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Talukdar S, Mal S, Kundu P. Physico-chemical features and functional relevance of tomato rhomboid proteases. Int J Biol Macromol 2024; 272:132681. [PMID: 38806088 DOI: 10.1016/j.ijbiomac.2024.132681] [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: 03/08/2024] [Revised: 05/13/2024] [Accepted: 05/24/2024] [Indexed: 05/30/2024]
Abstract
In plants, regulated intramembrane proteolysis (RIP) is crucial for proper growth, development, and stress management. Rhomboid proteases (RPs) residing in the membrane play a vital role in orchestrating RIP. Although RPs can be found in most sequenced genomes, tomato rhomboids (SlRPs) have not yet been studied. Using alternative and comprehensive strategies, we found ten SlRPs encoded in the tomato genome. These SlRPs possess signature motifs and transmembrane domains, showing structural similarity to other members of the RP family. Also, SlRPs are genetically related to other known RPs of the Solanaceae family. Seven of the SlRPs retain serine-histidine catalytic dyads, making them proteolytically active, while three iRhoms lack the dyad and other structural motifs. Although SlRPs could have functional redundancy, their distribution and expression pattern indicate tissue specificity and responsiveness to specific external stimuli. The presence of development and stress-response-related cis-elements in the promoters of SlRPs supports this view. Furthermore, our strategically designed substrate-reporter assay shows that SlRPs have proteolytic activity similar to that of known RPs. This study provides a detailed understanding of all SlRPs and their physico-chemical features, shedding light on their involvement in physiological processes.
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Affiliation(s)
- Sushmita Talukdar
- Department of Biological Sciences, Bose Institute, EN80, Sector V, Bidhannagar, Kolkata 700091, India
| | - Sayan Mal
- Department of Biological Sciences, Bose Institute, EN80, Sector V, Bidhannagar, Kolkata 700091, India
| | - Pallob Kundu
- Department of Biological Sciences, Bose Institute, EN80, Sector V, Bidhannagar, Kolkata 700091, India.
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2
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Riehl JFL, Cole CT, Morrow CJ, Barker HL, Bernhardsson C, Rubert‐Nason K, Ingvarsson PK, Lindroth RL. Genomic and transcriptomic analyses reveal polygenic architecture for ecologically important traits in aspen ( Populus tremuloides Michx.). Ecol Evol 2023; 13:e10541. [PMID: 37780087 PMCID: PMC10534199 DOI: 10.1002/ece3.10541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/30/2023] [Accepted: 09/04/2023] [Indexed: 10/03/2023] Open
Abstract
Intraspecific genetic variation in foundation species such as aspen (Populus tremuloides Michx.) shapes their impact on forest structure and function. Identifying genes underlying ecologically important traits is key to understanding that impact. Previous studies, using single-locus genome-wide association (GWA) analyses to identify candidate genes, have identified fewer genes than anticipated for highly heritable quantitative traits. Mounting evidence suggests that polygenic control of quantitative traits is largely responsible for this "missing heritability" phenomenon. Our research characterized the genetic architecture of 30 ecologically important traits using a common garden of aspen through genomic and transcriptomic analyses. A multilocus association model revealed that most traits displayed a highly polygenic architecture, with most variation explained by loci with small effects (likely below the detection levels of single-locus GWA methods). Consistent with a polygenic architecture, our single-locus GWA analyses found only 38 significant SNPs in 22 genes across 15 traits. Next, we used differential expression analysis on a subset of aspen genets with divergent concentrations of salicinoid phenolic glycosides (key defense traits). This complementary method to traditional GWA discovered 1243 differentially expressed genes for a polygenic trait. Soft clustering analysis revealed three gene clusters (241 candidate genes) involved in secondary metabolite biosynthesis and regulation. Our work reveals that ecologically important traits governing higher-order community- and ecosystem-level attributes of a foundation forest tree species have complex underlying genetic structures and will require methods beyond traditional GWA analyses to unravel.
