1
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Moretti-Horten DN, Peselj C, Taskin AA, Myketin L, Schulte U, Einsle O, Drepper F, Luzarowski M, Vögtle FN. Synchronized assembly of the oxidative phosphorylation system controls mitochondrial respiration in yeast. Dev Cell 2024; 59:1043-1057.e8. [PMID: 38508182 DOI: 10.1016/j.devcel.2024.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/19/2024] [Accepted: 02/28/2024] [Indexed: 03/22/2024]
Abstract
Control of protein stoichiometry is essential for cell function. Mitochondrial oxidative phosphorylation (OXPHOS) presents a complex stoichiometric challenge as the ratio of the electron transport chain (ETC) and ATP synthase must be tightly controlled, and assembly requires coordinated integration of proteins encoded in the nuclear and mitochondrial genome. How correct OXPHOS stoichiometry is achieved is unknown. We identify the Mitochondrial Regulatory hub for respiratory Assembly (MiRA) platform, which synchronizes ETC and ATP synthase biogenesis in yeast. Molecularly, this is achieved by a stop-and-go mechanism: the uncharacterized protein Mra1 stalls complex IV assembly. Two "Go" signals are required for assembly progression: binding of the complex IV assembly factor Rcf2 and Mra1 interaction with an Atp9-translating mitoribosome induce Mra1 degradation, allowing synchronized maturation of complex IV and the ATP synthase. Failure of the stop-and-go mechanism results in cell death. MiRA controls OXPHOS assembly, ensuring correct stoichiometry of protein machineries encoded by two different genomes.
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Affiliation(s)
- Daiana N Moretti-Horten
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Carlotta Peselj
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Asli Aras Taskin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lisa Myketin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Uwe Schulte
- Institute of Physiology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Oliver Einsle
- Institut für Biochemie, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Friedel Drepper
- CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; Biochemistry & Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Marcin Luzarowski
- Core Facility for Mass Spectrometry and Proteomics, Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - F-Nora Vögtle
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; Network Aging Research, Heidelberg University, 69120 Heidelberg, Germany.
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2
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Antonio LM, Martins GH, Aragão AZB, Quel NG, Zazeri G, Houry WA, Ramos CHI. Unveiling the Role of Sorghum RPAP3 in the Function of R2TP Complex: Insights into Protein Assembly in Plants. Plants (Basel) 2023; 12:2925. [PMID: 37631136 PMCID: PMC10458388 DOI: 10.3390/plants12162925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/04/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023]
Abstract
The chaperone R2TP has multiple subunits that assist in the proper folding, assembly, and stabilization of various protein complexes in cells and its study can offer valuable insights into the regulation and maintenance of protein assemblies in plant systems. The 'T' component of R2TP is Tah1 in yeast, consisting of 111 residues, while its counterpart in humans is RPAP3, with 665 residues. RPAP3 acts as a co-chaperone of Hsp90 and facilitates interactions between RUVBL proteins and other complex components, enhancing the recruitment of client proteins by the R2TP complex. These facts further underscore the relevance of studying this complex in different organisms. The putative gene corresponding to the RPAP3 in Sorghum bicolor, a monocotyledon plant, was cloned, and the protein (396 residues) purified for biochemical characterization. SbRPAP3 exists as a folded monomer and has a RPAP3 domain, which is present in human RPAP3 but absent in yeast Tah1. SbRPAP3 retains its functional capabilities, including binding with RUVBLs, Hsp90, and Hsp70. By elucidating the role of RPAP3 in plant R2TP complex, we can further comprehend the molecular mechanisms underlying plant-specific protein assembly and contribute to advancements in plant biology and biotechnological applications.
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Affiliation(s)
- Larissa Machado Antonio
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
| | - Gustavo Henrique Martins
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
| | - Annelize Zambon Barbosa Aragão
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
| | - Natália Galdi Quel
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
| | - Gabriel Zazeri
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
| | - Walid A. Houry
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada;
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
| | - Carlos Henrique Inacio Ramos
- Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13100-104, SP, Brazil; (L.M.A.); (G.H.M.); (A.Z.B.A.); (N.G.Q.); (G.Z.)
