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Chaudhary BP, Struppe J, Moktan H, Zoetewey D, Zhou DH, Mohanty S. Reconstitution and resonance assignments of yeast OST subunit Ost4 and its critical mutant Ost4V23D in liposomes by solid-state NMR. JOURNAL OF BIOMOLECULAR NMR 2024; 78:109-117. [PMID: 38421550 DOI: 10.1007/s10858-024-00437-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/12/2024] [Indexed: 03/02/2024]
Abstract
N-linked glycosylation is an essential and highly conserved co- and post-translational protein modification in all domains of life. In humans, genetic defects in N-linked glycosylation pathways result in metabolic diseases collectively called Congenital Disorders of Glycosylation. In this modification reaction, a mannose rich oligosaccharide is transferred from a lipid-linked donor substrate to a specific asparagine side-chain within the -N-X-T/S- sequence (where X ≠ Proline) of the nascent protein. Oligosaccharyltransferase (OST), a multi-subunit membrane embedded enzyme catalyzes this glycosylation reaction in eukaryotes. In yeast, Ost4 is the smallest of nine subunits and bridges the interaction of the catalytic subunit, Stt3, with Ost3 (or its homolog, Ost6). Mutations of any C-terminal hydrophobic residues in Ost4 to a charged residue destabilizes the enzyme and negatively impacts its function. Specifically, the V23D mutation results in a temperature-sensitive phenotype in yeast. Here, we report the reconstitution of both purified recombinant Ost4 and Ost4V23D each in a POPC/POPE lipid bilayer and their resonance assignments using heteronuclear 2D and 3D solid-state NMR with magic-angle spinning. The chemical shifts of Ost4 changed significantly upon the V23D mutation, suggesting a dramatic change in its chemical environment.
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Affiliation(s)
- Bharat P Chaudhary
- Department of Chemistry, Oklahoma State University, Stillwater, OK, 74078, USA
| | | | - Hem Moktan
- Department of Physics, Oklahoma State University, Stillwater, OK, 74078, USA
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - David Zoetewey
- Department of Chemistry, Physics and Astronomy, Georgia College and State University, Milledgeville, GA, 31061, USA
| | - Donghua H Zhou
- Department of Physics, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Smita Mohanty
- Department of Chemistry, Oklahoma State University, Stillwater, OK, 74078, USA.
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2
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Sakson R, Beedgen L, Bernhard P, Alp KM, Lübbehusen N, Röth R, Niesler B, Luzarowski M, Shevchuk O, Mayer MP, Thiel C, Ruppert T. Targeted Proteomics Reveals Quantitative Differences in Low-Abundance Glycosyltransferases of Patients with Congenital Disorders of Glycosylation. Int J Mol Sci 2024; 25:1191. [PMID: 38256263 PMCID: PMC10816918 DOI: 10.3390/ijms25021191] [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: 12/23/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Protein glycosylation is an essential post-translational modification in all domains of life. Its impairment in humans can result in severe diseases named congenital disorders of glycosylation (CDGs). Most of the glycosyltransferases (GTs) responsible for proper glycosylation are polytopic membrane proteins that represent challenging targets in proteomics. We established a multiple reaction monitoring (MRM) assay to comprehensively quantify GTs involved in the processes of N-glycosylation and O- and C-mannosylation in the endoplasmic reticulum. High robustness was achieved by using an enriched membrane protein fraction of isotopically labeled HEK 293T cells as an internal protein standard. The analysis of primary skin fibroblasts from eight CDG type I patients with impaired ALG1, ALG2, and ALG11 genes, respectively, revealed a substantial reduction in the corresponding protein levels. The abundance of the other GTs, however, remained unchanged at the transcript and protein levels, indicating that there is no fail-safe mechanism for the early steps of glycosylation in the endoplasmic reticulum. The established MRM assay was shared with the scientific community via the commonly used open source Skyline software environment, including Skyline Batch for automated data analysis. We demonstrate that another research group could easily reproduce all analysis steps, even while using different LC-MS hardware.
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Affiliation(s)
- Roman Sakson
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
- Heidelberg Biosciences International Graduate School (HBIGS), Heidelberg University, 69120 Heidelberg, Germany
| | - Lars Beedgen
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Patrick Bernhard
- Institute for Surgical Pathology, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - K. Merve Alp
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Nicole Lübbehusen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Ralph Röth
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Beate Niesler
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, 69120 Heidelberg, Germany
| | - Marcin Luzarowski
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Olga Shevchuk
- Department of Immunodynamics, Institute of Experimental Immunology and Imaging, University Hospital Essen, 45147 Essen, Germany
| | - Matthias P. Mayer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Christian Thiel
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Thomas Ruppert
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
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3
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Ramírez AS, Locher KP. Structural and mechanistic studies of the N-glycosylation machinery: from lipid-linked oligosaccharide biosynthesis to glycan transfer. Glycobiology 2023; 33:861-872. [PMID: 37399117 PMCID: PMC10859629 DOI: 10.1093/glycob/cwad053] [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: 05/29/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/05/2023] Open
Abstract
N-linked protein glycosylation is a post-translational modification that exists in all domains of life. It involves two consecutive steps: (i) biosynthesis of a lipid-linked oligosaccharide (LLO), and (ii) glycan transfer from the LLO to asparagine residues in secretory proteins, which is catalyzed by the integral membrane enzyme oligosaccharyltransferase (OST). In the last decade, structural and functional studies of the N-glycosylation machinery have increased our mechanistic understanding of the pathway. The structures of bacterial and eukaryotic glycosyltransferases involved in LLO elongation provided an insight into the mechanism of LLO biosynthesis, whereas structures of OST enzymes revealed the molecular basis of sequon recognition and catalysis. In this review, we will discuss approaches used and insight obtained from these studies with a special emphasis on the design and preparation of substrate analogs.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
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4
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Kim S, Min H, Nah J, Jeong J, Park K, Kim W, Lee Y, Kim J, An J, Seong RH. Defective N-glycosylation in tumor-infiltrating CD8 + T cells impairs IFN-γ-mediated effector function. Immunol Cell Biol 2023; 101:610-624. [PMID: 37114567 DOI: 10.1111/imcb.12647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 01/23/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023]
Abstract
T cell-mediated antitumor immunity is modulated, in part, by N-glycosylation. However, the interplay between N-glycosylation and the loss of effector function in exhausted T cells has not yet been fully investigated. Here, we delineated the impact of N-glycosylation on the exhaustion of tumor-infiltrating lymphocytes in a murine colon adenocarcinoma model, focusing on the IFN-γ-mediated immune response. We found that exhausted CD8+ T cells downregulated the oligosaccharyltransferase complex, which is indispensable for N-glycan transfer. Concordant N-glycosylation deficiency in tumor-infiltrating lymphocytes leads to loss of antitumor immunity. Complementing the oligosaccharyltransferase complex restored IFN-γ production and alleviated CD8+ T cell exhaustion, resulting in reduced tumor growth. Thus, aberrant glycosylation induced in the tumor microenvironment incapacitates effector CD8+ T cells. Our findings provide insights into CD8+ T cell exhaustion by incorporating N-glycosylation to understand the characteristic loss of IFN-γ, opening new opportunities to amend the glycosylation status in cancer immunotherapies.
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Affiliation(s)
- Soyeon Kim
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Hyungyu Min
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Jinwoo Nah
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Jinguk Jeong
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Kyungsoo Park
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Wooseob Kim
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Youngjin Lee
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Jieun Kim
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
| | - Jungeun An
- Department of Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Rho Hyun Seong
- School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea
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5
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Cui T, Ma Q, Zhang F, Chen S, Zhang C, Hao J, Liu X. Characterization of PcSTT3B as a Key Oligosaccharyltransferase Subunit Involved in N-glycosylation and Its Role in Development and Pathogenicity of Phytophthora capsici. Int J Mol Sci 2023; 24:ijms24087500. [PMID: 37108663 PMCID: PMC10141488 DOI: 10.3390/ijms24087500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/08/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Asparagine (Asn, N)-linked glycosylation is a conserved process and an essential post-translational modification that occurs on the NXT/S motif of the nascent polypeptides in endoplasmic reticulum (ER). The mechanism of N-glycosylation and biological functions of key catalytic enzymes involved in this process are rarely documented for oomycetes. In this study, an N-glycosylation inhibitor tunicamycin (TM) hampered the mycelial growth, sporangial release, and zoospore production of Phytophthora capsici, indicating that N-glycosylation was crucial for oomycete growth development. Among the key catalytic enzymes involved in N-glycosylation, the PcSTT3B gene was characterized by its functions in P. capsici. As a core subunit of the oligosaccharyltransferase (OST) complex, the staurosporine and temperature sensive 3B (STT3B) subunit were critical for the catalytic activity of OST. The PcSTT3B gene has catalytic activity and is highly conservative in P. capsici. By using a CRISPR/Cas9-mediated gene replacement system to delete the PcSTT3B gene, the transformants impaired mycelial growth, sporangial release, zoospore production, and virulence. The PcSTT3B-deleted transformants were more sensitive to an ER stress inducer TM and display low glycoprotein content in the mycelia, suggesting that PcSTT3B was associated with ER stress responses and N-glycosylation. Therefore, PcSTT3B was involved in the development, pathogenicity, and N-glycosylation of P. capsici.