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Affiliation(s)
| | | | - Clay J. Morrow
- Department of Forest and Wildlife EcologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Hilary L. Barker
- Department of EntomologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- Present address:
Office of Student SuccessWisconsin Technical College SystemMadisonWisconsinUSA
| | - Carolina Bernhardsson
- Department of Ecology and Environmental ScienceUmeå UniversityUmeåSweden
- Present address:
Department of Organismal Biology, Center for Evolutionary BiologyUppsala UniversityUppsalaSweden
| | - Kennedy Rubert‐Nason
- Department of EntomologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- Present address:
Division of Natural SciencesUniversity of Maine at Fort KentFort KentMaineUSA
| | - Pär K. Ingvarsson
- Department of Plant BiologySwedish University of Agricultural Sciences, Uppsala BioCenterUppsalaSweden
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Olenic S, Heo L, Feig M, Kroos L. Inhibitory proteins block substrate access by occupying the active site cleft of Bacillus subtilis intramembrane protease SpoIVFB. eLife 2022; 11:74275. [PMID: 35471152 PMCID: PMC9042235 DOI: 10.7554/elife.74275] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/25/2022] [Indexed: 12/16/2022] Open
Abstract
Intramembrane proteases (IPs) function in numerous signaling pathways that impact health, but elucidating the regulation of membrane-embedded proteases is challenging. We examined inhibition of intramembrane metalloprotease SpoIVFB by proteins BofA and SpoIVFA. We found that SpoIVFB inhibition requires BofA residues in and near a predicted transmembrane segment (TMS). This segment of BofA occupies the SpoIVFB active site cleft based on cross-linking experiments. SpoIVFB inhibition also requires SpoIVFA. The inhibitory proteins block access of the substrate N-terminal region to the membrane-embedded SpoIVFB active site, based on additional cross-linking experiments; however, the inhibitory proteins did not prevent interaction between the substrate C-terminal region and the SpoIVFB soluble domain. We built a structural model of SpoIVFB in complex with BofA and parts of SpoIVFA and substrate, using partial homology and constraints from cross-linking and co-evolutionary analyses. The model predicts that conserved BofA residues interact to stabilize a TMS and a membrane-embedded C-terminal region. The model also predicts that SpoIVFA bridges the BofA C-terminal region and SpoIVFB, forming a membrane-embedded inhibition complex. Our results reveal a novel mechanism of IP inhibition with clear implications for relief from inhibition in vivo and design of inhibitors as potential therapeutics.
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Affiliation(s)
- Sandra Olenic
- Michigan State University, East Lansing, United States
| | - Lim Heo
- Michigan State University, East Lansing, United States
| | - Michael Feig
- Michigan State University, East Lansing, United States
| | - Lee Kroos
- Michigan State University, East Lansing, United States
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4
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Meisrimler C, Pelgrom AJE, Oud B, Out S, Van den Ackerveken G. Multiple downy mildew effectors target the stress-related NAC transcription factor LsNAC069 in lettuce. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:1098-1115. [PMID: 31077456 PMCID: PMC9545932 DOI: 10.1111/tpj.14383] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/04/2019] [Accepted: 04/17/2019] [Indexed: 05/22/2023]
Abstract
To cause disease in lettuce, the biotrophic oomycete Bremia lactucae secretes potential RxLR effector proteins. Here we report the discovery of an effector-target hub consisting of four B. lactucae effectors and one lettuce protein target by a yeast-two-hybrid (Y2H) screening. Interaction of the lettuce tail-anchored NAC transcription factor, LsNAC069, with B. lactucae effectors does not require the N-terminal NAC domain but depends on the C-terminal region including the transmembrane domain. Furthermore, in Y2H experiments, B. lactucae effectors interact with Arabidopsis and potato tail-anchored NACs, suggesting that they are conserved effector targets. Transient expression of RxLR effector proteins BLR05 and BLR09 and their target LsNAC069 in planta revealed a predominant localization to the endoplasmic reticulum. Phytophthora capsici culture filtrate and polyethylene glycol treatment induced relocalization to the nucleus of a stabilized LsNAC069 protein, lacking the NAC-domain (LsNAC069ΔNAC ). Relocalization was significantly reduced in the presence of the Ser/Cys-protease inhibitor TPCK indicating proteolytic cleavage of LsNAC069 allows for relocalization. Co-expression of effectors with LsNAC069ΔNAC reduced its nuclear accumulation. Surprisingly, LsNAC069 silenced lettuce lines had decreased LsNAC069 transcript levels but did not show significantly altered susceptibility to B. lactucae. In contrast, LsNAC069 silencing increased resistance to Pseudomonas cichorii bacteria and reduced wilting effects under moderate drought stress, indicating a broad role of LsNAC069 in abiotic and biotic stress responses.