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3
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Zhang Y, Chen M, Liu T, Qin K, Fernie AR. Investigating the dynamics of protein-protein interactions in plants. Plant J 2023; 114:965-983. [PMID: 36919339 DOI: 10.1111/tpj.16182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 02/22/2023] [Accepted: 03/01/2023] [Indexed: 05/27/2023]
Abstract
Both stable and transient protein interactions play an important role in the complex assemblies required for the proper functioning of living cells. Several methods have been developed to monitor protein-protein interactions in plants. However, the detection of dynamic protein complexes is very challenging, with few technologies available for this purpose. Here, we developed a new platform using the plant UBIQUITIN promoter to drive transgene expression and thereby to detect protein interactions in planta. Typically, to decide which side of the protein to link the tags, the subcellular localization of the protein fused either N-terminal or C-terminal mCitrine was firstly confirmed by using eight different specific mCherry markers. Following stable or transient protein expression in plants, the protein interaction network was detected by affinity purification mass spectrometry. These interactions were subsequently confirmed by bimolecular fluorescence complementation (BiFC), bioluminescence resonance energy transfer and co-immunoprecipitation assays. The dynamics of these interactions were monitored by Förster resonance energy transfer (FRET) and split-nano luciferase, whilst the ternary protein complex association was monitored by BiFC-FRET. Using the canonical glycolytic metabolon as an example, the interaction between these enzymes was characterized under conditions that mimic physiologically relevant energy statuses.
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Affiliation(s)
- Youjun Zhang
- Center of Plant System Biology and Biotechnology, 4000, Plovdiv, Bulgaria
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Moxian Chen
- Co-Innovation Center for Sustainable Forestry in Southern China & Key Laboratory of National Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China
| | - Tieyuan Liu
- College of Grassland Agriculture, Northwest A&F University, Yangling, 712100, China
| | - Kezhen Qin
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Alisdair R Fernie
- Center of Plant System Biology and Biotechnology, 4000, Plovdiv, Bulgaria
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
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4
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Baek K, Scott DC, Henneberg LT, King MT, Mann M, Schulman BA. Systemwide disassembly and assembly of SCF ubiquitin ligase complexes. Cell 2023; 186:1895-1911.e21. [PMID: 37028429 PMCID: PMC10156175 DOI: 10.1016/j.cell.2023.02.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/06/2023] [Accepted: 02/27/2023] [Indexed: 04/09/2023]
Abstract
Cells respond to environmental cues by remodeling their inventories of multiprotein complexes. Cellular repertoires of SCF (SKP1-CUL1-F box protein) ubiquitin ligase complexes, which mediate much protein degradation, require CAND1 to distribute the limiting CUL1 subunit across the family of ∼70 different F box proteins. Yet, how a single factor coordinately assembles numerous distinct multiprotein complexes remains unknown. We obtained cryo-EM structures of CAND1-bound SCF complexes in multiple states and correlated mutational effects on structures, biochemistry, and cellular assays. The data suggest that CAND1 clasps idling catalytic domains of an inactive SCF, rolls around, and allosterically rocks and destabilizes the SCF. New SCF production proceeds in reverse, through SKP1-F box allosterically destabilizing CAND1. The CAND1-SCF conformational ensemble recycles CUL1 from inactive complexes, fueling mixing and matching of SCF parts for E3 activation in response to substrate availability. Our data reveal biogenesis of a predominant family of E3 ligases, and the molecular basis for systemwide multiprotein complex assembly.
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Affiliation(s)
- Kheewoong Baek
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Daniel C Scott
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Lukas T Henneberg
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Moeko T King
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried 82152, Germany; Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Abstract
The formation of protein complexes is crucial to most biological functions. The cellular mechanisms governing protein complex biogenesis are not yet well understood, but some principles of cotranslational and posttranslational assembly are beginning to emerge. In bacteria, this process is favored by operons encoding subunits of protein complexes. Eukaryotic cells do not have polycistronic mRNAs, raising the question of how they orchestrate the encounter of unassembled subunits. Here we review the constraints and mechanisms governing eukaryotic co- and posttranslational protein folding and assembly, including the influence of elongation rate on nascent chain targeting, folding, and chaperone interactions. Recent evidence shows that mRNAs encoding subunits of oligomeric assemblies can undergo localized translation and form cytoplasmic condensates that might facilitate the assembly of protein complexes. Understanding the interplay between localized mRNA translation and cotranslational proteostasis will be critical to defining protein complex assembly in vivo.
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Affiliation(s)
| | - Jae Ho Lee
- Department of Biology, Stanford University, Stanford, California, USA;
| | - Natália M Barbosa
- Department of Biology, Stanford University, Stanford, California, USA;
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, California, USA;
- Department of Genetics, Stanford University, Stanford, California, USA
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Saito Y, Santosa V, Ishiguro KI, Kanemaki MT. MCMBP promotes the assembly of the MCM2-7 hetero-hexamer to ensure robust DNA replication in human cells. eLife 2022; 11:77393. [PMID: 35438632 PMCID: PMC9018068 DOI: 10.7554/elife.77393] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/08/2022] [Indexed: 12/26/2022] Open
Abstract
The MCM2–7 hetero-hexamer is the replicative DNA helicase that plays a central role in eukaryotic DNA replication. In proliferating cells, the expression level of the MCM2–7 hexamer is kept high, which safeguards the integrity of the genome. However, how the MCM2–7 hexamer is assembled in living cells remains unknown. Here, we revealed that the MCM-binding protein (MCMBP) plays a critical role in the assembly of this hexamer in human cells. MCMBP associates with MCM3 which is essential for maintaining the level of the MCM2–7 hexamer. Acute depletion of MCMBP demonstrated that it contributes to MCM2–7 assembly using nascent MCM3. Cells depleted of MCMBP gradually ceased to proliferate because of reduced replication licensing. Under this condition, p53-positive cells exhibited arrest in the G1 phase, whereas p53-null cells entered the S phase and lost their viability because of the accumulation of DNA damage, suggesting that MCMBP is a potential target for killing p53-deficient cancers.