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Affiliation(s)
- Tongshan Cui
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Quanhe Ma
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Fan Zhang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Shanshan Chen
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Can Zhang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Jianjun Hao
- School of Food and Agriculture, University of Maine, Orono, ME 04469, USA
| | - Xili Liu
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, China
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6
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Ramírez AS, de Capitani M, Pesciullesi G, Kowal J, Bloch JS, Irobalieva RN, Reymond JL, Aebi M, Locher KP. Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase. Nat Commun 2022; 13:7296. [PMID: 36435935 PMCID: PMC9701220 DOI: 10.1038/s41467-022-35067-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/17/2022] [Indexed: 11/28/2022] Open
Abstract
Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAc2Man9Glc3, from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis. However, the molecular basis of the OST-donor glycan interaction is unknown. Here we present cryo-EM structures of S. cerevisiae OST in distinct functional states. Our findings reveal that the terminal glucoses (Glc3) of a chemo-enzymatically generated donor glycan analog bind to a pocket formed by the non-catalytic subunits WBP1 and OST2. We further find that binding either donor or acceptor substrate leads to distinct primed states of OST, where subsequent binding of the other substrate triggers conformational changes required for catalysis. This alternate priming allows OST to efficiently process closely spaced N-glycosylation sites.
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Affiliation(s)
- Ana S. Ramírez
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Mario de Capitani
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Giorgio Pesciullesi
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Julia Kowal
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Joël S. Bloch
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Rossitza N. Irobalieva
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Jean-Louis Reymond
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Markus Aebi
- grid.5801.c0000 0001 2156 2780Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Kaspar P. Locher
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
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7
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Using In Silico Bioinformatics Algorithms for the Accurate Prediction of the Impact of Spike Protein Mutations on the Pathogenicity, Stability, and Functionality of the SARS-CoV-2 Virus and Analysis of Potential Therapeutic Targets. Biochem Genet 2022; 61:778-808. [PMID: 36173498 PMCID: PMC9521556 DOI: 10.1007/s10528-022-10282-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 09/01/2022] [Indexed: 11/02/2022]
Abstract
Coronavirus disease 2019 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We have used bioinformatics to investigate seventeen mutations in the spike protein of SARS-CoV-2, as this mediates infection of human cells and is the target of most vaccine strategies and antibody-based therapies. Two mutations, H146Y and S221W, were identified as being most pathogenic. Mutations at positions D614G, A829T, and P1263L might also have deleterious effects on protein function. We hypothesized that candidate small molecules may be repurposed to combat viral infection. We investigated changes in binding energies of the ligands and the mutant proteins by assessing molecular docking. For an understanding of cellular function and organization, protein-protein interactions are also critical. Protein-protein docking for naïve and mutated structures of SARS-CoV-2 S protein was evaluated for their binding energy with the angiotensin-converting enzyme 2 (ACE2). These interactions might limit the binding of the SARS-CoV-2 spike protein to the ACE2 receptor or may have a deleterious effect on protein function that may limit infection. These results may have important implications for the transmission of SARS-CoV-2, its pathogenesis, and the potential for drug repurposing and immune therapies.
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8
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Gómez-Marín E, Posavec-Marjanović M, Zarzuela L, Basurto-Cayuela L, Guerrero-Martínez JA, Arribas G, Yerbes R, Ceballos-Chávez M, Rodríguez-Paredes M, Tomé M, Durán RV, Buschbeck M, Reyes JC. The high mobility group protein HMG20A cooperates with the histone reader PHF14 to modulate TGFβ and Hippo pathways. Nucleic Acids Res 2022; 50:9838-9857. [PMID: 36124662 PMCID: PMC9508832 DOI: 10.1093/nar/gkac766] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 08/01/2022] [Accepted: 09/15/2022] [Indexed: 11/20/2022] Open
Abstract
High mobility group (HMG) proteins are chromatin regulators with essential functions in development, cell differentiation and cell proliferation. The protein HMG20A is predicted by the AlphaFold2 software to contain three distinct structural elements, which we have functionally characterized: i) an amino-terminal, intrinsically disordered domain with transactivation activity; ii) an HMG box with higher binding affinity for double-stranded, four-way-junction DNA than for linear DNA; and iii) a long coiled-coil domain. Our proteomic study followed by a deletion analysis and structural modeling demonstrates that HMG20A forms a complex with the histone reader PHF14, via the establishment of a two-stranded alpha-helical coiled-coil structure. siRNA-mediated knockdown of either PHF14 or HMG20A in MDA-MB-231 cells causes similar defects in cell migration, invasion and homotypic cell–cell adhesion ability, but neither affects proliferation. Transcriptomic analyses demonstrate that PHF14 and HMG20A share a large subset of targets. We show that the PHF14-HMG20A complex modulates the Hippo pathway through a direct interaction with the TEAD1 transcription factor. PHF14 or HMG20A deficiency increases epithelial markers, including E-cadherin and the epithelial master regulator TP63 and impaired normal TGFβ-trigged epithelial-to-mesenchymal transition. Taken together, these data indicate that PHF14 and HMG20A cooperate in regulating several pathways involved in epithelial–mesenchymal plasticity.
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Affiliation(s)
- Elena Gómez-Marín
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Melanija Posavec-Marjanović
- Program for Predictive and Personalized Medicine of Cancer, Germans Trias i Pujol Research Institute (PMPPC-IGTP), Badalona, Spain
| | - Laura Zarzuela
- Cell Dynamics and Signaling Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Laura Basurto-Cayuela
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - José A Guerrero-Martínez
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Gonzalo Arribas
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Rosario Yerbes
- Cell Dynamics and Signaling Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - María Ceballos-Chávez
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Manuel Rodríguez-Paredes
- Institute of Toxicology, University Medical Center Mainz, Johannes Gutenberg University, 55131 Mainz, Germany
| | - Mercedes Tomé
- Cell Dynamics and Signaling Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Raúl V Durán
- Cell Dynamics and Signaling Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
| | - Marcus Buschbeck
- Program for Predictive and Personalized Medicine of Cancer, Germans Trias i Pujol Research Institute (PMPPC-IGTP), Badalona, Spain.,Cancer and Leukaemia Epigenetics and Biology Program, Josep Carreras Leukaemia Research Institute (IJC), 08916 Badalona, Spain
| | - José C Reyes
- Genome Biology Department. Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla-Universidad Pablo de Olavide (CSIC-USE-UPO), Av. Americo Vespucio, 41092 Seville, Spain
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9
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Swamy KBS, Lee HY, Ladra C, Liu CFJ, Chao JC, Chen YY, Leu JY. Proteotoxicity caused by perturbed protein complexes underlies hybrid incompatibility in yeast. Nat Commun 2022; 13:4394. [PMID: 35906261 PMCID: PMC9338014 DOI: 10.1038/s41467-022-32107-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 07/18/2022] [Indexed: 02/08/2023] Open
Abstract
Dobzhansky–Muller incompatibilities represent a major driver of reproductive isolation between species. They are caused when interacting components encoded by alleles from different species cannot function properly when mixed. At incipient stages of speciation, complex incompatibilities involving multiple genetic loci with weak effects are frequently observed, but the underlying mechanisms remain elusive. Here we show perturbed proteostasis leading to compromised mitosis and meiosis in Saccharomyces cerevisiae hybrid lines carrying one or two chromosomes from Saccharomyces bayanus var. uvarum. Levels of proteotoxicity are correlated with the number of protein complexes on replaced chromosomes. Proteomic approaches reveal that multi-protein complexes with subunits encoded by replaced chromosomes tend to be unstable. Furthermore, hybrid defects can be alleviated or aggravated, respectively, by up- or down-regulating the ubiquitin-proteasomal degradation machinery, suggesting that destabilized complex subunits overburden the proteostasis machinery and compromise hybrid fitness. Our findings reveal the general role of impaired protein complex assembly in complex incompatibilities. Hybrid incompatibility can be an important element of reproductive isolation and speciation. Using chromosome replacement lines of yeast, the authors show that perturbed proteostasis caused by destabilized hybrid protein complexes may represent a general mechanism of hybrid incompatibility.
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Affiliation(s)
- Krishna B S Swamy
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan.,Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Ahmedabad, 380009, India
| | - Hsin-Yi Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Carmina Ladra
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Chien-Fu Jeff Liu
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Jung-Chi Chao
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yi-Yun Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan
| | - Jun-Yi Leu
- Institute of Molecular Biology, Academia Sinica, Taipei, 11529, Taiwan.
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10
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Hsu KL, Yen HCS, Yeang CH. Cooperative stability renders protein complex formation more robust and controllable. Sci Rep 2022; 12:10490. [PMID: 35729235 PMCID: PMC9213465 DOI: 10.1038/s41598-022-14362-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/06/2022] [Indexed: 11/19/2022] Open
Abstract
Protein complexes are the fundamental units of many biological functions. Despite their many advantages, one major adverse impact of protein complexes is accumulations of unassembled subunits that may disrupt other processes or exert cytotoxic effects. Synthesis of excess subunits can be inhibited via negative feedback control or they can be degraded more efficiently than assembled subunits, with this latter being termed cooperative stability. Whereas controlled synthesis of complex subunits has been investigated extensively, how cooperative stability acts in complex formation remains largely unexplored. To fill this knowledge gap, we have built quantitative models of heteromeric complexes with or without cooperative stability and compared their behaviours in the presence of synthesis rate variations. A system displaying cooperative stability is robust against synthesis rate variations as it retains high dimer/monomer ratios across a broad range of parameter configurations. Moreover, cooperative stability can alleviate the constraint of limited supply of a given subunit and makes complex abundance more responsive to unilateral upregulation of another subunit. We also conducted an in silico experiment to comprehensively characterize and compare four types of circuits that incorporate combinations of negative feedback control and cooperative stability in terms of eight systems characteristics pertaining to optimality, robustness and controllability. Intriguingly, though individual circuits prevailed for distinct characteristics, the system with cooperative stability alone achieved the most balanced performance across all characteristics. Our study provides theoretical justification for the contribution of cooperative stability to natural biological systems and represents a guideline for designing synthetic complex formation systems with desirable characteristics.
