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Binamé F, Pham-Van LD, Bagnard D. Manipulating oligodendrocyte intrinsic regeneration mechanism to promote remyelination. Cell Mol Life Sci 2021; 78:5257-5273. [PMID: 34019104 PMCID: PMC11073109 DOI: 10.1007/s00018-021-03852-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/14/2021] [Accepted: 05/08/2021] [Indexed: 02/06/2023]
Abstract
In demyelinated lesions, astrocytes, activated microglia and infiltrating macrophages secrete several factors regulating oligodendrocyte precursor cells' behaviour. What appears to be the initiation of an intrinsic mechanism of myelin repair is only leading to partial recovery and inefficient remyelination, a process worsening over the course of the disease. This failure is largely due to the concomitant accumulation of inhibitory cues in and around the lesion sites opposing to growth promoting factors. Here starts a complex game of interactions between the signalling pathways controlling oligodendrocytes migration or differentiation. Receptors of positive or negative cues are modulating Ras, PI3K or RhoGTPases pathways acting on oligodendrocyte cytoskeleton remodelling. From the description of this intricate signalling network, this review addresses the extent to which the modulation of the global response to inhibitory cues may pave the route towards novel therapeutic approaches for myelin repair.
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Affiliation(s)
- Fabien Binamé
- INSERM U1119, Biopathology of Myelin, Neuroprotection and Therapeutic Strategy (BMNST Lab), Labex Medalis, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Pôle API, Ecole Supérieure de Biotechnologie, 300 Boulevard Sébastien Brant, 67412, Illkirch, France
| | - Lucas D Pham-Van
- INSERM U1119, Biopathology of Myelin, Neuroprotection and Therapeutic Strategy (BMNST Lab), Labex Medalis, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Pôle API, Ecole Supérieure de Biotechnologie, 300 Boulevard Sébastien Brant, 67412, Illkirch, France
| | - Dominique Bagnard
- INSERM U1119, Biopathology of Myelin, Neuroprotection and Therapeutic Strategy (BMNST Lab), Labex Medalis, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Pôle API, Ecole Supérieure de Biotechnologie, 300 Boulevard Sébastien Brant, 67412, Illkirch, France.
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2
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Sporny M, Guez-Haddad J, Lebendiker M, Ulisse V, Volf A, Mim C, Isupov MN, Opatowsky Y. Structural Evidence for an Octameric Ring Arrangement of SARM1. J Mol Biol 2019; 431:3591-3605. [PMID: 31278906 DOI: 10.1016/j.jmb.2019.06.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/16/2019] [Accepted: 06/25/2019] [Indexed: 12/11/2022]
Abstract
SARM1 induces axonal degeneration in response to various insults and is therefore considered an attractive drug target for the treatment of neuro-degenerative diseases as well as for brain and spinal cord injuries. SARM1 activity depends on the integrity of the protein's SAM domains, as well as on the enzymatic conversion of NAD+ to ADPR (ADP Ribose) products by the SARM1's TIR domain. Therefore, inhibition of either SAM or TIR functions may constitute an effective therapeutic strategy. However, there is currently no SARM1-directed therapeutic approach available because of an insufficient structural and mechanistic understanding of this protein. In this study, we found that SARM1 assembles into an octameric ring. This arrangement was not described before in other SAM proteins, but is reminiscent of the apoptosome and inflammasome-well-known apoptotic ring-like oligomers. We show that both SARM1 and the isolated tandem SAM1-2 domains form octamers in solution, and electron microscopy analysis reveals an octameric ring of SARM1. We determined the crystal structure of SAM1-2 and found that it also forms a closed octameric ring in the crystal lattice. The SAM1-2 ring interactions are mediated by complementing "lock and key" hydrophobic grooves and inserts and electrostatic charges between the neighboring protomers. We have mutated several interacting SAM1-2 interfaces and measured how these mutations affect SARM1 apoptotic activity in cultured cells, and in this way identified critical oligomerization sites that facilitate cell death. These results highlight the importance of oligomerization for SARM1 function and reveal critical epitopes for future targeted drug development.
