1
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Koh E, Chaturvedi AK, Javitt G, Brandis A, Fluhr R. Multiple paths of plant host toxicity are associated with the fungal toxin cercosporin. Plant Cell Environ 2023. [PMID: 37212197 DOI: 10.1111/pce.14613] [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] [Grants] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/30/2023] [Accepted: 05/06/2023] [Indexed: 05/23/2023]
Abstract
The Cercospora species of fungi are responsible for leaf spot disease affecting many key economic crops. Most of these fungi secrete a toxic photodynamic molecule, cercosporin, that reacts with light and oxygen to produce reactive singlet oxygen (1 O2 ) contributing to fungal virulence. We show similar cellular localization and aetiology of cercosporin in the non-host Arabidopsis and the host Nicotiana benthamiana. Cercosporin accumulates in cell membranes in an oxidized state and in plastids in a mixture of redox states in a manner that is dependent on ongoing photosynthetic processes. We observed that cercosporin rapidly compromised photosynthesis as measured by Fv /Fm , NPQ, and photosystem I (PSI) parameters. Stomatal guard cells in particular demonstrated rapid light-dependent membrane permeabilization that led to changes in leaf conductance. We showed that cercosporin-mediated 1 O2 generation oxidized RNA to form 8-oxoguanosine (8-oxoG), leading to translational attenuation and induction of 1 O2 signature gene transcripts. We also identified a subset of cercosporin-induced transcripts that were independent of the photodynamic effect. Our results point to the multimodal action of cercosporin that includes the inhibition of photosynthesis, the direct oxidation of nucleic acid residues and the elicitation of complex transcriptome responses.
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Affiliation(s)
- Eugene Koh
- Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Gabriel Javitt
- Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Alexander Brandis
- Life Sciences Core Facility, Weizmann Institute of Science, Rehovot, Israel
| | - Robert Fluhr
- Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
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2
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Ilani T, Reznik N, Yeshaya N, Feldman T, Vilela P, Lansky Z, Javitt G, Shemesh M, Brenner O, Elkis Y, Varsano N, Jaramillo AM, Evans CM, Fass D. The disulfide catalyst QSOX1 maintains the colon mucosal barrier by regulating Golgi glycosyltransferases. EMBO J 2023; 42:e111869. [PMID: 36245281 PMCID: PMC9841341 DOI: 10.15252/embj.2022111869] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/25/2022] [Accepted: 09/29/2022] [Indexed: 01/27/2023] Open
Abstract
Mucus is made of enormous mucin glycoproteins that polymerize by disulfide crosslinking in the Golgi apparatus. QSOX1 is a catalyst of disulfide bond formation localized to the Golgi. Both QSOX1 and mucins are highly expressed in goblet cells of mucosal tissues, leading to the hypothesis that QSOX1 catalyzes disulfide-mediated mucin polymerization. We found that knockout mice lacking QSOX1 had impaired mucus barrier function due to production of defective mucus. However, an investigation on the molecular level revealed normal disulfide-mediated polymerization of mucins and related glycoproteins. Instead, we detected a drastic decrease in sialic acid in the gut mucus glycome of the QSOX1 knockout mice, leading to the discovery that QSOX1 forms regulatory disulfides in Golgi glycosyltransferases. Sialylation defects in the colon are known to cause colitis in humans. Here we show that QSOX1 redox control of sialylation is essential for maintaining mucosal function.