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Affiliation(s)
- Kuan-Lun Hsu
- Institute of Molecular Biology, Academia Sinica, 128 Academia Road, Section 2, Taipei, Taiwan
| | - Hsueh-Chi S Yen
- Institute of Molecular Biology, Academia Sinica, 128 Academia Road, Section 2, Taipei, Taiwan
| | - Chen-Hsiang Yeang
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Taipei, Taiwan.
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11
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Ramírez AS, Nosol K, Locher KP. Production of Human ABC Transporters and Oligosaccharyltransferase Complexes for Structural Studies. Methods Mol Biol 2022; 2507:273-294. [PMID: 35773587 DOI: 10.1007/978-1-0716-2368-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Structural studies of membrane proteins require high-quality samples. The target proteins should not only be pure and homogeneous but should also be active and allow the capture of a functionally relevant state. Here we present optimized methods for the expression and purification of human ABC transporters and oligosaccharyltransferase (OST) complexes that can be used for high-resolution structure determination using single-particle cryo-electron microscopy (cryo-EM). The protocols are based on the generation of stable cell lines that enable tetracycline-inducible expression of the target proteins. For the multidrug exporter ABCB1, we describe a protocol for reconstitution into nanodiscs and evaluation of the ATPase activity in the presence of drugs. For human OST, we describe a strategy for the purification of OST-A and OST-B complexes, including techniques to evaluate their integrity and activity using in vitro glycosylation assays. These protocols can be adapted for the production of other human ABC transporters and multimeric membrane protein complexes.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Kamil Nosol
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.
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12
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Neuhaus JD, Wild R, Eyring J, Irobalieva RN, Kowal J, Lin CW, Locher KP, Aebi M. Functional analysis of Ost3p and Ost6p containing yeast oligosaccharyltransferases. Glycobiology 2021; 31:1604-1615. [PMID: 34974622 DOI: 10.1093/glycob/cwab084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 07/14/2021] [Accepted: 08/05/2021] [Indexed: 11/14/2022] Open
Abstract
The oligosaccharyltransferase (OST) is the central enzyme in the N-glycosylation pathway. It transfers a defined oligosaccharide from a lipid-linker onto the asparagine side chain of proteins. The yeast OST consists of eight subunits and exists in two catalytically distinct isoforms that differ in one subunit, Ost3p or Ost6p. The cryo-electron microscopy structure of the Ost6p containing complex was found to be highly similar to the Ost3p containing OST. OST enzymes with altered Ost3p/Ost6p subunits were generated and functionally analyzed. The three C-terminal transmembrane helices were responsible for the higher turnover-rate of the Ost3p vs. the Ost6p containing enzyme in vitro and the more severe hypoglycosylation in Ost3p lacking strains in vivo. Glycosylation of specific OST target sites required the N-terminal thioredoxin domain of Ost3p or Ost6p. This Ost3p/Ost6p dependence was glycosylation site but not protein specific. We concluded that the Ost3p/Ost6p subunits modulate the catalytic activity of OST and provide additional specificity for OST substrate recognition.
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Affiliation(s)
- Julia D Neuhaus
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Rebekka Wild
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.,Institut de Biologie Structurale, CNRS, CEA, Université Grenoble-Alpes, 38000 Grenoble, France
| | - Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Rossitza N Irobalieva
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.,Functional Genomic Center Zurich, 8057 Zurich, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
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13
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Ishikawa K. Multilayered regulation of proteome stoichiometry. Curr Genet 2021; 67:883-890. [PMID: 34382105 PMCID: PMC8592966 DOI: 10.1007/s00294-021-01205-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 01/02/2023]
Abstract
Cellular systems depend on multiprotein complexes whose functionalities require defined stoichiometries of subunit proteins. Proper stoichiometry is achieved by controlling the amount of protein synthesis and degradation even in the presence of genetic perturbations caused by changes in gene dosage. As a consequence of increased gene copy number, excess subunits unassembled into the complex are synthesized and rapidly degraded by the ubiquitin–proteasome system. This mechanism, called protein-level dosage compensation, is widely observed not only under such perturbed conditions but also in unperturbed physiological cells. Recent studies have shown that recognition of unassembled subunits and their selective degradation are intricately regulated. This review summarizes the nature, strategies, and increasing complexity of protein-level dosage compensation and discusses possible mechanisms for controlling proteome stoichiometry in multiple layers of biological processes.
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Affiliation(s)
- Koji Ishikawa
- Center for Molecular Biology, ZMBH-DKFZ Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
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14
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Eyring J, Lin CW, Ngwa EM, Boilevin J, Pesciullesi G, Locher KP, Darbre T, Reymond JL, Aebi M. Substrate specificities and reaction kinetics of the yeast oligosaccharyltransferase isoforms. J Biol Chem 2021; 296:100809. [PMID: 34023382 PMCID: PMC8191290 DOI: 10.1016/j.jbc.2021.100809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/07/2021] [Accepted: 05/19/2021] [Indexed: 12/02/2022] Open
Abstract
Oligosaccharyltransferase (OST) catalyzes the central step in N-linked protein glycosylation, the transfer of a preassembled oligosaccharide from its lipid carrier onto asparagine residues of secretory proteins. The prototypic hetero-octameric OST complex from the yeast Saccharomyces cerevisiae exists as two isoforms that contain either Ost3p or Ost6p, both noncatalytic subunits. These two OST complexes have different protein substrate specificities in vivo. However, their detailed biochemical mechanisms and the basis for their different specificities are not clear. The two OST complexes were purified from genetically engineered strains expressing only one isoform. The kinetic properties and substrate specificities were characterized using a quantitative in vitro glycosylation assay with short peptides and different synthetic lipid-linked oligosaccharide (LLO) substrates. We found that the peptide sequence close to the glycosylation sequon affected peptide affinity and turnover rate. The length of the lipid moiety affected LLO affinity, while the lipid double-bond stereochemistry had a greater influence on LLO turnover rates. The two OST complexes had similar affinities for both the peptide and LLO substrates but showed significantly different turnover rates. These data provide the basis for a functional analysis of the Ost3p and Ost6p subunits.
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Affiliation(s)
- Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland; Functional Genomics Center Zürich, University of Zürich/ETH Zürich, Zürich, Switzerland
| | - Elsy Mankah Ngwa
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Giorgio Pesciullesi
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.
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15
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Kong KYE, Coelho JPL, Feige MJ, Khmelinskii A. Quality control of mislocalized and orphan proteins. Exp Cell Res 2021; 403:112617. [PMID: 33930402 DOI: 10.1016/j.yexcr.2021.112617] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 04/10/2021] [Accepted: 04/18/2021] [Indexed: 12/16/2022]
Abstract
A healthy and functional proteome is essential to cell physiology. However, this is constantly being challenged as most steps of protein metabolism are error-prone and changes in the physico-chemical environment can affect protein structure and function, thereby disrupting proteome homeostasis. Among a variety of potential mistakes, proteins can be targeted to incorrect compartments or subunits of protein complexes may fail to assemble properly with their partners, resulting in the formation of mislocalized and orphan proteins, respectively. Quality control systems are in place to handle these aberrant proteins, and to minimize their detrimental impact on cellular functions. Here, we discuss recent findings on quality control mechanisms handling mislocalized and orphan proteins. We highlight common principles involved in their recognition and summarize how accumulation of these aberrant molecules is associated with aging and disease.
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Affiliation(s)
| | - João P L Coelho
- Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - Matthias J Feige
- Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Garching, Germany
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16
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Salovska B, Zhu H, Gandhi T, Frank M, Li W, Rosenberger G, Wu C, Germain PL, Zhou H, Hodny Z, Reiter L, Liu Y. Isoform-resolved correlation analysis between mRNA abundance regulation and protein level degradation. Mol Syst Biol 2021; 16:e9170. [PMID: 32175694 PMCID: PMC7073818 DOI: 10.15252/msb.20199170] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 02/06/2020] [Accepted: 02/12/2020] [Indexed: 12/15/2022] Open
Abstract
Profiling of biological relationships between different molecular layers dissects regulatory mechanisms that ultimately determine cellular function. To thoroughly assess the role of protein post‐translational turnover, we devised a strategy combining pulse stable isotope‐labeled amino acids in cells (pSILAC), data‐independent acquisition mass spectrometry (DIA‐MS), and a novel data analysis framework that resolves protein degradation rate on the level of mRNA alternative splicing isoforms and isoform groups. We demonstrated our approach by the genome‐wide correlation analysis between mRNA amounts and protein degradation across different strains of HeLa cells that harbor a high grade of gene dosage variation. The dataset revealed that specific biological processes, cellular organelles, spatial compartments of organelles, and individual protein isoforms of the same genes could have distinctive degradation rate. The protein degradation diversity thus dissects the corresponding buffering or concerting protein turnover control across cancer cell lines. The data further indicate that specific mRNA splicing events such as intron retention significantly impact the protein abundance levels. Our findings support the tight association between transcriptome variability and proteostasis and provide a methodological foundation for studying functional protein degradation.