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Affiliation(s)
- Michael Sporny
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Mario Lebendiker
- Wolfson Centre for Applied Structural Biology, The Hebrew University of Jerusalem, Israel
| | - Valeria Ulisse
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Allison Volf
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Carsten Mim
- Department of Biomedical Engineering and Health Solutions, Royal Technical Institute (KTH), Stockholm, Sweden; Department of Nutrition and Biosciences, Karolinska Institute, Huddinge, Sweden
| | | | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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3
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Barak R, Yom-Tov G, Guez-Haddad J, Gasri-Plotnitsky L, Maimon R, Cohen-Berkman M, McCarthy AA, Perlson E, Henis-Korenblit S, Isupov MN, Opatowsky Y. Structural Principles in Robo Activation and Auto-inhibition. Cell 2019; 177:272-285.e16. [PMID: 30853216 DOI: 10.1016/j.cell.2019.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 12/06/2018] [Accepted: 02/06/2019] [Indexed: 01/28/2023]
Abstract
Proper brain function requires high-precision neuronal expansion and wiring, processes controlled by the transmembrane Roundabout (Robo) receptor family and their Slit ligands. Despite their great importance, the molecular mechanism by which Robos' switch from "off" to "on" states remains unclear. Here, we report a 3.6 Å crystal structure of the intact human Robo2 ectodomain (domains D1-8). We demonstrate that Robo cis dimerization via D4 is conserved through hRobo1, 2, and 3 and the C. elegans homolog SAX-3 and is essential for SAX-3 function in vivo. The structure reveals two levels of auto-inhibition that prevent premature activation: (1) cis blocking of the D4 dimerization interface and (2) trans interactions between opposing Robo receptors that fasten the D4-blocked conformation. Complementary experiments in mouse primary neurons and C. elegans support the auto-inhibition model. These results suggest that Slit stimulation primarily drives the release of Robo auto-inhibition required for dimerization and activation.
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Affiliation(s)
- Reut Barak
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | - Galit Yom-Tov
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | | | - Roy Maimon
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Moran Cohen-Berkman
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel
| | | | - Eran Perlson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | | | | | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Israel.
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4
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Sporny M, Guez-Haddad J, Kreusch A, Shakartzi S, Neznansky A, Cross A, Isupov MN, Qualmann B, Kessels MM, Opatowsky Y. Structural History of Human SRGAP2 Proteins. Mol Biol Evol 2017; 34:1463-1478. [PMID: 28333212 PMCID: PMC5435084 DOI: 10.1093/molbev/msx094] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the development of the human brain, human-specific genes are considered to play key roles, conferring its unique advantages and vulnerabilities. At the time of Homo lineage divergence from Australopithecus, SRGAP2C gradually emerged through a process of serial duplications and mutagenesis from ancestral SRGAP2A (3.4–2.4 Ma). Remarkably, ectopic expression of SRGAP2C endows cultured mouse brain cells, with human-like characteristics, specifically, increased dendritic spine length and density. To understand the molecular mechanisms underlying this change in neuronal morphology, we determined the structure of SRGAP2A and studied the interplay between SRGAP2A and SRGAP2C. We found that: 1) SRGAP2A homo-dimerizes through a large interface that includes an F-BAR domain, a newly identified F-BAR extension (Fx), and RhoGAP-SH3 domains. 2) SRGAP2A has an unusual inverse geometry, enabling associations with lamellipodia and dendritic spine heads in vivo, and scaffolding of membrane protrusions in cell culture. 3) As a result of the initial partial duplication event (∼3.4 Ma), SRGAP2C carries a defective Fx-domain that severely compromises its solubility and membrane-scaffolding ability. Consistently, SRGAP2A:SRAGP2C hetero-dimers form, but are insoluble, inhibiting SRGAP2A activity. 4) Inactivation of SRGAP2A is sensitive to the level of hetero-dimerization with SRGAP2C. 5) The primal form of SRGAP2C (P-SRGAP2C, existing between ∼3.4 and 2.4 Ma) is less effective in hetero-dimerizing with SRGAP2A than the modern SRGAP2C, which carries several substitutions (from ∼2.4 Ma). Thus, the genetic mutagenesis phase contributed to modulation of SRGAP2A’s inhibition of neuronal expansion, by introducing and improving the formation of inactive SRGAP2A:SRGAP2C hetero-dimers, indicating a stepwise involvement of SRGAP2C in human evolutionary history.
