1
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Chen CC, Huang YR, Chan YT, Lin HY, Lin HJ, Hsiao CD, Ko TP, Lin TW, Lan YH, Lin HY, Chang HY. A distinct dimer configuration of a diatom Get3 forming a tetrameric complex with its tail-anchored membrane cargo. BMC Biol 2024; 22:136. [PMID: 38867239 PMCID: PMC11170914 DOI: 10.1186/s12915-024-01933-x] [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: 12/06/2023] [Accepted: 06/05/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND Most tail-anchored (TA) membrane proteins are delivered to the endoplasmic reticulum through a conserved posttranslational pathway. Although core mechanisms underlying the targeting and insertion of TA proteins are well established in eukaryotes, their role in mediating TA protein biogenesis in plants remains unclear. We reported the crystal structures of algal arsenite transporter 1 (ArsA1), which possesses an approximately 80-kDa monomeric architecture and carries chloroplast-localized TA proteins. However, the mechanistic basis of ArsA2, a Get3 (guided entry of TA proteins 3) homolog in plants, for TA recognition remains unknown. RESULTS Here, for the first time, we present the crystal structures of the diatom Pt-Get3a that forms a distinct ellipsoid-shaped tetramer in the open (nucleotide-bound) state through crystal packing. Pulldown assay results revealed that only tetrameric Pt-Get3a can bind to TA proteins. The lack of the conserved zinc-coordination CXXC motif in Pt-Get3a potentially leads to the spontaneous formation of a distinct parallelogram-shaped dimeric conformation in solution, suggesting a new dimer state for subsequent tetramerization upon TA targeting. Pt-Get3a nonspecifically binds to different subsets of TA substrates due to the lower hydrophobicity of its α-helical subdomain, which is implicated in TA recognition. CONCLUSIONS Our study provides new insights into the mechanisms underlying TA protein shielding by tetrameric Get3 during targeting to the diatom's cell membrane.
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Affiliation(s)
- Chi-Chih Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan
- Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung, Taiwan
| | - Yu-Ru Huang
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan
| | - Yuen Ting Chan
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan
| | - Hung-Yun Lin
- Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan
| | - Han-Jia Lin
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung City, Taiwan
| | | | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Tai-Wen Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Ya-Hsuan Lan
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan
| | - Hsuan-Ya Lin
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan
| | - Hsin-Yang Chang
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Beitou Dist, No. 155, Sec. 2, Linong St, Taipei City, 112304, Taiwan.
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2
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Lathe RS, McFarlane HE, Kesten C, Wang L, Khan GA, Ebert B, Ramírez-Rodríguez EA, Zheng S, Noord N, Frandsen K, Bhalerao RP, Persson S. NKS1/ELMO4 is an integral protein of a pectin synthesis protein complex and maintains Golgi morphology and cell adhesion in Arabidopsis. Proc Natl Acad Sci U S A 2024; 121:e2321759121. [PMID: 38579009 PMCID: PMC11009649 DOI: 10.1073/pnas.2321759121] [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: 01/03/2024] [Accepted: 03/07/2024] [Indexed: 04/07/2024] Open
Abstract
Adjacent plant cells are connected by specialized cell wall regions, called middle lamellae, which influence critical agricultural characteristics, including fruit ripening and organ abscission. Middle lamellae are enriched in pectin polysaccharides, specifically homogalacturonan (HG). Here, we identify a plant-specific Arabidopsis DUF1068 protein, called NKS1/ELMO4, that is required for middle lamellae integrity and cell adhesion. NKS1 localizes to the Golgi apparatus and loss of NKS1 results in changes to Golgi structure and function. The nks1 mutants also display HG deficient phenotypes, including reduced seedling growth, changes to cell wall composition, and tissue integrity defects. These phenotypes are comparable to qua1 and qua2 mutants, which are defective in HG biosynthesis. Notably, genetic interactions indicate that NKS1 and the QUAs work in a common pathway. Protein interaction analyses and modeling corroborate that they work together in a stable protein complex with other pectin-related proteins. We propose that NKS1 is an integral part of a large pectin synthesis protein complex and that proper function of this complex is important to support Golgi structure and function.