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Affiliation(s)
- Barbora Salovska
- Yale Cancer Biology Institute, Yale University, West Haven, CT, USA.,Department of Genome Integrity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Hongwen Zhu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | | | - Max Frank
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Wenxue Li
- Yale Cancer Biology Institute, Yale University, West Haven, CT, USA
| | | | - Chongde Wu
- Yale Cancer Biology Institute, Yale University, West Haven, CT, USA
| | - Pierre-Luc Germain
- Institute for Neuroscience, D-HEST, ETH Zurich, Zurich, Switzerland.,Statistical Bioinformatics Lab, DMLS, University of Zürich, Zurich, Switzerland
| | - Hu Zhou
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Zdenek Hodny
- Department of Genome Integrity, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | | | - Yansheng Liu
- Yale Cancer Biology Institute, Yale University, West Haven, CT, USA.,Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
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17
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Chaudhary BP, Zoetewey DL, McCullagh MJ, Mohanty S. NMR and MD Simulations Reveal the Impact of the V23D Mutation on the Function of Yeast Oligosaccharyltransferase Subunit Ost4. Glycobiology 2021; 31:838-850. [PMID: 33442744 DOI: 10.1093/glycob/cwab002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 11/14/2022] Open
Abstract
Asparagine-linked glycosylation, also known as N-linked glycosylation, is an essential and highly conserved co- and post-translational protein modification in eukaryotes and some prokaryotes. In the central step of this reaction, a carbohydrate moiety is transferred from a lipid-linked donor to the side-chain of a consensus asparagine in a nascent protein as it is synthesized at the ribosome. Complete loss of oligosaccharyltransferase (OST) function is lethal in eukaryotes. This reaction is carried out by a membrane-associated multi-subunit enzyme, OST, localized in the endoplasmic reticulum (ER). The smallest subunit, Ost4, contains a single membrane-spanning helix that is critical for maintaining stability and activity of OST. Mutation of any residue from Met18 to Ile24 of Ost4 destabilizes the enzyme complex, affecting its activity. Here, we report solution NMR structures and molecular dynamics simulations of Ost4 and Ost4V23D in micelles. Our studies revealed that while the point mutation did not impact the structure of the protein, it affected its position and solvent exposure in the membrane mimetic environment. Furthermore, our molecular dynamics simulations of the membrane-bound OST complex containing either WT or V23D mutant demonstrated disruption of most hydrophobic helix-helix interactions between Ost4V23D and transmembrane (TM)12 and TM13 of Stt3. This disengagement of Ost4V23D from the OST complex led to solvent exposure of the D23 residue in the hydrophobic pocket created by these interactions. Our study not only solves the structures of yeast Ost4 subunit and its mutant but also provides a basis for the destabilization of the OST complex and reduced OST activity.
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Affiliation(s)
- Bharat P Chaudhary
- Department of Chemistry, Oklahoma State University, Stillwater, OK, USA, 74078
| | - David L Zoetewey
- Department of Chemistry, Oklahoma State University, Stillwater, OK, USA, 74078
| | - Martin J McCullagh
- Department of Chemistry, Oklahoma State University, Stillwater, OK, USA, 74078
| | - Smita Mohanty
- Department of Chemistry, Oklahoma State University, Stillwater, OK, USA, 74078
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18
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Bohl H, Bai L, Li H. Recent Progress in Structural Studies on the GT-C Superfamily of Protein Glycosyltransferases. Subcell Biochem 2021; 96:259-271. [PMID: 33252732 DOI: 10.1007/978-3-030-58971-4_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Protein glycosylation is an essential covalent modification involved in protein secretion, stability, binding, folding, and activity. One or more sugars may be O-, N-, S-, or C-linked to specific amino acids by glycosyltransferases, which catalyze the transfer of these sugars from a phosphate-containing carrier molecule. Most glycosyltransferases are members of the GT-A, GT-B, or GT-C structural superfamilies. GT-C enzymes are integral membrane proteins that utilize a phospho-isoprenoid carrier for sugar transfer. To-date, two families of GT-Cs involved in protein glycosylation have been structurally characterized: the family represented by PglB, AglB, and Stt3, which catalyzes oligosaccharide transfer to Asn, and the family represented by Pmt1 and Pmt2, which catalyzes mannose transfer to Thr or Ser. This chapter reviews progress made over recent years on the structure and function of these two GT-C families.
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Affiliation(s)
- Heather Bohl
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, 49503, USA
| | - Lin Bai
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, 100083, Beijing, P. R. China
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, Michigan, 49503, USA.
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19
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Zraly CB, Zakkar A, Perez JH, Ng J, White KP, Slattery M, Dingwall AK. The Drosophila MLR COMPASS complex is essential for programming cis-regulatory information and maintaining epigenetic memory during development. Nucleic Acids Res 2020; 48:3476-3495. [PMID: 32052053 PMCID: PMC7144903 DOI: 10.1093/nar/gkaa082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 01/17/2020] [Accepted: 01/30/2020] [Indexed: 12/29/2022] Open
Abstract
The MLR COMPASS complex monomethylates H3K4 that serves to epigenetically mark transcriptional enhancers to drive proper gene expression during animal development. Chromatin enrichment analyses of the Drosophila MLR complex reveals dynamic association with promoters and enhancers in embryos with late stage enrichments biased toward both active and poised enhancers. RNAi depletion of the Cmi (also known as Lpt) subunit that contains the chromatin binding PHD finger domains attenuates enhancer functions, but unexpectedly results in inappropriate enhancer activation during stages when hormone responsive enhancers are poised, revealing critical epigenetic roles involved in both the activation and repression of enhancers depending on developmental context. Cmi is necessary for robust H3K4 monomethylation and H3K27 acetylation that mark active enhancers, but not for the chromatin binding of Trr, the MLR methyltransferase. Our data reveal two likely major regulatory modes of MLR function, contributions to enhancer commissioning in early embryogenesis and bookmarking enhancers to enable rapid transcriptional re-activation at subsequent developmental stages.
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Affiliation(s)
- Claudia B Zraly
- Department of Cancer Biology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Abdul Zakkar
- Department of Biology, Program in Bioinformatics, Loyola University Chicago, Chicago, IL 60660, USA
| | - John Hertenstein Perez
- Department of Cancer Biology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Jeffrey Ng
- Department of Cancer Biology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.,Department of Biology, Program in Bioinformatics, Loyola University Chicago, Chicago, IL 60660, USA
| | - Kevin P White
- Institute for Genomics and Systems Biology and Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Matthew Slattery
- Institute for Genomics and Systems Biology and Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.,Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA
| | - Andrew K Dingwall
- Department of Cancer Biology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.,Department of Pathology & Laboratory Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
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20
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Structural Insight into the Mechanism of N-Linked Glycosylation by Oligosaccharyltransferase. Biomolecules 2020; 10:biom10040624. [PMID: 32316603 PMCID: PMC7226087 DOI: 10.3390/biom10040624] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/06/2020] [Accepted: 04/10/2020] [Indexed: 02/06/2023] Open
Abstract
Asparagine-linked glycosylation, also known as N-linked glycosylation is an essential and highly conserved post-translational protein modification that occurs in all three domains of life. This modification is essential for specific molecular recognition, protein folding, sorting in the endoplasmic reticulum, cell-cell communication, and stability. Defects in N-linked glycosylation results in a class of inherited diseases known as congenital disorders of glycosylation (CDG). N-linked glycosylation occurs in the endoplasmic reticulum (ER) lumen by a membrane associated enzyme complex called the oligosaccharyltransferase (OST). In the central step of this reaction, an oligosaccharide group is transferred from a lipid-linked dolichol pyrophosphate donor to the acceptor substrate, the side chain of a specific asparagine residue of a newly synthesized protein. The prokaryotic OST enzyme consists of a single polypeptide chain, also known as single subunit OST or ssOST. In contrast, the eukaryotic OST is a complex of multiple non-identical subunits. In this review, we will discuss the biochemical and structural characterization of the prokaryotic, yeast, and mammalian OST enzymes. This review explains the most recent high-resolution structures of OST determined thus far and the mechanistic implication of N-linked glycosylation throughout all domains of life. It has been shown that the ssOST enzyme, AglB protein of the archaeon Archaeoglobus fulgidus, and the PglB protein of the bacterium Campylobactor lari are structurally and functionally similar to the catalytic Stt3 subunit of the eukaryotic OST enzyme complex. Yeast OST enzyme complex contains a single Stt3 subunit, whereas the human OST complex is formed with either STT3A or STT3B, two paralogues of Stt3. Both human OST complexes, OST-A (with STT3A) and OST-B (containing STT3B), are involved in the N-linked glycosylation of proteins in the ER. The cryo-EM structures of both human OST-A and OST-B complexes were reported recently. An acceptor peptide and a donor substrate (dolichylphosphate) were observed to be bound to the OST-B complex whereas only dolichylphosphate was bound to the OST-A complex suggesting disparate affinities of two OST complexes for the acceptor substrates. However, we still lack an understanding of the independent role of each eukaryotic OST subunit in N-linked glycosylation or in the stabilization of the enzyme complex. Discerning the role of each subunit through structure and function studies will potentially reveal the mechanistic details of N-linked glycosylation in higher organisms. Thus, getting an insight into the requirement of multiple non-identical subunits in the N-linked glycosylation process in eukaryotes poses an important future goal.
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21
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Knopf JD, Landscheidt N, Pegg CL, Schulz BL, Kühnle N, Chao CW, Huck S, Lemberg MK. Intramembrane protease RHBDL4 cleaves oligosaccharyltransferase subunits to target them for ER-associated degradation. J Cell Sci 2020; 133:jcs243790. [PMID: 32005703 DOI: 10.1242/jcs.243790] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 01/21/2020] [Indexed: 08/31/2023] Open
Abstract
The endoplasmic reticulum (ER)-resident intramembrane rhomboid protease RHBDL4 generates metastable protein fragments and together with the ER-associated degradation (ERAD) machinery provides a clearance mechanism for aberrant and surplus proteins. However, the endogenous substrate spectrum and with that the role of RHBDL4 in physiological ERAD is mainly unknown. Here, we use a substrate trapping approach in combination with quantitative proteomics to identify physiological RHBDL4 substrates. This revealed oligosaccharyltransferase (OST) complex subunits such as the catalytic active subunit STT3A as substrates for the RHBDL4-dependent ERAD pathway. RHBDL4-catalysed cleavage inactivates OST subunits by triggering dislocation into the cytoplasm and subsequent proteasomal degradation. RHBDL4 thereby controls the abundance and activity of OST, suggesting a novel link between the ERAD machinery and glycosylation tuning.
