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Jiang T, Mu B, Zhao R. Plastid chaperone HSP90C guides precursor proteins to the SEC translocase for thylakoid transport. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7073-7087. [PMID: 32853383 PMCID: PMC7906790 DOI: 10.1093/jxb/eraa399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 08/24/2020] [Indexed: 05/04/2023]
Abstract
Chloroplast stromal factors involved in regulating thylakoid protein targeting are poorly understood. We previously reported that in Arabidopsis thaliana, the stromal-localized chaperone HSP90C (plastid heat shock protein 90) interacted with the nuclear-encoded thylakoid lumen protein PsbO1 (PSII subunit O isoform 1) and suggested a role for HSP90C in aiding PsbO1 thylakoid targeting. Using in organello transport assays, particularly with model substrates naturally expressed in stroma, we showed that light, exogenous ATP, and HSP90C activity were required for Sec-dependent transport of green fluorescent protein (GFP) led by the PsbO1 thylakoid targeting sequence. Using a previously identified PsbO1T200A mutant, we provided evidence that a stronger interaction between HSP90C and PsbO1 better facilitated its stroma-thylakoid trafficking. We also demonstrated that SecY1, the channel protein of the thylakoid SEC translocase, specifically interacted with HSP90C in vivo. Inhibition of the chaperone ATPase activity suppressed the association of the PsbO1GFP-HSP90C complex with SecY1. Together with analyzing the expression and accumulation of a few other thylakoid proteins that utilize the SRP, TAT, or SEC translocation pathways, we propose a model in which HSP90C forms a guiding complex that interacts with thylakoid protein precursors and assists in their specific targeting to the thylakoid SEC translocon.
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Affiliation(s)
- Tim Jiang
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Bona Mu
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rongmin Zhao
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Correspondence:
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Tichá T, Samakovli D, Kuchařová A, Vavrdová T, Šamaj J. Multifaceted roles of HEAT SHOCK PROTEIN 90 molecular chaperones in plant development. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3966-3985. [PMID: 32293686 DOI: 10.1093/jxb/eraa177] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/06/2020] [Indexed: 05/20/2023]
Abstract
HEAT SHOCK PROTEINS 90 (HSP90s) are molecular chaperones that mediate correct folding and stability of many client proteins. These chaperones act as master molecular hubs involved in multiple aspects of cellular and developmental signalling in diverse organisms. Moreover, environmental and genetic perturbations affect both HSP90s and their clients, leading to alterations of molecular networks determining respectively plant phenotypes and genotypes and contributing to a broad phenotypic plasticity. Although HSP90 interaction networks affecting the genetic basis of phenotypic variation and diversity have been thoroughly studied in animals, such studies are just starting to emerge in plants. Here, we summarize current knowledge and discuss HSP90 network functions in plant development and cellular homeostasis.
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Affiliation(s)
- Tereza Tichá
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Despina Samakovli
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Anna Kuchařová
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Tereza Vavrdová
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Jozef Šamaj
- Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
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Biebl MM, Buchner J. Structure, Function, and Regulation of the Hsp90 Machinery. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a034017. [PMID: 30745292 DOI: 10.1101/cshperspect.a034017] [Citation(s) in RCA: 166] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone involved in the maturation of a plethora of substrates ("clients"), including protein kinases, transcription factors, and E3 ubiquitin ligases, positioning Hsp90 as a central regulator of cellular proteostasis. Hsp90 undergoes large conformational changes during its ATPase cycle. The processing of clients by cytosolic Hsp90 is assisted by a cohort of cochaperones that affect client recruitment, Hsp90 ATPase function or conformational rearrangements in Hsp90. Because of the importance of Hsp90 in regulating central cellular pathways, strategies for the pharmacological inhibition of the Hsp90 machinery in diseases such as cancer and neurodegeneration are being developed. In this review, we summarize recent structural and mechanistic progress in defining the function of organelle-specific and cytosolic Hsp90, including the impact of individual cochaperones on the maturation of specific clients and complexes with clients as well as ways of exploiting Hsp90 as a drug target.