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Affiliation(s)
- Michael Sporny
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Annett Kreusch
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Sivan Shakartzi
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Avi Neznansky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Alice Cross
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Michail N Isupov
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Britta Qualmann
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Michael M Kessels
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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Yom-Tov G, Barak R, Matalon O, Barda-Saad M, Guez-Haddad J, Opatowsky Y. Robo Ig4 Is a Dimerization Domain. J Mol Biol 2017; 429:3606-3616. [PMID: 29017837 DOI: 10.1016/j.jmb.2017.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 01/06/2023]
Abstract
Robo receptors play pivotal roles in axonal guidance as well as in neurogenesis, angiogenesis, cell migration, and cancer progression and invasiveness. They are considered to be attractive drug targets for the treatment of cancer, ocular neovascular disorders, chronic kidney diseases, and more. Despite their great importance, the mechanisms by which Robo receptors switch from their "off" to "on" states remain obscure. One possibility involves a monomer-to-dimer or dimer-to-monomer transition that facilitates the recruitment and activation of enzymatic effectors to instigate intracellular signaling. However, it is not known which domains mediate Robo dimerization, or the structural properties of the dimeric interactions. Here, we identify the extracellular Ig4 (D4) as a Robo dimerization domain. We have determined the crystal structure of the tandem Ig4-5 domains (D4-5) of human Robo2 and found that a hydrophobic surface on D4 mediates close homotypic contacts with a reciprocal D4. Analytical ultracentrifugation measurements of intact and mutated D4-5 shows that dimerization through the D4 interface is specific and has a dimerization dissociation constant of 16.9μM in solution. Direct fluorescence resonance energy transfer dimerization measurements in HEK293 cells corroborate the dimerization of transmembrane hRobo2 through D4, and a functional COS-7 cell collapse assay links D4-mediated dimerization with Robo intracellular signaling. The high level of conservation in the D4 dimerization interface throughout all Robo orthologs and paralogs implies that D4-mediated dimerization is a central hallmark in Robo activation and signaling.
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Affiliation(s)
- Galit Yom-Tov
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Reut Barak
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Omri Matalon
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Mira Barda-Saad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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6
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Sporny M, Guez-Haddad J, Waterman DG, Isupov MN, Opatowsky Y. Molecular symmetry-constrained systematic search approach to structure solution of the coiled-coil SRGAP2 F-BARx domain. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:1241-1253. [PMID: 27917825 DOI: 10.1107/s2059798316016697] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 10/18/2016] [Indexed: 02/05/2023]
Abstract
SRGAP2 (Slit-Robo GTPase-activating protein 2) is a cytoplasmic protein found to be involved in neuronal branching, restriction of neuronal migration and restriction of the length and density of dendritic postsynaptic spines. The extended F-BAR (F-BARx) domain of SRGAP2 generates membrane protrusions when expressed in COS-7 cells, while most F-BARs induce the opposite effect: membrane invaginations. As a first step to understand this discrepancy, the F-BARx domain of SRGAP2 was isolated and crystallized after co-expression with the carboxy domains of the protein. Diffraction data were collected from two significantly non-isomorphous crystals in the same monoclinic C2 space group. A correct molecular-replacment solution was obtained by applying a molecular symmetry-constrained systematic search approach that took advantage of the conserved biological symmetry of the F-BAR domains. It is shown that similar approaches can solve other F-BAR structures that were previously determined by experimental phasing. Diffraction data were reprocessed with a high-resolution cutoff of 2.2 Å, chosen using less strict statistical criteria. This has improved the outcome of multi-crystal averaging and other density-modification procedures.
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Affiliation(s)
- Michael Sporny
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Julia Guez-Haddad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | | | | | - Yarden Opatowsky
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
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7
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Pittel I, Alper N, Yonai S, Basch S, Blum L, Bachur A, Paas Y. Computational and biochemical design of a nanopore cleavable by a cancer-secreted enzyme. Chembiochem 2015; 16:463-71. [PMID: 25581099 DOI: 10.1002/cbic.201402378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Indexed: 11/11/2022]
Abstract
Many proteinaceous macromolecules selectively transport substrates across lipid bilayers and effectively serve as gated nanopores. Here, we engineered cleavage-site motifs for human matrix metalloprotease 7 (MMP-7) into the extracellular and pore-constricting loops of OprD, a bacterial substrate-specific transmembrane channel. Concurrent removal of two extracellular loops allowed MMP-7 to access and hydrolyze a cleavage-site motif engineered within the pore's major constricting loop, in both membrane-incorporated and detergent-solubilized OprDs. Import of antibiotics by the engineered OprDs into living bacteria pointed to their proper folding and integration in biological membranes. Purified engineered OprDs were also found to be properly folded in detergent. Hence, this study demonstrates the design of nanopores with a constriction cleavable by tumor-secreted enzymes (like MMP-7) for their potential incorporation in lipid-based nanoparticles to accelerate drug release at the tumor site.
