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Nebli S, Rebai A, Ayadi I. Screening clusters of charged residues in plants' mitochondrial proteins and biological significance. Mitochondrion 2024; 78:101938. [PMID: 39013535 DOI: 10.1016/j.mito.2024.101938] [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: 04/06/2024] [Revised: 07/09/2024] [Accepted: 07/12/2024] [Indexed: 07/18/2024]
Abstract
Protein function is dependent on charge interactions and charge biased regions, which are involved in a wide range of cellular and biochemical processes. We report the development of a new algorithm implemented in Python and its use to identify charge clusters CC (NegativeCC: NCC, PositiveCC: PCC and MixedCC: MCC) and compare their presence in mitochondrial proteins of plant groups. To characterize the resulting CC, statistical, structural and functional analyses were conducted. The screening of 105 399 protein sequences showed that 2.6 %, 0.48 % and 0.03 % of the proteins contain NCC, PCC and MCC, respectively. Mitochondrial proteins encoded by the nuclear genome of green algae have the biggest proportion of both PCC (1.6 %) and MCC (0.4 %) and mitochondrial proteins coded by the nuclear genome of other plants group have the highest portion of NCC (7.5 %). The mapping of the identified CC showed that they are mainly located in the terminal regions of the protein. Annotation showed that proteins with CC are classified as binding proteins, are included in the transmembrane transport processes, and are mainly located in the membrane. The CC scanning revealed the presence of 2373 and 784 sites and 192 and 149 motif profiles within NCC and PCC, respectively. The investigation of CC within pentatricopeptide repeat-containing proteins revealed that they are involved in correct and specific RNA editing. CC were proven to play a key role in providing insightful structural and functional information of complex protein assemblies which could be useful in biotechnological applications.
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Affiliation(s)
- Syrine Nebli
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, P. O. Box 1177, 3018 Sfax, Tunisia.
| | - Ahmed Rebai
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, P. O. Box 1177, 3018 Sfax, Tunisia.
| | - Imen Ayadi
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, P. O. Box 1177, 3018 Sfax, Tunisia.
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Hirata R, Mogi Y, Takahashi K, Nozaki H, Higashiyama T, Yoshida Y. Simple prerequisite of presequence for mitochondrial protein import in the unicellular red alga Cyanidioschyzon merolae. J Cell Sci 2024; 137:jcs262042. [PMID: 38940185 PMCID: PMC11298712 DOI: 10.1242/jcs.262042] [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: 02/19/2024] [Accepted: 06/13/2024] [Indexed: 06/29/2024] Open
Abstract
Mitochondrial biogenesis relies on hundreds of proteins that are derived from genes encoded in the nucleus. According to the characteristic properties of N-terminal targeting peptides (TPs) and multi-step authentication by the protein translocase called the TOM complex, nascent polypeptides satisfying the requirements are imported into mitochondria. However, it is unknown whether eukaryotic cells with a single mitochondrion per cell have a similar complexity of presequence requirements for mitochondrial protein import compared to other eukaryotes with multiple mitochondria. Based on putative mitochondrial TP sequences in the unicellular red alga Cyanidioschyzon merolae, we designed synthetic TPs and showed that functional TPs must have at least one basic residue and a specific amino acid composition, although their physicochemical properties are not strictly determined. Combined with the simple composition of the TOM complex in C. merolae, our results suggest that a regional positive charge in TPs is verified solely by TOM22 for mitochondrial protein import in C. merolae. The simple authentication mechanism indicates that the monomitochondrial C. merolae does not need to increase the cryptographic complexity of the lock-and-key mechanism for mitochondrial protein import.
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Affiliation(s)
- Riko Hirata
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yuko Mogi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kohei Takahashi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hisayoshi Nozaki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Biodiversity Division, National Institute for Environmental Studies, Ibaraki 305-8506, Japan
| | - Tetsuya Higashiyama
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yamato Yoshida
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Japan Science and Technology Agency (JST), PRESTO, Tokyo 113-0033, Japan
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Zhao X, Wang J, Li D, Ma F, Fang Y, Lu J, Hou N. Investigation of non-classical secretion of oxalate decarboxylase in Bacillus mojavensis XH1 mediated by exopeptide YydF: Mechanism and application. Int J Biol Macromol 2024; 264:130662. [PMID: 38453118 DOI: 10.1016/j.ijbiomac.2024.130662] [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: 09/14/2023] [Revised: 02/20/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024]
Abstract
Non-classical secretory proteins are widely found in bacteria and have been extensively studied due to their important physiological roles. However, the relevant non-classical secretory mechanisms remain unclear. In this study, we found that oxalate decarboxylase (Bacm OxDC) from Bacillus mojavensis XH1 belongs to non-classical secretory proteins. Its N-terminus showed high hydrophilicity, which was different from the conventional signal peptide. The truncation test revealed that the deletion of the N-terminus affects the structure resulting in its inability to cross the cell membrane. Further studies verified that the exported peptide YydF played an important role in the secretion process of Bacm OxDC. Experimental results on the secretion mechanism indicated that Bacm OxDC bound to the exported peptide YydF and they are translocated to the cell membrane together, after which Bacm OxDC caused cell membrane relaxation for transmembrane secretion. Thereafter, three recombinant proteins were successfully secreted with certain enzymatic activity by fusing Bacm OxDC as a guide protein with various target proteins. To the best of our knowledge, this was the first time that non-classical secretion mechanism in bacteria has been analyzed. The novel discovery may provide a reference and broaden the horizons of the secretion pathway and expression regulation of proteins.
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Affiliation(s)
- Xin Zhao
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Jian Wang
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Dapeng Li
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China.
| | - Fang Ma
- College of Environment, Harbin Institute of Technology, No. 73 Yellow River Street, Harbin, Heilongjiang 150090, PR China
| | - Yongping Fang
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Jia Lu
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China
| | - Ning Hou
- College of Resources and Environment, Northeast Agricultural University, No. 600 Changjiang Street, Harbin, Heilongjiang 150030, PR China.