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Affiliation(s)
- Maximilian M Biebl
- Center for Integrated Protein Science, Department of Chemistry, Technische Universität München, D-85748 Garching, Germany
| | - Johannes Buchner
- Center for Integrated Protein Science, Department of Chemistry, Technische Universität München, D-85748 Garching, Germany
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Jiang T, Oh ES, Bonea D, Zhao R. HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis. PLoS One 2017; 12:e0190168. [PMID: 29281724 PMCID: PMC5745004 DOI: 10.1371/journal.pone.0190168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/08/2017] [Indexed: 11/29/2022] Open
Abstract
Arabidopsis plastidic HSP90C is an HSP90 family molecular chaperone that is required for chloroplast development and function. To understand the mechanism of action of HSP90C within the chloroplast, we conducted a yeast two-hybrid screening and revealed it interacts directly with the photosystem II extrinsic protein PsbO1, which performs a canonical function in the thylakoid lumen. To understand the biological significance of HSP90C-PsbO1 interaction, we investigated the role of HSP90C in modulating the stromal and thylakoid distribution of PsbO1GFP fusion protein. Fusion to GFP significantly delays the PsbO1 thylakoid transport and induces a variegation phenotype. Overexpression of HSP90C promotes the thylakoid distribution of PsbO1GFP and alleviates the leaf variegation. By tracking the chloroplast maturation during photomorphogenesis, we observed PsbO1GFP tends to form distinct fluorescent clusters within the stroma with delayed thylakoid membrane biogenesis, while HSP90C overexpression corrects these adverse effects. We also demonstrated that active HSP90C function is specifically required for stable accumulation of mature PsbO1GFP in thylakoid by using specific inhibitor geldanamycin. This study therefore not only identified novel HSP90C interactors, but also reports for the first time that PsbO1 enroute from the cytoplasm to thylakoid lumen is tightly regulated by the HSP90C chaperone complex in plastid stroma; whereas the proper HSP90C homeostasis is also critical for chloroplast maturation and function.
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Affiliation(s)
- Tim Jiang
- Departments of Biological Sciences and Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Edward Saehong Oh
- Departments of Biological Sciences and Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Diana Bonea
- Departments of Biological Sciences and Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rongmin Zhao
- Departments of Biological Sciences and Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Menon C, Sheerin DJ, Hiltbrunner A. SPA proteins: SPAnning the gap between visible light and gene expression. PLANTA 2016; 244:297-312. [PMID: 27100111 DOI: 10.1007/s00425-016-2509-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 03/26/2016] [Indexed: 05/23/2023]
Abstract
In this review we focus on the role of SPA proteins in light signalling and discuss different aspects, including molecular mechanisms, specificity, and evolution. The ability of plants to perceive and respond to their environment is key to their survival under ever-changing conditions. The abiotic factor light is of particular importance for plants. Light provides plants energy for carbon fixation through photosynthesis, but also is a source of information for the adaptation of growth and development to the environment. Cryptochromes and phytochromes are major photoreceptors involved in control of developmental decisions in response to light cues, including seed germination, seedling de-etiolation, and induction of flowering. The SPA protein family acts in complex with the E3 ubiquitin ligase COP1 to target positive regulators of light responses for degradation by the 26S proteasome to suppress photomorphogenic development in darkness. Light-activated cryptochromes and phytochromes both repress the function of COP1, allowing accumulation of positive photomorphogenic factors in light. In this review, we highlight the role of the SPA proteins in this process and discuss recent advances in understanding how SPAs link light-activation of photoreceptors and downstream signaling.
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Affiliation(s)
- Chiara Menon
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - David J Sheerin
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Andreas Hiltbrunner
- Faculty of Biology, Institute of Biology II, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany.
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104, Freiburg, Germany.