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Affiliation(s)
- Claudia‐Nicole Meisrimler
- Plant–Microbe InteractionsDepartment of BiologyUtrecht UniversityPadualaan 83584 CHUtrechtthe Netherlands
- University of CanterburyIlamPrivate Bag 4800Christchurch8041New Zealand
| | - Alexandra J. E. Pelgrom
- Plant–Microbe InteractionsDepartment of BiologyUtrecht UniversityPadualaan 83584 CHUtrechtthe Netherlands
| | - Bart Oud
- Enza ZadenHaling 1‐EEnkhuizen1602 DBthe Netherlands
| | - Suzan Out
- Enza ZadenHaling 1‐EEnkhuizen1602 DBthe Netherlands
| | - Guido Van den Ackerveken
- Plant–Microbe InteractionsDepartment of BiologyUtrecht UniversityPadualaan 83584 CHUtrechtthe Netherlands
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5
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Tornkvist A, Liu C, Moschou PN. Proteolysis and nitrogen: emerging insights. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2009-2019. [PMID: 30715465 DOI: 10.1093/jxb/erz024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/10/2019] [Indexed: 05/07/2023]
Abstract
Nitrogen (N) is a core component of fertilizers used in modern agriculture to increase yields and thus to help feed a growing global population. However, this comes at a cost to the environment, through run-off of excess N as a result of poor N-use efficiency (NUE) by crops. An obvious remedy to this problem would therefore be the improvement of NUE, which requires advancing our understanding on N homeostasis, sensing, and uptake. Proteolytic pathways are linked to N homeostasis as they recycle proteins that contain N and carbon; however, emerging data suggest that their functions extend beyond this simple recycling. Here, we highlight roles of proteolytic pathways in non-symbiotic and symbiotic N uptake and in systemic N sensing. We also offer a novel view in which we suggest that proteolytic pathways have roles in N homeostasis that differ from their accepted function in recycling.
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Affiliation(s)
- Anna Tornkvist
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Chen Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Panagiotis N Moschou
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
- Department of Biology, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece
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6
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Interaction of intramembrane metalloprotease SpoIVFB with substrate Pro-σ K. Proc Natl Acad Sci U S A 2017; 114:E10677-E10686. [PMID: 29180425 DOI: 10.1073/pnas.1711467114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Intramembrane proteases (IPs) cleave membrane-associated substrates in nearly all organisms and regulate diverse processes. A better understanding of how these enzymes interact with their substrates is necessary for rational design of IP modulators. We show that interaction of Bacillus subtilis IP SpoIVFB with its substrate Pro-σK depends on particular residues in the interdomain linker of SpoIVFB. The linker plus either the N-terminal membrane domain or the C-terminal cystathione-β-synthase (CBS) domain of SpoIVFB was sufficient for the interaction but not for cleavage of Pro-σK Chemical cross-linking and mass spectrometry of purified, inactive SpoIVFB-Pro-σK complex indicated residues of the two proteins in proximity. A structural model of the complex was built via partial homology and by using constraints based on cross-linking data. In the model, the Proregion of Pro-σK loops into the membrane domain of SpoIVFB, and the rest of Pro-σK interacts extensively with the linker and the CBS domain of SpoIVFB. The extensive interaction is proposed to allow coordination between ATP binding by the CBS domain and Pro-σK cleavage by the membrane domain.