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Affiliation(s)
- Ilya Pittel
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900 (Israel)
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8
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Zakrys L, Ward RJ, Pediani JD, Godin AG, Graham GJ, Milligan G. Roundabout 1 exists predominantly as a basal dimeric complex and this is unaffected by binding of the ligand Slit2. Biochem J 2014; 461:61-73. [PMID: 24673457 DOI: 10.1042/bj20140190] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Robo (Roundabout) receptors and their Slit polypeptide ligands are known to play key roles in neuronal development and have been implicated in both angiogenesis and cancer. Like the other family members, Robo1 is a large single transmembrane domain polypeptide containing a series of well-defined extracellular elements. However, the intracellular domain lacks structural definition and little is known about the quaternary structure of Robo receptors or how binding of a Slit might affect this. To address these questions combinations of both autofluorescent protein-based FRET imaging and time-resolved FRET were employed. Both approaches identified oligomeric organization of Robo1 that did not require the presence of the intracellular domain. SpIDA (spatial intensity distribution analysis) of eGFP-tagged forms of Robo1 indicated that for a C-terminally deleted version approximately two-thirds of the receptor was present as a dimer and one-third as a monomer. By contrast, full-length Robo1 was present almost exclusively as a dimer. In each case this was unaffected by the addition of Slit2, although parallel studies demonstrated the biological activity of Slit2 and its interaction with Robo1. Deletion of both the immunoglobulin and fibronectin type III extracellular repeats prevented dimer formation, with the immunoglobulin repeats providing the bulk of the protein-protein interaction affinity.
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Affiliation(s)
| | - Richard J Ward
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - John D Pediani
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Antoine G Godin
- ‡Laboratoire Photonique, Numérique et Nanosciences (LP2N) Institut d'Optique Graduate School, CNRS and Université Bordeaux, 351 cours de la libération, 33405 Talence Cedex, France
| | - Gerard J Graham
- †Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Graeme Milligan
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
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9
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Neznansky A, Opatowsky Y. Expression, purification and crystallization of the phosphate-binding PstS protein from Pseudomonas aeruginosa. Acta Crystallogr F Struct Biol Commun 2014; 70:906-10. [PMID: 25005086 PMCID: PMC4089529 DOI: 10.1107/s2053230x14010279] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 05/06/2014] [Indexed: 11/10/2022] Open
Abstract
Pseudomonas aeruginosa (PA) infections pose a serious threat to human health. PA is a leading cause of fatal lung infections in cystic fibrosis and immune-suppressed patients, of sepsis in burn victims and of nosocomial infections. An important element in PA virulence is its ability to establish biofilms that evade suppression by the host's immune system and antibiotics. PstS, a periplasmic subunit of the Pst phosphate-transport system of PA, plays a critical role in the establishment of biofilms. In some drug-resistant PA strains, PstS is secreted in large quantities from the bacteria, where it participates in the assembly of adhesion fibres that enhance bacterial virulence. In order to understand the dual function of PstS in biofilm formation and phosphate transport, the crystal structure of PA PstS was determined. Here, the overexpression in Escherichia coli and purification of PA PstS in the presence of phosphate are described. Two crystal forms were obtained using the vapour-diffusion method at 20°C and X-ray diffraction data were collected. The first crystal form belonged to the centred orthorhombic space group C222₁, with unit-cell parameters a=67.5, b=151.3, c=108.9 Å. Assuming the presence of a dimer in the asymmetric unit gives a crystal volume per protein weight (VM) of 2.09 Å3 Da(-1) and a solvent content of 41%. The second crystal form belonged to the primitive orthorhombic space group P2₁2₁2₁, with unit-cell parameters a=35.4, b=148.3, c=216.7 Å. Assuming the presence of a tetramer in the asymmetric unit gives a crystal volume per protein weight (VM) of 2.14 Å3 Da(-1) and a solvent content of 42.65%. A pseudo-translational symmetry is present in the P212121 crystal form which is consistent with a filamentous arrangement of PstS in the crystal lattice.
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Affiliation(s)
- Avi Neznansky
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Yarden Opatowsky
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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10
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Barak R, Lahmi R, Gevorkyan-Airapetov L, Levy E, Tzur A, Opatowsky Y. Crystal structure of the extracellular juxtamembrane region of Robo1. J Struct Biol 2014; 186:283-91. [PMID: 24607414 DOI: 10.1016/j.jsb.2014.02.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/26/2014] [Accepted: 02/28/2014] [Indexed: 12/17/2022]
Abstract
Robo receptors play pivotal roles in neurodevelopment, and their deregulation is implicated in several neuropathological conditions and cancers. To date, the mechanism of Robo activation and regulation remains obscure. Here we present the crystal structure of the juxtamembrane (JM) domains of human Robo1. The structure exhibits unexpectedly high backbone similarity to the netrin and RGM binding region of neogenin and DCC, which are functionally related receptors of Robo1. Comparison of these structures reveals a conserved surface that overlaps with a cluster of oncogenic and neuropathological mutations found in all Robo isoforms. The structure also reveals the intricate folding of the JM linker, which points to its role in Robo1 activation. Further experiments with cultured cells demonstrate that exposure or relief of the folded JM linker results in enhanced shedding of the Robo1 ectodomain.
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Affiliation(s)
- Reut Barak
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Roxane Lahmi
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel; Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Lada Gevorkyan-Airapetov
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Eliad Levy
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Amit Tzur
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel; Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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