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Oh SE, Yeung C, Babaei-Rad R, Zhao R. Cosuppression of the chloroplast localized molecular chaperone HSP90.5 impairs plant development and chloroplast biogenesis in Arabidopsis. BMC Res Notes 2014; 7:643. [PMID: 25216779 PMCID: PMC4168064 DOI: 10.1186/1756-0500-7-643] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 09/11/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND HSP90.5 is a chloroplast localized HSP90 family molecular chaperone in Arabidopsis, and it has been implicated in plant abiotic stress resistance, photomorphogenesis and nuclear-encoded protein import into the chloroplast. However, how these processes are controlled by HSP90 is not well understood. To understand the role of HSP90.5 in chloroplast function and biogenesis, in this study, we generated transgenic Arabidopsis plants that overexpress a C-terminally FLAG-tagged HSP90.5. By characterizing three HSP90.5 cosuppression lines, we demonstrated the essential role of HSP90.5 in plant growth and chloroplast biogenesis. RESULTS Immunoblotting and quantitative PCR analyses revealed three independent HSP90.5 cosuppressing transgenic lines. All three cosuppression lines displayed a certain degree of variegated phenotype in photosynthetic tissues, and the cosuppression did not affect the expression of cytosolic HSP90 isoforms. HSP90.5 cosuppression was shown to be developmentally regulated and occurred mostly at late developmental stage in adult leaves and inflorescence tissues. HSP90.5 cosuppression also caused significantly reduced rosette leaf growth, transient starch storage, but did not affect rosette leaf initiation or inflorescence production, although the fertility was reduced. Isolation of chloroplasts and size exclusion chromatography analysis indicated that the FLAG at the HSP90.5 C-terminus does not affect its proper chloroplast localization and dimerization. Finally, transmission electron microscopy indicated that chloroplast development in HSP90.5 cosuppression leaves was significantly impaired and the integrity of chloroplast is highly correlated to the expression level of HSP90.5. CONCLUSION We thoroughly characterized three HSP90.5 cosuppression lines, and demonstrated that properly controlled expression of HSP90.5 is required for plant growth and development in many tissues, and especially essential for chloroplast thylakoid formation. Since the homozygote of HSP90.5 knockout mutant is embryonically lethal, this study provides transgenic lines that mimic the conditional knockout line or siRNA line of the essential HSP90.5 gene in Arabidopsis.
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Affiliation(s)
- Saehong E Oh
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Scarborough, Ontario M1C 1A4 Canada
| | - Christine Yeung
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Scarborough, Ontario M1C 1A4 Canada
| | - Rebecca Babaei-Rad
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Scarborough, Ontario M1C 1A4 Canada
| | - Rongmin Zhao
- Department of Biological Sciences, University of Toronto, 1265 Military Trail, Scarborough, Ontario M1C 1A4 Canada
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Genome-wide analysis of the Populus Hsp90 gene family reveals differential expression patterns, localization, and heat stress responses. BMC Genomics 2013; 14:532. [PMID: 23915275 PMCID: PMC3750472 DOI: 10.1186/1471-2164-14-532] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 07/30/2013] [Indexed: 11/21/2022] Open
Abstract
Background Members of the heat shock protein 90 (Hsp90) class of proteins are evolutionarily conserved molecular chaperones. They are involved in protein folding, assembly, stabilization, activation, and degradation in many normal cellular processes and under stress conditions. Unlike many other well-characterized molecular chaperones, Hsp90s play key roles in signal transduction, cell-cycle control, genomic silencing, and protein trafficking. However, no systematic analysis of genome organization, gene structure, and expression compendium has been performed in the Populus model tree genus to date. Results We performed a comprehensive analysis of the Populus Hsp90 gene family and identified 10 Populus Hsp90 genes, which were phylogenetically clustered into two major groups. Gene structure and motif composition are relatively conserved in each group. In Populus trichocarpa, we identified three paralogous pairs, among which the PtHsp90-5a/PtHsp90-5b paralogous pair might be created by duplication of a genome segment. Subcellular localization analysis shows that PtHsp90 members are localized in different subcellular compartments. PtHsp90-3 is localized both in the nucleus and in the cytoplasm, PtHsp90-5a and PtHsp90-5b are in chloroplasts, and PtHsp90-7 is in the endoplasmic reticulum (ER). Furthermore, microarray and semi-quantitative real-time RT-PCR analyses show that a number of Populus Hsp90 genes are differentially expressed upon exposure to various stresses. Conclusions The gene structure and motif composition of PtHsp90s are highly conserved among group members, suggesting that members of the same group may also have conserved functions. Microarray and RT-PCR analyses show that most PtHsp90s were induced by various stresses, including heat stress. Collectively, these observations lay the foundation for future efforts to unravel the biological roles of PtHsp90 genes.