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Affiliation(s)
- Rahul S. Lathe
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
- Max-Planck Institute for Molecular Plant Physiology, Potsdam14476, Germany
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, UmeåSE-90187, Sweden
| | - Heather E. McFarlane
- Department of Cell & Systems Biology, University of Toronto, Toronto, ONM5S 3G5, Canada
- School of Biosciences, University of Melbourne, Parkville, VIC3010, Australia
| | - Christopher Kesten
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
| | - Liu Wang
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
- School of Biosciences, University of Melbourne, Parkville, VIC3010, Australia
| | - Ghazanfar Abbas Khan
- School of Biosciences, University of Melbourne, Parkville, VIC3010, Australia
- Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC3086, Australia
| | - Berit Ebert
- School of Biosciences, University of Melbourne, Parkville, VIC3010, Australia
- Department of Biology and Biotechnology, Ruhr University Bochum, Bochum44780, Germany
| | | | - Shuai Zheng
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
| | - Niels Noord
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, UmeåSE-90187, Sweden
| | - Kristian Frandsen
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
| | - Rishikesh P. Bhalerao
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, UmeåSE-90187, Sweden
| | - Staffan Persson
- Copenhagen Plant Science Center, Department of Plant & Environmental Sciences, University of Copenhagen, Frederiksberg C1871, Denmark
- Max-Planck Institute for Molecular Plant Physiology, Potsdam14476, Germany
- School of Biosciences, University of Melbourne, Parkville, VIC3010, Australia
- Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, University of AdelaideJoint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai200240, China
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3
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Ricardi MM, Wallmeroth N, Cermesoni C, Mehlhorn DG, Richter S, Zhang L, Mittendorf J, Godehardt I, Berendzen KW, von Roepenack-Lahaye E, Stierhof YD, Lipka V, Jürgens G, Grefen C. A tyrosine phospho-switch within the Longin domain of VAMP721 modulates SNARE functionality. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:1633-1651. [PMID: 37659090 DOI: 10.1111/tpj.16451] [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: 03/20/2023] [Revised: 08/08/2023] [Accepted: 08/16/2023] [Indexed: 09/04/2023]
Abstract
The final step in secretion is membrane fusion facilitated by SNARE proteins that reside in opposite membranes. The formation of a trans-SNARE complex between one R and three Q coiled-coiled SNARE domains drives the final approach of the membranes providing the mechanical energy for fusion. Biological control of this mechanism is exerted by additional domains within some SNAREs. For example, the N-terminal Longin domain (LD) of R-SNAREs (also called Vesicle-associated membrane proteins, VAMPs) can fold back onto the SNARE domain blocking interaction with other cognate SNAREs. The LD may also determine the subcellular localization via interaction with other trafficking-related proteins. Here, we provide cell-biological and genetic evidence that phosphorylation of the Tyrosine57 residue regulates the functionality of VAMP721. We found that an aspartate mutation mimics phosphorylation, leading to protein instability and subsequent degradation in lytic vacuoles. The mutant SNARE also fails to rescue the defects of vamp721vamp722 loss-of-function lines in spite of its wildtype-like localization within the secretory pathway and the ability to interact with cognate SNARE partners. Most importantly, it imposes a dominant negative phenotype interfering with root growth, normal secretion and cytokinesis in wildtype plants generating large aggregates that mainly contain secretory vesicles. Non-phosphorylatable VAMP721Y57F needs higher gene dosage to rescue double mutants in comparison to native VAMP721 underpinning that phosphorylation modulates SNARE function. We propose a model where short-lived phosphorylation of Y57 serves as a regulatory step to control VAMP721 activity, favoring its open state and interaction with cognate partners to ultimately drive membrane fusion.