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Affiliation(s)
- Yuichiro Saito
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan
| | - Venny Santosa
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan
| | - Kei-Ichiro Ishiguro
- Department of Chromosome Biology, Institute of Molecular Embryology and Genetics (IMEG), Kumamoto University, Kumamoto, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Japan.,Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
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7
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Yang L, Pandeya A, Li L, Ojo I, Li Z, Wei Y. Transport Across Two Membrane Bilayers in E. coli by Efflux Pumps of Different Dimensions. J Mol Biol 2021; 434:167376. [PMID: 34838522 DOI: 10.1016/j.jmb.2021.167376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/30/2022]
Abstract
AcrAB-TolC and CusBAC are two of the most well-studied Resistance-Nodulation-Division (RND) family tripartite efflux pumps in E. coli. AcrAB-TolC is a multidrug efflux system, while CusBAC transports Cu(I), Cu(II) and Ag(I). The RND pump complexes span both the inner membrane (IM) and the outer membrane (OM). The long axis dimension of the fully assembled AcrAB-TolC is ∼3 nm longer than that of CusBAC. To probe if these two efflux systems with different dimensions affect each other when they need to work simultaneously in the same cell, two real-time assays were used to monitor the efflux activities of these two pumps and their impact on each other. The results showed that the presence of AcrAB-TolC substrates accelerated the accumulation of Cu(I) in BW25113 but not in BW25113ΔcusBA or BW25113ΔtolC strains. Similarly, the presence of Ag(I) slowed down the Nile red efflux in the parent strain more significantly than in the CusBA deficient mutant. To further investigate the impact of the OM/IM distance on the function of these tripartite complexes, we experimented with strains lacking the lipoprotein Lpp or containing Lpp mutant of different lengths. Data from efflux/accumulation assays and susceptibility tests revealed that mutation of Lpp resulted in functional deficiency of both AcrAB-TolC and CusBAC. In conclusion, this study demonstrated that when AcrAB-TolC and CusBAC functioned simultaneously, it took the cell a few minutes to adjust. Furthermore, the presence of Lpp of proper length is important to support full efflux activity of transporters spanning both membrane layers in E. coli.
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Affiliation(s)
- Ling Yang
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Ankit Pandeya
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Lan Li
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Isoiza Ojo
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Zhenyu Li
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA.
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Pleiner T, Hazu M, Tomaleri GP, Januszyk K, Oania RS, Sweredoski MJ, Moradian A, Guna A, Voorhees RM. WNK1 is an assembly factor for the human ER membrane protein complex. Mol Cell 2021; 81:2693-2704.e12. [PMID: 33964204 DOI: 10.1016/j.molcel.2021.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 03/02/2021] [Accepted: 04/14/2021] [Indexed: 12/13/2022]
Abstract
The assembly of nascent proteins into multi-subunit complexes is a tightly regulated process that must occur at high fidelity to maintain cellular homeostasis. The ER membrane protein complex (EMC) is an essential insertase that requires seven membrane-spanning and two soluble cytosolic subunits to function. Here, we show that the kinase with no lysine 1 (WNK1), known for its role in hypertension and neuropathy, functions as an assembly factor for the human EMC. WNK1 uses a conserved amphipathic helix to stabilize the soluble subunit, EMC2, by binding to the EMC2-8 interface. Shielding this hydrophobic surface prevents promiscuous interactions of unassembled EMC2 and directly competes for binding of E3 ubiquitin ligases, permitting assembly. Depletion of WNK1 thus destabilizes both the EMC and its membrane protein clients. This work describes an unexpected role for WNK1 in protein biogenesis and defines the general requirements of an assembly factor that will apply across the proteome.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Robert S Oania
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Michael J Sweredoski
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Annie Moradian
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Alina Guna
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
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9
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Coulombe B, Derksen A, La Piana R, Brais B, Gauthier MS, Bernard G. POLR3-related leukodystrophy: How do mutations affecting RNA polymerase III subunits cause hypomyelination? Fac Rev 2021; 10:12. [PMID: 33659930 PMCID: PMC7894263 DOI: 10.12703/r/10-12] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Hypomyelinating leukodystrophies are a group of genetic disorders characterized by insufficient myelin deposition during development. A subset of hypomyelinating leukodystrophies, named RNA polymerase III (Pol III or POLR3)-related leukodystrophy or 4H (Hypomyelination, Hypodontia and Hypogonadotropic Hypogonadism) leukodystrophy, was found to be caused by biallelic variants in genes encoding subunits of the enzyme Pol III, including POLR3A, POLR3B, POLR3K, and POLR1C. Pol III is one of the three nuclear RNA polymerases that synthesizes small non-coding RNAs, such as tRNAs, 5S RNA, and others, that are involved in the regulation of essential cellular processes, including transcription, translation and RNA maturation. Affinity purification coupled with mass spectrometry (AP-MS) revealed that a number of mutations causing POLR3-related leukodystrophy impair normal assembly or biogenesis of Pol III, often causing a retention of the unassembled subunits in the cytoplasm. Even though these proteomic studies have helped to understand the molecular defects associated with leukodystrophy, how these mutations cause hypomyelination has yet to be defined. In this review we propose two main hypotheses to explain how mutations affecting Pol III subunits can cause hypomyelination.
