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Papadopoulou AA, Stelzer W, Silber M, Schlosser C, Spitz C, Haug-Kröper M, Straub T, Müller SA, Lichtenthaler SF, Muhle-Goll C, Langosch D, Fluhrer R. Helical stability of the GnTV transmembrane domain impacts on SPPL3 dependent cleavage. Sci Rep 2022; 12:20987. [PMID: 36470941 PMCID: PMC9722940 DOI: 10.1038/s41598-022-24772-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Signal-Peptide Peptidase Like-3 (SPPL3) is an intramembrane cleaving aspartyl protease that causes secretion of extracellular domains from type-II transmembrane proteins. Numerous Golgi-localized glycosidases and glucosyltransferases have been identified as physiological SPPL3 substrates. By SPPL3 dependent processing, glycan-transferring enzymes are deactivated inside the cell, as their active site-containing domain is cleaved and secreted. Thus, SPPL3 impacts on glycan patterns of many cellular and secreted proteins and can regulate protein glycosylation. However, the characteristics that make a substrate a favourable candidate for SPPL3-dependent cleavage remain unknown. To gain insights into substrate requirements, we investigated the function of a GxxxG motif located in the transmembrane domain of N-acetylglucosaminyltransferase V (GnTV), a well-known SPPL3 substrate. SPPL3-dependent secretion of the substrate's ectodomain was affected by mutations disrupting the GxxxG motif. Using deuterium/hydrogen exchange and NMR spectroscopy, we studied the effect of these mutations on the helix flexibility of the GnTV transmembrane domain and observed that increased flexibility facilitates SPPL3-dependent shedding and vice versa. This study provides first insights into the characteristics of SPPL3 substrates, combining molecular biology, biochemistry, and biophysical techniques and its results will provide the basis for better understanding the characteristics of SPPL3 substrates with implications for the substrates of other intramembrane proteases.
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Affiliation(s)
- Alkmini A. Papadopoulou
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Walter Stelzer
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Mara Silber
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Christine Schlosser
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Charlotte Spitz
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Martina Haug-Kröper
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Tobias Straub
- grid.5252.00000 0004 1936 973XCore Facility Bioinformatics, Biomedical Center, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Stephan A. Müller
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany
| | - Stefan F. Lichtenthaler
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany ,grid.15474.330000 0004 0477 2438Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany ,grid.452617.3Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Claudia Muhle-Goll
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Dieter Langosch
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Regina Fluhrer
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
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Scheidt HA, Kolocaj K, Veje Kristensen J, Huster D, Langosch D. Transmembrane Helix Induces Membrane Fusion through Lipid Binding and Splay. J Phys Chem Lett 2018; 9:3181-3186. [PMID: 29799756 DOI: 10.1021/acs.jpclett.8b00859] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The fusion of biological membranes may require splayed lipids whose tails transiently visit the headgroup region of the bilayer, a scenario suggested by molecular dynamics simulations. Here, we examined the lipid splay hypothesis experimentally by relating liposome fusion and lipid splay induced by model transmembrane domains (TMDs). Our results reveal that a conformationally flexible transmembrane helix promotes outer leaflet mixing and lipid splay more strongly than a conformationally rigid one. The lipid dependence of basal as well as of TMD-driven lipid mixing and splay suggests that the cone-shaped phosphatidylethanolamine stimulates basal fusion via enhancing lipid splay and that the negatively charged phosphatidylserine inhibits fusion via electrostatic repulsion. Phosphatidylserine also strongly differentiates basal and helix-driven fusion, which is related to its preferred interaction with the conformationally more flexible transmembrane helix. Thus, the contribution of a transmembrane helix to membrane fusion appears to depend on lipid binding, which results in lipid splay.