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Affiliation(s)
- Martiniano Maria Ricardi
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Bochum, Germany
- Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Niklas Wallmeroth
- University of Tübingen, ZMBP Developmental Genetics, Tübingen, Germany
| | - Cecilia Cermesoni
- Departamento de Fisiología y Biología Molecular y Celular (FBMC), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Sandra Richter
- University of Tübingen, ZMBP Developmental Genetics, Tübingen, Germany
- University of Tübingen, ZMBP Central Facilities, Tübingen, Germany
| | - Lei Zhang
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Bochum, Germany
| | - Josephine Mittendorf
- University of Göttingen, Albrecht-von-Haller-Institute of Plant Sciences, Göttingen, Germany
| | - Ingeborg Godehardt
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Bochum, Germany
| | | | | | | | - Volker Lipka
- University of Göttingen, Albrecht-von-Haller-Institute of Plant Sciences, Göttingen, Germany
| | - Gerd Jürgens
- University of Tübingen, ZMBP Developmental Genetics, Tübingen, Germany
| | - Christopher Grefen
- Ruhr University Bochum, Faculty of Biology and Biotechnology, Bochum, Germany
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4
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Hagiwara T, Minami R, Ushio C, Yokota N, Kawahara H. Proteotoxic stresses stimulate dissociation of UBL4A from the tail-anchored protein recognition complex. Biochem J 2023; 480:1583-1598. [PMID: 37747814 PMCID: PMC10586765 DOI: 10.1042/bcj20230267] [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: 07/13/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 09/27/2023]
Abstract
Inclusion body formation is associated with cytotoxicity in a number of neurodegenerative diseases. However, the molecular basis of the toxicity caused by the accumulation of aggregation-prone proteins remains controversial. In this study, we found that disease-associated inclusions induced by elongated polyglutamine chains disrupt the complex formation of BAG6 with UBL4A, a mammalian homologue of yeast Get5. UBL4A also dissociated from BAG6 in response to proteotoxic stresses such as proteasomal inhibition and mitochondrial depolarization. These findings imply that the cytotoxicity of pathological protein aggregates might be attributed in part to disruption of the BAG6-UBL4A complex that is required for the biogenesis of tail-anchored proteins.
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Affiliation(s)
- Takumi Hagiwara
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Ryosuke Minami
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Chizuru Ushio
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Naoto Yokota
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Hiroyuki Kawahara
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
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5
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Barlow AN, Manu MS, Saladi SM, Tarr PT, Yadav Y, Thinn AMM, Zhu Y, Laganowsky AD, Clemons WM, Ramasamy S. Structures of Get3d reveal a distinct architecture associated with the emergence of photosynthesis. J Biol Chem 2023; 299:104752. [PMID: 37100288 PMCID: PMC10248533 DOI: 10.1016/j.jbc.2023.104752] [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: 02/16/2023] [Revised: 04/16/2023] [Accepted: 04/21/2023] [Indexed: 04/28/2023] Open
Abstract
Homologs of the protein Get3 have been identified in all domains yet remain to be fully characterized. In the eukaryotic cytoplasm, Get3 delivers tail-anchored (TA) integral membrane proteins, defined by a single transmembrane helix at their C terminus, to the endoplasmic reticulum. While most eukaryotes have a single Get3 gene, plants are notable for having multiple Get3 paralogs. Get3d is conserved across land plants and photosynthetic bacteria and includes a distinctive C-terminal α-crystallin domain. After tracing the evolutionary origin of Get3d, we solve the Arabidopsis thaliana Get3d crystal structure, identify its localization to the chloroplast, and provide evidence for a role in TA protein binding. The structure is identical to that of a cyanobacterial Get3 homolog, which is further refined here. Distinct features of Get3d include an incomplete active site, a "closed" conformation in the apo-state, and a hydrophobic chamber. Both homologs have ATPase activity and are capable of binding TA proteins, supporting a potential role in TA protein targeting. Get3d is first found with the development of photosynthesis and conserved across 1.2 billion years into the chloroplasts of higher plants across the evolution of photosynthesis suggesting a role in the homeostasis of photosynthetic machinery.
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Affiliation(s)
- Alexandra N Barlow
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - M S Manu
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India
| | - Shyam M Saladi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Paul T Tarr
- Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Yashpal Yadav
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India
| | - Aye M M Thinn
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Yun Zhu
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | | | - William M Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
| | - Sureshkumar Ramasamy
- Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, India.