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Affiliation(s)
- Benoit Coulombe
- Department of Translational Proteomics, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC, Canada
| | - Alexa Derksen
- Department of Translational Proteomics, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
| | - Roberta La Piana
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
- Department of Diagnostic Radiology, McGill University, Montréal, QC, Canada
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montréal, QC, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
| | - Marie-Soleil Gauthier
- Department of Translational Proteomics, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - Geneviève Bernard
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montréal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, QC, Canada
- Department of Human Genetics, McGill University, Montréal, QC, Canada
- Department of Pediatrics, McGill University, Montréal, QC, Canada
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montréal, QC, Canada
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10
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Cloutier P, Poitras C, Faubert D, Bouchard A, Blanchette M, Gauthier MS, Coulombe B. Upstream ORF-Encoded ASDURF Is a Novel Prefoldin-like Subunit of the PAQosome. J Proteome Res 2019; 19:18-27. [PMID: 31738558 DOI: 10.1021/acs.jproteome.9b00599] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The PAQosome is an 11-subunit chaperone involved in the biogenesis of several human protein complexes. We show that ASDURF, a recently discovered upstream open reading frame (uORF) in the 5' UTR of ASNSD1 mRNA, encodes the 12th subunit of the PAQosome. ASDURF displays significant structural homology to β-prefoldins and assembles with the five known subunits of the prefoldin-like module of the PAQosome to form a heterohexameric prefoldin-like complex. A model of the PAQosome prefoldin-like module is presented. The data presented here provide an example of a eukaryotic uORF-encoded polypeptide whose function is not limited to cis-acting translational regulation of downstream coding sequence and highlights the importance of including alternative ORF products in proteomic studies.
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Affiliation(s)
- Philippe Cloutier
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada
| | - Christian Poitras
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada
| | - Denis Faubert
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada
| | - Annie Bouchard
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada
| | - Mathieu Blanchette
- School of Computer Science , McGill University , 3480 University Street , Montréal , Quebec H3A 0E9 , Canada
| | - Marie-Soleil Gauthier
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada
| | - Benoit Coulombe
- Institut de Recherches Cliniques de Montréal , 110 Avenue des Pins Ouest , Montréal , Quebec H2W 1R7 , Canada.,Département de Biochimie et Médecine Moléculaire, Faculté de Médecine , Université de Montréal , 2900 Boulevard Édouart-Montpetit , Montréal , Quebec H3T 1J4 , Canada
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11
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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: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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Mashtalir N, D'Avino AR, Michel BC, Luo J, Pan J, Otto JE, Zullow HJ, McKenzie ZM, Kubiak RL, St Pierre R, Valencia AM, Poynter SJ, Cassel SH, Ranish JA, Kadoch C. Modular Organization and Assembly of SWI/SNF Family Chromatin Remodeling Complexes. Cell 2018; 175:1272-1288.e20. [PMID: 30343899 DOI: 10.1016/j.cell.2018.09.032] [Citation(s) in RCA: 387] [Impact Index Per Article: 64.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 06/28/2018] [Accepted: 09/14/2018] [Indexed: 02/06/2023]
Abstract
Mammalian SWI/SNF (mSWI/SNF) ATP-dependent chromatin remodeling complexes are multi-subunit molecular machines that play vital roles in regulating genomic architecture and are frequently disrupted in human cancer and developmental disorders. To date, the modular organization and pathways of assembly of these chromatin regulators remain unknown, presenting a major barrier to structural and functional determination. Here, we elucidate the architecture and assembly pathway across three classes of mSWI/SNF complexes-canonical BRG1/BRM-associated factor (BAF), polybromo-associated BAF (PBAF), and newly defined ncBAF complexes-and define the requirement of each subunit for complex formation and stability. Using affinity purification of endogenous complexes from mammalian and Drosophila cells coupled with cross-linking mass spectrometry (CX-MS) and mutagenesis, we uncover three distinct and evolutionarily conserved modules, their organization, and the temporal incorporation of these modules into each complete mSWI/SNF complex class. Finally, we map human disease-associated mutations within subunits and modules, defining specific topological regions that are affected upon subunit perturbation.
