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Sommer K, Garibagaoglu H, Paap EM, Wiendl M, Müller TM, Atreya I, Krönke G, Neurath MF, Zundler S. Discrepant Phenotyping of Monocytes Based on CX3CR1 and CCR2 Using Fluorescent Reporters and Antibodies. Cells 2024; 13:819. [PMID: 38786041 PMCID: PMC11119841 DOI: 10.3390/cells13100819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
Monocytes, as well as downstream macrophages and dendritic cells, are essential players in the immune system, fulfilling key roles in homeostasis as well as in inflammatory conditions. Conventionally, driven by studies on reporter models, mouse monocytes are categorized into a classical and a non-classical subset based on their inversely correlated surface expression of Ly6C/CCR2 and CX3CR1. Here, we aimed to challenge this concept by antibody staining and reporter mouse models. Therefore, we took advantage of Cx3cr1GFP and Ccr2RFP reporter mice, in which the respective gene was replaced by a fluorescent reporter protein gene. We analyzed the expression of CX3CR1 and CCR2 by flow cytometry using several validated fluorochrome-coupled antibodies and compared them with the reporter gene signal in these reporter mouse strains. Although we were able to validate the specificity of the fluorochrome-coupled flow cytometry antibodies, mouse Ly6Chigh classical and Ly6Clow non-classical monocytes showed no differences in CX3CR1 expression levels in the peripheral blood and spleen when stained with these antibodies. On the contrary, in Cx3cr1GFP reporter mice, we were able to reproduce the inverse correlation of the CX3CR1 reporter gene signal and Ly6C surface expression. Furthermore, differential CCR2 surface expression correlating with the expression of Ly6C was observed by antibody staining, but not in Ccr2RFP reporter mice. In conclusion, our data suggest that phenotyping strategies for mouse monocyte subsets should be carefully selected. In accordance with the literature, the suitability of CX3CR1 antibody staining is limited, whereas for CCR2, caution should be applied when using reporter mice.
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Affiliation(s)
- Katrin Sommer
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
| | - Hilal Garibagaoglu
- Department of Medicine 3, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany;
| | - Eva-Maria Paap
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
| | - Maximilian Wiendl
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
| | - Tanja M. Müller
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
- Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, 91054 Erlangen, Germany
| | - Imke Atreya
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
- Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, 91054 Erlangen, Germany
| | - Gerhard Krönke
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
- Medical Department of Rheumatology and Clinical Immunology, Charité—Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Markus F. Neurath
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
- Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, 91054 Erlangen, Germany
| | - Sebastian Zundler
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (K.S.); (E.-M.P.); (T.M.M.); (I.A.); (G.K.); (M.F.N.)
- Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, 91054 Erlangen, Germany
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2
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Gutierrez Guarnizo SA, Kellogg MK, Miller SC, Tikhonova E, Karamysheva ZN, Karamyshev AL. Pathogenic signal peptide variants in the human genome. NAR Genom Bioinform 2023; 5:lqad093. [PMID: 37859801 PMCID: PMC10583284 DOI: 10.1093/nargab/lqad093] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/05/2023] [Accepted: 09/29/2023] [Indexed: 10/21/2023] Open
Abstract
Secreted and membrane proteins represent a third of all cellular proteins and contain N-terminal signal peptides that are required for protein targeting to endoplasmic reticulum (ER). Mutations in signal peptides affect protein targeting, translocation, processing, and stability, and are associated with human diseases. However, only a few of them have been identified or characterized. In this report, we identified pathogenic signal peptide variants across the human genome using bioinformatic analyses and predicted the molecular mechanisms of their pathology. We recovered more than 65 thousand signal peptide mutations, over 11 thousand we classified as pathogenic, and proposed framework for distinction of their molecular mechanisms. The pathogenic mutations affect over 3.3 thousand genes coding for secreted and membrane proteins. Most pathogenic mutations alter the signal peptide hydrophobic core, a critical recognition region for the signal recognition particle, potentially activating the Regulation of Aberrant Protein Production (RAPP) quality control and specific mRNA degradation. The remaining pathogenic variants (about 25%) alter either the N-terminal region or signal peptidase processing site that can result in translocation deficiencies at the ER membrane or inhibit protein processing. This work provides a conceptual framework for the identification of mutations across the genome and their connection with human disease.
