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Yan Y, Guo YT, Chang CY, Li XM, Zhang MQ, Ding CH, Cui D, Sun C, Ren Y, Wang ML, Xie C, Ni Z, Sun Q, Chen F, Gou 缑金营 JY. HSP90.2 modulates 2Q2-mediated wheat resistance against powdery mildew. PLANT, CELL & ENVIRONMENT 2023; 46:1935-1945. [PMID: 36890722 DOI: 10.1111/pce.14579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/30/2023] [Accepted: 03/06/2023] [Indexed: 05/04/2023]
Abstract
Wheat (Triticum aestivum L.) is a critical food crop feeding the world, but pathogens threaten its production. Wheat Heat Shock Protein 90.2 (HSP90.2) is a pathogen-inducible molecular chaperone folding nascent preproteins. Here, we used wheat HSP90.2 to isolate clients regulated at the posttranslational level. Tetraploid wheat hsp90.2 knockout mutant was susceptible to powdery mildew, while the HSP90.2 overexpression line was resistant, suggesting that HSP90.2 was essential for wheat resistance against powdery mildew. We next isolated 1500 clients of HSP90.2, which contained a wide variety of clients with different biological classifications. We utilized 2Q2, a nucleotide-binding leucine repeat-rich protein, as a model to investigate the potential of HSP90.2 interactome in fungal resistance. The transgenic line co-suppressing 2Q2 was more susceptible to powdery mildew, suggesting 2Q2 as a novel Pm-resistant gene. The 2Q2 protein resided in chloroplasts, and HSP90.2 played a critical role in the accumulation of 2Q2 in thylakoids. Our data provided over 1500 HSP90.2 clients with a potential regulation at the protein folding process and contributed a nontypical approach to isolate pathogenesis-related proteins.
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Affiliation(s)
- Yan Yan
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
- School of Life Sciences, Fudan University, Shanghai, China
| | - Yue-Ting Guo
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Chao-Yan Chang
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Xiao-Ming Li
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Mei-Qi Zhang
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Ci-Hang Ding
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Dangqun Cui
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Congwei Sun
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Yan Ren
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Meng-Lu Wang
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Chaojie Xie
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Zhongfu Ni
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Qixin Sun
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
| | - Feng Chen
- National Key Laboratory of Wheat and Maize Crop Science/CIMMYT-China Wheat and Maize Improvement Joint Center/College of Agronomy, Henan Agricultural University, Zhengzhou, China
| | - Jin-Ying Gou 缑金营
- School of Life Sciences, Fudan University, Shanghai, China
- Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China
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2
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Günsel U, Klöpfer K, Häusler E, Hitzenberger M, Bölter B, Sperl LE, Zacharias M, Soll J, Hagn F. Structural basis of metabolite transport by the chloroplast outer envelope channel OEP21. Nat Struct Mol Biol 2023:10.1038/s41594-023-00984-y. [PMID: 37156968 DOI: 10.1038/s41594-023-00984-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/31/2023] [Indexed: 05/10/2023]
Abstract
Triose phosphates (TPs) are the primary products of photosynthetic CO2 fixation in chloroplasts, which need to be exported into the cytosol across the chloroplast inner envelope (IE) and outer envelope (OE) membranes to sustain plant growth. While transport across the IE is well understood, the mode of action of the transporters in the OE remains unclear. Here we present the high-resolution nuclear magnetic resonance (NMR) structure of the outer envelope protein 21 (OEP21) from garden pea, the main exit pore for TPs in C3 plants. OEP21 is a cone-shaped β-barrel pore with a highly positively charged interior that enables binding and translocation of negatively charged metabolites in a competitive manner, up to a size of ~1 kDa. ATP stabilizes the channel and keeps it in an open state. Despite the broad substrate selectivity of OEP21, these results suggest that control of metabolite transport across the OE might be possible.