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Ludwig-Müller J. Production of Plant Proteins and Peptides with Pharmacological Potential. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2024; 188:51-81. [PMID: 38286902 DOI: 10.1007/10_2023_246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
The use of plant proteins or peptides in biotechnology is based on their identification as possessing bioactive potential in plants. This is usually the case for antimicrobial, fungicidal, or insecticidal components of the plant's defense system. They function in addition to a large number of specialized metabolites. Such proteins can be classified according to their sequence, length, and structure, and this has been tried to describe for a few examples here. Even though such proteins or peptides can be induced during plant-pathogen interaction, they are still present in rather small amounts that make the system not suitable for the production in large-scale systems. Therefore, a suitable type of host needs to be identified, such as cell cultures or adult plants. Bioinformatic predictions can also be used to add to the number of bioactive sequences. Some problems that can occur in production by the plant system itself will be discussed, such as choice of promoter for gene expression, posttranslational protein modifications, protein stability, secretion of proteins, or induction by elicitors. Finally, the plant needs to be set up by biotechnological or molecular methods for production, and the product needs to be enriched or purified. In some cases of small peptides, a direct chemical synthesis might be feasible. Altogether, the process needs to be considered marketable.
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Schwarze J, Carolan JC, Stewart GS, McCabe PF, Kacprzyk J. The boundary of life and death: changes in mitochondrial and cytosolic proteomes associated with programmed cell death of Arabidopsis thaliana suspension culture cells. FRONTIERS IN PLANT SCIENCE 2023; 14:1194866. [PMID: 37593044 PMCID: PMC10431908 DOI: 10.3389/fpls.2023.1194866] [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: 03/27/2023] [Accepted: 06/22/2023] [Indexed: 08/19/2023]
Abstract
Introduction Despite the critical role of programmed cell death (PCD) in plant development and defense responses, its regulation is not fully understood. It has been proposed that mitochondria may be important in the control of the early stages of plant PCD, but the details of this regulation are currently unknown. Methods We used Arabidopsis thaliana cell suspension culture, a model system that enables induction and precise monitoring of PCD rates, as well as chemical manipulation of this process to generate a quantitative profile of the alterations in mitochondrial and cytosolic proteomes associated with early stages of plant PCD induced by heat stress. The cells were subjected to PCD-inducing heat levels (10 min, 54°C), with/without the calcium channel inhibitor and PCD blocker LaCl3. The stress treatment was followed by separation of cytosolic and mitochondrial fractions and mass spectrometry-based proteome analysis. Results Heat stress induced rapid and extensive changes in protein abundance in both fractions, with release of mitochondrial proteins into the cytosol upon PCD induction. In our system, LaCl3 appeared to act downstream of cell death initiation signal, as it did not affect the release of mitochondrial proteins, but instead partially inhibited changes occurring in the cytosolic fraction, including upregulation of proteins with hydrolytic activity. Discussion We characterized changes in protein abundance and localization associated with the early stages of heat stress-induced PCD. Collectively, the generated data provide new insights into the regulation of cell death and survival decisions in plant cells.
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Affiliation(s)
- Johanna Schwarze
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | | | - Gavin S. Stewart
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Paul F. McCabe
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Joanna Kacprzyk
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
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Christian R, Labbancz J, Usadel B, Dhingra A. Understanding protein import in diverse non-green plastids. Front Genet 2023; 14:969931. [PMID: 37007964 PMCID: PMC10063809 DOI: 10.3389/fgene.2023.969931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 02/24/2023] [Indexed: 03/19/2023] Open
Abstract
The spectacular diversity of plastids in non-green organs such as flowers, fruits, roots, tubers, and senescing leaves represents a Universe of metabolic processes in higher plants that remain to be completely characterized. The endosymbiosis of the plastid and the subsequent export of the ancestral cyanobacterial genome to the nuclear genome, and adaptation of the plants to all types of environments has resulted in the emergence of diverse and a highly orchestrated metabolism across the plant kingdom that is entirely reliant on a complex protein import and translocation system. The TOC and TIC translocons, critical for importing nuclear-encoded proteins into the plastid stroma, remain poorly resolved, especially in the case of TIC. From the stroma, three core pathways (cpTat, cpSec, and cpSRP) may localize imported proteins to the thylakoid. Non-canonical routes only utilizing TOC also exist for the insertion of many inner and outer membrane proteins, or in the case of some modified proteins, a vesicular import route. Understanding this complex protein import system is further compounded by the highly heterogeneous nature of transit peptides, and the varying transit peptide specificity of plastids depending on species and the developmental and trophic stage of the plant organs. Computational tools provide an increasingly sophisticated means of predicting protein import into highly diverse non-green plastids across higher plants, which need to be validated using proteomics and metabolic approaches. The myriad plastid functions enable higher plants to interact and respond to all kinds of environments. Unraveling the diversity of non-green plastid functions across the higher plants has the potential to provide knowledge that will help in developing climate resilient crops.
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Affiliation(s)
- Ryan Christian
- Department of Horticulture, Washington State University, Pullman, WA, United States
| | - June Labbancz
- Department of Horticulture, Washington State University, Pullman, WA, United States
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, United States
| | | | - Amit Dhingra
- Department of Horticulture, Washington State University, Pullman, WA, United States
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, United States
- *Correspondence: Amit Dhingra,
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Lee J, Moon B, Lee DW, Hwang I. Translation rate underpins specific targeting of N-terminal transmembrane proteins to mitochondria. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023. [PMID: 36897023 DOI: 10.1111/jipb.13475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Protein biogenesis is a complex process, and complexity is greatly increased in eukaryotic cells through specific targeting of proteins to different organelles. To direct targeting, organellar proteins carry an organelle-specific targeting signal for recognition by organelle-specific import machinery. However, the situation is confusing for transmembrane domain (TMD)-containing signal-anchored (SA) proteins of various organelles because TMDs function as an endoplasmic reticulum (ER) targeting signal. Although ER targeting of SA proteins is well understood, how they are targeted to mitochondria and chloroplasts remains elusive. Here, we investigated how the targeting specificity of SA proteins is determined for specific targeting to mitochondria and chloroplasts. Mitochondrial targeting requires multiple motifs around and within TMDs: a basic residue and an arginine-rich region flanking the N- and C-termini of TMDs, respectively, and an aromatic residue in the C-terminal side of the TMD that specify mitochondrial targeting in an additive manner. These motifs play a role in slowing down the elongation speed during translation, thereby ensuring mitochondrial targeting in a co-translational manner. By contrast, the absence of any of these motifs individually or together causes at varying degrees chloroplast targeting that occurs in a post-translational manner.