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Affiliation(s)
- Julia D Knopf
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Nina Landscheidt
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Cassandra L Pegg
- School of Chemistry and Molecular Biosciences, ARC Training Centre for Biopharmaceutical Innovation, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Benjamin L Schulz
- School of Chemistry and Molecular Biosciences, ARC Training Centre for Biopharmaceutical Innovation, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Nathalie Kühnle
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Chao-Wei Chao
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Simon Huck
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
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22
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Baumert HM, Metzger E, Fahrner M, George J, Thomas RK, Schilling O, Schüle R. Depletion of histone methyltransferase KMT9 inhibits lung cancer cell proliferation by inducing non-apoptotic cell death. Cancer Cell Int 2020; 20:52. [PMID: 32095117 PMCID: PMC7027090 DOI: 10.1186/s12935-020-1141-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 02/10/2020] [Indexed: 12/24/2022] Open
Abstract
Background Lung cancer is the leading cause of cancer related death worldwide. Over the past 15 years no major improvement of survival rates could be accomplished. The recently discovered histone methyltransferase KMT9 that acts as epigenetic regulator of prostate tumor growth has now raised hopes of enabling new cancer therapies. In this study, we aimed to identify the function of KMT9 in lung cancer. Methods We unraveled the KMT9 transcriptome and proteome in A549 lung adenocarcinoma cells using RNA-Seq and mass spectrometry and linked them with functional cell culture, real-time proliferation and flow cytometry assays. Results We show that KMT9α and -β subunits of KMT9 are expressed in lung cancer tissue and cell lines. Importantly, high levels of KMT9α correlate with poor patient survival. We identified 460 genes that are deregulated at the RNA and protein level upon knock-down of KMT9α in A549 cells. These genes cluster with proliferation, cell cycle and cell death gene sets as well as with subcellular organelles in gene ontology analysis. Knock-down of KMT9α inhibits lung cancer cell proliferation and induces non-apoptotic cell death in A549 cells. Conclusions The novel histone methyltransferase KMT9 is crucial for proliferation and survival of lung cancer cells harboring various mutations. Small molecule inhibitors targeting KMT9 therefore should be further examined as potential milestones in modern epigenetic lung cancer therapy.
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Affiliation(s)
- Hannah Maria Baumert
- 1Klinik für Urologie und Zentrale Klinische Forschung, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Universitätsklinikum Freiburg, Freiburg, Germany
| | - Eric Metzger
- 1Klinik für Urologie und Zentrale Klinische Forschung, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Universitätsklinikum Freiburg, Freiburg, Germany
| | - Matthias Fahrner
- 2Institute for Surgical Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,3Faculty of Biology, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,4Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Julie George
- 5Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Roman K Thomas
- 5Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, 50931 Cologne, Germany.,6Department of Pathology, University Hospital Cologne, 50937 Cologne, Germany.,7German Cancer Research Center, German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Oliver Schilling
- 2Institute for Surgical Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Deutsches Konsortium für Translationale Krebsforschung, Standort Freiburg, Freiburg, Germany.,9BIOSS Centre of Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Roland Schüle
- 1Klinik für Urologie und Zentrale Klinische Forschung, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Universitätsklinikum Freiburg, Freiburg, Germany.,Deutsches Konsortium für Translationale Krebsforschung, Standort Freiburg, Freiburg, Germany.,9BIOSS Centre of Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,10CIBSS Centre for Integrative Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,K-metics GmbH, Freiburg, Germany
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23
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Abstract
The endoplasmic reticulum (ER) translocon complex is the main gate into the secretory pathway, facilitating the translocation of nascent peptides into the ER lumen or their integration into the lipid membrane. Protein biogenesis in the ER involves additional processes, many of them occurring co-translationally while the nascent protein resides at the translocon complex, including recruitment of ER-targeted ribosome-nascent-chain complexes, glycosylation, signal peptide cleavage, membrane protein topogenesis and folding. To perform such varied functions on a broad range of substrates, the ER translocon complex has different accessory components that associate with it either stably or transiently. Here, we review recent structural and functional insights into this dynamically constituted central hub in the ER and its components. Recent cryo-electron microscopy (EM) studies have dissected the molecular organization of the co-translational ER translocon complex, comprising the Sec61 protein-conducting channel, the translocon-associated protein complex and the oligosaccharyl transferase complex. Complemented by structural characterization of the post-translational import machinery, key molecular principles emerge that distinguish co- and post-translational protein import and biogenesis. Further cryo-EM structures promise to expand our mechanistic understanding of the various biochemical functions involving protein biogenesis and quality control in the ER.
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Affiliation(s)
- Max Gemmer
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Friedrich Förster
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands
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24
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Castells-Ballester J, Rinis N, Kotan I, Gal L, Bausewein D, Kats I, Zatorska E, Kramer G, Bukau B, Schuldiner M, Strahl S. Translational Regulation of Pmt1 and Pmt2 by Bfr1 Affects Unfolded Protein O-Mannosylation. Int J Mol Sci 2019; 20:ijms20246220. [PMID: 31835530 PMCID: PMC6940804 DOI: 10.3390/ijms20246220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 12/15/2022] Open
Abstract
O-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding green fluorescent protein (GFP) as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.
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Affiliation(s)
- Joan Castells-Ballester
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Natalie Rinis
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Ilgin Kotan
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (L.G.); (M.S.)
| | - Daniela Bausewein
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
- spm—Safety Projects & More GmbH, D-69493 Hirschberg a. d. Bergstraße, Germany
| | - Ilia Kats
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Ewa Zatorska
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Günter Kramer
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (L.G.); (M.S.)
| | - Sabine Strahl
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
- Correspondence: ; Tel.: +49-6221-54-6286
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25
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Tanwar H, Kumar DT, Doss CGP, Zayed H. Bioinformatics classification of mutations in patients with Mucopolysaccharidosis IIIA. Metab Brain Dis 2019; 34:1577-1594. [PMID: 31385193 PMCID: PMC6858298 DOI: 10.1007/s11011-019-00465-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/08/2019] [Indexed: 02/06/2023]
Abstract
Mucopolysaccharidosis (MPS) IIIA, also known as Sanfilippo syndrome type A, is a severe, progressive disease that affects the central nervous system (CNS). MPS IIIA is inherited in an autosomal recessive manner and is caused by a deficiency in the lysosomal enzyme sulfamidase, which is required for the degradation of heparan sulfate. The sulfamidase is produced by the N-sulphoglucosamine sulphohydrolase (SGSH) gene. In MPS IIIA patients, the excess of lysosomal storage of heparan sulfate often leads to mental retardation, hyperactive behavior, and connective tissue impairments, which occur due to various known missense mutations in the SGSH, leading to protein dysfunction. In this study, we focused on three mutations (R74C, S66W, and R245H) based on in silico pathogenic, conservation, and stability prediction tool studies. The three mutations were further subjected to molecular dynamic simulation (MDS) analysis using GROMACS simulation software to observe the structural changes they induced, and all the mutants exhibited maximum deviation patterns compared with the native protein. Conformational changes were observed in the mutants based on various geometrical parameters, such as conformational stability, fluctuation, and compactness, followed by hydrogen bonding, physicochemical properties, principal component analysis (PCA), and salt bridge analyses, which further validated the underlying cause of the protein instability. Additionally, secondary structure and surrounding amino acid analyses further confirmed the above results indicating the loss of protein function in the mutants compared with the native protein. The present results reveal the effects of three mutations on the enzymatic activity of sulfamidase, providing a molecular explanation for the cause of the disease. Thus, this study allows for a better understanding of the effect of SGSH mutations through the use of various computational approaches in terms of both structure and functions and provides a platform for the development of therapeutic drugs and potential disease treatments.
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Affiliation(s)
- Himani Tanwar
- Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - D Thirumal Kumar
- Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India
| | - C George Priya Doss
- Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India.
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health and Sciences, Qatar University, Doha, Qatar.
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26
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Natarajan N, Foresti O, Wendrich K, Stein A, Carvalho P. Quality Control of Protein Complex Assembly by a Transmembrane Recognition Factor. Mol Cell 2019; 77:108-119.e9. [PMID: 31679820 PMCID: PMC6941229 DOI: 10.1016/j.molcel.2019.10.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 08/27/2019] [Accepted: 10/01/2019] [Indexed: 01/08/2023]
Abstract
The inner nuclear membrane (INM) is continuous with the endoplasmic reticulum (ER) but harbors a distinctive proteome essential for nuclear functions. In yeast, the Asi1/Asi2/Asi3 ubiquitin ligase complex safeguards the INM proteome through the clearance of mislocalized ER membrane proteins. How the Asi complex selectively targets mislocalized proteins and coordinates its activity with other ER functions, such as protein biogenesis, is unclear. Here, we uncover a link between INM proteome identity and membrane protein complex assembly in the remaining ER. We show that lone proteins and complex subunits failing to assemble in the ER access the INM for Asi-mediated degradation. Substrates are recognized by direct binding of Asi2 to their transmembrane domains for subsequent ubiquitination by Asi1/Asi3 and membrane extraction. Our data suggest a model in which spatial segregation of membrane protein complex assembly and quality control improves assembly efficiency and reduces the levels of orphan subunits. Quality control of unassembled subunits of membrane complexes is restricted to the INM The Asi complex promotes degradation of folded but unassembled membrane proteins Binding of Asi2 to membrane domain of unassembled subunits mediates their recognition INM quality control maintains complex subunits within near-stoichiometric levels
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Affiliation(s)
- Nivedita Natarajan
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ombretta Foresti
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Dr. Aiguader, 88, 08003 Barcelona, Spain
| | - Kim Wendrich
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Alexander Stein
- Research Group Membrane Protein Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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27
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Samant RS, Masto VB, Frydman J. Dosage compensation plans: protein aggregation provides additional insurance against aneuploidy. Genes Dev 2019; 33:1027-1030. [PMID: 31371460 PMCID: PMC6672054 DOI: 10.1101/gad.329383.119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Gene dosage alterations caused by aneuploidy are a common feature of most cancers yet pose severe proteotoxic challenges. Therefore, cells have evolved various dosage compensation mechanisms to limit the damage caused by the ensuing protein level imbalances. For instance, for heteromeric protein complexes, excess nonstoichiometric subunits are rapidly recognized and degraded. In this issue of Genes & Development, Brennan et al. (pp. 1031-1047) reveal that sequestration of nonstoichiometric subunits into aggregates is an alternative mechanism for dosage compensation in aneuploid budding yeast and human cell lines. Using a combination of proteomic and genetic techniques, they found that excess proteins undergo either degradation or aggregation but not both. Which route is preferred depends on the half-life of the protein in question. Given the multitude of diseases linked to either aneuploidy or protein aggregation, this study could serve as a springboard for future studies with broad-spanning implications.