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Affiliation(s)
- Umut Günsel
- Bavarian NMR Center (BNMRZ), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany
- Institute of Structural Biology, Helmholtz Munich, Neuherberg, Germany
| | - Kai Klöpfer
- Bavarian NMR Center (BNMRZ), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - Elisabeth Häusler
- Institute of Structural Biology, Helmholtz Munich, Neuherberg, Germany
| | - Manuel Hitzenberger
- Lehrstuhl für Theoretische Biophysik (T38), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - Bettina Bölter
- Biozentrum, LMU München, Department of Biology, Planegg-Martinsried, Germany
| | - Laura E Sperl
- Bavarian NMR Center (BNMRZ), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - Martin Zacharias
- Lehrstuhl für Theoretische Biophysik (T38), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany
| | - Jürgen Soll
- Biozentrum, LMU München, Department of Biology, Planegg-Martinsried, Germany
| | - Franz Hagn
- Bavarian NMR Center (BNMRZ), Department of Bioscience, School of Natural Sciences, Technical University of Munich, Garching, Germany.
- Institute of Structural Biology, Helmholtz Munich, Neuherberg, Germany.
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3
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Overly Cottom C, Stephenson R, Wilson L, Noinaj N. Targeting BAM for Novel Therapeutics against Pathogenic Gram-Negative Bacteria. Antibiotics (Basel) 2023; 12:679. [PMID: 37107041 PMCID: PMC10135246 DOI: 10.3390/antibiotics12040679] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 04/29/2023] Open
Abstract
The growing emergence of multidrug resistance in bacterial pathogens is an immediate threat to human health worldwide. Unfortunately, there has not been a matching increase in the discovery of new antibiotics to combat this alarming trend. Novel contemporary approaches aimed at antibiotic discovery against Gram-negative bacterial pathogens have expanded focus to also include essential surface-exposed receptors and protein complexes, which have classically been targeted for vaccine development. One surface-exposed protein complex that has gained recent attention is the β-barrel assembly machinery (BAM), which is conserved and essential across all Gram-negative bacteria. BAM is responsible for the biogenesis of β-barrel outer membrane proteins (β-OMPs) into the outer membrane. These β-OMPs serve essential roles for the cell including nutrient uptake, signaling, and adhesion, but can also serve as virulence factors mediating pathogenesis. The mechanism for how BAM mediates β-OMP biogenesis is known to be dynamic and complex, offering multiple modes for inhibition by small molecules and targeting by larger biologics. In this review, we introduce BAM and establish why it is a promising and exciting new therapeutic target and present recent studies reporting novel compounds and vaccines targeting BAM across various bacteria. These reports have fueled ongoing and future research on BAM and have boosted interest in BAM for its therapeutic promise in combatting multidrug resistance in Gram-negative bacterial pathogens.
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Affiliation(s)
- Claire Overly Cottom
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Robert Stephenson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lindsey Wilson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Nicholas Noinaj
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
- Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
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Sierra J, McQuinn RP, Leon P. The role of carotenoids as a source of retrograde signals: impact on plant development and stress responses. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:7139-7154. [PMID: 35776102 DOI: 10.1093/jxb/erac292] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Communication from plastids to the nucleus via retrograde signal cascades is essential to modulate nuclear gene expression, impacting plant development and environmental responses. Recently, a new class of plastid retrograde signals has emerged, consisting of acyclic and cyclic carotenoids and/or their degradation products, apocarotenoids. Although the biochemical identity of many of the apocarotenoid signals is still under current investigation, the examples described herein demonstrate the central roles that these carotenoid-derived signals play in ensuring plant development and survival. We present recent advances in the discovery of apocarotenoid signals and their role in various plant developmental transitions and environmental stress responses. Moreover, we highlight the emerging data exposing the highly complex signal transduction pathways underlying plastid to nucleus apocarotenoid retrograde signaling cascades. Altogether, this review summarizes the central role of the carotenoid pathway as a major source of retrograde signals in plants.