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Affiliation(s)
- Holger A Scheidt
- Institute for Medical Physics and Biophysics , Leipzig University , Härtelstrasse 16-18 , 04107 Leipzig , Germany
| | - Katja Kolocaj
- Lehrstuhl für Chemie der Biopolymere , Technische Universität München , Weihenstephaner Berg 3 , 85354 Freising , Germany
- Munich Center For Integrated Protein Science (CIPSM) , Butenandtstrasse 5 , 81377 München , Germany
| | - Julie Veje Kristensen
- Lehrstuhl für Chemie der Biopolymere , Technische Universität München , Weihenstephaner Berg 3 , 85354 Freising , Germany
- Munich Center For Integrated Protein Science (CIPSM) , Butenandtstrasse 5 , 81377 München , Germany
| | - Daniel Huster
- Institute for Medical Physics and Biophysics , Leipzig University , Härtelstrasse 16-18 , 04107 Leipzig , Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere , Technische Universität München , Weihenstephaner Berg 3 , 85354 Freising , Germany
- Munich Center For Integrated Protein Science (CIPSM) , Butenandtstrasse 5 , 81377 München , Germany
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LeBarron J, London E. Highly Hydrophilic Segments Attached to Hydrophobic Peptides Translocate Rapidly across Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10752-10760. [PMID: 27649909 DOI: 10.1021/acs.langmuir.6b02597] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hydrophilic segments attached to transmembrane helices often cross membranes. In an increasing number of cases, it has become apparent that this occurs in a biologically relevant post-translational event. In this study, we investigate whether juxta-membrane (JM) hydrophilic sequences attached to hydrophobic helices are able to rapidly cross lipid bilayers via their ability or inability to block hydrophobic helix interconversion between a transmembrane (TM) and non-TM membrane-associated state. Interconversion was triggered by changing the protonation state of an Asp residue in the hydrophobic core of the peptides, and peptide configuration was monitored by the fluorescence of a Trp residue at the center of the hydrophobic sequence. In POPC vesicles, conversion of the TM to non-TM state at high pH and the non-TM to TM state at low pH was rapid (seconds or less) for KK, KKNN, and the KKNNNNNN flanking sequences on both N- and C-termini and the KLFAGHQ sequence that flanks the spontaneously TM-inserting 3A protein of polio virus. In vesicles composed of 6:4 (mol/mol) POPC/cholesterol, interconversion was still rapid, with the exception of the peptide flanked by KKNNNNNN sequences, for which the half time of interconversion slowed to minutes. This behavior suggests that, at least in membranes with low levels of cholesterol, movement of hydrophilic JM segments (and analogous hydrophobic loops in multipass TM proteins) across membranes may be more facile than previously thought. This may have important biological implications.
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Affiliation(s)
- Jamie LeBarron
- Stony Brook University Stony Brook, New York 11794-5215, United States
| | - Erwin London
- Stony Brook University Stony Brook, New York 11794-5215, United States
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Herpesvirus gB: A Finely Tuned Fusion Machine. Viruses 2015; 7:6552-69. [PMID: 26690469 PMCID: PMC4690880 DOI: 10.3390/v7122957] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 11/15/2015] [Accepted: 11/27/2015] [Indexed: 01/03/2023] Open
Abstract
Enveloped viruses employ a class of proteins known as fusogens to orchestrate the merger of their surrounding envelope and a target cell membrane. Most fusogens accomplish this task alone, by binding cellular receptors and subsequently catalyzing the membrane fusion process. Surprisingly, in herpesviruses, these functions are distributed among multiple proteins: the conserved fusogen gB, the conserved gH/gL heterodimer of poorly defined function, and various non-conserved receptor-binding proteins. We summarize what is currently known about gB from two closely related herpesviruses, HSV-1 and HSV-2, with emphasis on the structure of the largely uncharted membrane interacting regions of this fusogen. We propose that the unusual mechanism of herpesvirus fusion could be linked to the unique architecture of gB.