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Affiliation(s)
- Tal Ilani
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Nava Reznik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Noa Yeshaya
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Tal Feldman
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Patrick Vilela
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Zipora Lansky
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Gabriel Javitt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Shemesh
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Ori Brenner
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | | | - Neta Varsano
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Ana M Jaramillo
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Christopher M Evans
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, USA.,Department of Medicine, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Deborah Fass
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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3
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Javitt G, Yeshaya N, Khmelnitsky L, Fass D. Assembly of von Willebrand factor tubules with in vivo helical parameters requires A1 domain insertion. Blood 2022; 140:2835-2843. [PMID: 36179246 PMCID: PMC10653096 DOI: 10.1182/blood.2022017153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/02/2022] [Accepted: 09/23/2022] [Indexed: 01/05/2023] Open
Abstract
The von Willebrand factor (VWF) glycoprotein is stored in tubular form in Weibel-Palade bodies (WPBs) before secretion from endothelial cells into the bloodstream. The organization of VWF in the tubules promotes formation of covalently linked VWF polymers and enables orderly secretion without polymer tangling. Recent studies have described the high-resolution structure of helical tubular cores formed in vitro by the D1D2 and D'D3 amino-terminal protein segments of VWF. Here we show that formation of tubules with the helical geometry observed for VWF in intracellular WPBs requires also the VWA1 (A1) domain. We reconstituted VWF tubules from segments containing the A1 domain and discovered it to be inserted between helical turns of the tubule, altering helical parameters and explaining the increased robustness of tubule formation when A1 is present. The conclusion from this observation is that the A1 domain has a direct role in VWF assembly, along with its known activity in hemostasis after secretion.
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Affiliation(s)
- Gabriel Javitt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Noa Yeshaya
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Lev Khmelnitsky
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Deborah Fass
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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4
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Reznik N, Gallo AD, Rush KW, Javitt G, Fridmann-Sirkis Y, Ilani T, Nairner NA, Fishilevich S, Gokhman D, Chacón KN, Franz KJ, Fass D. Intestinal mucin is a chaperone of multivalent copper. Cell 2022; 185:4206-4215.e11. [PMID: 36206754 DOI: 10.1016/j.cell.2022.09.021] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/21/2022] [Accepted: 09/09/2022] [Indexed: 01/26/2023]
Abstract
Mucus protects the epithelial cells of the digestive and respiratory tracts from pathogens and other hazards. Progress in determining the molecular mechanisms of mucus barrier function has been limited by the lack of high-resolution structural information on mucins, the giant, secreted, gel-forming glycoproteins that are the major constituents of mucus. Here, we report how mucin structures we determined enabled the discovery of an unanticipated protective role of mucus: managing the toxic transition metal copper. Using two juxtaposed copper binding sites, one for Cu2+ and the other for Cu1+, the intestinal mucin, MUC2, prevents copper toxicity by blocking futile redox cycling and the squandering of dietary antioxidants, while nevertheless permitting uptake of this important trace metal into cells. These findings emphasize the value of molecular structure in advancing mucosal biology, while introducing mucins, produced in massive quantities to guard extensive mucosal surfaces, as extracellular copper chaperones.
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Affiliation(s)
- Nava Reznik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Annastassia D Gallo
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Katherine W Rush
- Department of Chemistry, Reed College, Portland, Oregon 97202, United States; Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Gabriel Javitt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yael Fridmann-Sirkis
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tal Ilani
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Noa A Nairner
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Simon Fishilevich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - David Gokhman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Kelly N Chacón
- Department of Chemistry, Reed College, Portland, Oregon 97202, United States
| | - Katherine J Franz
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Deborah Fass
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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5
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Javitt G, Kinzel A, Reznik N, Fass D. Conformational switches and redox properties of the colon cancer-associated human lectin ZG16. FEBS J 2021; 288:6465-6475. [PMID: 34077620 PMCID: PMC9291870 DOI: 10.1111/febs.16044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/16/2021] [Accepted: 06/01/2021] [Indexed: 11/30/2022]
Abstract
Zymogen granule membrane protein 16 (ZG16) is produced in organs that secrete large quantities of enzymes and other proteins into the digestive tract. ZG16 binds microbial pathogens, and lower ZG16 expression levels correlate with colorectal cancer, but the physiological function of the protein is poorly understood. One prominent attribute of ZG16 is its ability to bind glycans, but other aspects of the protein may also contribute to activity. An intriguing feature of ZG16 is a CXXC motif at the carboxy terminus. Here, we describe crystal structures and biochemical studies showing that the CXXC motif is on a flexible tail, where it contributes little to structure or stability but is available to engage in redox reactions. Specifically, we demonstrate that the ZG16 cysteine thiols can be oxidized to a disulfide by quiescin sulfhydryl oxidase 1, which is a sulfhydryl oxidase present together with ZG16 in the Golgi apparatus and in mucus, as well as by protein disulfide isomerase. ZG16 crystal structures also draw attention to a nonproline cis peptide bond that can isomerize within the protein and to the mobility of glycine‐rich loops in the glycan‐binding site. An understanding of the properties of the ZG16 CXXC motif and the discovery of internal conformational switches extend existing knowledge relating to the glycan‐binding activity of the protein.