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Affiliation(s)
| | - Morgana K Kellogg
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sarah C Miller
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Elena B Tikhonova
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | | | - Andrey L Karamyshev
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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3
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Fasciani I, Carli M, Petragnano F, Colaianni F, Aloisi G, Maggio R, Scarselli M, Rossi M. GPCRs in Intracellular Compartments: New Targets for Drug Discovery. Biomolecules 2022; 12:1343. [PMID: 36291552 PMCID: PMC9599219 DOI: 10.3390/biom12101343] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 08/02/2023] Open
Abstract
The architecture of eukaryotic cells is defined by extensive membrane-delimited compartments, which entails separate metabolic processes that would otherwise interfere with each other, leading to functional differences between cells. G protein-coupled receptors (GPCRs) are the largest class of cell surface receptors, and their signal transduction is traditionally viewed as a chain of events initiated from the plasma membrane. Furthermore, their intracellular trafficking, internalization, and recycling were considered only to regulate receptor desensitization and cell surface expression. On the contrary, accumulating data strongly suggest that GPCRs also signal from intracellular compartments. GPCRs localize in the membranes of endosomes, nucleus, Golgi and endoplasmic reticulum apparatuses, mitochondria, and cell division compartments. Importantly, from these sites they have shown to orchestrate multiple signals that regulate different cell pathways. In this review, we summarize the current knowledge of this fascinating phenomenon, explaining how GPCRs reach the intracellular sites, are stimulated by the endogenous ligands, and their potential physiological/pathophysiological roles. Finally, we illustrate several mechanisms involved in the modulation of the compartmentalized GPCR signaling by drugs and endogenous ligands. Understanding how GPCR signaling compartmentalization is regulated will provide a unique opportunity to develop novel pharmaceutical approaches to target GPCRs and potentially lead the way towards new therapeutic approaches.
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Affiliation(s)
- Irene Fasciani
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Marco Carli
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Francesco Petragnano
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Francesco Colaianni
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Gabriella Aloisi
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Roberto Maggio
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Marco Scarselli
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Mario Rossi
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy
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4
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Taliaferro JM. Transcriptome-scale methods for uncovering subcellular RNA localization mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119202. [PMID: 34998919 PMCID: PMC9035289 DOI: 10.1016/j.bbamcr.2021.119202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 12/03/2021] [Accepted: 12/17/2021] [Indexed: 12/21/2022]
Abstract
Across a variety of systems, thousands of RNAs are localized to specific subcellular locations. However, for the vast majority of these RNAs, the mechanisms that underlie their transport are unknown. Historically, these mechanisms were uncovered for a single transcript at a time by laboriously testing the ability of RNA fragments to direct transcript localization. Recently developed methods profile the content of subcellular transcriptomes using high-throughput sequencing, allowing the analysis of the localization of thousands of transcripts at once. By identifying commonalities shared among multiple localized transcripts, these methods have the potential to rapidly expand our understanding of RNA localization mechanisms.
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Affiliation(s)
- J Matthew Taliaferro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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5
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Diederichs KA, Buchanan SK, Botos I. Building Better Barrels - β-barrel Biogenesis and Insertion in Bacteria and Mitochondria. J Mol Biol 2021; 433:166894. [PMID: 33639212 PMCID: PMC8292188 DOI: 10.1016/j.jmb.2021.166894] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 01/20/2023]
Abstract
β-barrel proteins are folded and inserted into outer membranes by multi-subunit protein complexes that are conserved across different types of outer membranes. In Gram-negative bacteria this complex is the barrel-assembly machinery (BAM), in mitochondria it is the sorting and assembly machinery (SAM) complex, and in chloroplasts it is the outer envelope protein Oep80. Mitochondrial β-barrel precursor proteins are translocated from the cytoplasm to the intermembrane space by the translocase of the outer membrane (TOM) complex, and stabilized by molecular chaperones before interaction with the assembly machinery. Outer membrane bacterial BamA interacts with four periplasmic accessory proteins, whereas mitochondrial Sam50 interacts with two cytoplasmic accessory proteins. Despite these major architectural differences between BAM and SAM complexes, their core proteins, BamA and Sam50, seem to function the same way. Based on the new SAM complex structures, we propose that the mitochondrial β-barrel folding mechanism follows the budding model with barrel-switching aiding in the release of new barrels. We also built a new molecular model for Tom22 interacting with Sam37 to identify regions that could mediate TOM-SAM supercomplex formation.