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Affiliation(s)
- Junho Lee
- Department of Life Science, Pohang University of Science and Technology, Pohang, 790-784, South Korea
| | - Byeongho Moon
- Department of Life Science, Pohang University of Science and Technology, Pohang, 790-784, South Korea
| | - Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, South Korea
- Department Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, South Korea
| | - Inhwan Hwang
- Department of Life Science, Pohang University of Science and Technology, Pohang, 790-784, South Korea
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Caspari OD, Garrido C, Law CO, Choquet Y, Wollman FA, Lafontaine I. Converting antimicrobial into targeting peptides reveals key features governing protein import into mitochondria and chloroplasts. PLANT COMMUNICATIONS 2023:100555. [PMID: 36733255 PMCID: PMC10363480 DOI: 10.1016/j.xplc.2023.100555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/18/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
We asked what peptide features govern targeting to the mitochondria versus the chloroplast, using antimicrobial peptides as a starting point. This approach was inspired by the endosymbiotic hypothesis that organelle-targeting peptides derive from antimicrobial amphipathic peptides delivered by the host cell, to which organelle progenitors became resistant. To explore the molecular changes required to convert antimicrobial into targeting peptides, we expressed a set of 13 antimicrobial peptides in Chlamydomonas reinhardtii. Peptides were systematically modified to test distinctive features of mitochondrion- and chloroplast-targeting peptides, and we assessed their targeting potential by following the intracellular localization and maturation of a Venus fluorescent reporter used as a cargo protein. Mitochondrial targeting can be achieved by some unmodified antimicrobial peptide sequences. Targeting to both organelles is improved by replacing lysines with arginines. Chloroplast targeting is enabled by the presence of flanking unstructured sequences, additional constraints consistent with chloroplast endosymbiosis having occurred in a cell that already contained mitochondria. If indeed targeting peptides evolved from antimicrobial peptides, then required modifications imply a temporal evolutionary scenario with an early exchange of cationic residues and a late acquisition of chloroplast-specific motifs.
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Affiliation(s)
- Oliver D Caspari
- UMR7141 (CNRS/Sorbonne Université), Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France.
| | - Clotilde Garrido
- UMR7141 (CNRS/Sorbonne Université), Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Chris O Law
- Centre for Microscopy and Cellular Imaging, Biology Department Loyola Campus of Concordia University, 7141 Sherbrooke W., Montréal, QC H4B 1R6, Canada
| | - Yves Choquet
- UMR7141 (CNRS/Sorbonne Université), Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Francis-André Wollman
- UMR7141 (CNRS/Sorbonne Université), Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Ingrid Lafontaine
- UMR7141 (CNRS/Sorbonne Université), Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France.
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Kim DB, Na C, Hwang I, Lee DW. Understanding protein translocation across chloroplast membranes: Translocons and motor proteins. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:408-416. [PMID: 36223071 DOI: 10.1111/jipb.13385] [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: 08/29/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Subcellular organelles in eukaryotes are surrounded by lipid membranes. In an endomembrane system, vesicle trafficking is the primary mechanism for the delivery of organellar proteins to specific organelles. However, organellar proteins for chloroplasts, mitochondria, the nucleus, and peroxisomes that are translated in the cytosol are directly imported into their target organelles. Chloroplasts are a plant-specific organelle with outer and inner envelope membranes, a dual-membrane structure that is similar to mitochondria. Interior chloroplast proteins translated by cytosolic ribosomes are thus translocated through TOC and TIC complexes (translocons in the outer and inner envelope of chloroplasts, respectively), with stromal ATPase motor proteins playing a critical role in pulling pre-proteins through these import channels. Over the last three decades, the identity and function of TOC/TIC components and stromal motor proteins have been actively investigated, which has shed light on the action mechanisms at a molecular level. However, there remains some disagreement over the exact composition of TIC complexes and genuine stromal motor proteins. In this review, we discuss recent findings on the mechanisms by which proteins are translocated through TOC/TIC complexes and discuss future prospects for this field of research.
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Affiliation(s)
- Da Been Kim
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Changhee Na
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju, 61186, Korea
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Spatola Rossi T, Kriechbaumer V. An Interplay between Mitochondrial and ER Targeting of a Bacterial Signal Peptide in Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:617. [PMID: 36771701 PMCID: PMC9920398 DOI: 10.3390/plants12030617] [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: 12/06/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
Protein targeting is essential in eukaryotic cells to maintain cell function and organelle identity. Signal peptides are a major type of targeting sequences containing a tripartite structure, which is conserved across all domains in life. They are frequently included in recombinant protein design in plants to increase yields by directing them to the endoplasmic reticulum (ER) or apoplast. The processing of bacterial signal peptides by plant cells is not well understood but could aid in the design of efficient heterologous expression systems. Here we analysed the signal peptide of the enzyme PmoB from methanotrophic bacteria. In plant cells, the PmoB signal peptide targeted proteins to both mitochondria and the ER. This dual localisation was still observed in a mutated version of the signal peptide sequence with enhanced mitochondrial targeting efficiency. Mitochondrial targeting was shown to be dependent on a hydrophobic region involved in transport to the ER. We, therefore, suggest that the dual localisation could be due to an ER-SURF pathway recently characterised in yeast. This work thus sheds light on the processing of bacterial signal peptides by plant cells and proposes a novel pathway for mitochondrial targeting in plants.