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Affiliation(s)
- Nazar Mashtalir
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Andrew R D'Avino
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Brittany C Michel
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA 02215, USA
| | - Jie Luo
- Institute for Systems Biology, Seattle, WA 98109, USA
| | - Joshua Pan
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA 02215, USA
| | - Jordan E Otto
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Chemical Biology Program, Harvard University, Cambridge, MA 02138, USA
| | - Hayley J Zullow
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA 02215, USA
| | - Zachary M McKenzie
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Rachel L Kubiak
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
| | - Roodolph St Pierre
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Chemical Biology Program, Harvard University, Cambridge, MA 02138, USA
| | - Alfredo M Valencia
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Chemical Biology Program, Harvard University, Cambridge, MA 02138, USA
| | - Steven J Poynter
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Chemical Biology Program, Harvard University, Cambridge, MA 02138, USA
| | - Seth H Cassel
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA 02215, USA
| | | | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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13
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Carlisle C, Prill K, Pilgrim D. Chaperones and the Proteasome System: Regulating the Construction and Demolition of Striated Muscle. Int J Mol Sci 2017; 19:E32. [PMID: 29271938 PMCID: PMC5795982 DOI: 10.3390/ijms19010032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 11/28/2017] [Accepted: 12/18/2017] [Indexed: 12/21/2022] Open
Abstract
Protein folding factors (chaperones) are required for many diverse cellular functions. In striated muscle, chaperones are required for contractile protein function, as well as the larger scale assembly of the basic unit of muscle, the sarcomere. The sarcomere is complex and composed of hundreds of proteins and the number of proteins and processes recognized to be regulated by chaperones has increased dramatically over the past decade. Research in the past ten years has begun to discover and characterize the chaperones involved in the assembly of the sarcomere at a rapid rate. Because of the dynamic nature of muscle, wear and tear damage is inevitable. Several systems, including chaperones and the ubiquitin proteasome system (UPS), have evolved to regulate protein turnover. Much of our knowledge of muscle development focuses on the formation of the sarcomere but recent work has begun to elucidate the requirement and role of chaperones and the UPS in sarcomere maintenance and disease. This review will cover the roles of chaperones in sarcomere assembly, the importance of chaperone homeostasis and the cooperation of chaperones and the UPS in sarcomere integrity and disease.
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Affiliation(s)
- Casey Carlisle
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
| | - Kendal Prill
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
| | - Dave Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
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Magistrelli G, Poitevin Y, Schlosser F, Pontini G, Malinge P, Josserand S, Corbier M, Fischer N. Optimizing assembly and production of native bispecific antibodies by codon de-optimization. MAbs 2017; 9:231-239. [PMID: 28001485 DOI: 10.1080/19420862.2016.1267088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
When production of bispecific antibodies requires the co-expression and assembly of three or four polypeptide chains, low expression of one chain can significantly limit assembly and yield. κλ bodies, fully human bispecific antibodies with native IgG structure, are composed of a common heavy chain and two different light chains, one kappa and one lambda. No engineering is applied to force pairing of the chains, thus both monospecific and bispecific antibodies are secreted in the supernatant. In this context, stoichiometric expression of the two light chains allows for maximal assembly of the bispecific antibody. In this study, we selected a κλ body with suboptimal characteristics due to low kappa chain expression. Codon optimization to increase expression of the kappa chain did not improve bispecific yield. Surprisingly, progressive introduction of non-optimal codons into the sequence of the lambda chain resulted in lowering its expression for an optimal tuning of the relative distribution of monospecific and bispecific antibodies. This codon de-optimization led to doubling of the κλ body yield. These results indicate that assembly of different proteins into a recombinant complex is an interconnected process and that reducing the expression of one polypeptide can actually increase the overall yield.