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Affiliation(s)
- Julio Sierra
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad, Ciudada de México, México
| | - Ryan P McQuinn
- School of Science, Western Sydney University, Penrith, NSW, Australia
| | - Patricia Leon
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad, Ciudada de México, México
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5
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Sáiz-Bonilla M, Martín Merchán A, Pallás V, Navarro JA. Molecular characterization, targeting and expression analysis of chloroplast and mitochondrion protein import components in Nicotiana benthamiana. FRONTIERS IN PLANT SCIENCE 2022; 13:1040688. [PMID: 36388587 PMCID: PMC9643744 DOI: 10.3389/fpls.2022.1040688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Improved bioinformatics tools for annotating gene function are becoming increasingly available, but such information must be considered theoretical until further experimental evidence proves it. In the work reported here, the genes for the main components of the translocons of the outer membrane of chloroplasts (Toc) and mitochondria (Tom), including preprotein receptors and protein-conducting channels of N. benthamiana, were identified. Sequence identity searches and phylogenetic relationships with functionally annotated sequences such as those of A. thaliana revealed that N. benthamiana orthologs mainly exist as recently duplicated loci. Only a Toc34 ortholog was found (NbToc34), while Toc159 receptor family was composed of four orthologs but somewhat different from those of A. thaliana. Except for NbToc90, the rest (NbToc120, NbToc159A and NbToc159B) had a molecular weight of about 150 kDa and an acidic domain similar in length. Only two orthologs of the Tom20 receptors, NbTom20-1 and NbTom20-2, were found. The number of the Toc and Tom receptor isoforms in N. benthamiana was comparable to that previously reported in tomato and what we found in BLAST searches in other species in the genera Nicotiana and Solanum. After cloning, the subcellular localization of N. benthamiana orthologs was studied, resulting to be identical to that of A. thaliana receptors. Phenotype analysis after silencing together with relative expression analysis in roots, stems and leaves revealed that, except for the Toc and Tom channel-forming components (NbToc75 and NbTom40) and NbToc34, functional redundancy could be observed either among Toc159 or mitochondrial receptors. Finally, heterodimer formation between NbToc34 and the NbToc159 family receptors was confirmed by two alternative techniques indicating that different Toc complexes could be assembled. Additional work needs to be addressed to know if this results in a functional specialization of each Toc complex.
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Affiliation(s)
| | | | - Vicente Pallás
- *Correspondence: Vicente Pallas, ; Jose Antonio Navarro,
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6
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Li Y, Jian Y, Mao Y, Meng F, Shao Z, Wang T, Zheng J, Wang Q, Liu L. "Omics" insights into plastid behavior toward improved carotenoid accumulation. FRONTIERS IN PLANT SCIENCE 2022; 13:1001756. [PMID: 36275568 PMCID: PMC9583013 DOI: 10.3389/fpls.2022.1001756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Plastids are a group of diverse organelles with conserved carotenoids synthesizing and sequestering functions in plants. They optimize the carotenoid composition and content in response to developmental transitions and environmental stimuli. In this review, we describe the turbulence and reforming of transcripts, proteins, and metabolic pathways for carotenoid metabolism and storage in various plastid types upon organogenesis and external influences, which have been studied using approaches including genomics, transcriptomics, proteomics, and metabonomics. Meanwhile, the coordination of plastid signaling and carotenoid metabolism including the effects of disturbed carotenoid biosynthesis on plastid morphology and function are also discussed. The "omics" insight extends our understanding of the interaction between plastids and carotenoids and provides significant implications for designing strategies for carotenoid-biofortified crops.