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Affiliation(s)
- Tatiana Spatola Rossi
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Oxford Brookes Centre for Bioimaging, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Verena Kriechbaumer
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Oxford Brookes Centre for Bioimaging, Oxford Brookes University, Oxford OX3 0BP, UK
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Gao LL, Hong ZH, Wang Y, Wu GZ. Chloroplast proteostasis: A story of birth, life, and death. PLANT COMMUNICATIONS 2023; 4:100424. [PMID: 35964157 PMCID: PMC9860172 DOI: 10.1016/j.xplc.2022.100424] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/02/2022] [Accepted: 08/10/2022] [Indexed: 06/02/2023]
Abstract
Protein homeostasis (proteostasis) is a dynamic balance of protein synthesis and degradation. Because of the endosymbiotic origin of chloroplasts and the massive transfer of their genetic information to the nucleus of the host cell, many protein complexes in the chloroplasts are constituted from subunits encoded by both genomes. Hence, the proper function of chloroplasts relies on the coordinated expression of chloroplast- and nucleus-encoded genes. The biogenesis and maintenance of chloroplast proteostasis are dependent on synthesis of chloroplast-encoded proteins, import of nucleus-encoded chloroplast proteins from the cytosol, and clearance of damaged or otherwise undesired "old" proteins. This review focuses on the regulation of chloroplast proteostasis, its interaction with proteostasis of the cytosol, and its retrograde control over nuclear gene expression. We also discuss significant issues and perspectives for future studies and potential applications for improving the photosynthetic performance and stress tolerance of crops.
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Affiliation(s)
- Lin-Lin Gao
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Zheng-Hui Hong
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yinsong Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Guo-Zhang Wu
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
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12
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Rozov SM, Deineko EV. Increasing the Efficiency of the Accumulation of Recombinant Proteins in Plant Cells: The Role of Transport Signal Peptides. PLANTS (BASEL, SWITZERLAND) 2022; 11:2561. [PMID: 36235427 PMCID: PMC9572730 DOI: 10.3390/plants11192561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The problem with increasing the yield of recombinant proteins is resolvable using different approaches, including the transport of a target protein to cell compartments with a low protease activity. In the cell, protein targeting involves short-signal peptide sequences recognized by intracellular protein transport systems. The main systems of the protein transport across membranes of the endoplasmic reticulum and endosymbiotic organelles are reviewed here, as are the major types and structure of the signal sequences targeting proteins to the endoplasmic reticulum and its derivatives, to plastids, and to mitochondria. The role of protein targeting to certain cell organelles depending on specific features of recombinant proteins and the effect of this targeting on the protein yield are discussed, in addition to the main directions of the search for signal sequences based on their primary structure. This knowledge makes it possible not only to predict a protein localization in the cell but also to reveal the most efficient sequences with potential biotechnological utility.
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13
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Jeong J, Moon B, Hwang I, Lee DW. GREEN FLUORESCENT PROTEIN variants with enhanced folding are more efficiently imported into chloroplasts. PLANT PHYSIOLOGY 2022; 190:238-249. [PMID: 35699510 PMCID: PMC9434181 DOI: 10.1093/plphys/kiac291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/05/2022] [Indexed: 06/15/2023]
Abstract
Chloroplasts and mitochondria are subcellular organelles that evolved from cyanobacteria and α-proteobacteria, respectively. Although they have their own genomes, the majority of their proteins are encoded by nuclear genes, translated by cytosolic ribosomes, and imported via outer and inner membrane translocon complexes. The unfolding of mature regions of proteins is thought to be a prerequisite for the import of the proteins into these organelles. However, it is not fully understood how protein folding properties affect their import into these organelles. In this study, we examined the import behavior of chloroplast and mitochondrial reporters with normal green fluorescent protein (GFP) and two GFP variants with enhanced folding propensity, superfolder GFP (sfGFP) and extra-superfolder GFP (esGFP), which is folded better than sfGFP. sfGFP and esGFP were less dependent on the sequence motifs of the transit peptide (TP) and import machinery during protein import into Arabidopsis (Arabidopsis thaliana) chloroplasts, compared with normal GFP. sfGFP and esGFP were efficiently imported into chloroplasts by a mutant TP with an alanine substitution in the N-terminal MLM motif, whereas the same mutant TP showed a defect in importing normal GFP into chloroplasts. Moreover, sfGFP and esGFP were efficiently imported into plastid protein import 2 (ppi2) and heat shock protein 93-V (hsp93-V) plants, which have mutations in atToc159 and Hsp93-V, respectively. In contrast, the presequence-mediated mitochondrial import of sfGFP and esGFP was severely impaired. Based on these results, we propose that the chloroplast import machinery is more tolerant to different folding states of preproteins, whereas the mitochondrial machinery is more specialized in the translocation of unfolded preproteins.
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Affiliation(s)
- Jinseung Jeong
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, South Korea
| | - Byeongho Moon
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, South Korea
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14
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Woo S, Moon B, Hwang I. Both metaxin and Tom20 together with two mitochondria-specific motifs support mitochondrial targeting of dual-targeting AtSufE1. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2022; 64:1596-1613. [PMID: 35713200 DOI: 10.1111/jipb.13312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Plant cells have two endosymbiotic organelles, chloroplasts, and mitochondria. These organelles perform specific functions that depend on organelle-specific proteins. The majority of chloroplast and mitochondrial proteins are specifically imported by the transit peptide and presequence, respectively. However, a significant number of proteins are also dually targeted to these two organelles. Currently, it is not fully understood how proteins are dually targeted to both chloroplasts and mitochondria. In this study, the mechanism underlying mitochondrial targeting of dual targeting AtSufE1 in Arabidopsis was elucidated. The N-terminal fragment containing 80 residues of AtSufE1 (AtSufE1N80) was sufficient to confer dual targeting of reporter protein, AtSufE1N80:GFP, in protoplasts. Two sequence motifs, two arginine residues at 15th and 21st positions, and amino acid (aa) sequence motif AKTLLLRPLK from the 31st to 40th aa position, were responsible for targeting to mitochondria a portion of reporter proteins amid the chloroplast targeting. The sequence motif PSEVPFRRT from the 41st to 50th aa position constitutes a common motif for targeting to both chloroplasts and mitochondria. For mitochondrial import of AtSufE1:N80, Metaxin played a critical role. In addition, BiFC and protein pull-down experiments showed that AtSufE1N80 specifically interacts with import receptors, Metaxin and Tom20. The interaction of AtSufE1N80 with Metaxin was required for the interaction with Tom20. Based on these results, we propose that mitochondrial targeting of dual-targeting AtSufE1 is mediated by both mitochondria-specific and common sequence motifs in the signal sequence through the interaction with import receptors, Metaxin and Tom20, in a successive manner.