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Wang X, Bian Y, Cheng K, Zou H, Sun SSM, He JX. A Comprehensive Differential Proteomic Study of Nitrate Deprivation in Arabidopsis Reveals Complex Regulatory Networks of Plant Nitrogen Responses. J Proteome Res 2012; 11:2301-15. [DOI: 10.1021/pr2010764] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Xu Wang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
- Division of Life Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China
- State Key Laboratory of Agrobiotechnology
and School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Yangyang Bian
- Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Kai Cheng
- Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Hanfa Zou
- Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Samuel Sai-Ming Sun
- State Key Laboratory of Agrobiotechnology
and School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Jun-Xian He
- State Key Laboratory of Agrobiotechnology
and School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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Integrating Rare-Variant Testing, Function Prediction, and Gene Network in Composite Resequencing-Based Genome-Wide Association Studies (CR-GWAS). G3-GENES GENOMES GENETICS 2011; 1:233-43. [PMID: 22384334 PMCID: PMC3276137 DOI: 10.1534/g3.111.000364] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/05/2011] [Indexed: 01/08/2023]
Abstract
High-density array-based genome-wide association studies (GWAS) are complemented by exome sequencing and whole-genome resequencing-based association studies. Here we present a composite resequencing-based genome-wide association study (CR-GWAS) strategy that systematically exploits collective biological information and analytical tools for a robust analysis. We showcased the utility of this strategy by using Arabidopsis (Arabidopsis thaliana) resequencing data. Bioinformatic predictions of biological function alteration at each locus were integrated into the process of association testing of both common and rare variants for complex traits with a suite of statistics. Significant signals were then filtered with a priori candidate loci generated from genome database and gene network models to obtain a posteriori candidate loci. A probabilistic gene network (AraNet) that interrogates network neighborhoods of genes was then used to expand the filtering power to examine the significant testing signals. Using this strategy, we confirmed the known true positives and identified several new promising associations. Promising genes (AP1, FCA, FRI, FLC, FLM, SPL5, FY, and DCL2) were shown to control for flowering time through either common variants or rare variants within a diverse set of Arabidopsis accessions. Although many of these candidate genes were cloned earlier with mutational studies, identifying their allele variation contribution to overall phenotypic variation among diverse natural accessions is critical. Our rare allele testing established a greater number of connections than previous analyses in which this issue was not addressed. More importantly, our results demonstrated the potential of integrating various biological, statistical, and bioinformatic tools into complex trait dissection.