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Affiliation(s)
- Yuanyuan Li
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Yue Jian
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Yuanyu Mao
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Fanliang Meng
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Zhiyong Shao
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Tonglin Wang
- Hangzhou Academy of Agricultural Sciences, Hangzhou, China
| | - Jirong Zheng
- Hangzhou Academy of Agricultural Sciences, Hangzhou, China
| | - Qiaomei Wang
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
| | - Lihong Liu
- Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou, China
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TIC236 gain-of-function mutations unveil the link between plastid division and plastid protein import. Proc Natl Acad Sci U S A 2022; 119:e2123353119. [PMID: 35275795 PMCID: PMC8931380 DOI: 10.1073/pnas.2123353119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although plastid division is critical for plant development, how components of the plastid division machinery (PDM) are imported into plastids remains unexplored. A forward genetic screen to identify suppressors of a crumpled leaf (crl) mutant deficient in plastid division led us to find dominant gain-of-function (GF) mutations in TIC236, which significantly increases the import of PDM components and completely rescues crl phenotypes. The defective plastid division phenotypes in crl and tic236-knockdown mutants and CRL-TIC236 association in a functional complex indicate that the CRL-TIC236 module is vital for plastid division. Hence, we report the first GF translocon mutants and unveil CRL as a novel functional partner of TIC236 for PDM import. TIC236 is an essential component of the translocon for protein import into chloroplasts, as evidenced by the embryonic lethality of the knockout mutant. Here, we unveil a TIC236-allied component, the chloroplast outer membrane protein CRUMPLED LEAF (CRL), absence of which impairs plastid division and induces autoimmune responses in Arabidopsis thaliana. A forward genetic screen exploring CRL function found multiple dominant TIC236 gain-of-function (tic236-gf) mutations that abolished crl-induced phenotypes. Moreover, CRL associates with TIC236, and a tic236-knockdown mutant exhibited multiple lesions similar to the crl mutant, supporting their shared functionality. Consistent with the defective plastid division phenotype of crl, CRL interacts with the transit peptides of proteins essential in plastid division, with tic236-gf mutations reinforcing their import via increased TIC236 stability. Ensuing reverse genetic analyses further revealed genetic interaction between CRL and SP1, a RING-type ubiquitin E3 ligase, as well as with the plastid protease FTSH11, which function in TOC and TIC protein turnover, respectively. Loss of either SP1 or FTSH11 rescued crl mutant phenotypes to varying degrees due to increased translocon levels. Collectively, our data shed light on the links between plastid protein import, plastid division, and plant stress responses.
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Backes S, Bykov YS, Flohr T, Räschle M, Zhou J, Lenhard S, Krämer L, Mühlhaus T, Bibi C, Jann C, Smith JD, Steinmetz LM, Rapaport D, Storchová Z, Schuldiner M, Boos F, Herrmann JM. The chaperone-binding activity of the mitochondrial surface receptor Tom70 protects the cytosol against mitoprotein-induced stress. Cell Rep 2021; 35:108936. [PMID: 33826901 PMCID: PMC7615001 DOI: 10.1016/j.celrep.2021.108936] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/22/2020] [Accepted: 03/11/2021] [Indexed: 02/08/2023] Open
Abstract
Most mitochondrial proteins are synthesized as precursors in the cytosol and post-translationally transported into mitochondria. The mitochondrial surface protein Tom70 acts at the interface of the cytosol and mitochondria. In vitro import experiments identified Tom70 as targeting receptor, particularly for hydrophobic carriers. Using in vivo methods and high-content screens, we revisit the question of Tom70 function and considerably expand the set of Tom70-dependent mitochondrial proteins. We demonstrate that the crucial activity of Tom70 is its ability to recruit cytosolic chaperones to the outer membrane. Indeed, tethering an unrelated chaperone-binding domain onto the mitochondrial surface complements most of the defects caused by Tom70 deletion. Tom70-mediated chaperone recruitment reduces the proteotoxicity of mitochondrial precursor proteins, particularly of hydrophobic inner membrane proteins. Thus, our work suggests that the predominant function of Tom70 is to tether cytosolic chaperones to the outer mitochondrial membrane, rather than to serve as a mitochondrion-specifying targeting receptor.
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Affiliation(s)
- Sandra Backes
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Yury S Bykov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tamara Flohr
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jialin Zhou
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Svenja Lenhard
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Chen Bibi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Cosimo Jann
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Department of Biology, Institute of Biochemistry, ETH Zürich, 8093 Zürich, Switzerland
| | - Justin D Smith
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lars M Steinmetz
- Genome Biology Unit, EMBL, Meyerhofstraße 1, 69117 Heidelberg, Germany; Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Zuzana Storchová
- Molecular Genetics, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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9
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Kreimendahl S, Rassow J. The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity. Int J Mol Sci 2020; 21:E7262. [PMID: 33019591 PMCID: PMC7583919 DOI: 10.3390/ijms21197262] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 02/08/2023] Open
Abstract
Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.