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Affiliation(s)
- Gabriel Javitt
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Alisa Kinzel
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Nava Reznik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Deborah Fass
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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6
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Javitt G, Khmelnitsky L, Albert L, Bigman LS, Elad N, Morgenstern D, Ilani T, Levy Y, Diskin R, Fass D. Assembly Mechanism of Mucin and von Willebrand Factor Polymers. Cell 2020; 183:717-729.e16. [PMID: 33031746 PMCID: PMC7599080 DOI: 10.1016/j.cell.2020.09.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/25/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022]
Abstract
The respiratory and intestinal tracts are exposed to physical and biological hazards accompanying the intake of air and food. Likewise, the vasculature is threatened by inflammation and trauma. Mucin glycoproteins and the related von Willebrand factor guard the vulnerable cell layers in these diverse systems. Colon mucins additionally house and feed the gut microbiome. Here, we present an integrated structural analysis of the intestinal mucin MUC2. Our findings reveal the shared mechanism by which complex macromolecules responsible for blood clotting, mucociliary clearance, and the intestinal mucosal barrier form protective polymers and hydrogels. Specifically, cryo-electron microscopy and crystal structures show how disulfide-rich bridges and pH-tunable interfaces control successive assembly steps in the endoplasmic reticulum and Golgi apparatus. Remarkably, a densely O-glycosylated mucin domain performs an organizational role in MUC2. The mucin assembly mechanism and its adaptation for hemostasis provide the foundation for rational manipulation of barrier function and coagulation.
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Affiliation(s)
- Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lev Khmelnitsky
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lis Albert
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lavi Shlomo Bigman
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nadav Elad
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - David Morgenstern
- De Botton Institute for Protein Profiling, Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tal Ilani
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yaakov Levy
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ron Diskin
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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7
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Warszawski S, Borenstein Katz A, Lipsh R, Khmelnitsky L, Ben Nissan G, Javitt G, Dym O, Unger T, Knop O, Albeck S, Diskin R, Fass D, Sharon M, Fleishman SJ. Correction: Optimizing antibody affinity and stability by the automated design of the variable light-heavy chain interfaces. PLoS Comput Biol 2020; 16:e1008382. [PMID: 33085658 PMCID: PMC7577468 DOI: 10.1371/journal.pcbi.1008382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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8
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Abstract
Aims: The post-translational oxidation of methionine to methionine sulfoxide (MetSO) is a reversible process, enabling the repair of oxidative damage to proteins and the use of sulfoxidation as a regulatory switch. MetSO reductases catalyze the stereospecific reduction of MetSO. One of the mammalian MetSO reductases, MsrB3, has a signal sequence for entry into the endoplasmic reticulum (ER). In the ER, MsrB3 is expected to encounter a distinct redox environment compared with its paralogs in the cytosol, nucleus, and mitochondria. We sought to determine the location and arrangement of MsrB3 redox-active cysteines, which may couple MsrB3 activity to other redox events in the ER. Results: We determined the human MsrB3 structure by using X-ray crystallography. The structure revealed that a disulfide bond near the protein amino terminus is distant in space from the active site. Nevertheless, biochemical assays showed that these amino-terminal cysteines are oxidized by the MsrB3 active site after its reaction with MetSO. Innovation: This study reveals a mechanism to shuttle oxidizing equivalents from the primary MsrB3 active site toward the enzyme surface, where they would be available for further dithiol-disulfide exchange reactions. Conclusion: Conformational changes must occur during the MsrB3 catalytic cycle to transfer oxidizing equivalents from the active site to the amino-terminal redox-active disulfide. The accessibility of this exposed disulfide may help couple MsrB3 activity to other dithiol-disulfide redox events in the secretory pathway.
