this novel product can also be formed with the endogenously occurring S-nitrosothiols S-nitroso-l-cysteine (CysNO) and S-nitrosoglutathione (GSNO). Further, to explore the reason responsible for the unique formation of an N-thiosulfoximide in DDAH-1 we have expanded these studies to cytidine triphosphate synthetase (CTPS), which shows a similar active site architecture. ESI-MS and activity measurements showed that the bulky GSNO does not react with both enzymes. In contrast, S-nitrosylation of the active site Cys occurred in DDAH-1 with CysNO and in CTPS with CysNO and HcyNO. Although kinetic analysis indicated that these compounds act as specific irreversible inhibitors, no N-thiosulfoximide was formed. The reasons likely responsible for the absence of the N-thiosulfoximide formation are discussed using molecular models of DDAH-1 and CTPS. In tissue extracts DDAH was inhibited only by HcyNO, with an IC(50) value similar to that of the isolated protein. Biological implications of these studies for the function of both enzymes are discussed.
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Affiliation(s)
- Oliver Braun
- Department of Biochemistry, University of Zürich, CH-8057 Zürich, Switzerland
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12
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Ramadan T, Camargo SMR, Summa V, Hunziker P, Chesnov S, Pos KM, Verrey F. Basolateral aromatic amino acid transporter TAT1 (Slc16a10) functions as an efflux pathway. J Cell Physiol 2006; 206:771-9. [PMID: 16245314 DOI: 10.1002/jcp.20531] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Basolateral efflux is a necessary step in transepithelial (re)absorption of amino acids from small intestine and kidney proximal tubule. The best characterized basolateral amino acid transporters are y+LAT1-4F2hc and LAT2-4F2hc that function as obligatory exchangers and thus, do not contribute to net amino acid (re)absorption. The aromatic amino acid transporter TAT1 was shown previously to localize basolaterally in rat's small intestine and to mediate the efflux of L-Trp in the absence of exchange substrate, upon expression in Xenopus oocytes. We compared here the amino acid influx and efflux via mouse TAT1 in Xenopus oocytes. The results show that mTAT1 functions as facilitated diffusion pathway for aromatic amino acids and that its properties are symmetrical in terms of selectivity and apparent affinity. We show by real-time RT-PCR that its mRNA is highly expressed in mouse small intestine mucosa, kidney, liver, and skeletal muscle as well as present in all other tested tissues. We show that mTAT1 is not N-glycosylated and that it localizes to the mouse kidney proximal tubule. This expression is characterized by an axial gradient similar to that of the luminal neutral amino acid transporter B0AT1 and shows the same basolateral localization as 4F2hc. mTAT1 also localizes to the basolateral membrane of small intestine enterocytes and to the sinusoidal side of perivenous hepatocytes. In summary, we show that TAT1 is a basolateral epithelial transporter and that it can function as a net efflux pathway for aromatic amino acids. We propose that it, thereby, may supply parallel exchangers with recycling uptake substrates that could drive the efflux of other amino acids.
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Affiliation(s)
- Tamara Ramadan
- Institute of Physiology and Centre for Integrative Human Physiology (ZIHP), University of Zürich, Winterthurerstrasse, Zürich, Switzerland
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