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6
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Fry MY, Najdrová V, Maggiolo AO, Saladi SM, Doležal P, Clemons WM. Structurally derived universal mechanism for the catalytic cycle of the tail-anchored targeting factor Get3. Nat Struct Mol Biol 2022; 29:820-830. [DOI: 10.1038/s41594-022-00798-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/26/2022] [Indexed: 11/09/2022]
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7
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Wilson MP, Durin Z, Unal Ö, Ng BG, Marrecau T, Keldermans L, Souche E, Rymen D, Gündüz M, Köse G, Sturiale L, Garozzo D, Freeze HH, Jaeken J, Foulquier F, Matthijs G. CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking. Hum Mol Genet 2022; 31:2571-2581. [PMID: 35262690 PMCID: PMC9396942 DOI: 10.1093/hmg/ddac055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 02/15/2022] [Accepted: 03/07/2022] [Indexed: 12/03/2022] Open
Abstract
The transmembrane domain recognition complex (TRC) pathway is required for the insertion of C-terminal tail-anchored (TA) proteins into the lipid bilayer of specific intracellular organelles such as the endoplasmic reticulum (ER) membrane. In order to facilitate correct insertion, the recognition complex (consisting of BAG6, GET4 and UBL4A) must first bind to TA proteins and then to GET3 (TRC40, ASNA1), which chaperones the protein to the ER membrane. Subsequently, GET1 (WRB) and CAML form a receptor that enables integration of the TA protein within the lipid bilayer. We report an individual with the homozygous c.633 + 4A>G splice variant in CAMLG, encoding CAML. This variant leads to aberrant splicing and lack of functional protein in patient-derived fibroblasts. The patient displays a predominantly neurological phenotype with psychomotor disability, hypotonia, epilepsy and structural brain abnormalities. Biochemically, a combined O-linked and type II N-linked glycosylation defect was found. Mislocalization of syntaxin-5 in patient fibroblasts and in siCAMLG deleted Hela cells confirms this as a consistent cellular marker of TRC dysfunction. Interestingly, the level of the v-SNARE Bet1L is also drastically reduced in both of these models, indicating a fundamental role of the TRC complex in the assembly of Golgi SNARE complexes. It also points towards a possible mechanism behind the hyposialylation of N and O-glycans. This is the first reported patient with pathogenic variants in CAMLG. CAMLG-CDG is the third disorder, after GET4 and GET3 deficiencies, caused by pathogenic variants in a member of the TRC pathway, further expanding this novel group of disorders.
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Affiliation(s)
- Matthew P Wilson
- Laboratory for Molecular Diagnosis, Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Zoé Durin
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Özlem Unal
- Division of Pediatric Metabolism and Nutrition, Ankara Children's Training and Research Hospital, Ankara, Turkey
| | - Bobby G Ng
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, CA 92037, USA
| | - Thomas Marrecau
- Laboratory for Molecular Diagnosis, Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Liesbeth Keldermans
- Laboratory for Molecular Diagnosis, Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Erika Souche
- Laboratory for Molecular Diagnosis, Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Daisy Rymen
- Department of Pediatrics, Center for Metabolic Diseases, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Mehmet Gündüz
- Division of Pediatric Metabolism and Nutrition, Ankara Children's Training and Research Hospital, Ankara, Turkey
| | - Gülşen Köse
- Department of Pediatric Neurology, Şişli Etfal Education and Research Hospital, Istanbul, Turkey
| | - Luisa Sturiale
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Domenico Garozzo
- CNR, Institute for Polymers, Composites and Biomaterials, IPCB, Catania, Italy
| | - Hudson H Freeze
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, CA 92037, USA
| | - Jaak Jaeken
- Department of Pediatrics, Center for Metabolic Diseases, University Hospitals Leuven, 3000 Leuven, Belgium
| | - François Foulquier
- Univ. Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Gert Matthijs
- Laboratory for Molecular Diagnosis, Center for Human Genetics, KU Leuven, 3000 Leuven, Belgium
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8
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Zhu D, Xiong H, Wu J, Zheng C, Lu D, Zhang L, Xu X. Protein Targeting Into the Thylakoid Membrane Through Different Pathways. Front Physiol 2022; 12:802057. [PMID: 35095563 PMCID: PMC8790069 DOI: 10.3389/fphys.2021.802057] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/07/2021] [Indexed: 01/19/2023] Open
Abstract
In higher plants, chloroplasts are essential semi-autonomous organelles with complex compartments. As part of these sub-organellar compartments, the sheet-like thylakoid membranes contain abundant light-absorbing chlorophylls bound to the light-harvesting proteins and to some of the reaction center proteins. About half of the thylakoid membrane proteins are encoded by nuclear genes and synthesized in the cytosol as precursors before being imported into the chloroplast. After translocation across the chloroplast envelope by the Toc/Tic system, these proteins are subsequently inserted into or translocated across the thylakoid membranes through distinct pathways. The other half of thylakoid proteins are encoded by the chloroplast genome, synthesized in the stroma and integrated into the thylakoid through a cotranslational process. Much progress has been made in identification and functional characterization of new factors involved in protein targeting into the thylakoids, and new insights into this process have been gained. In this review, we introduce the distinct transport systems mediating the translocation of substrate proteins from chloroplast stroma to the thylakoid membrane, and present the recent advances in the identification of novel components mediating these pathways. Finally, we raise some unanswered questions involved in the targeting of chloroplast proteins into the thylakoid membrane, along with perspectives for future research.