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Abstract
Transmembrane (TM) helices of integral membrane proteins can facilitate strong and specific noncovalent protein-protein interactions. Mutagenesis and structural analyses have revealed numerous examples in which the interaction between TM helices of single-pass membrane proteins is dependent on a GxxxG or (small)xxx(small) motif. It is therefore tempting to use the presence of these simple motifs as an indicator of TM helix interactions. In this Current Topic review, we point out that these motifs are quite common, with more than 50% of single-pass TM domains containing a (small)xxx(small) motif. However, the actual interaction strength of motif-containing helices depends strongly on sequence context and membrane properties. In addition, recent studies have revealed several GxxxG-containing TM domains that interact via alternative interfaces involving hydrophobic, polar, aromatic, or even ionizable residues that do not form recognizable motifs. In multipass membrane proteins, GxxxG motifs can be important for protein folding, and not just oligomerization. Our current knowledge thus suggests that the presence of a GxxxG motif alone is a weak predictor of protein dimerization in the membrane.
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Affiliation(s)
- Mark G Teese
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München , 85354 Freising, Germany.,Center for Integrated Protein Science Munich (CIPSM) , 81377 Munich, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München , 85354 Freising, Germany.,Center for Integrated Protein Science Munich (CIPSM) , 81377 Munich, Germany
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Pester O, Barrett PJ, Hornburg D, Hornburg P, Pröbstle R, Widmaier S, Kutzner C, Dürrbaum M, Kapurniotu A, Sanders CR, Scharnagl C, Langosch D. The backbone dynamics of the amyloid precursor protein transmembrane helix provides a rationale for the sequential cleavage mechanism of γ-secretase. J Am Chem Soc 2013; 135:1317-29. [PMID: 23265086 PMCID: PMC3560327 DOI: 10.1021/ja3112093] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The etiology of Alzheimer's disease depends on the relative abundance of different amyloid-β (Aβ) peptide species. These peptides are produced by sequential proteolytic cleavage within the transmembrane helix of the 99 residue C-terminal fragment of the amyloid precursor protein (C99) by the intramembrane protease γ-secretase. Intramembrane proteolysis is thought to require local unfolding of the substrate helix, which has been proposed to be cleaved as a homodimer. Here, we investigated the backbone dynamics of the substrate helix. Amide exchange experiments of monomeric recombinant C99 and of synthetic transmembrane domain peptides reveal that the N-terminal Gly-rich homodimerization domain exchanges much faster than the C-terminal cleavage region. MD simulations corroborate the differential backbone dynamics, indicate a bending motion at a diglycine motif connecting dimerization and cleavage regions, and detect significantly different H-bond stabilities at the initial cleavage sites. Our results are consistent with the following hypotheses about cleavage of the substrate: First, the GlyGly hinge may precisely position the substrate within γ-secretase such that its catalytic center must start proteolysis at the known initial cleavage sites. Second, the ratio of cleavage products formed by subsequent sequential proteolysis could be influenced by differential extents of solvation and by the stabilities of H-bonds at alternate initial sites. Third, the flexibility of the Gly-rich domain may facilitate substrate movement within the enzyme during sequential proteolysis. Fourth, dimerization may affect substrate processing by decreasing the dynamics of the dimerization region and by increasing that of the C-terminal part of the cleavage region.
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Affiliation(s)
- Oxana Pester
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Paul J. Barrett
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee USA 37232-8725
| | - Daniel Hornburg
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Philipp Hornburg
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Rasmus Pröbstle
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Simon Widmaier
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Christoph Kutzner
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Milena Dürrbaum
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
| | - Aphrodite Kapurniotu
- Fachgebiet Peptidbiochemie, Technische Universität München, Emil-Erlenmeyer-Forum 5, 85354 Freising, Germany
| | - Charles R. Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee USA 37232-8725
| | - Christina Scharnagl
- Fakultät für Physik E14, Technische Universität München, Maximus-von-Imhof-Forum 4, 85354 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPS), Germany
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