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Affiliation(s)
- Rahul S Samant
- Department of Biology, Stanford University, Stanford, California 94305, USA
| | - Vincent B Masto
- Department of Biology, Stanford University, Stanford, California 94305, USA
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, California 94305, USA
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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28
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Bergendahl LT, Gerasimavicius L, Miles J, Macdonald L, Wells JN, Welburn JPI, Marsh JA. The role of protein complexes in human genetic disease. Protein Sci 2019; 28:1400-1411. [PMID: 31219644 DOI: 10.1002/pro.3667] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 06/10/2019] [Indexed: 12/20/2022]
Abstract
Many human genetic disorders are caused by mutations in protein-coding regions of DNA. Taking protein structure into account has therefore provided key insight into the molecular mechanisms underlying human genetic disease. Although most studies have focused on the intramolecular effects of mutations, the critical role of the assembly of proteins into complexes is being increasingly recognized. Here, we review multiple ways in which consideration of protein complexes can help us to understand and explain the effects of pathogenic mutations. First, we discuss disorders caused by mutations that perturb intersubunit interactions in homomeric and heteromeric complexes. Second, we address how protein complex assembly can facilitate a dominant-negative mechanism, whereby mutated subunits can disrupt the activity of wild-type protein. Third, we show how mutations that change protein expression levels can lead to damaging stoichiometric imbalances. Finally, we review how mutations affecting different subunits of the same heteromeric complex often cause similar diseases, whereas mutations in different interfaces of the same subunit can cause distinct phenotypes.
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Affiliation(s)
- L Therese Bergendahl
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Lukas Gerasimavicius
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Jamilla Miles
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Lewis Macdonald
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
| | - Jonathan N Wells
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, 14850
| | - Julie P I Welburn
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3BF, United Kingdom
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, United Kingdom
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29
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Shrimal S, Gilmore R. Oligosaccharyltransferase structures provide novel insight into the mechanism of asparagine-linked glycosylation in prokaryotic and eukaryotic cells. Glycobiology 2019; 29:288-297. [PMID: 30312397 DOI: 10.1093/glycob/cwy093] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/26/2018] [Accepted: 10/09/2018] [Indexed: 11/12/2022] Open
Abstract
Asparagine-linked (N-linked) glycosylation is one of the most common protein modification reactions in eukaryotic cells, occurring upon the majority of proteins that enter the secretory pathway. X-ray crystal structures of the single subunit OSTs from eubacterial and archaebacterial organisms revealed the location of donor and acceptor substrate binding sites and provided the basis for a catalytic mechanism. Cryoelectron microscopy structures of the octameric yeast OST provided substantial insight into the organization and assembly of the multisubunit oligosaccharyltransferases. Furthermore, the cryoelectron microscopy structure of a complex consisting of a mammalian OST complex, the protein translocation channel and a translating ribosome revealed new insight into the mechanism of cotranslational glycosylation.
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Affiliation(s)
- Shiteshu Shrimal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, USA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, USA
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30
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Eraslan B, Wang D, Gusic M, Prokisch H, Hallström BM, Uhlén M, Asplund A, Pontén F, Wieland T, Hopf T, Hahne H, Kuster B, Gagneur J. Quantification and discovery of sequence determinants of protein-per-mRNA amount in 29 human tissues. Mol Syst Biol 2019; 15:e8513. [PMID: 30777893 PMCID: PMC6379048 DOI: 10.15252/msb.20188513] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 12/15/2022] Open
Abstract
Despite their importance in determining protein abundance, a comprehensive catalogue of sequence features controlling protein-to-mRNA (PTR) ratios and a quantification of their effects are still lacking. Here, we quantified PTR ratios for 11,575 proteins across 29 human tissues using matched transcriptomes and proteomes. We estimated by regression the contribution of known sequence determinants of protein synthesis and degradation in addition to 45 mRNA and 3 protein sequence motifs that we found by association testing. While PTR ratios span more than 2 orders of magnitude, our integrative model predicts PTR ratios at a median precision of 3.2-fold. A reporter assay provided functional support for two novel UTR motifs, and an immobilized mRNA affinity competition-binding assay identified motif-specific bound proteins for one motif. Moreover, our integrative model led to a new metric of codon optimality that captures the effects of codon frequency on protein synthesis and degradation. Altogether, this study shows that a large fraction of PTR ratio variation in human tissues can be predicted from sequence, and it identifies many new candidate post-transcriptional regulatory elements.
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Affiliation(s)
- Basak Eraslan
- Computational Biology, Department of Informatics, Technical University of Munich, Garching Munich, Germany
- Graduate School of Quantitative Biosciences (QBM), Ludwig-Maximilians-Universität München, Munich, Germany
| | - Dongxue Wang
- Chair of Proteomics and Bioanalytics, Technical University of Munich, Freising, Germany
| | - Mirjana Gusic
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Björn M Hallström
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Mathias Uhlén
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Anna Asplund
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Frederik Pontén
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Thomas Wieland
- Chair of Proteomics and Bioanalytics, Technical University of Munich, Freising, Germany
| | - Thomas Hopf
- Chair of Proteomics and Bioanalytics, Technical University of Munich, Freising, Germany
| | | | - Bernhard Kuster
- Chair of Proteomics and Bioanalytics, Technical University of Munich, Freising, Germany
- Center For Integrated Protein Science Munich (CIPSM), Munich, Germany
| | - Julien Gagneur
- Computational Biology, Department of Informatics, Technical University of Munich, Garching Munich, Germany
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31
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Eisenberg AR, Higdon A, Keskin A, Hodapp S, Jovanovic M, Brar GA. Precise Post-translational Tuning Occurs for Most Protein Complex Components during Meiosis. Cell Rep 2018; 25:3603-3617.e2. [PMID: 30590036 PMCID: PMC6328264 DOI: 10.1016/j.celrep.2018.12.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/27/2018] [Accepted: 11/29/2018] [Indexed: 12/20/2022] Open
Abstract
Protein degradation is known to be a key component of expression regulation for individual genes, but its global impact on gene expression has been difficult to determine. We analyzed a parallel gene expression dataset of yeast meiotic differentiation, identifying instances of coordinated protein-level decreases to identify new cases of regulated meiotic protein degradation, including of ribosomes and targets of the meiosis-specific anaphase-promoting complex adaptor Ama1. Comparison of protein and translation measurements over time also revealed that, although meiotic cells are capable of synthesizing protein complex members at precisely matched levels, they typically do not. Instead, the members of most protein complexes are synthesized imprecisely, but their protein levels are matched, indicating that wild-type eukaryotic cells routinely use post-translational adjustment of protein complex partner levels to achieve proper stoichiometry. Outlier cases, in which specific complex components show divergent protein-level trends, suggest timed regulation of these complexes.
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Affiliation(s)
- Amy Rose Eisenberg
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Andrea Higdon
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Abdurrahman Keskin
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Stefanie Hodapp
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Marko Jovanovic
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Gloria Ann Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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32
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Riedlinger T, Liefke R, Meier-Soelch J, Jurida L, Nist A, Stiewe T, Kracht M, Schmitz ML. NF-κB p65 dimerization and DNA-binding is important for inflammatory gene expression. FASEB J 2018; 33:4188-4202. [PMID: 30526044 PMCID: PMC6404571 DOI: 10.1096/fj.201801638r] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Increasing evidence shows that many transcription factors execute important biologic functions independent from their DNA-binding capacity. The NF-κB p65 (RELA) subunit is a central regulator of innate immunity. Here, we investigated the relative functional contribution of p65 DNA-binding and dimerization in p65-deficient human and murine cells reconstituted with single amino acid mutants preventing either DNA-binding (p65 E/I) or dimerization (p65 FL/DD). DNA-binding of p65 was required for RelB-dependent stabilization of the NF-κB p100 protein. The antiapoptotic function of p65 and expression of the majority of TNF-α–induced genes were dependent on p65’s ability to bind DNA and to dimerize. Chromatin immunoprecipitation with massively parallel DNA sequencing experiments revealed that impaired DNA-binding and dimerization strongly diminish the chromatin association of p65. However, there were also p65-independent TNF-α–inducible genes and a subgroup of p65 binding sites still allowed some residual chromatin association of the mutants. These sites were enriched in activator protein 1 (AP-1) binding motifs and showed increased chromatin accessibility and basal transcription. This suggests a mechanism of assisted p65 chromatin association that can be in part facilitated by chromatin priming and cooperativity with other transcription factors such as AP-1.—Riedlinger, T., Liefke, R., Meier-Soelch, J., Jurida, L., Nist, A., Stiewe, T., Kracht, M., Schmitz, M. L. NF-κB p65 dimerization and DNA-binding is important for inflammatory gene expression.