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Affiliation(s)
- Kathryn A Diederichs
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Susan K Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Istvan Botos
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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6
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Reindl M, Stock J, Hussnaetter KP, Genc A, Brachmann A, Schipper K. A Novel Factor Essential for Unconventional Secretion of Chitinase Cts1. Front Microbiol 2020; 11:1529. [PMID: 32733418 PMCID: PMC7358432 DOI: 10.3389/fmicb.2020.01529] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/12/2020] [Indexed: 12/15/2022] Open
Abstract
Subcellular targeting of proteins is essential to orchestrate cytokinesis in eukaryotic cells. During cell division of Ustilago maydis, for example, chitinases must be specifically targeted to the fragmentation zone at the site of cell division to degrade remnant chitin and thus separate mother and daughter cells. Chitinase Cts1 is exported to this location via an unconventional secretion pathway putatively operating in a lock-type manner. The underlying mechanism is largely unexplored. Here, we applied a forward genetic screen based on UV mutagenesis to identify components essential for Cts1 export. The screen revealed a novel factor termed Jps1 lacking known protein domains. Deletion of the corresponding gene confirmed its essential role for Cts1 secretion. Localization studies demonstrated that Jps1 colocalizes with Cts1 in the fragmentation zone of dividing yeast cells. While loss of Jps1 leads to exclusion of Cts1 from the fragmentation zone and strongly reduced unconventional secretion, deletion of the chitinase does not disturb Jps1 localization. Yeast-two hybrid experiments indicate that the two proteins might interact. In essence, we identified a novel component of unconventional secretion that functions in the fragmentation zone to enable export of Cts1. We hypothesize that Jps1 acts as an anchoring factor for Cts1.
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Affiliation(s)
- Michèle Reindl
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Bioeconomy Science Center, Forschungszentrum Jülich, Jülich, Germany
| | - Janpeter Stock
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Bioeconomy Science Center, Forschungszentrum Jülich, Jülich, Germany
| | - Kai P. Hussnaetter
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Bioeconomy Science Center, Forschungszentrum Jülich, Jülich, Germany
| | - Aycin Genc
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Andreas Brachmann
- Genetics, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Kerstin Schipper
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Bioeconomy Science Center, Forschungszentrum Jülich, Jülich, Germany
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7
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Wiesemann K, Simm S, Mirus O, Ladig R, Schleiff E. Regulation of two GTPases Toc159 and Toc34 in the translocon of the outer envelope of chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2019; 1867:627-636. [PMID: 30611779 DOI: 10.1016/j.bbapap.2019.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/20/2018] [Accepted: 01/02/2019] [Indexed: 01/03/2023]
Abstract
The GTPases Toc159 and Toc34 of the translocon of the outer envelope of chloroplasts (TOC) are involved in recognition and transfer of precursor proteins at the cytosolic face of the organelle. Both proteins engage multiple interactions within the translocon during the translocation process, including dimeric states of their G-domains. The units of the Toc34 homodimer are involved in the recognition of the transit peptide representing the translocation signal of precursor proteins. This substrate recognition is part of the regulation of the GTPase cycle of Toc34. The Toc159 monomer and the Toc34 homodimer recognize the transit peptide of the small subunit of Rubisco at the N- and at the C-terminal region, respectively. Analysis of the transit peptide interaction by crosslinking shows that the heterodimer between both G-domains binds pSSU most efficiently. While substrate recognition by Toc34 homodimer was shown to regulate nucleotide exchange, we provide evidence that the high activation energy of the GTPase Toc159 is lowered by substrate recognition. The nucleotide affinity of Toc34G homodimer and Toc159G monomer are distinct, Toc34G homodimer recognizes GDP and Toc159G GTP with highest affinity. Moreover, the analysis of the nucleotide association rates of the monomeric and dimeric receptor units suggests that the heterodimer has an arrangement distinct from the homodimer of Toc34. Based on the biochemical parameters determined we propose a model for the order of events at the cytosolic side of TOC. The molecular processes described by this hypothesis range from transit peptide recognition to perception of the substrate by the translocation channel.