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7
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Enfissi EMA, Nogueira M, Bramley PM, Fraser PD. The regulation of carotenoid formation in tomato fruit. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:774-788. [PMID: 27865019 DOI: 10.1111/tpj.13428] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 10/14/2016] [Accepted: 11/14/2016] [Indexed: 05/23/2023]
Abstract
Carotenoid biosynthesis in plants includes a complex series of desaturation/isomerisation reactions, catalyzed by four independent enzymes. In bacteria and fungi one desaturase/isomerase enzyme completes the same series of reactions. In the present study, a bacterial desaturase (crtI) from Pantoea ananatis has been overexpressed in the tangerine mutant of tomato (Solanum lycopersicon) which accumulates cis-carotene isomers in the fruit due to a defective isomerase (CRTISO) and the old gold crimson (ogc ) tomato mutant, which is defective in the fruit-enhanced lycopene β-cyclase (CYCB). Comprehensive molecular and biochemical characterization of the resulting lines expressing crtI has revealed negative feedback mechanisms, acting predominantly at the level of phytoene synthase-1 (PSY1), and feed-forward mechanisms inducing cyclisation. In both cases, altered transcription appears to be the progenitor, with subsequent post-transcriptional modulation highlighting the complexity of the processes involved in modulating carotenoid homeostasis in plant tissues.
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Affiliation(s)
- Eugenia M A Enfissi
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK
| | - Marilise Nogueira
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK
| | - Peter M Bramley
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK
| | - Paul D Fraser
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK
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8
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Nishimura K, Kato Y, Sakamoto W. Essentials of Proteolytic Machineries in Chloroplasts. MOLECULAR PLANT 2017; 10:4-19. [PMID: 27585878 DOI: 10.1016/j.molp.2016.08.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/17/2016] [Accepted: 08/21/2016] [Indexed: 05/22/2023]
Abstract
Plastids are unique organelles that can alter their structure and function in response to environmental and developmental stimuli. Chloroplasts are one type of plastid and are the sites for various metabolic processes, including photosynthesis. For optimal photosynthetic activity, the chloroplast proteome must be properly shaped and maintained through regulated proteolysis and protein quality control mechanisms. Enzymatic functions and activities are conferred by protein maturation processes involving consecutive proteolytic reactions. Protein abundances are optimized by the balanced protein synthesis and degradation, which is depending on the metabolic status. Malfunctioning proteins are promptly degraded. Twenty chloroplast proteolytic machineries have been characterized to date. Specifically, processing peptidases and energy-driven processive proteases are the major players in chloroplast proteome biogenesis, remodeling, and maintenance. Recently identified putative proteases are potential regulators of photosynthetic functions. Here we provide an updated, comprehensive overview of chloroplast protein degradation machineries and discuss their importance for photosynthesis. Wherever possible, we also provide structural insights into chloroplast proteases that implement regulated proteolysis of substrate proteins/peptides.
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Affiliation(s)
- Kenji Nishimura
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046, Japan
| | - Yusuke Kato
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046, Japan
| | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046, Japan.