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Affiliation(s)
| | - Joachim Rassow
- Institute for Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44801 Bochum, Germany;
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10
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Intrinsic Disorder in Tetratricopeptide Repeat Proteins. Int J Mol Sci 2020; 21:ijms21103709. [PMID: 32466138 PMCID: PMC7279152 DOI: 10.3390/ijms21103709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/12/2020] [Accepted: 05/22/2020] [Indexed: 12/27/2022] Open
Abstract
Among the realm of repeat containing proteins that commonly serve as “scaffolds” promoting protein-protein interactions, there is a family of proteins containing between 2 and 20 tetratricopeptide repeats (TPRs), which are functional motifs consisting of 34 amino acids. The most distinguishing feature of TPR domains is their ability to stack continuously one upon the other, with these stacked repeats being able to affect interaction with binding partners either sequentially or in combination. It is known that many repeat-containing proteins are characterized by high levels of intrinsic disorder, and that many protein tandem repeats can be intrinsically disordered. Furthermore, it seems that TPR-containing proteins share many characteristics with hybrid proteins containing ordered domains and intrinsically disordered protein regions. However, there has not been a systematic analysis of the intrinsic disorder status of TPR proteins. To fill this gap, we analyzed 166 human TPR proteins to determine the degree to which proteins containing TPR motifs are affected by intrinsic disorder. Our analysis revealed that these proteins are characterized by different levels of intrinsic disorder and contain functional disordered regions that are utilized for protein-protein interactions and often serve as targets of various posttranslational modifications.
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11
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Richardson LGL, Schnell DJ. Origins, function, and regulation of the TOC-TIC general protein import machinery of plastids. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1226-1238. [PMID: 31730153 PMCID: PMC7031061 DOI: 10.1093/jxb/erz517] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 11/14/2019] [Indexed: 05/11/2023]
Abstract
The evolution of chloroplasts from the original endosymbiont involved the transfer of thousands of genes from the ancestral bacterial genome to the host nucleus, thereby combining the two genetic systems to facilitate coordination of gene expression and achieve integration of host and organelle functions. A key element of successful endosymbiosis was the evolution of a unique protein import system to selectively and efficiently target nuclear-encoded proteins to their site of function within the chloroplast after synthesis in the cytoplasm. The chloroplast TOC-TIC (translocon at the outer chloroplast envelope-translocon at the inner chloroplast envelope) general protein import system is conserved across the plant kingdom, and is a system of hybrid origin, with core membrane transport components adapted from bacterial protein targeting systems, and additional components adapted from host genes to confer the specificity and directionality of import. In vascular plants, the TOC-TIC system has diversified to mediate the import of specific, functionally related classes of plastid proteins. This functional diversification occurred as the plastid family expanded to fulfill cell- and tissue-specific functions in terrestrial plants. In addition, there is growing evidence that direct regulation of TOC-TIC activities plays an essential role in the dynamic remodeling of the organelle proteome that is required to coordinate plastid biogenesis with developmental and physiological events.
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Affiliation(s)
- Lynn G L Richardson
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Danny J Schnell
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
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12
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Co-Translational Protein Folding and Sorting in Chloroplasts. PLANTS 2020; 9:plants9020214. [PMID: 32045984 PMCID: PMC7076657 DOI: 10.3390/plants9020214] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 01/22/2023]
Abstract
Cells depend on the continuous renewal of their proteome composition during the cell cycle and in order to replace aberrant proteins or to react to changing environmental conditions. In higher eukaryotes, protein synthesis is achieved by up to five million ribosomes per cell. With the fast kinetics of translation, the large number of newly made proteins generates a substantial burden for protein homeostasis and requires a highly orchestrated cascade of factors promoting folding, sorting and final maturation. Several of the involved factors directly bind to translating ribosomes for the early processing of emerging nascent polypeptides and the translocation of ribosome nascent chain complexes to target membranes. In plant cells, protein synthesis also occurs in chloroplasts serving the expression of a relatively small set of 60–100 protein-coding genes. However, most of these proteins, together with nucleus-derived subunits, form central complexes majorly involved in the essential processes of photosynthetic light reaction, carbon fixation, metabolism and gene expression. Biogenesis of these heterogenic complexes adds an additional level of complexity for protein biogenesis. In this review, we summarize the current knowledge about co-translationally binding factors in chloroplasts and discuss their role in protein folding and ribosome translocation to thylakoid membranes.