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Affiliation(s)
- Dan Zhu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Haibo Xiong
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Jianghao Wu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Canhui Zheng
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Dandan Lu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Lixin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Xiumei Xu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
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9
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Eaglesfield R, Tokatlidis K. Targeting and Insertion of Membrane Proteins in Mitochondria. Front Cell Dev Biol 2022; 9:803205. [PMID: 35004695 PMCID: PMC8740019 DOI: 10.3389/fcell.2021.803205] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/09/2021] [Indexed: 01/26/2023] Open
Abstract
Mitochondrial membrane proteins play an essential role in all major mitochondrial functions. The respiratory complexes of the inner membrane are key for the generation of energy. The carrier proteins for the influx/efflux of essential metabolites to/from the matrix. Many other inner membrane proteins play critical roles in the import and processing of nuclear encoded proteins (∼99% of all mitochondrial proteins). The outer membrane provides another lipidic barrier to nuclear-encoded protein translocation and is home to many proteins involved in the import process, maintenance of ionic balance, as well as the assembly of outer membrane components. While many aspects of the import and assembly pathways of mitochondrial membrane proteins have been elucidated, many open questions remain, especially surrounding the assembly of the respiratory complexes where certain highly hydrophobic subunits are encoded by the mitochondrial DNA and synthesised and inserted into the membrane from the matrix side. This review will examine the various assembly pathways for inner and outer mitochondrial membrane proteins while discussing the most recent structural and biochemical data examining the biogenesis process.
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Affiliation(s)
- Ross Eaglesfield
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Scotland, United Kingdom
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10
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Tirincsi A, Sicking M, Hadzibeganovic D, Haßdenteufel S, Lang S. The Molecular Biodiversity of Protein Targeting and Protein Transport Related to the Endoplasmic Reticulum. Int J Mol Sci 2021; 23:143. [PMID: 35008565 PMCID: PMC8745461 DOI: 10.3390/ijms23010143] [Citation(s) in RCA: 12] [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: 10/27/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/15/2022] Open
Abstract
Looking at the variety of the thousands of different polypeptides that have been focused on in the research on the endoplasmic reticulum from the last five decades taught us one humble lesson: no one size fits all. Cells use an impressive array of components to enable the safe transport of protein cargo from the cytosolic ribosomes to the endoplasmic reticulum. Safety during the transit is warranted by the interplay of cytosolic chaperones, membrane receptors, and protein translocases that together form functional networks and serve as protein targeting and translocation routes. While two targeting routes to the endoplasmic reticulum, SRP (signal recognition particle) and GET (guided entry of tail-anchored proteins), prefer targeting determinants at the N- and C-terminus of the cargo polypeptide, respectively, the recently discovered SND (SRP-independent) route seems to preferentially cater for cargos with non-generic targeting signals that are less hydrophobic or more distant from the termini. With an emphasis on targeting routes and protein translocases, we will discuss those functional networks that drive efficient protein topogenesis and shed light on their redundant and dynamic nature in health and disease.
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Affiliation(s)
- Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Sarah Haßdenteufel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
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Mehlhorn DG, Asseck LY, Grefen C. Looking for a safe haven: tail-anchored proteins and their membrane insertion pathways. PLANT PHYSIOLOGY 2021; 187:1916-1928. [PMID: 35235667 PMCID: PMC8644595 DOI: 10.1093/plphys/kiab298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/05/2021] [Indexed: 06/14/2023]
Abstract
Insertion of membrane proteins into the lipid bilayer is a crucial step during their biosynthesis. Eukaryotic cells face many challenges in directing these proteins to their predestined target membrane. The hydrophobic signal peptide or transmembrane domain (TMD) of the nascent protein must be shielded from the aqueous cytosol and its target membrane identified followed by transport and insertion. Components that evolved to deal with each of these challenging steps range from chaperones to receptors, insertases, and sophisticated translocation complexes. One prominent translocation pathway for most proteins is the signal recognition particle (SRP)-dependent pathway which mediates co-translational translocation of proteins across or into the endoplasmic reticulum (ER) membrane. This textbook example of protein insertion is stretched to its limits when faced with secretory or membrane proteins that lack an amino-terminal signal sequence or TMD. Particularly, a large group of so-called tail-anchored (TA) proteins that harbor a single carboxy-terminal TMD require an alternative, post-translational insertion route into the ER membrane. In this review, we summarize the current research in TA protein insertion with a special focus on plants, address challenges, and highlight future research avenues.