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9
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Verhelst SHL. Intramembrane proteases as drug targets. FEBS J 2017; 284:1489-1502. [PMID: 27889944 DOI: 10.1111/febs.13979] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/14/2016] [Accepted: 11/24/2016] [Indexed: 01/04/2023]
Abstract
Proteases are considered attractive drug targets. Various drugs targeting classical, soluble proteases have been approved for treatment of human disease. Intramembrane proteases (IMPs) are a more recently discovered group of proteolytic enzymes. They are embedded in lipid bilayers and their active sites are located in the plane of a membrane. All four mechanistic families of IMPs have been linked to disease, but currently, no drugs against IMPs have entered the market. In this review, I will outline the function of IMPs with a focus on the ones involved in human disease, which includes Alzheimer's disease, cancer, and infectious diseases by microorganisms. Inhibitors of IMPs are known for all mechanistic classes, but are not yet very potent or selective - aside from those targeting γ-secretase. I will here describe the different features of IMP inhibitors and discuss a list of issues that need attention in the near future in order to improve the drug development for IMPs.
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Affiliation(s)
- Steven H L Verhelst
- Department of Cellular and Molecular Medicine, KU Leuven - University of Leuven, Belgium.,AG Chemical Proteomics, Leibniz Institute for Analytical Sciences ISAS, Dortmund, Germany
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10
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Proteases from Canavalia ensiformis: Active and Thermostable Enzymes with Potential of Application in Biotechnology. BIOTECHNOLOGY RESEARCH INTERNATIONAL 2016; 2016:3427098. [PMID: 27630776 PMCID: PMC5005583 DOI: 10.1155/2016/3427098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/27/2016] [Accepted: 07/10/2016] [Indexed: 01/25/2023]
Abstract
Extracts of leaves, seeds, roots, and stem from a tropical legume, C. ensiformis, were prepared employing buffers and detergent in aqueous solution. Leaf extracts had the highest protein content and the most pronounced peptidase activity with optimal pH in the neutral to alkaline range. All extracts exhibited peaks of activity at various pH values, suggesting the presence of distinctive classes of proteases. N-α-Tosyl-L-arginine methyl ester hydrolysis was maximal at 30°C to 60°C and peptidase activity from all extracts presented very good thermal stability after 24 h incubation at 70°C. C. ensiformis proteases exhibited molecular masses of about 200–57, 40–37, and 20–15 kDa by SDS-PAGE analysis. These enzymes cleaved hemoglobin, bovine serum albumin, casein, and gelatin at different levels. Serine and metalloproteases are the major proteases in C. ensiformis extracts, modulated by divalent cations, stable at 1% of surfactant Triton X-100 and at different concentrations of the reducing agent β-mercaptoethanol. Thus, C. ensiformis expresses a particular set of proteases in distinctive organs with high activity and stability, making this legume an important source of proteases with biotechnological potential.
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11
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Duggan SP, McCarthy JV. Beyond γ-secretase activity: The multifunctional nature of presenilins in cell signalling pathways. Cell Signal 2015; 28:1-11. [PMID: 26498858 DOI: 10.1016/j.cellsig.2015.10.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 10/19/2015] [Indexed: 01/24/2023]
Abstract
The presenilins are the catalytic subunit of the membrane-embedded tetrameric γ-secretase protease complexes. More that 90 transmembrane proteins have been reported to be γ-secretase substrates, including the widely studied amyloid precursor protein (APP) and the Notch receptor, which are precursors for the generation of amyloid-β peptides and biologically active APP intracellular domain (AICD) and Notch intracellular domain (NICD). The diversity of γ-secretase substrates highlights the importance of presenilin-dependent γ-secretase protease activities as a regulatory mechanism in a range of biological systems. However, there is also a growing body of evidence that supports the existence of γ-secretase-independent functions for the presenilins in the regulation and progression of an array of cell signalling pathways. In this review, we will present an overview of current literature that proposes evolutionarily conserved presenilin functions outside of the γ-secretase complex, with a focus on the suggested role of the presenilins in the regulation of Wnt/β-catenin signalling, protein trafficking and degradation, calcium homeostasis and apoptosis.
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Affiliation(s)
- Stephen P Duggan
- Signal Transduction Laboratory, School of Biochemistry & Cell Biology, ABCRF, Western Gateway Building, University College Cork, Cork, Ireland
| | - Justin V McCarthy
- Signal Transduction Laboratory, School of Biochemistry & Cell Biology, ABCRF, Western Gateway Building, University College Cork, Cork, Ireland.