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Affiliation(s)
| | - Yves Poitevin
- a Novimmune SA , Plan-les-Ouates , Geneva , Switzerland
| | | | | | | | | | - Marie Corbier
- a Novimmune SA , Plan-les-Ouates , Geneva , Switzerland
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15
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Pasalic D, Weber B, Giannone C, Anelli T, Müller R, Fagioli C, Felkl M, John C, Mossuto MF, Becker CFW, Sitia R, Buchner J. A peptide extension dictates IgM assembly. Proc Natl Acad Sci U S A 2017; 114:E8575-84. [PMID: 28973899 DOI: 10.1073/pnas.1701797114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Professional secretory cells can produce large amounts of high-quality complex molecules, including IgM antibodies. Owing to their multivalency, polymeric IgM antibodies provide an efficient first-line of defense against pathogens. To decipher the mechanisms of IgM assembly, we investigated its biosynthesis in living cells and faithfully reconstituted the underlying processes in vitro. We find that a conserved peptide extension at the C-terminal end of the IgM heavy (Ig-μ) chains, termed the tailpiece, is necessary and sufficient to establish the correct geometry. Alanine scanning revealed that hydrophobic amino acids in the first half of the tailpiece contain essential information for generating the correct topology. Assembly is triggered by the formation of a disulfide bond linking two tailpieces. This induces conformational changes in the tailpiece and the adjacent domain, which drive further polymerization. Thus, the biogenesis of large and topologically challenging IgM complexes is dictated by a local conformational switch in a peptide extension.
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16
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McShane E, Sin C, Zauber H, Wells JN, Donnelly N, Wang X, Hou J, Chen W, Storchova Z, Marsh JA, Valleriani A, Selbach M. Kinetic Analysis of Protein Stability Reveals Age-Dependent Degradation. Cell 2016; 167:803-815.e21. [PMID: 27720452 DOI: 10.1016/j.cell.2016.09.015] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/19/2016] [Accepted: 09/07/2016] [Indexed: 12/18/2022]
Abstract
Do young and old protein molecules have the same probability to be degraded? We addressed this question using metabolic pulse-chase labeling and quantitative mass spectrometry to obtain degradation profiles for thousands of proteins. We find that >10% of proteins are degraded non-exponentially. Specifically, proteins are less stable in the first few hours of their life and stabilize with age. Degradation profiles are conserved and similar in two cell types. Many non-exponentially degraded (NED) proteins are subunits of complexes that are produced in super-stoichiometric amounts relative to their exponentially degraded (ED) counterparts. Within complexes, NED proteins have larger interaction interfaces and assemble earlier than ED subunits. Amplifying genes encoding NED proteins increases their initial degradation. Consistently, decay profiles can predict protein level attenuation in aneuploid cells. Together, our data show that non-exponential degradation is common, conserved, and has important consequences for complex formation and regulation of protein abundance.
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17
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Thong S, Ercan B, Torta F, Fong ZY, Wong HYA, Wenk MR, Chng SS. Defining key roles for auxiliary proteins in an ABC transporter that maintains bacterial outer membrane lipid asymmetry. eLife 2016; 5. [PMID: 27529189 PMCID: PMC5016091 DOI: 10.7554/elife.19042] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/14/2016] [Indexed: 01/16/2023] Open
Abstract
In Gram-negative bacteria, lipid asymmetry is critical for the function of the outer membrane (OM) as a selective permeability barrier, but how it is established and maintained is poorly understood. Here, we characterize a non-canonical ATP-binding cassette (ABC) transporter in Escherichia coli that provides energy for maintaining OM lipid asymmetry via the transport of aberrantly localized phospholipids (PLs) from the OM to the inner membrane (IM). We establish that the transporter comprises canonical components, MlaF and MlaE, and auxiliary proteins, MlaD and MlaB, of previously unknown functions. We further demonstrate that MlaD forms extremely stable hexamers within the complex, functions in substrate binding with strong affinity for PLs, and modulates ATP hydrolytic activity. In addition, MlaB plays critical roles in both the assembly and activity of the transporter. Our work provides mechanistic insights into how the MlaFEDB complex participates in ensuring active retrograde PL transport to maintain OM lipid asymmetry. DOI:http://dx.doi.org/10.7554/eLife.19042.001 Escherichia coli are bacteria that can cause vomiting and diarrhoea in humans and other mammals. Each E. coli cell is surrounded by two membranes, which are each made of two layers of fat molecules known as lipids. The outer membrane prevents the entry of toxic compounds and allows E. coli to withstand damaging agents from outside the cell, such as antibiotics. The outer membrane’s ability to act as an effective barrier depends on an asymmetric, or uneven, distribution of lipid molecules across its two layers. The inside layer is dominated by phospholipids, whereas the outside layer is comprised mainly of lipids with attached sugars. The distribution of the two lipid types is maintained by a molecular machine with components that can be found in both the inner and outer membranes. This machine is thought to remove phospholipids from the outside layer of the outer membrane and transport them back to the inner membrane. A group (or”complex”) of proteins known as MIaFEDB operates as a part of this machine at the inner membrane. MlaFEDB is believed to use energy derived from the breakdown of a molecule called ATP to help ensure that phospholipids removed from the outside layer of the outer membrane are reinserted into the inner membrane. It was proposed that the complex contains four proteins, but it was not clear exactly how these components are arranged. Now, Thong et al. reveal how MlaFEDB is organized and characterize the roles of the individual protein components. The experiments confirm that the MlaFEDB complex is made up of four proteins, including two core components and two support proteins (called MlaB and MlaD). There are six copies of MlaD in the complex. In addition, MlaD has a strong affinity for phospholipids and plays a role in controlling the rate at which energy is harnessed through the breakdown of ATP. Further experiments show that the other support protein MlaB is necessary for both the proper assembly and activity of the complex, likely through its interaction with one of the core components. The next step following on from this work is to directly observe MlaFEDB in action to find out how it uses energy to insert lipids into the inner membrane. In the long term, more information about the structure of the complex would be needed to further understand how it works at the molecular level. DOI:http://dx.doi.org/10.7554/eLife.19042.002