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Affiliation(s)
- Dietmar G Mehlhorn
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Lisa Y Asseck
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Christopher Grefen
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
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Kumar T, Maitra S, Rahman A, Bhattacharjee S. A conserved guided entry of tail-anchored pathway is involved in the trafficking of a subset of membrane proteins in Plasmodium falciparum. PLoS Pathog 2021; 17:e1009595. [PMID: 34780541 PMCID: PMC8629386 DOI: 10.1371/journal.ppat.1009595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 11/29/2021] [Accepted: 10/19/2021] [Indexed: 01/22/2023] Open
Abstract
Tail-anchored (TA) proteins are defined by the absence of N-terminus signal sequence and the presence of a single transmembrane domain (TMD) proximal to their C-terminus. They play fundamental roles in cellular processes including vesicular trafficking, protein translocation and quality control. Some of the TA proteins are post-translationally integrated by the Guided Entry of TA (GET) pathway to the cellular membranes; with their N-terminus oriented towards the cytosol and C-terminus facing the organellar lumen. The TA repertoire and the GET machinery have been extensively characterized in the yeast and mammalian systems, however, they remain elusive in the human malaria parasite Plasmodium falciparum. In this study, we bioinformatically predicted a total of 63 TA proteins in the P. falciparum proteome and revealed the association of a subset with the P. falciparum homolog of Get3 (PfGet3). In addition, our proximity labelling studies either definitively identified or shortlisted the other eligible GET constituents, and our in vitro association studies validated associations between PfGet3 and the corresponding homologs of Get4 and Get2 in P. falciparum. Collectively, this study reveals the presence of proteins with hallmark TA signatures and the involvement of evolutionary conserved GET trafficking pathway for their targeted delivery within the parasite. Tail-anchored (TA) membrane proteins are known to play essential cellular functions in the eukaryotes. These proteins are trafficked to their respective destinations by post-translational translocation pathways that are evolutionarily conserved from yeast to human. However, they remain unidentified in the malaria parasite Plasmodium falciparum. We have used bioinformatic prediction algorithms in conjunction with functional validation studies to identify the candidate TA repertoire and some of the homologs of the trafficking machinery in P. falciparum. Initially, we predicted the presence of 63 putative TA proteins localized to distinct compartments within this parasite, including a few confirmed TA homologs in other eukaryotic systems. We then identified and characterized PfGet3 as a central component in the Guided-Entry of TA (GET) translocation machinery, and our bacterial co-expression and pulldown assays with two selected recombinant TA proteins, PfBOS1 and PfUSE1, showed co-association with PfGet3. We also identified PfGet2 and PfGet4 as the other two components of the GET machinery in P. falciparum using proximity biotinylation followed by mass spectrometry. Interestingly, we also found six TA proteins in the parasite enriched in this fraction. We further validated the direct interactions between a few TA candidates, PfGet4 and PfGet2 with PfGet3 using recombinant-based pulldown studies. In conclusion, this study classified a subset of membrane proteins with the TA nomenclature and implicated a previously unidentified GET pathway for their translocation in this apicomplexan parasite.
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Affiliation(s)
- Tarkeshwar Kumar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Satarupa Maitra
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Abdur Rahman
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Souvik Bhattacharjee
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
- * E-mail:
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Farkas Á, Bohnsack KE. Capture and delivery of tail-anchored proteins to the endoplasmic reticulum. J Cell Biol 2021; 220:212470. [PMID: 34264263 PMCID: PMC8287540 DOI: 10.1083/jcb.202105004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/20/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022] Open
Abstract
Tail-anchored (TA) proteins fulfill diverse cellular functions within different organellar membranes. Their characteristic C-terminal transmembrane segment renders TA proteins inherently prone to aggregation and necessitates their posttranslational targeting. The guided entry of TA proteins (GET in yeast)/transmembrane recognition complex (TRC in humans) pathway represents a major route for TA proteins to the endoplasmic reticulum (ER). Here, we review important new insights into the capture of nascent TA proteins at the ribosome by the GET pathway pretargeting complex and the mechanism of their delivery into the ER membrane by the GET receptor insertase. Interestingly, several alternative routes by which TA proteins can be targeted to the ER have emerged, raising intriguing questions about how selectivity is achieved during TA protein capture. Furthermore, mistargeting of TA proteins is a fundamental cellular problem, and we discuss the recently discovered quality control machineries in the ER and outer mitochondrial membrane for displacing mislocalized TA proteins.
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Affiliation(s)
- Ákos Farkas
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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