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12
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Abstract
The protein content of plant cells is constantly being updated. This process is driven by the opposing actions of protein degradation, which defines the half-life of each polypeptide, and protein synthesis. Our understanding of the processes that regulate protein synthesis and degradation in plants has advanced significantly over the past decade. Post-transcriptional modifications that influence features of the mRNA populations, such as poly(A) tail length and secondary structure, contribute to the regulation of protein synthesis. Post-translational modifications such as phosphorylation, ubiquitination and non-enzymatic processes such as nitrosylation and carbonylation, govern the rate of degradation. Regulators such as the plant TOR kinase, and effectors such as the E3 ligases, allow plants to balance protein synthesis and degradation under developmental and environmental change. Establishing an integrated understanding of the processes that underpin changes in protein abundance under various physiological and developmental scenarios will accelerate our ability to model and rationally engineer plants.
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Affiliation(s)
- Clark J Nelson
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Western Australia, Australia
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Western Australia, Australia
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Biogenesis of light harvesting proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:861-71. [PMID: 25687893 DOI: 10.1016/j.bbabio.2015.02.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/04/2015] [Accepted: 02/07/2015] [Indexed: 11/20/2022]
Abstract
The LHC family includes nuclear-encoded, integral thylakoid membrane proteins, most of which coordinate chlorophyll and xanthophyll chromophores. By assembling with the core complexes of both photosystems, LHCs form a flexible peripheral moiety for enhancing light-harvesting cross-section, regulating its efficiency and providing protection against photo-oxidative stress. Upon its first appearance, LHC proteins underwent evolutionary diversification into a large protein family with a complex genetic redundancy. Such differentiation appears as a crucial event in the adaptation of photosynthetic organisms to changing environmental conditions and land colonization. The structure of photosystems, including nuclear- and chloroplast-encoded subunits, presented the cell with a number of challenges for the control of the light harvesting function. Indeed, LHC-encoding messages are translated in the cytosol, and pre-proteins imported into the chloroplast, processed to their mature size and targeted to the thylakoids where are assembled with chromophores. Thus, a tight coordination between nuclear and plastid gene expression, in response to environmental stimuli, is required to adjust LHC composition during photoacclimation. In recent years, remarkable progress has been achieved in elucidating structure, function and regulatory pathways involving LHCs; however, a number of molecular details still await elucidation. In this review, we will provide an overview on the current knowledge on LHC biogenesis, ranging from organization of pigment-protein complexes to the modulation of gene expression, import and targeting to the photosynthetic membranes, and regulation of LHC assembly and turnover. Genes controlling these events are potential candidate for biotechnological applications aimed at optimizing light use efficiency of photosynthetic organisms. This article is part of a Special Issue entitled: Chloroplast biogenesis.
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14
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van Wijk KJ. Protein maturation and proteolysis in plant plastids, mitochondria, and peroxisomes. ANNUAL REVIEW OF PLANT BIOLOGY 2015; 66:75-111. [PMID: 25580835 DOI: 10.1146/annurev-arplant-043014-115547] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Plastids, mitochondria, and peroxisomes are key organelles with dynamic proteomes in photosynthetic eukaryotes. Their biogenesis and activity must be coordinated and require intraorganellar protein maturation, degradation, and recycling. The three organelles together are predicted to contain ∼200 presequence peptidases, proteases, aminopeptidases, and specific protease chaperones/adaptors, but the substrates and substrate selection mechanisms are poorly understood. Similarly, lifetime determinants of organellar proteins, such as N-end degrons and tagging systems, have not been identified, but the substrate recognition mechanisms likely share similarities between organelles. Novel degradomics tools for systematic analysis of protein lifetime and proteolysis could define such protease-substrate relationships, degrons, and protein lifetime. Intraorganellar proteolysis is complemented by autophagy of whole organelles or selected organellar content, as well as by cytosolic protein ubiquitination and degradation by the proteasome. This review summarizes (putative) plant organellar protease functions and substrate-protease relationships. Examples illustrate key proteolytic events.