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Affiliation(s)
- Tabea Riedlinger
- Institute of Biochemistry, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany
| | - Robert Liefke
- Institute of Biochemistry, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany.,Institute of Molecular Biology and Tumor Research (IMT), Philipps University Marburg, Marburg, Germany
| | - Johanna Meier-Soelch
- Rudolf-Buchheim-Institute of Pharmacology, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany; and
| | - Liane Jurida
- Rudolf-Buchheim-Institute of Pharmacology, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany; and
| | - Andrea Nist
- Genomics Core Facility-Institute of Molecular Oncology, Philipps University Marburg, Marburg, Germany
| | - Thorsten Stiewe
- Genomics Core Facility-Institute of Molecular Oncology, Philipps University Marburg, Marburg, Germany
| | - Michael Kracht
- Rudolf-Buchheim-Institute of Pharmacology, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany; and
| | - M Lienhard Schmitz
- Institute of Biochemistry, Member of the German Center for Lung Research, Justus-Liebig-University, Giessen, Germany
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33
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Wang SH, Hsiao CJ, Khan Z, Pritchard JK. Post-translational buffering leads to convergent protein expression levels between primates. Genome Biol 2018; 19:83. [PMID: 29950183 PMCID: PMC6020354 DOI: 10.1186/s13059-018-1451-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 05/10/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Differences in gene regulation between human and closely related species influence phenotypes that are distinctly human. While gene regulation is a multi-step process, the majority of research concerning divergence in gene regulation among primates has focused on transcription. RESULTS To gain a comprehensive view of gene regulation, we surveyed genome-wide ribosome occupancy, which reflects levels of protein translation, in lymphoblastoid cell lines derived from human, chimpanzee, and rhesus macaque. We further integrated messenger RNA and protein level measurements collected from matching cell lines. We find that, in addition to transcriptional regulation, the major factor determining protein level divergence between human and closely related species is post-translational buffering. Inter-species divergence in transcription is generally propagated to the level of protein translation. In contrast, gene expression divergence is often attenuated post-translationally, potentially mediated through post-translational modifications. CONCLUSIONS Results from our analysis indicate that post-translational buffering is a conserved mechanism that led to relaxation of selective constraint on transcript levels in humans.
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Affiliation(s)
- Sidney H. Wang
- Center for Human Genetics, The Brown foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX USA
| | | | - Zia Khan
- Genentech, 1 DNA Way, South San Francisco, CA USA
| | - Jonathan K. Pritchard
- Department of Genetics, Stanford University, Stanford, CA USA
- Department of Biology, Stanford University, Stanford, CA USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA USA
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34
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Wild R, Kowal J, Eyring J, Ngwa EM, Aebi M, Locher KP. Structure of the yeast oligosaccharyltransferase complex gives insight into eukaryotic N-glycosylation. Science 2018; 359:545-550. [PMID: 29301962 DOI: 10.1126/science.aar5140] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/22/2017] [Indexed: 12/18/2022]
Abstract
Oligosaccharyltransferase (OST) is an essential membrane protein complex in the endoplasmic reticulum, where it transfers an oligosaccharide from a dolichol-pyrophosphate-activated donor to glycosylation sites of secretory proteins. Here we describe the atomic structure of yeast OST determined by cryo-electron microscopy, revealing a conserved subunit arrangement. The active site of the catalytic STT3 subunit points away from the center of the complex, allowing unhindered access to substrates. The dolichol-pyrophosphate moiety binds to a lipid-exposed groove of STT3, whereas two noncatalytic subunits and an ordered N-glycan form a membrane-proximal pocket for the oligosaccharide. The acceptor polypeptide site faces an oxidoreductase domain in stand-alone OST complexes or is immediately adjacent to the translocon, suggesting how eukaryotic OSTs efficiently glycosylate a large number of polypeptides before their folding.
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Affiliation(s)
- Rebekka Wild
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Elsy M Ngwa
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
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35
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Poljak K, Breitling J, Gauss R, Rugarabamu G, Pellanda M, Aebi M. Analysis of substrate specificity of Trypanosoma brucei oligosaccharyltransferases (OSTs) by functional expression of domain-swapped chimeras in yeast. J Biol Chem 2017; 292:20342-20352. [PMID: 29042445 DOI: 10.1074/jbc.m117.811133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/11/2017] [Indexed: 11/06/2022] Open
Abstract
N-Linked protein glycosylation is an essential and highly conserved post-translational modification in eukaryotes. The transfer of a glycan from a lipid-linked oligosaccharide (LLO) donor to the asparagine residue of a nascent polypeptide chain is catalyzed by an oligosaccharyltransferase (OST) in the lumen of the endoplasmic reticulum (ER). Trypanosoma brucei encodes three paralogue single-protein OSTs called TbSTT3A, TbSTT3B, and TbSTT3C that can functionally complement the Saccharomyces cerevisiae OST, making it an ideal experimental system to study the fundamental properties of OST activity. We characterized the LLO and polypeptide specificity of all three TbOST isoforms and their chimeric forms in the heterologous expression host S. cerevisiae where we were able to apply yeast genetic tools and newly developed glycoproteomics methods. We demonstrated that TbSTT3A accepted LLO substrates ranging from Man5GlcNAc2 to Man7GlcNAc2 In contrast, TbSTT3B required more complex precursors ranging from Man6GlcNAc2 to Glc3Man9GlcNAc2 structures, and TbSTT3C did not display any LLO preference. Sequence differences between the isoforms cluster in three distinct regions. We have swapped the individual regions between different OST proteins and identified region 2 to influence the specificity toward the LLO and region 1 to influence polypeptide substrate specificity. These results provide a basis to further investigate the molecular mechanisms and contribution of single amino acids in OST interaction with its substrates.
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Affiliation(s)
- Kristina Poljak
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Jörg Breitling
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Robert Gauss
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - George Rugarabamu
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Mauro Pellanda
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland.
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36
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Poljak K, Selevsek N, Ngwa E, Grossmann J, Losfeld ME, Aebi M. Quantitative Profiling of N-linked Glycosylation Machinery in Yeast Saccharomyces cerevisiae. Mol Cell Proteomics 2017; 17:18-30. [PMID: 28993419 DOI: 10.1074/mcp.ra117.000096] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Indexed: 11/06/2022] Open
Abstract
Asparagine-linked glycosylation is a common posttranslational protein modification regulating the structure, stability and function of many proteins. The N-linked glycosylation machinery involves enzymes responsible for the assembly of the lipid-linked oligosaccharide (LLO), which is then transferred to the asparagine residues on the polypeptides by the enzyme oligosaccharyltransferase (OST). A major goal in the study of protein glycosylation is to establish quantitative methods for the analysis of site-specific extent of glycosylation. We developed a sensitive approach to examine glycosylation site occupancy in Saccharomyces cerevisiae by coupling stable isotope labeling (SILAC) approach to parallel reaction monitoring (PRM) mass spectrometry (MS). We combined the method with genetic tools and validated the approach with the identification of novel glycosylation sites dependent on the Ost3p and Ost6p regulatory subunits of OST. Based on the observations that alternations in LLO substrate structure and OST subunits activity differentially alter the systemic output of OST, we conclude that sequon recognition is a direct property of the catalytic subunit Stt3p, auxiliary subunits such as Ost3p and Ost6p extend the OST substrate range by modulating interfering pathways such as protein folding. In addition, our proteomics approach revealed a novel regulatory network that connects isoprenoid lipid biosynthesis and LLO substrate assembly.
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Affiliation(s)
- Kristina Poljak
- From the ‡Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Nathalie Selevsek
- §Functional Genomics Center Zurich, UZH/ETH Zurich, CH-8057 Zurich, Switzerland
| | - Elsy Ngwa
- From the ‡Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Jonas Grossmann
- §Functional Genomics Center Zurich, UZH/ETH Zurich, CH-8057 Zurich, Switzerland
| | - Marie Estelle Losfeld
- From the ‡Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- From the ‡Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland;
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37
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Shrimal S, Cherepanova NA, Gilmore R. DC2 and KCP2 mediate the interaction between the oligosaccharyltransferase and the ER translocon. J Cell Biol 2017; 216:3625-3638. [PMID: 28860277 PMCID: PMC5674889 DOI: 10.1083/jcb.201702159] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/29/2017] [Accepted: 07/27/2017] [Indexed: 12/21/2022] Open
Abstract
The STT3A isoform of the oligosaccharyltransferase is adjacent to the protein translocation channel to catalyze co-translational N-glycosylation of proteins in the endoplasmic reticulum. Shrimal et al. show that the DC2 and KCP2 subunits of the STT3A isoform of the oligosaccharyltransferase are responsible for mediating the interaction between the STT3A complex and the protein translocation channel to allow co-translational N-glycosylation of proteins. In metazoan organisms, the STT3A isoform of the oligosaccharyltransferase is localized adjacent to the protein translocation channel to catalyze co-translational N-linked glycosylation of proteins in the endoplasmic reticulum. The mechanism responsible for the interaction between the STT3A complex and the translocation channel has not been addressed. Using genetically modified human cells that are deficient in DC2 or KCP2 proteins, we show that loss of DC2 causes a defect in co-translational N-glycosylation of proteins that mimics an STT3A−/− phenotype. Biochemical analysis showed that DC2 and KCP2 are responsible for mediating the interaction between the protein translocation channel and the STT3A complex. Importantly, DC2- and KCP2-deficient STT3A complexes are stable and enzymatically active. Deletion mutagenesis revealed that a conserved motif in the C-terminal tail of DC2 is critical for assembly into the STT3A complex, whereas the lumenal loop and the N-terminal cytoplasmic segment are necessary for the functional interaction between the STT3A and Sec61 complexes.