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Affiliation(s)
- Seungjin Woo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Byeongho Moon
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
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15
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Caspari OD. Transit Peptides Often Require Downstream Unstructured Sequence for Efficient Chloroplast Import in Chlamydomonas reinhardtii. FRONTIERS IN PLANT SCIENCE 2022; 13:825797. [PMID: 35646025 PMCID: PMC9133816 DOI: 10.3389/fpls.2022.825797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
The N-terminal sequence stretch that defines subcellular targeting for most nuclear encoded chloroplast proteins is usually considered identical to the sequence that is cleaved upon import. Yet here this study shows that for eight out of ten tested Chlamydomonas chloroplast transit peptides, significant additional sequence stretches past the cleavage site are required to enable efficient chloroplast import of heterologous cargo proteins. Analysis of Chlamydomonas cTPs with known cleavage sites and replacements of native post-cleavage residues with alternative sequences points to a role for unstructured sequence at mature protein N-termini.
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16
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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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17
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New Insights into the Chloroplast Outer Membrane Proteome and Associated Targeting Pathways. Int J Mol Sci 2022; 23:ijms23031571. [PMID: 35163495 PMCID: PMC8836251 DOI: 10.3390/ijms23031571] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 12/04/2022] Open
Abstract
Plastids are a dynamic class of organelle in plant cells that arose from an ancient cyanobacterial endosymbiont. Over the course of evolution, most genes encoding plastid proteins were transferred to the nuclear genome. In parallel, eukaryotic cells evolved a series of targeting pathways and complex proteinaceous machinery at the plastid surface to direct these proteins back to their target organelle. Chloroplasts are the most well-characterized plastids, responsible for photosynthesis and other important metabolic functions. The biogenesis and function of chloroplasts rely heavily on the fidelity of intracellular protein trafficking pathways. Therefore, understanding these pathways and their regulation is essential. Furthermore, the chloroplast outer membrane proteome remains relatively uncharted territory in our understanding of protein targeting. Many key players in the cytosol, receptors at the organelle surface, and insertases that facilitate insertion into the chloroplast outer membrane remain elusive for this group of proteins. In this review, we summarize recent advances in the understanding of well-characterized chloroplast outer membrane protein targeting pathways as well as provide new insights into novel targeting signals and pathways more recently identified using a bioinformatic approach. As a result of our analyses, we expand the known number of chloroplast outer membrane proteins from 117 to 138.
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18
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Heidorn-Czarna M, Maziak A, Janska H. Protein Processing in Plant Mitochondria Compared to Yeast and Mammals. FRONTIERS IN PLANT SCIENCE 2022; 13:824080. [PMID: 35185991 PMCID: PMC8847149 DOI: 10.3389/fpls.2022.824080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 01/12/2022] [Indexed: 05/02/2023]
Abstract
Limited proteolysis, called protein processing, is an essential post-translational mechanism that controls protein localization, activity, and in consequence, function. This process is prevalent for mitochondrial proteins, mainly synthesized as precursor proteins with N-terminal sequences (presequences) that act as targeting signals and are removed upon import into the organelle. Mitochondria have a distinct and highly conserved proteolytic system that includes proteases with sole function in presequence processing and proteases, which show diverse mitochondrial functions with limited proteolysis as an additional one. In virtually all mitochondria, the primary processing of N-terminal signals is catalyzed by the well-characterized mitochondrial processing peptidase (MPP). Subsequently, a second proteolytic cleavage occurs, leading to more stabilized residues at the newly formed N-terminus. Lately, mitochondrial proteases, intermediate cleavage peptidase 55 (ICP55) and octapeptidyl protease 1 (OCT1), involved in proteolytic cleavage after MPP and their substrates have been described in the plant, yeast, and mammalian mitochondria. Mitochondrial proteins can also be processed by removing a peptide from their N- or C-terminus as a maturation step during insertion into the membrane or as a regulatory mechanism in maintaining their function. This type of limited proteolysis is characteristic for processing proteases, such as IMP and rhomboid proteases, or the general mitochondrial quality control proteases ATP23, m-AAA, i-AAA, and OMA1. Identification of processing protease substrates and defining their consensus cleavage motifs is now possible with the help of large-scale quantitative mass spectrometry-based N-terminomics, such as combined fractional diagonal chromatography (COFRADIC), charge-based fractional diagonal chromatography (ChaFRADIC), or terminal amine isotopic labeling of substrates (TAILS). This review summarizes the current knowledge on the characterization of mitochondrial processing peptidases and selected N-terminomics techniques used to uncover protease substrates in the plant, yeast, and mammalian mitochondria.
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Jeong J, Hwang I, Lee DW. Functional Organization of Sequence Motifs in Diverse Transit Peptides of Chloroplast Proteins. Front Physiol 2021; 12:795156. [PMID: 34880786 PMCID: PMC8645953 DOI: 10.3389/fphys.2021.795156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 10/28/2021] [Indexed: 11/17/2022] Open
Abstract
Although the chloroplasts in plants are characterized by an inherent genome, the chloroplast proteome is composed of proteins encoded by not only the chloroplast genome but also the nuclear genome. Nuclear-encoded chloroplast proteins are synthesized on cytosolic ribosomes and post-translationally targeted to the chloroplasts. In the latter process, an N-terminal cleavable transit peptide serves as a targeting signal required for the import of nuclear-encoded chloroplast interior proteins. This import process is mediated via an interaction between the sequence motifs in transit peptides and the components of the TOC/TIC (translocon at the outer/inner envelope of chloroplasts) translocons. Despite a considerable diversity in primary structures, several common features have been identified among transit peptides, including N-terminal moderate hydrophobicity, multiple proline residues dispersed throughout the transit peptide, preferential usage of basic residues over acidic residues, and an absence of N-terminal arginine residues. In this review, we will recapitulate and discuss recent progress in our current understanding of the functional organization of sequence elements commonly present in diverse transit peptides, which are essential for the multi-step import of chloroplast proteins.