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Affiliation(s)
- Klaas J van Wijk
- Department of Plant Biology, Cornell University, Ithaca, New York 14853;
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15
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Plastid intramembrane proteolysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:910-4. [PMID: 25528366 DOI: 10.1016/j.bbabio.2014.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 12/09/2014] [Accepted: 12/12/2014] [Indexed: 01/25/2023]
Abstract
Progress in the field of regulated intramembrane proteolysis (RIP) in recent years has not surpassed plant biology. Nevertheless, reports on RIP in plants, and especially in chloroplasts, are still scarce. Of the four different families of intramembrane proteases, only two have been linked to chloroplasts so far, rhomboids and site-2 proteases (S2Ps). The lack of chloroplast-located rhomboid proteases was associated with reduced fertility and aberrations in flower morphology, probably due to perturbations in jasmonic acid biosynthesis, which occurs in chloroplasts. Mutations in homologues of S2P resulted in chlorophyll deficiency and impaired chloroplast development, through a yet unknown mechanism. To date, the only known substrate of RIP in chloroplasts is a PHD transcription factor, located in the envelope. Upon proteolytic cleavage by an unknown protease, the soluble N-terminal domain of this protein is released from the membrane and relocates to the nucleus, where it activates the transcription of the ABA response gene ABI4. Continuing studies on these proteases and substrates, as well as identification of the genes responsible for different chloroplast mutant phenotypes, are expected to shed more light on the roles of intramembrane proteases in chloroplast biology.
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Rochaix JD, Ramundo S. Conditional repression of essential chloroplast genes: Evidence for new plastid signaling pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:986-92. [PMID: 25486627 DOI: 10.1016/j.bbabio.2014.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/26/2014] [Indexed: 01/28/2023]
Abstract
The development of a repressible chloroplast gene expression system in Chlamydomonas reinhardtii has opened the door for studying the role of essential chloroplast genes. This approach has been used to analyze three chloroplast genes of this sort coding for the α subunit of RNA polymerase (rpoA), a ribosomal protein (rps12) and the catalytic subunit of the ATP-dependent ClpP protease (clpP1). Depletion of the three corresponding proteins leads to growth arrest and cell death. Shutdown of chloroplast transcription and translation increases the abundance of a set of plastid transcripts that includes mainly those involved in transcription, translation and proteolysis and reveals multiple regulatory feedback loops in the chloroplast gene circuitry. Depletion of ClpP profoundly affects plastid protein homeostasis and elicits an autophagy-like response with extensive cytoplasmic vacuolization of cells. It also triggers changes in chloroplast and nuclear gene expression resulting in increased abundance of chaperones, proteases, ubiquitin-related proteins and proteins involved in lipid trafficking and thylakoid biogenesis. These features are hallmarks of an unfolded protein response in the chloroplast and raise new questions on plastid protein homeostasis and plastid signaling. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Jean-David Rochaix
- Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland; Department of Plant Biology, University of Geneva, 1211 Geneva, Switzerland.