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Yu X, Liu H, Klejnot J, Lin C. The Cryptochrome Blue Light Receptors. THE ARABIDOPSIS BOOK 2010; 8:e0135. [PMID: 21841916 PMCID: PMC3155252 DOI: 10.1199/tab.0135] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cryptochromes are photolyase-like blue light receptors originally discovered in Arabidopsis but later found in other plants, microbes, and animals. Arabidopsis has two cryptochromes, CRY1 and CRY2, which mediate primarily blue light inhibition of hypocotyl elongation and photoperiodic control of floral initiation, respectively. In addition, cryptochromes also regulate over a dozen other light responses, including circadian rhythms, tropic growth, stomata opening, guard cell development, root development, bacterial and viral pathogen responses, abiotic stress responses, cell cycles, programmed cell death, apical dominance, fruit and ovule development, seed dormancy, and magnetoreception. Cryptochromes have two domains, the N-terminal PHR (Photolyase-Homologous Region) domain that bind the chromophore FAD (flavin adenine dinucleotide), and the CCE (CRY C-terminal Extension) domain that appears intrinsically unstructured but critical to the function and regulation of cryptochromes. Most cryptochromes accumulate in the nucleus, and they undergo blue light-dependent phosphorylation or ubiquitination. It is hypothesized that photons excite electrons of the flavin molecule, resulting in redox reaction or circular electron shuttle and conformational changes of the photoreceptors. The photoexcited cryptochrome are phosphorylated to adopt an open conformation, which interacts with signaling partner proteins to alter gene expression at both transcriptional and posttranslational levels and consequently the metabolic and developmental programs of plants.
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Affiliation(s)
- Xuhong Yu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - Hongtao Liu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - John Klejnot
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
| | - Chentao Lin
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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New Insights into the Roles of Molecular Chaperones in Chlamydomonas and Volvox. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:75-113. [DOI: 10.1016/b978-0-12-381047-2.00002-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Schroda M, Mühlhaus T. A 'foldosome' in the chloroplast? PLANT SIGNALING & BEHAVIOR 2009; 4:301-3. [PMID: 19794845 PMCID: PMC2664489 DOI: 10.4161/psb.4.4.7758] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2009] [Accepted: 01/05/2009] [Indexed: 05/20/2023]
Abstract
The proper functioning of many cytosolic proteins involved in signal transduction depends on protein folding steps carried out cooperatively by a multichaperone complex containing the Hsp90 and Hsp70 machineries. We have recently found that also in the chloroplast the Hsp90 and Hsp70 machineries form a multichaperone complex, although chloroplast Hsp90 and Hsp70 are from eukaryotic and prokaryotic origin, respectively. In earlier work by others it was shown that plants expressing a mutated form of a chloroplast-targeted Hsp90 were impaired in the light induction of several nuclear genes. These data suggest that, like in the cytosol, the folding of chloroplast proteins involved in chloroplast-to-nucleus signalling might depend on the cooperative action of the chloroplast Hsp70–Hsp90 machineries.
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Affiliation(s)
- Michael Schroda
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany.
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Willmund F, Dorn KV, Schulz-Raffelt M, Schroda M. The chloroplast DnaJ homolog CDJ1 of Chlamydomonas reinhardtii is part of a multichaperone complex containing HSP70B, CGE1, and HSP90C. PLANT PHYSIOLOGY 2008; 148:2070-82. [PMID: 18931144 PMCID: PMC2593681 DOI: 10.1104/pp.108.127944] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Accepted: 10/14/2008] [Indexed: 05/20/2023]
Abstract
We report on the molecular and biochemical characterization of CDJ1, one of three zinc-finger-containing J-domain proteins encoded by the Chlamydomonas reinhardtii genome. Fractionation experiments indicate that CDJ1 is a plastidic protein. In the chloroplast, CDJ1 was localized to the soluble stroma fraction, but also to thylakoids and to low density membranes. Although the CDJ1 gene was strongly heat shock inducible, CDJ1 protein levels increased only slightly during heat shock. Cellular CDJ1 concentrations were close to those of heat shock protein 70B (HSP70B), the major HSP70 in the Chlamydomonas chloroplast. CDJ1 complemented the temperature-sensitive phenotype of an Escherichia coli mutant lacking its dnaJ gene and interacted with E. coli DnaK, hence classifying it as a bona fide DnaJ protein. In soluble cell extracts, CDJ1 was found to organize into stable dimers and into complexes of high molecular mass. Immunoprecipitation experiments revealed that CDJ1 forms common complexes with plastidic HSP90C, HSP70B, and CGE1. In blue native-polyacrylamide gel electrophoresis, all four (co)chaperones migrated at 40% to 90% higher apparent than calculated molecular masses, indicating that greatest care must be taken when molecular masses of protein complexes are estimated from their migration relative to standard native marker proteins. Immunoprecipitation experiments from size-fractioned soluble cell extracts suggested that HSP90C and HSP70B exist as preformed complex that is joined by CDJ1. In summary, CDJ1 and CGE1 are novel cohort proteins of the chloroplast HSP90-HSP70 multichaperone complex. As HSP70B, CDJ1, and CGE1 are derived from the endosymbiont, whereas HSP90C is of eukaryotic origin, we observe in the chloroplast the interaction of two chaperone systems of distinct evolutionary origin.