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Schnell DJ. The TOC GTPase Receptors: Regulators of the Fidelity, Specificity and Substrate Profiles of the General Protein Import Machinery of Chloroplasts. Protein J 2020; 38:343-350. [PMID: 31201619 PMCID: PMC6589150 DOI: 10.1007/s10930-019-09846-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
More than 2500 nuclear encoded preproteins are required for the function of chloroplasts in terrestrial plants. These preproteins are imported into chloroplasts via the concerted action of two multi-subunit translocons of the outer (TOC) and inner (TIC) membranes of the chloroplast envelope. This general import machinery functions to recognize and import proteins with high fidelity and efficiency to ensure that organelle biogenesis is properly coordinated with developmental and physiological events. Two components of the TOC machinery, Toc34 and Toc159, act as the primary receptors for preproteins at the chloroplast surface. They interact with the intrinsic targeting signals (transit peptides) of preproteins to mediate the selectivity of targeting, and they contribute to the quality control of import by constituting a GTP-dependent checkpoint in the import reaction. The TOC receptor family has expanded to regulate the import of distinct classes of preproteins that are required for remodeling of organelle proteomes during plastid-type transitions that accompany developmental changes. As such, the TOC receptors function as central regulators of the fidelity, specificity and selectivity of the general import machinery, thereby contributing to the integration of protein import with plastid biogenesis.
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Affiliation(s)
- Danny J Schnell
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.
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Könnel A, Bugaeva W, Gügel IL, Philippar K. BANFF: bending of bilayer membranes by amphiphilic α-helices is necessary for form and function of organelles 1. Biochem Cell Biol 2018; 97:243-256. [PMID: 30208283 DOI: 10.1139/bcb-2018-0150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
By binding to and inserting into the lipid bilayer, amphiphilic α-helices of proteins are involved in the curvature of biological membranes in all organisms. In particular, they are involved in establishing the complex membrane architecture of intracellular organelles like the endoplasmatic reticulum, Golgi apparatus, mitochondria, and chloroplasts. Thus, amphiphilic α-helices are essential for maintenance of cellular metabolism and fitness of organisms. Here we focus on the structure and function of membrane-intrinsic proteins, which are involved in membrane curvature by amphiphilic α-helices, in mitochondria and chloroplasts of the eukaryotic model organisms yeast and Arabidopsis thaliana. Further, we propose a model for transport of fatty acids and lipid compounds across the envelope of chloroplasts in which amphiphilic α-helices might play a role.
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Affiliation(s)
- Anne Könnel
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
| | - Wassilina Bugaeva
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
| | - Irene L Gügel
- b Department of Biology I - Botany, Ludwig-Maximilians University München, Großhaderner-Str. 2, 82152 Planegg-Martinsried, Germany
| | - Katrin Philippar
- a Center for Human- and Molecular Biology (ZHMB) - Plant Biology, Saarland University, Campus A 2.4, 66123 Saarbrücken, Germany
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The impact of a changing atmosphere on chloroplast function, photosynthesis, yield, and food security. Essays Biochem 2018; 62:1-11. [DOI: 10.1042/ebc20180023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 03/07/2018] [Accepted: 03/07/2018] [Indexed: 11/17/2022]
Abstract
A convergence of global factors is adding to the difficulties of securing a sustainable supply of food and feed to support the increasing global population. The positive impact of the rise in atmospheric CO2 on photosynthesis is more than offset by the increase in average global temperatures accompanying the change in atmospheric composition. This article provides a brief overview of how these adverse events affect some of the critical molecular processes of the chloroplast and by extension how this impacts the yields of the major crops. Although the tools are available to introduce genetic elements in most crops that will mitigate these adverse factors, the time needed to validate and optimize these traits can be extensive. There is a major concern that at the current rate of change to atmospheric composition and the accompanying rise in temperature the benefits of these traits may be rendered less effective soon after their introduction.
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