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Affiliation(s)
- Jinseung Jeong
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea.,Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, South Korea
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20
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Wang D, Wang C, Li C, Song H, Qin J, Chang H, Fu W, Wang Y, Wang F, Li B, Hao Y, Xu M, Fu A. Functional Relationship of Arabidopsis AOXs and PTOX Revealed via Transgenic Analysis. FRONTIERS IN PLANT SCIENCE 2021; 12:692847. [PMID: 34367216 PMCID: PMC8336870 DOI: 10.3389/fpls.2021.692847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/07/2021] [Indexed: 06/01/2023]
Abstract
Alternative oxidase (AOX) and plastid terminal oxidase (PTOX) are terminal oxidases of electron transfer in mitochondria and chloroplasts, respectively. Here, taking advantage of the variegation phenotype of the Arabidopsis PTOX deficient mutant (im), we examined the functional relationship between PTOX and its five distantly related homologs (AOX1a, 1b, 1c, 1d, and AOX2). When engineered into chloroplasts, AOX1b, 1c, 1d, and AOX2 rescued the im defect, while AOX1a partially suppressed the mutant phenotype, indicating that AOXs could function as PQH2 oxidases. When the full length AOXs were overexpressed in im, only AOX1b and AOX2 rescued its variegation phenotype. In vivo fluorescence analysis of GFP-tagged AOXs and subcellular fractionation assays showed that AOX1b and AOX2 could partially enter chloroplasts while AOX1c and AOX1d were exclusively present in mitochondria. Surprisingly, the subcellular fractionation, but not the fluorescence analysis of GFP-tagged AOX1a, revealed that a small portion of AOX1a could sort into chloroplasts. We further fused and expressed the targeting peptides of AOXs with the mature form of PTOX in im individually; and found that targeting peptides of AOX1a, AOX1b, and AOX2, but not that of AOX1c or AOX1d, could direct PTOX into chloroplasts. It demonstrated that chloroplast-localized AOXs, but not mitochondria-localized AOXs, can functionally compensate for the PTOX deficiency in chloroplasts, providing a direct evidence for the functional relevance of AOX and PTOX, shedding light on the interaction between mitochondria and chloroplasts and the complex mechanisms of protein dual targeting in plant cells.
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Affiliation(s)
- Danfeng Wang
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Chunyu Wang
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Cai Li
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Haifeng Song
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Jing Qin
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Han Chang
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Weihan Fu
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Yuhua Wang
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Fei Wang
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Beibei Li
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Yaqi Hao
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Min Xu
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
| | - Aigen Fu
- Chinese Education Ministry’s Key Laboratory of Western Resources and Modern Biotechnology, Key Laboratory of Biotechnology Shaanxi Province, College of Life Sciences, Northwest University, Xi’an, China
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21
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Lee DW, Hwang I. Understanding the evolution of endosymbiotic organelles based on the targeting sequences of organellar proteins. THE NEW PHYTOLOGIST 2021; 230:924-930. [PMID: 33404103 DOI: 10.1111/nph.17167] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 12/14/2020] [Indexed: 05/17/2023]
Abstract
Organellogenesis, a key aspect of eukaryotic cell evolution, critically depends on the successful establishment of organellar protein import mechanisms. Phylogenetic analysis revealed that the evolution of the two endosymbiotic organelles, the mitochondrion and the chloroplast, is thought to have occurred at time periods far from each other. Despite this, chloroplasts and mitochondria have highly similar protein import mechanisms. This raises intriguing questions such as what underlies such similarity in the import mechanisms and how these similar mechanisms have evolved. In this review, we summarise the recent findings regarding sorting and specific targeting of these organellar proteins. Based on these findings, we propose possible evolutionary scenarios regarding how the signal sequences of chloroplasts and mitochondrial proteins ended up having such relationship.
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Affiliation(s)
- Dong Wook Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, 61186, Korea
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, 61186, Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju, 61186, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Korea
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, 100083, China
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22
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Caspari OD, Lafontaine I. The role of antimicrobial peptides in the evolution of endosymbiotic protein import. PLoS Pathog 2021; 17:e1009466. [PMID: 33857255 PMCID: PMC8049325 DOI: 10.1371/journal.ppat.1009466] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Oliver D. Caspari
- UMR7141, Institut de Biologie Physico-Chimique (CNRS/Sorbonne Université), Paris, France
- * E-mail: (ODC); (IL)
| | - Ingrid Lafontaine
- UMR7141, Institut de Biologie Physico-Chimique (CNRS/Sorbonne Université), Paris, France
- * E-mail: (ODC); (IL)
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23
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Terada K, Gimenez-Dejoz J, Kurita T, Oikawa K, Uji H, Tsuchiya K, Numata K. Synthetic Mitochondria-Targeting Peptides Incorporating α-Aminoisobutyric Acid with a Stable Amphiphilic Helix Conformation in Plant Cells. ACS Biomater Sci Eng 2021; 7:1475-1484. [PMID: 33606492 DOI: 10.1021/acsbiomaterials.0c01533] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the genetic modification of plant cells, the mitochondrion is an important target in addition to the nucleus and plastid. However, gene delivery into the mitochondria of plant cells has yet to be established by conventional methods, such as particle bombardment, because of the small size and high mobility of mitochondria. To develop an efficient mitochondria-targeting signal (MTS) that functions in plant cells, we designed the artificial peptide (LURL)3 and its analogues, which periodically feature hydrophobic α-aminoisobutyric acid (Aib, U) and cationic arginine (R), considering the consensus motif recognized by the mitochondrial import receptor Tom20. Circular dichroism measurements and molecular dynamics simulation studies revealed that (LURL)3 had a propensity to form a stable α-helix in 0.1 M phosphate buffer solution containing 1.0 wt % sodium dodecyl sulfate. After internalization into plant cells via particle bombardment, (LURL)3 revealed highly selective accumulation in the mitochondria, whereas its analogue (LARL)3 was predominantly located in the vacuoles in addition to mitochondria. The high selectivity of (LURL)3 can be attributed to the incorporation of Aib, which promotes the hydrophobic interaction between the MTS and Tom20 by increasing the hydrophobicity and helicity of (LURL)3. The present study provided a prospective mitochondrial targeting system using the simple design of artificial peptides.