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Affiliation(s)
- Gabriel Javitt
- Department of Structural Biology and Weizmann Institute of Science, Rehovot, Israel
| | - Zhenbo Cao
- Institute of Molecular, Cellular and Systems Biology, CMVLS, University of Glasgow, Glasgow, United Kingdom
| | - Efrat Resnick
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Ronen Gabizon
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Neil J Bulleid
- Institute of Molecular, Cellular and Systems Biology, CMVLS, University of Glasgow, Glasgow, United Kingdom
| | - Deborah Fass
- Department of Structural Biology and Weizmann Institute of Science, Rehovot, Israel
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9
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Warszawski S, Borenstein Katz A, Lipsh R, Khmelnitsky L, Ben Nissan G, Javitt G, Dym O, Unger T, Knop O, Albeck S, Diskin R, Fass D, Sharon M, Fleishman SJ. Optimizing antibody affinity and stability by the automated design of the variable light-heavy chain interfaces. PLoS Comput Biol 2019; 15:e1007207. [PMID: 31442220 PMCID: PMC6728052 DOI: 10.1371/journal.pcbi.1007207] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 09/05/2019] [Accepted: 06/21/2019] [Indexed: 11/18/2022] Open
Abstract
Antibodies developed for research and clinical applications may exhibit suboptimal stability, expressibility, or affinity. Existing optimization strategies focus on surface mutations, whereas natural affinity maturation also introduces mutations in the antibody core, simultaneously improving stability and affinity. To systematically map the mutational tolerance of an antibody variable fragment (Fv), we performed yeast display and applied deep mutational scanning to an anti-lysozyme antibody and found that many of the affinity-enhancing mutations clustered at the variable light-heavy chain interface, within the antibody core. Rosetta design combined enhancing mutations, yielding a variant with tenfold higher affinity and substantially improved stability. To make this approach broadly accessible, we developed AbLIFT, an automated web server that designs multipoint core mutations to improve contacts between specific Fv light and heavy chains (http://AbLIFT.weizmann.ac.il). We applied AbLIFT to two unrelated antibodies targeting the human antigens VEGF and QSOX1. Strikingly, the designs improved stability, affinity, and expression yields. The results provide proof-of-principle for bypassing laborious cycles of antibody engineering through automated computational affinity and stability design. Antibodies are highly important in research, biotechnology, and medical applications. Despite their great utility, however, many antibodies exhibit suboptimal stability and affinity, raising production costs and limiting their practical usefulness. To tackle this general limitation, we used deep mutational scanning to characterize the effects of mutations in an antibody variable fragment on its antigen-binding affinity. Surprisingly, many of the affinity-enhancing mutations clustered at the variable light-heavy chain interface. We, therefore, developed an automated method, called AbLIFT (http://AbLIFT.weizmann.ac.il) to optimize this interface through design. Two unrelated antibodies were tested and showed improvements in expression levels, stability, and antigen-binding affinity. Since AbLIFT requires testing of only a few dozen specific designs, it may dramatically accelerate the development of promising antibodies into useful research and clinical tools.