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Affiliation(s)
- Katharina Wiesemann
- Department of Molecular Cell Biology of Plants, Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Stefan Simm
- Department of Molecular Cell Biology of Plants, Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany; Frankfurt Institute for Advanced Studies, Ruth-Moufang-Straße 1, D-60438 Frankfurt, Germany
| | - Oliver Mirus
- Department of Molecular Cell Biology of Plants, Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Roman Ladig
- Department of Molecular Cell Biology of Plants, Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany; Cluster of Excellence Frankfurt, Goethe University, D-60438 Frankfurt, Germany
| | - Enrico Schleiff
- Department of Molecular Cell Biology of Plants, Goethe University, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany; Frankfurt Institute for Advanced Studies, Ruth-Moufang-Straße 1, D-60438 Frankfurt, Germany; Cluster of Excellence Frankfurt, Goethe University, D-60438 Frankfurt, Germany; Buchmann Institute for Molecular Life Sciences, Goethe University, Max-von-Laue Str. 15, D-60438 Frankfurt, Germany.
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Brouwer E, Ngo G, Yadav S, Ladig R, Schleiff E. Tic22 from
Anabaena
sp. PCC 7120 with holdase function involved in outer membrane protein biogenesis shuttles between plasma membrane and Omp85. Mol Microbiol 2019; 111:1302-1316. [DOI: 10.1111/mmi.14222] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Eva‐Maria Brouwer
- Institute for Molecular Biosciences Goethe University Frankfurt am Main Frankfurt am Main Germany
| | - Giang Ngo
- Institute for Molecular Biosciences Goethe University Frankfurt am Main Frankfurt am Main Germany
| | - Shivam Yadav
- Institute for Molecular Biosciences Goethe University Frankfurt am Main Frankfurt am Main Germany
- Centre of Advanced Studies in Botany, Institute of Science Banaras Hindu University Varanasi India
| | - Roman Ladig
- Institute for Molecular Biosciences Goethe University Frankfurt am Main Frankfurt am Main Germany
| | - Enrico Schleiff
- Institute for Molecular Biosciences Goethe University Frankfurt am Main Frankfurt am Main Germany
- Buchman Institute for Molecular Life Sciences Goethe University Frankfurt am Main Frankfurt am Main Germany
- Frankfurt Institute of Advanced Studies Frankfurt am Main Germany
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9
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Klinger A, Gosch V, Bodensohn U, Ladig R, Schleiff E. The signal distinguishing between targeting of outer membrane β-barrel protein to plastids and mitochondria in plants. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:663-672. [PMID: 30633951 DOI: 10.1016/j.bbamcr.2019.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/03/2018] [Accepted: 01/07/2019] [Indexed: 12/15/2022]
Abstract
The proteome of the outer membrane of mitochondria and chloroplasts consists of membrane proteins anchored by α-helical or β-sheet elements. While proteins with α-helical transmembrane domains are present in all cellular membranes, proteins with β-barrel structure are specific for these two membranes. The organellar β-barrel proteins are encoded in the nuclear genome and thus, have to be targeted to the outer organellar membrane where they are recognized by surface exposed translocation complexes. In the last years, the signals that ensure proper targeting of these proteins have been investigated as essential base for an understanding of the regulation of cellular protein distribution. However, the organellar β-barrel proteins are unique as most of them do not contain a typical targeting information in form of an N-terminal cleavable targeting signal. Recently, it was discovered that targeting and surface recognition of mitochondrial β-barrel proteins in yeast, humans and plants depends on the hydrophobicity of the last β-hairpin of the β-barrel. However, we demonstrate that the hydrophobicity is not sufficient for the discrimination of targeting to chloroplasts or mitochondria. By domain swapping between mitochondrial and chloroplast targeted β-barrel proteins atVDAC1 and psOEP24 we demonstrate that the presence of a hydrophilic amino acid at the C-terminus of the penultimate β-strand is required for mitochondrial targeting. A mutation of the chloroplast β-barrel protein psOEP24 which mimics such profile is efficiently targeted to mitochondria. Thus, we present the properties of the signal for mitochondrial targeting of β-barrel proteins in plants.