| | - Silvia Ramundo
- Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland; Department of Plant Biology, University of Geneva, 1211 Geneva, Switzerland
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Ramundo S, Casero D, Mühlhaus T, Hemme D, Sommer F, Crèvecoeur M, Rahire M, Schroda M, Rusch J, Goodenough U, Pellegrini M, Perez-Perez ME, Crespo JL, Schaad O, Civic N, Rochaix JD. Conditional Depletion of the Chlamydomonas Chloroplast ClpP Protease Activates Nuclear Genes Involved in Autophagy and Plastid Protein Quality Control. THE PLANT CELL 2014; 26:2201-2222. [PMID: 24879428 PMCID: PMC4079378 DOI: 10.1105/tpc.114.124842] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 04/16/2014] [Accepted: 05/09/2014] [Indexed: 05/14/2023]
Abstract
Plastid protein homeostasis is critical during chloroplast biogenesis and responses to changes in environmental conditions. Proteases and molecular chaperones involved in plastid protein quality control are encoded by the nucleus except for the catalytic subunit of ClpP, an evolutionarily conserved serine protease. Unlike its Escherichia coli ortholog, this chloroplast protease is essential for cell viability. To study its function, we used a recently developed system of repressible chloroplast gene expression in the alga Chlamydomonas reinhardtii. Using this repressible system, we have shown that a selective gradual depletion of ClpP leads to alteration of chloroplast morphology, causes formation of vesicles, and induces extensive cytoplasmic vacuolization that is reminiscent of autophagy. Analysis of the transcriptome and proteome during ClpP depletion revealed a set of proteins that are more abundant at the protein level, but not at the RNA level. These proteins may comprise some of the ClpP substrates. Moreover, the specific increase in accumulation, both at the RNA and protein level, of small heat shock proteins, chaperones, proteases, and proteins involved in thylakoid maintenance upon perturbation of plastid protein homeostasis suggests the existence of a chloroplast-to-nucleus signaling pathway involved in organelle quality control. We suggest that this represents a chloroplast unfolded protein response that is conceptually similar to that observed in the endoplasmic reticulum and in mitochondria.
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Affiliation(s)
- Silvia Ramundo
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
| | - David Casero
- Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095
| | - Timo Mühlhaus
- Max Planck Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm Germany
| | - Dorothea Hemme
- Max Planck Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm Germany
| | - Frederik Sommer
- Max Planck Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm Germany
| | - Michèle Crèvecoeur
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Michèle Rahire
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Michael Schroda
- Max Planck Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm Germany
| | - Jannette Rusch
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Ursula Goodenough
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, California 90095
| | - Maria Esther Perez-Perez
- Instituto de Bioquimica Vegetal y Fotosintesis, Consejo Superior de Investigaciones Cientificas, Universidad de Sevilla, 41092 Sevilla, Spain
| | - José Luis Crespo
- Instituto de Bioquimica Vegetal y Fotosintesis, Consejo Superior de Investigaciones Cientificas, Universidad de Sevilla, 41092 Sevilla, Spain
| | - Olivier Schaad
- Genomics Platform, University of Geneva, 1211 Geneva, Switzerland Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
| | - Natacha Civic
- Genomics Platform, University of Geneva, 1211 Geneva, Switzerland
| | - Jean David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
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Urban S. Mechanisms and cellular functions of intramembrane proteases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2797-800. [PMID: 23831604 DOI: 10.1016/j.bbamem.2013.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The turn of the millennium coincided with the branding of a fundamentally different class of enzyme - proteases that reside immersed inside the membrane. This new field was the convergence of completely separate lines of research focused on cholesterol homeostasis, Alzheimer's disease, and developmental genetics. None intended their ultimate path, but soon became a richly-integrated fabric for an entirely new field: regulated intramembrane proteolysis. Our aim in this Special Issue is to focus on the ancient and nearly ubiquitous enzymes that catalyze this unexpected yet important reaction. The pace of progress has been dramatic, resulting in a rapidly-expanding universe of known cellular functions, and a paradigm shift in the biochemical understanding of these once heretical enzymes. More recently, the first therapeutic successes have been attained by targeting an intramembrane protease. We consider these advances and identify oncoming opportunities in four parts: growing spectra of cellular roles, insights into biochemical mechanisms, therapeutic strategies, and newly-emerging topics. Recent studies also expose challenges for the future, including non-linear relationships between substrate identification and physiological functions, and the need for potent and specific, not broad-class, inhibitors.
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Affiliation(s)
- Siniša Urban
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA.
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