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Affiliation(s)
- Shuhua Thong
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Bilge Ercan
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Federico Torta
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Zhen Yang Fong
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Hui Yi Alvina Wong
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Markus R Wenk
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore, Singapore.,Singapore Center on Environmental Life Sciences Engineering, National University of Singapore, Singapore, Singapore
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18
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Nsiah-Sefaa A, McKenzie M. Combined defects in oxidative phosphorylation and fatty acid β-oxidation in mitochondrial disease. Biosci Rep 2016; 36:e00313. [PMID: 26839416 DOI: 10.1042/BSR20150295] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/02/2016] [Indexed: 12/20/2022] Open
Abstract
Mitochondria provide the main source of energy to eukaryotic cells, oxidizing fats and sugars to generate ATP. Mitochondrial fatty acid β-oxidation (FAO) and oxidative phosphorylation (OXPHOS) are two metabolic pathways which are central to this process. Defects in these pathways can result in diseases of the brain, skeletal muscle, heart and liver, affecting approximately 1 in 5000 live births. There are no effective therapies for these disorders, with quality of life severely reduced for most patients. The pathology underlying many aspects of these diseases is not well understood; for example, it is not clear why some patients with primary FAO deficiencies exhibit secondary OXPHOS defects. However, recent findings suggest that physical interactions exist between FAO and OXPHOS proteins, and that these interactions are critical for both FAO and OXPHOS function. Here, we review our current understanding of the interactions between FAO and OXPHOS proteins and how defects in these two metabolic pathways contribute to mitochondrial disease pathogenesis.
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Westerhof LB, Wilbers RHP, van Raaij DR, van Wijk CZ, Goverse A, Bakker J, Schots A. Transient Expression of Secretory IgA In Planta is Optimal Using a Multi-Gene Vector and may be Further Enhanced by Improving Joining Chain Incorporation. Front Plant Sci 2015; 6:1200. [PMID: 26793201 PMCID: PMC4707260 DOI: 10.3389/fpls.2015.01200] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/14/2015] [Indexed: 05/16/2023]
Abstract
Secretory IgA (sIgA) is a crucial antibody in host defense at mucosal surfaces. It is a promising antibody isotype in a variety of therapeutic settings such as passive vaccination and treatment of inflammatory disorders. However, heterologous production of this heteromultimeric protein complex is still suboptimal. The challenge is the coordinate expression of the four required polypeptides; the alpha heavy chain, the light chain, the joining chain, and part of the polymeric-Ig-receptor called the secretory component, in a 4:4:1:1 ratio. We evaluated the transient expression of three sIgAκ variants, harboring the heavy chain isotype α1, α2m1, or α2m2, of the clinical antibody Ustekinumab in planta. Ustekinumab is directed against the p40 subunit that is shared by the pro-inflammatory cytokines interleukin (IL)-12 and IL-23. A sIgA variant of this antibody may enable localized treatment of inflammatory bowel disease. Of the three different sIgA variants we obtained the highest yield with sIgA1κ reaching up to 373 μg sIgA/mg total soluble protein. The use of a multi-cassette vector containing all four expression cassettes was most efficient. However, not the expression strategy, but the incorporation of the joining chain turned out to be the limiting step for sIgA production. Our data demonstrate that transient expression in planta is suitable for the economic production of heteromultimeric protein complexes such as sIgA.
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Xu J, Hendrix RW, Duda RL. A balanced ratio of proteins from gene G and frameshift-extended gene GT is required for phage lambda tail assembly. J Mol Biol 2013; 425:3476-87. [PMID: 23851014 DOI: 10.1016/j.jmb.2013.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/21/2013] [Accepted: 07/02/2013] [Indexed: 10/26/2022]
Abstract
In bacteriophage λ, the overlapping open reading frames G and T are expressed by a programmed translational frameshift similar to that of the gag-pol genes of many retroviruses to produce the proteins gpG and gpGT. An analogous frameshift is widely conserved among other dsDNA tailed phages in their corresponding "G" and "GT" tail genes even in the absence of detectable sequence homology. The longer protein gpGT is known to be essential for tail assembly, but the requirement for the shorter gpG remained unclear because mutations in gene G affect both proteins. A plasmid system that can direct the efficient synthesis of tails was created and used to show that gpG and gpGT are both essential for correct tail assembly. Phage complementation assays under conditions where levels of plasmid-expressed gpG or gpGT could be altered independently revealed that the correct molar ratio of these two related proteins, normally determined by the efficiency of the frameshift, is also crucial for efficient assembly of functional tails. Finally, the physical connection between the G and T domains of gpGT, a consequence of the frameshift mechanism of protein expression, appears to be important for efficient tail assembly.