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Affiliation(s)
- Kayo Terada
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Joan Gimenez-Dejoz
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Taichi Kurita
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazusato Oikawa
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Hirotaka Uji
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kousuke Tsuchiya
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Keiji Numata
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.,Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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24
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Iannetta AA, Rogers HT, Al-Mohanna T, O'Brien JN, Wommack AJ, Popescu SC, Hicks LM. Profiling thimet oligopeptidase-mediated proteolysis in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:336-350. [PMID: 33481299 DOI: 10.1111/tpj.15165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
Protein homeostasis (proteostasis) is crucial for proper cellular function, including the production of peptides with biological functions through controlled proteolysis. Proteostasis has roles in maintenance of cellular functions and plant interactions with the environment under physiological conditions. Plant stress continues to reduce agricultural yields causing substantial economic losses; thus, it is critical to understand how plants perceive stress signals to elicit responses for survival. As previously shown in Arabidopsis thaliana, thimet oligopeptidases (TOPs) TOP1 (also referred to as organellar oligopeptidase) and TOP2 (also referred to as cytosolic oligopeptidase) are essential components in plant response to pathogens, but further characterization of TOPs and their peptide substrates is required to understand their contributions to stress perception and defense signaling. Herein, label-free peptidomics via liquid chromatography-tandem mass spectrometry was used to differentially quantify 1111 peptides, originating from 369 proteins, between the Arabidopsis Col-0 wild type and top1top2 knock-out mutant. This revealed 350 peptides as significantly more abundant in the mutant, representing accumulation of these potential TOP substrates. Ten direct substrates were validated using in vitro enzyme assays with recombinant TOPs and synthetic candidate peptides. These TOP substrates are derived from proteins involved in photosynthesis, glycolysis, protein folding, biogenesis, and antioxidant defense, implicating TOP involvement in processes aside from defense signaling. Sequence motif analysis revealed TOP cleavage preference for non-polar residues in the positions surrounding the cleavage site. Identification of these substrates provides a framework for TOP signaling networks, through which the interplay between proteolytic pathways and defense signaling can be further characterized.
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Affiliation(s)
- Anthony A Iannetta
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Holden T Rogers
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thualfeqar Al-Mohanna
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi, MS, USA
| | | | - Andrew J Wommack
- Department of Chemistry, High Point University, High Point, NC, USA
| | - Sorina C Popescu
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi, MS, USA
| | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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25
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Sun JL, Li JY, Wang MJ, Song ZT, Liu JX. Protein Quality Control in Plant Organelles: Current Progress and Future Perspectives. MOLECULAR PLANT 2021; 14:95-114. [PMID: 33137518 DOI: 10.1016/j.molp.2020.10.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 05/20/2023]
Abstract
The endoplasmic reticulum, chloroplasts, and mitochondria are major plant organelles for protein synthesis, photosynthesis, metabolism, and energy production. Protein homeostasis in these organelles, maintained by a balance between protein synthesis and degradation, is essential for cell functions during plant growth, development, and stress resistance. Nucleus-encoded chloroplast- and mitochondrion-targeted proteins and ER-resident proteins are imported from the cytosol and undergo modification and maturation within their respective organelles. Protein folding is an error-prone process that is influenced by both developmental signals and environmental cues; a number of mechanisms have evolved to ensure efficient import and proper folding and maturation of proteins in plant organelles. Misfolded or damaged proteins with nonnative conformations are subject to degradation via complementary or competing pathways: intraorganelle proteases, the organelle-associated ubiquitin-proteasome system, and the selective autophagy of partial or entire organelles. When proteins in nonnative conformations accumulate, the organelle-specific unfolded protein response operates to restore protein homeostasis by reducing protein folding demand, increasing protein folding capacity, and enhancing components involved in proteasome-associated protein degradation and autophagy. This review summarizes recent progress on the understanding of protein quality control in the ER, chloroplasts, and mitochondria in plants, with a focus on common mechanisms shared by these organelles during protein homeostasis.
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Affiliation(s)
- Jing-Liang Sun
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Jin-Yu Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Mei-Jing Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Ze-Ting Song
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
| | - Jian-Xiang Liu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310027, China.
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26
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Imai K, Nakai K. Tools for the Recognition of Sorting Signals and the Prediction of Subcellular Localization of Proteins From Their Amino Acid Sequences. Front Genet 2020; 11:607812. [PMID: 33324450 PMCID: PMC7723863 DOI: 10.3389/fgene.2020.607812] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
At the time of translation, nascent proteins are thought to be sorted into their final subcellular localization sites, based on the part of their amino acid sequences (i.e., sorting or targeting signals). Thus, it is interesting to computationally recognize these signals from the amino acid sequences of any given proteins and to predict their final subcellular localization with such information, supplemented with additional information (e.g., k-mer frequency). This field has a long history and many prediction tools have been released. Even in this era of proteomic atlas at the single-cell level, researchers continue to develop new algorithms, aiming at accessing the impact of disease-causing mutations/cell type-specific alternative splicing, for example. In this article, we overview the entire field and discuss its future direction.
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Affiliation(s)
- Kenichiro Imai
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan
| | - Kenta Nakai
- The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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Evidence Supporting an Antimicrobial Origin of Targeting Peptides to Endosymbiotic Organelles. Cells 2020; 9:cells9081795. [PMID: 32731621 PMCID: PMC7463930 DOI: 10.3390/cells9081795] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/24/2020] [Accepted: 07/24/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria and chloroplasts emerged from primary endosymbiosis. Most proteins of the endosymbiont were subsequently expressed in the nucleo-cytosol of the host and organelle-targeted via the acquisition of N-terminal presequences, whose evolutionary origin remains enigmatic. Using a quantitative assessment of their physico-chemical properties, we show that organelle targeting peptides, which are distinct from signal peptides targeting other subcellular compartments, group with a subset of antimicrobial peptides. We demonstrate that extant antimicrobial peptides target a fluorescent reporter to either the mitochondria or the chloroplast in the green alga Chlamydomonas reinhardtii and, conversely, that extant targeting peptides still display antimicrobial activity. Thus, we provide strong computational and functional evidence for an evolutionary link between organelle-targeting and antimicrobial peptides. Our results support the view that resistance of bacterial progenitors of organelles to the attack of host antimicrobial peptides has been instrumental in eukaryogenesis and in the emergence of photosynthetic eukaryotes.