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Affiliation(s)
- Shira Warszawski
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Rosalie Lipsh
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Lev Khmelnitsky
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Gili Ben Nissan
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Orly Dym
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Unger
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel
| | - Orli Knop
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shira Albeck
- Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel
| | - Ron Diskin
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Sharon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Sarel J. Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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10
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Javitt G, Calvo MLG, Albert L, Reznik N, Ilani T, Diskin R, Fass D. Intestinal Gel-Forming Mucins Polymerize by Disulfide-Mediated Dimerization of D3 Domains. J Mol Biol 2019; 431:3740-3752. [PMID: 31310764 PMCID: PMC6739602 DOI: 10.1016/j.jmb.2019.07.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/03/2019] [Accepted: 07/09/2019] [Indexed: 01/06/2023]
Abstract
The mucin 2 glycoprotein assembles into a complex hydrogel that protects intestinal epithelia and houses the gut microbiome. A major step in mucin 2 assembly is further multimerization of preformed mucin dimers, thought to produce a honeycomb-like arrangement upon hydrogel expansion. Important open questions are how multiple mucin 2 dimers become covalently linked to one another and how mucin 2 multimerization compares with analogous processes in related polymers such as respiratory tract mucins and the hemostasis protein von Willebrand factor. Here we report the x-ray crystal structure of the mucin 2 multimerization module, found to form a dimer linked by two intersubunit disulfide bonds. The dimer structure calls into question the current model for intestinal mucin assembly, which proposes disulfide-mediated trimerization of the same module. Key residues making interactions across the dimer interface are highly conserved in intestinal mucin orthologs, supporting the physiological relevance of the observed quaternary structure. With knowledge of the interface residues, it can be demonstrated that many of these amino acids are also present in other mucins and in von Willebrand factor, further indicating that the stable dimer arrangement reported herein is likely to be shared across this functionally broad protein family. The mucin 2 module structure thus reveals the manner by which both mucins and von Willebrand factor polymerize, drawing deep structural parallels between macromolecular assemblies critical to mucosal epithelia and the vasculature.
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Affiliation(s)
- Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | | | - Lis Albert
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nava Reznik
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tal Ilani
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ron Diskin
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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11
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Javitt G, Grossman‐Haham I, Alon A, Resnick E, Mutsafi Y, Ilani T, Fass D. cis-Proline mutants of quiescin sulfhydryl oxidase 1 with altered redox properties undermine extracellular matrix integrity and cell adhesion in fibroblast cultures. Protein Sci 2019; 28:228-238. [PMID: 30367560 PMCID: PMC6295897 DOI: 10.1002/pro.3537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/22/2018] [Accepted: 10/22/2018] [Indexed: 11/13/2022]
Abstract
The thioredoxin superfamily has expanded and diverged extensively throughout evolution such that distant members no longer show appreciable sequence homology. Nevertheless, redox-active thioredoxin-fold proteins functioning in diverse physiological contexts often share canonical amino acids near the active-site (di-)cysteine motif. Quiescin sulfhydryl oxidase 1 (QSOX1), a catalyst of disulfide bond formation secreted by fibroblasts, is a multi-domain thioredoxin superfamily enzyme with certain similarities to the protein disulfide isomerase (PDI) enzymes. Among other potential functions, QSOX1 supports extracellular matrix assembly in fibroblast cultures. We introduced mutations at a cis-proline in QSOX1 that is conserved across the thioredoxin superfamily and was previously observed to modulate redox interactions of the bacterial enzyme DsbA. The resulting QSOX1 variants showed a striking detrimental effect when added exogenously to fibroblasts: they severely disrupted the extracellular matrix and cell adhesion, even in the presence of naturally secreted, wild-type QSOX1. The specificity of this phenomenon for particular QSOX1 mutants inspired an investigation of the effects of mutation on catalytic and redox properties. For a series of QSOX1 mutants, the detrimental effect correlated with the redox potential of the first redox-active site, and an X-ray crystal structure of one of the mutants revealed the reorganization of the cis-proline loop caused by the mutations. Due to the conservation of the mutated residues across the PDI family and beyond, insights obtained in this study may be broadly applicable to a variety of physiologically important redox-active enzymes. IMPACT STATEMENT: We show that mutation of a conserved cis-proline amino acid, analogous to a mutation used to trap substrates of a bacterial disulfide catalyst, has a dramatic effect on the physiological function of the mammalian disulfide catalyst QSOX1. As the active-site region of QSOX1 is shared with the large family of protein disulfide isomerases in humans, the effects of such mutations on redox properties, enzymatic activity, and biological targeting may be relevant across the family.