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Affiliation(s)
- Shiteshu Shrimal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Natalia A Cherepanova
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
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38
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Post-Translational Dosage Compensation Buffers Genetic Perturbations to Stoichiometry of Protein Complexes. PLoS Genet 2017; 13:e1006554. [PMID: 28121980 PMCID: PMC5266272 DOI: 10.1371/journal.pgen.1006554] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/28/2016] [Indexed: 01/07/2023] Open
Abstract
Understanding buffering mechanisms for various perturbations is essential for understanding robustness in cellular systems. Protein-level dosage compensation, which arises when changes in gene copy number do not translate linearly into protein level, is one mechanism for buffering against genetic perturbations. Here, we present an approach to identify genes with dosage compensation by increasing the copy number of individual genes using the genetic tug-of-war technique. Our screen of chromosome I suggests that dosage-compensated genes constitute approximately 10% of the genome and consist predominantly of subunits of multi-protein complexes. Importantly, because subunit levels are regulated in a stoichiometry-dependent manner, dosage compensation plays a crucial role in maintaining subunit stoichiometries. Indeed, we observed changes in the levels of a complex when its subunit stoichiometries were perturbed. We further analyzed compensation mechanisms using a proteasome-defective mutant as well as ribosome profiling, which provided strong evidence for compensation by ubiquitin-dependent degradation but not reduced translational efficiency. Thus, our study provides a systematic understanding of dosage compensation and highlights that this post-translational regulation is a critical aspect of robustness in cellular systems. Cells are exposed to environmental changes leading to fluctuations in biological processes. For example, changes in gene copy number are a source of such fluctuations. An increase in gene copy number generally leads to a linear increase in the amount of protein; however, a small number of genes do not show a proportional increase in protein level. We investigated how many of the genes exhibit this nonlinearity between gene copy number and protein level. Our screen of chromosome I suggests that genes with such nonlinear relationships constitute approximately 10% of the genome and consist predominantly of subunits of multi-protein complexes. Because previous studies showed that an imbalance of complex subunits is very toxic for cell growth, a function of the nonlinear relationship may be to correct the balance of complex subunits. We also investigated the underlying mechanisms of the nonlinearity by focusing on protein synthesis and degradation. Our data indicate that protein degradation, but not synthesis, is responsible for maintaining a balance of complex subunits. Thus, this study provides insight into the mechanisms for coping with the fluctuations in biological processes.
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39
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Scott NE, Rogers LD, Prudova A, Brown NF, Fortelny N, Overall CM, Foster LJ. Interactome disassembly during apoptosis occurs independent of caspase cleavage. Mol Syst Biol 2017; 13:906. [PMID: 28082348 PMCID: PMC5293159 DOI: 10.15252/msb.20167067] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Protein-protein interaction networks (interactomes) define the functionality of all biological systems. In apoptosis, proteolysis by caspases is thought to initiate disassembly of protein complexes and cell death. Here we used a quantitative proteomics approach, protein correlation profiling (PCP), to explore changes in cytoplasmic and mitochondrial interactomes in response to apoptosis initiation as a function of caspase activity. We measured the response to initiation of Fas-mediated apoptosis in 17,991 interactions among 2,779 proteins, comprising the largest dynamic interactome to date. The majority of interactions were unaffected early in apoptosis, but multiple complexes containing known caspase targets were disassembled. Nonetheless, proteome-wide analysis of proteolytic processing by terminal amine isotopic labeling of substrates (TAILS) revealed little correlation between proteolytic and interactome changes. Our findings show that, in apoptosis, significant interactome alterations occur before and independently of caspase activity. Thus, apoptosis initiation includes a tight program of interactome rearrangement, leading to disassembly of relatively few, select complexes. These early interactome alterations occur independently of cleavage of these protein by caspases.
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Affiliation(s)
- Nichollas E Scott
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Lindsay D Rogers
- Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, BC, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Anna Prudova
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Nat F Brown
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Nikolaus Fortelny
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Christopher M Overall
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.,Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, BC, Canada.,Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Leonard J Foster
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada .,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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40
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Holman SW, Hammond DE, Simpson DM, Waters J, Hurst JL, Beynon RJ. Protein turnover measurement using selected reaction monitoring-mass spectrometry (SRM-MS). PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0362. [PMID: 27644981 PMCID: PMC5031629 DOI: 10.1098/rsta.2015.0362] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/23/2016] [Indexed: 05/28/2023]
Abstract
Protein turnover represents an important mechanism in the functioning of cells, with deregulated synthesis and degradation of proteins implicated in many diseased states. Therefore, proteomics strategies to measure turnover rates with high confidence are of vital importance to understanding many biological processes. In this study, the more widely used approach of non-targeted precursor ion signal intensity (MS1) quantification is compared with selected reaction monitoring (SRM), a data acquisition strategy that records data for specific peptides, to determine if improved quantitative data would be obtained using a targeted quantification approach. Using mouse liver as a model system, turnover measurement of four tricarboxylic acid cycle proteins was performed using both MS1 and SRM quantification strategies. SRM outperformed MS1 in terms of sensitivity and selectivity of measurement, allowing more confident determination of protein turnover rates. SRM data are acquired using cheaper and more widely available tandem quadrupole mass spectrometers, making the approach accessible to a larger number of researchers than MS1 quantification, which is best performed on high mass resolution instruments. SRM acquisition is ideally suited to focused studies where the turnover of tens of proteins is measured, making it applicable in determining the dynamics of proteins complexes and complete metabolic pathways.This article is part of the themed issue 'Quantitative mass spectrometry'.
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Affiliation(s)
- Stephen W Holman
- Centre for Proteome Research, Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Dean E Hammond
- Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Deborah M Simpson
- Centre for Proteome Research, Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - John Waters
- Mammalian Behaviour and Evolution Group, Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Leahurst Campus, Neston CH64 7TE, UK
| | - Jane L Hurst
- Mammalian Behaviour and Evolution Group, Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Leahurst Campus, Neston CH64 7TE, UK
| | - Robert J Beynon
- Centre for Proteome Research, Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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41
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Zacchi LF, Schulz BL. SWATH-MS Glycoproteomics Reveals Consequences of Defects in the Glycosylation Machinery. Mol Cell Proteomics 2016; 15:2435-47. [PMID: 27094473 DOI: 10.1074/mcp.m115.056366] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 12/16/2022] Open
Abstract
Glycan macro- and microheterogeneity have profound impacts on protein folding and function. This heterogeneity can be regulated by physiological or environmental factors. However, unregulated heterogeneity can lead to disease, and mutations in the glycosylation process cause a growing number of Congenital Disorders of Glycosylation. We systematically studied how mutations in the N-glycosylation pathway lead to defects in mature proteins using all viable Saccharomyces cerevisiae strains with deletions in genes encoding Endoplasmic Reticulum lumenal mannosyltransferases (Alg3, Alg9, and Alg12), glucosyltransferases (Alg6, Alg8, and Die2/Alg10), or oligosaccharyltransferase subunits (Ost3, Ost5, and Ost6). To measure the changes in glycan macro- and microheterogeneity in mature proteins caused by these mutations we developed a SWATH-mass spectrometry glycoproteomics workflow. We measured glycan structures and occupancy on mature cell wall glycoproteins, and relative protein abundance, in the different mutants. All mutants showed decreased glycan occupancy and altered cell wall proteomes compared with wild-type cells. Mutations in earlier mannosyltransferase or glucosyltransferase steps of glycan biosynthesis had stronger hypoglycosylation phenotypes, but glucosyltransferase defects were more severe. ER mannosyltransferase mutants displayed substantial global changes in glycan microheterogeneity consistent with truncations in the glycan transferred to protein in these strains. Although ER glucosyltransferase and oligosaccharyltransferase subunit mutants broadly showed no change in glycan structures, ost3Δ cells had shorter glycan structures at some sites, consistent with increased protein quality control mannosidase processing in this severely hypoglycosylating mutant. This method allows facile relative quantitative glycoproteomics, and our results provide insights into global regulation of site-specific glycosylation.
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Affiliation(s)
- Lucia F Zacchi
- From the ‡School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, 4072, Australia; §Fundación Instituto Leloir, Avenida Patricias Argentinas 435, Ciudad Autónoma de Buenos Aires, 1405, Argentina
| | - Benjamin L Schulz
- From the ‡School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, 4072, Australia;
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42
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Pisoni GB, Molinari M. Five Questions (with their Answers) on ER-Associated Degradation. Traffic 2016; 17:341-50. [PMID: 27004930 DOI: 10.1111/tra.12373] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/06/2016] [Accepted: 01/06/2016] [Indexed: 01/17/2023]
Abstract
Production of a functional proteome is a major burden for our cells. Native proteins operate inside and outside the cells to eventually warrant life and adaptation to metabolic and environmental changes, there is no doubt that production and inappropriate handling of misfolded proteins may cause severe disease states. This review focuses on protein destruction, which is, paradoxically, a crucial event for cell and organism survival. It regulates the physiological turnover of proteins and the clearance of faulty biosynthetic products. It mainly relies on the intervention of two catabolic machineries, the ubiquitin proteasome system and the (auto)lysosomal system. Here, we have selected five questions dealing with how, why and when proteins produced in the mammalian endoplasmic reticulum are eventually selected for destruction.
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Affiliation(s)
- Giorgia Brambilla Pisoni
- Institute for Research in Biomedicine, CH-6500, Bellinzona, Switzerland.,Università della Svizzera italiana, CH-6900, Lugano, Switzerland.,ETH Zurich, D-BIOL, 8093, Zurich, Switzerland
| | - Maurizio Molinari
- Institute for Research in Biomedicine, CH-6500, Bellinzona, Switzerland.,Università della Svizzera italiana, CH-6900, Lugano, Switzerland.,School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
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