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28
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Lee DW, Lee S, Min CK, Park C, Kim JM, Hwang CS, Park SK, Cho NH, Hwang I. Cross-Species Functional Conservation and Possible Origin of the N-Terminal Specificity Domain of Mitochondrial Presequences. FRONTIERS IN PLANT SCIENCE 2020; 11:64. [PMID: 32117399 PMCID: PMC7031408 DOI: 10.3389/fpls.2020.00064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/16/2020] [Indexed: 05/28/2023]
Abstract
Plants have two endosymbiotic organelles, chloroplast and mitochondrion. Although they have their own genomes, proteome assembly in these organelles depends on the import of proteins encoded by the nuclear genome. Previously, we elucidated the general design principles of chloroplast and mitochondrial targeting signals, transit peptide, and presequence, respectively, which are highly diverse in primary structure. Both targeting signals are composed of N-terminal specificity domain and C-terminal translocation domain. Especially, the N-terminal specificity domain of mitochondrial presequences contains multiple arginine residues and hydrophobic sequence motif. In this study we investigated whether the design principles of plant mitochondrial presequences can be applied to those in other eukaryotic species. We provide evidence that both presequences and import mechanisms are remarkably conserved throughout the species. In addition, we present evidence that the N-terminal specificity domain of presequence might have evolved from the bacterial TAT (twin-arginine translocation) signal sequence.
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Affiliation(s)
- Dong Wook Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, South Korea
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, South Korea
| | - Sumin Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Chan-Ki Min
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, South Korea
| | - Cana Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Jeong-Mok Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Cheol-Sang Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Sang Ki Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Nam-Hyuk Cho
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, South Korea
| | - Inhwan Hwang
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, South Korea
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
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29
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Knopp M, Garg SG, Handrich M, Gould SB. Major Changes in Plastid Protein Import and the Origin of the Chloroplastida. iScience 2020; 23:100896. [PMID: 32088393 PMCID: PMC7038456 DOI: 10.1016/j.isci.2020.100896] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/09/2020] [Accepted: 02/04/2020] [Indexed: 12/26/2022] Open
Abstract
Core components of plastid protein import and the principle of using N-terminal targeting sequences are conserved across the Archaeplastida, but lineage-specific differences exist. Here we compare, in light of plastid protein import, the response to high-light stress from representatives of the three archaeplastidal groups. Similar to land plants, Chlamydomonas reinhardtii displays a broad response to high-light stress, not observed to the same degree in the glaucophyte Cyanophora paradoxa or the rhodophyte Porphyridium purpureum. We find that only the Chloroplastida encode both Toc75 and Oep80 in parallel and suggest that elaborate high-light stress response is supported by changes in plastid protein import. We propose the origin of a phenylalanine-independent import pathway via Toc75 allowed higher import rates to rapidly service high-light stress, but with the cost of reduced specificity. Changes in plastid protein import define the origin of the green lineage, whose greatest evolutionary success was arguably the colonization of land. Chloroplastida evolved a dual system, Toc75/Oep80, for high throughput protein import Loss of F-based targeting led to dual organelle targeting using a single ambiguous NTS Relaxation of functional constraints allowed a wider Toc/Tic modification A broad response to high-light stress appears unique to Chloroplastida
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Affiliation(s)
- Michael Knopp
- Institute for Molecular Evolution, HH-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Sriram G Garg
- Institute for Molecular Evolution, HH-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Maria Handrich
- Institute for Molecular Evolution, HH-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Sven B Gould
- Institute for Molecular Evolution, HH-University Düsseldorf, 40225 Düsseldorf, Germany.
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30
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Protein import into chloroplasts via the Tic40-dependent and -independent pathways depends on the amino acid composition of the transit peptide. Biochem Biophys Res Commun 2019; 518:66-71. [PMID: 31400859 DOI: 10.1016/j.bbrc.2019.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/03/2019] [Indexed: 11/23/2022]
Abstract
Preprotein import into chloroplasts is mediated by the coordinated actions of translocons at the outer and inner envelopes of chloroplasts (Toc and Tic, respectively). The cleavable N-terminal transit peptide (TP) of preproteins plays an essential role in the import of preproteins into chloroplasts. The Tic40 protein, a component of the Tic complex, is believed to mediate the import of preproteins through the inner envelope. In this study, we aimed to obtain in vivo evidence supporting the role of Tic40 in preprotein import into chloroplasts. Contrary to previous findings, the import of various preproteins with wild-type TPs showed no difference between tic40 and wild-type protoplasts of Arabidopsis thaliana. However, the import of N-terminal mutants of the RbcS protein (RbcS-nt), in which basic amino acid residues (arginine and lysine) in the central region of the TP were substituted with neutral (alanine) or acidic (glutamic acid) amino acid residues, was dependent on Tic40. In addition, in tic40 protoplasts, the inner envelope protein Tic40 tagged with HA (hemagglutinin) showed more intermediate form present in the stroma. Based on these results, we propose that protein can be imported into chloroplast by either Tic40-independent or Tic40-dependent pathways depending on the types of TP.
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31
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McKinnon L, Theg SM. Determinants of the Specificity of Protein Targeting to Chloroplasts or Mitochondria. MOLECULAR PLANT 2019; 12:893-895. [PMID: 31128277 DOI: 10.1016/j.molp.2019.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 04/22/2019] [Accepted: 05/08/2019] [Indexed: 05/17/2023]
Affiliation(s)
- Lucas McKinnon
- Department of Plant Biology, University of California Davis, Davis, CA, USA
| | - Steven M Theg
- Department of Plant Biology, University of California Davis, Davis, CA, USA.
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