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Affiliation(s)
- Anna Klinger
- Institute for Molecular Biosciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Victoria Gosch
- Institute for Molecular Biosciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Uwe Bodensohn
- Institute for Molecular Biosciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Roman Ladig
- Institute for Molecular Biosciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 9, D-60438 Frankfurt, Germany; Buchman Institute for Molecular Life Sciences, Goethe University Frankfurt am Main, Max-von-Laue Str. 15, D-60438 Frankfurt, Germany; Frankfurt Institute of Advanced Studies, Ruth-Moufang-Straße 1, D-60438 Frankfurt, Germany.
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10
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Kempf G, Stjepanovic G, Sloan J, Hendricks A, Lapouge K, Sinning I. The Escherichia coli SRP Receptor Forms a Homodimer at the Membrane. Structure 2018; 26:1440-1450.e5. [PMID: 30146170 DOI: 10.1016/j.str.2018.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/14/2018] [Accepted: 07/22/2018] [Indexed: 01/19/2023]
Abstract
The Escherichia coli signal recognition particle (SRP) receptor, FtsY, plays a fundamental role in co-translational targeting of membrane proteins via the SRP pathway. Efficient targeting relies on membrane interaction of FtsY and heterodimerization with the SRP protein Ffh, which is driven by detachment of α helix (αN1) in FtsY. Here we show that apart from the heterodimer, FtsY forms a nucleotide-dependent homodimer on the membrane, and upon αN1 removal also in solution. Homodimerization triggers reciprocal stimulation of GTP hydrolysis and occurs in vivo. Biochemical characterization together with integrative modeling suggests that the homodimer employs the same interface as the heterodimer. Structure determination of FtsY NG+1 with GMPPNP shows that a dimerization-induced conformational switch of the γ-phosphate is conserved in Escherichia coli, filling an important gap in SRP GTPase activation. Our findings add to the current understanding of SRP GTPases and may challenge previous studies that did not consider homodimerization of FtsY.
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Affiliation(s)
- Georg Kempf
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany
| | - Goran Stjepanovic
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany
| | - Jeremy Sloan
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany
| | - Astrid Hendricks
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany
| | - Karine Lapouge
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Centre, Heidelberg 69120, Germany.
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11
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The remembrance of the things past: Conserved signalling pathways link protozoa to mammalian nervous system. Cell Calcium 2018; 73:25-39. [DOI: 10.1016/j.ceca.2018.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/01/2018] [Accepted: 04/01/2018] [Indexed: 12/13/2022]
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12
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Mosaic nature of the mitochondrial proteome: Implications for the origin and evolution of mitochondria. Proc Natl Acad Sci U S A 2015; 112:10133-8. [PMID: 25848019 DOI: 10.1073/pnas.1421379112] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Comparative studies of the mitochondrial proteome have identified a conserved core of proteins descended from the α-proteobacterial endosymbiont that gave rise to the mitochondrion and was the source of the mitochondrial genome in contemporary eukaryotes. A surprising result of phylogenetic analyses is the relatively small proportion (10-20%) of the mitochondrial proteome displaying a clear α-proteobacterial ancestry. A large fraction of mitochondrial proteins typically has detectable homologs only in other eukaryotes and is presumed to represent proteins that emerged specifically within eukaryotes. A further significant fraction of the mitochondrial proteome consists of proteins with homologs in prokaryotes, but without a robust phylogenetic signal affiliating them with specific prokaryotic lineages. The presumptive evolutionary source of these proteins is quite different in contending models of mitochondrial origin.
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