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Affiliation(s)
- Gabriel Javitt
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Iris Grossman‐Haham
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Assaf Alon
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Efrat Resnick
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Yael Mutsafi
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Tal Ilani
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
| | - Deborah Fass
- Department of Structural BiologyWeizmann Institute of ScienceRehovot7610001Israel
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12
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Horowitz B, Javitt G, Ilani T, Gat Y, Morgenstern D, Bard FA, Fass D. Quiescin sulfhydryl oxidase 1 (QSOX1) glycosite mutation perturbs secretion but not Golgi localization. Glycobiology 2018; 28:580-591. [PMID: 29757379 DOI: 10.1093/glycob/cwy044] [Citation(s) in RCA: 8] [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] [Received: 09/12/2017] [Accepted: 05/08/2018] [Indexed: 12/13/2022] Open
Abstract
Quiescin sulfhydryl oxidase 1 (QSOX1) catalyzes the formation of disulfide bonds in protein substrates. Unlike other enzymes with related activities, which are commonly found in the endoplasmic reticulum, QSOX1 is localized to the Golgi apparatus or secreted. QSOX1 is upregulated in quiescent fibroblast cells and secreted into the extracellular environment, where it contributes to extracellular matrix assembly. QSOX1 is also upregulated in adenocarcinomas, though the extent to which it is secreted in this context is currently unknown. To achieve a better understanding of factors that dictate QSOX1 localization and function, we aimed to determine how post-translational modifications affect QSOX1 trafficking and activity. We found a highly conserved N-linked glycosylation site to be required for QSOX1 secretion from fibroblasts and other cell types. Notably, QSOX1 lacking a glycan at this site arrives at the Golgi, suggesting that it passes endoplasmic reticulum quality control but is not further transported to the cell surface for secretion. The QSOX1 transmembrane segment is dispensable for Golgi localization and secretion, as fully luminal and transmembrane variants displayed the same trafficking behavior. This study provides a key example of the effect of glycosylation on Golgi exit and contributes to an understanding of late secretory sorting and quality control.
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Affiliation(s)
- Ben Horowitz
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Tal Ilani
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Yair Gat
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - David Morgenstern
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Frederic A Bard
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 61 Biopolis Drive, Proteos, Singapore
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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Javitt G, Katsanis S, Scott J, Hudson K. Developing the blueprint for a genetic testing registry. Public Health Genomics 2009; 13:95-105. [PMID: 19556748 PMCID: PMC2830737 DOI: 10.1159/000226593] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 04/07/2009] [Indexed: 11/19/2022] Open
Abstract
While the number of genetic tests continues to grow, publicly accessible information about the analytic and clinical validity of such tests is lagging. Information gaps impede informed decision making by health care providers and patients. Enhancing the transparency of information about what tests are being offered, for which indications tests are being offered, and the analytic and clinical validity of tests is a key prerequisite to ensuring test quality. A recent government recommendation for a mandatory genetic test registry has received wide stakeholder support but leaves many practical questions unanswered. We propose a 'blueprint' for the creation of a genetic test registry in order to expedite its implementation. We describe the goals of a registry, propose criteria for the inclusion of registrants and tests in the registry, and define the categories of information that should be included for such tests. We discuss the sources of legal authority that empower the government to mandate that a registry be established and identify the federal agencies with the relevant expertise and resources to do so. We conclude that establishing a registry is a critical first step in the development of a more transparent, quality-centered system of oversight that will better inform and protect the public.
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Affiliation(s)
- G Javitt
- Genetics and Public Policy Center, Berman Institute of Bioethics, Johns Hopkins University, Washington, DC 20036, USA.
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Affiliation(s)
- S H Katsanis
- Genetics and Public Policy Center, Berman Institute of Bioethics [corrected], The Johns Hopkins University, Washington, DC 20036, USA
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