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Affiliation(s)
- Jun Xu
- Department of Biological Sciences, University of Pittsburgh, PA 15260, USA
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21
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Nick S, Meurer J, Soll J, Ankele E. Nucleus-encoded light-harvesting chlorophyll a/b proteins are imported normally into chlorophyll b-free chloroplasts of Arabidopsis. Mol Plant 2013; 6:860-871. [PMID: 23041941 DOI: 10.1093/mp/sss113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Chloroplast-located proteins which are encoded by the nuclear genome have to be imported from the cytosol into the organelle in a posttranslational manner. Among these nuclear-encoded chloroplast proteins are the light-harvesting chlorophyll a/b-binding proteins (LHCPs). After translation in the cytosol, precursor proteins of LHCPs are imported via the TOC/TIC translocase, processed to their mature size to insert into thylakoid membranes where they recruit chlorophylls a and b to form pigment-protein complexes. The translocation of proteins is a highly regulated process which employs several regulators. To analyze whether CAO (chlorophyll a oxigenase) which converts chlorophyll a to chlorophyll b at the inner chloroplast membrane, is one of these regulators, we performed import reactions utilizing a homozygous loss-of-function mutant (cao-1). We imported in vitro translated and (35)S-labeled precursor proteins of light-harvesting proteins of photosystem II LHCB1, LHCB4, and LHCB5 into chloroplasts isolated from cao-1 and show that import of precursor proteins and their processing to mature forms are not impaired in the mutant. Therefore, regulation of the import machinery cannot be responsible for the decreased steady-state levels of light-harvesting complex (LHC) proteins. Regulation does not take place at the transcriptional level either, because Lhcb mRNAs are not down-regulated. Additionally, reduced steady-state levels of LHCPs also do not occur due to posttranslational turnover of non-functional LHCPs in chloroplasts. Taken together, our data show that plants in the absence of CAO and therefore devoid of chlorophyll b are not influenced in their import behavior of LHC proteins.
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Affiliation(s)
- Sabine Nick
- Dept Biologie I-Botanik, Biozentrum LMU München, Grosshadernerstrasse 2-4, D-82152 Planegg-Martinsried, Germany
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22
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Nickelsen J, Zerges W. Thylakoid biogenesis has joined the new era of bacterial cell biology. Front Plant Sci 2013; 4:458. [PMID: 24312109 PMCID: PMC3826073 DOI: 10.3389/fpls.2013.00458] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 10/25/2013] [Indexed: 05/20/2023]
Affiliation(s)
- Jörg Nickelsen
- Molecular Plant Sciences, Ludwig-Maximillians-UniversityPlanegg-Martinsried, Germany
- *Correspondence: ;
| | - William Zerges
- Biology Department, Concordia UniversityMontreal, QC, Canada
- *Correspondence: ;
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Oreb M, Höfle A, Mirus O, Schleiff E. Phosphorylation regulates the assembly of chloroplast import machinery. J Exp Bot 2008; 59:2309-16. [PMID: 18487635 PMCID: PMC2423650 DOI: 10.1093/jxb/ern095] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 03/06/2008] [Accepted: 03/10/2008] [Indexed: 05/24/2023]
Abstract
Chloroplast function depends on the translocation of cytosolically synthesized precursor proteins into the organelle. The recognition and transfer of most precursor proteins across the outer membrane depend on a membrane inserted complex. Two receptor components of this complex, Toc34 and Toc159, are GTPases, which can be phosphorylated by kinases present in the hosting membrane. However, the physiological function of phosphorylation is not yet understood in detail. It is demonstrated that both receptors are phosphorylated within their G-domains. In vitro, the phosphorylation of Toc34 disrupts both homo- and heterodimerization of the G-domains as determined using a phospho-mimicking mutant. In endogenous membranes this mutation or phosphorylation of the wild-type receptor disturbs the association of Toc34, but not of Toc159 with the translocation pore. Therefore, phosphorylation serves as an inhibitor for the association of Toc34 with other components of the complex and phosphorylation can now be discussed as a mechanism to exchange different isoforms of Toc34 within this ensemble.
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Affiliation(s)
| | | | | | - Enrico Schleiff
- Present address and to whom correspondence should be sent: Molecular Plant Sciences, Biocenter, N 200, 3. OG, Max-von-Laue-Str. 9, D-60438 Frankfurt/Main, Germany. E-mail:
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