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Affiliation(s)
- Felix Willmund
- Institute of Biology II, Plant Biochemistry, University of Freiburg, D-79104 Freiburg, Germany
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Abstract
The Hsp90 chaperone machine facilitates the maturation of a diverse set of 'client' proteins. Many of these Hsp90 clients are essential nodes in signal transduction pathways and regulatory circuits,accounting for the important role Hsp90 plays in organismal development and responses to the environment. Recent findings suggest a broader impact of the chaperone on phenotype: fully functional Hsp90 canalizes wild-type phenotypes by suppressing underlying genetic and epigenetic variation. This variation can be expressed upon challenging the Hsp90 machinery by environmental stress, genetic or pharmaceutical targeting of Hsp90. The existence of Hsp90-buffered genetic and epigenetic variation together with plausible release mechanisms has wide-ranging implication for phenotype and possibly evolutionary processes. Here,we discuss the role of Hsp90 in canalization and organismal plasticity,and highlight important questions for future experimental inquiry.
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Affiliation(s)
- Neeraj Salathia
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
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15
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Samakovli D, Thanou A, Valmas C, Hatzopoulos P. Hsp90 canalizes developmental perturbation. JOURNAL OF EXPERIMENTAL BOTANY 2007; 58:3513-3524. [PMID: 18057034 DOI: 10.1093/jxb/erm191] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Stochastic processes are intrinsic phenomena that perturb developmental processes. However, the canalization process restricts the magnitude of perturbation and hence the magnitude of morphological variation during development. Heat-shock protein 90 (Hsp90) chaperones are a class of proteins stabilizing a network of 'client' proteins that are involved in diverse signal transduction pathways affecting development. Here it is reported that a reduction of Hsp90 gene dose creates canalization perturbations that affect many aspects of Arabidopsis development and results in a plethora of morphological alterations. Hence, Hsp90 restricts stochastic phenomena by minimizing perturbations, thereby canalizing development. It is also shown that morphogenesis is determined by three mutually inter-related parameters: genotype, environment, and time. Hsp90 is involved in the interaction of these three parameters which ultimately affect developmental processes. The amount of phenotypic variation upon the reduction of Hsp90 function could be perceived as adaptive and could have an impact on the evolutionary process.
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Affiliation(s)
- Despina Samakovli
- Laboratory of Molecular Biology, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
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Willmund F, Schroda M. HEAT SHOCK PROTEIN 90C is a bona fide Hsp90 that interacts with plastidic HSP70B in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 2005; 138:2310-22. [PMID: 15995001 PMCID: PMC1183417 DOI: 10.1104/pp.105.063578] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report on the molecular and biochemical characterization of HEAT SHOCK PROTEIN 90C (HSP90C), one of the three Hsp90 chaperones encoded by the Chlamydomonas reinhardtii genome. Fractionation experiments indicate that HSP90C is a plastidic protein. In the chloroplast, HSP90C was localized to the soluble stroma fraction, but also to thylakoids and low-density membranes containing inner envelopes. HSP90C is expressed under basal conditions and is strongly induced by heat shock and moderately by light. In soluble cell extracts, HSP90C was mainly found to organize into dimers, but also into complexes of high molecular mass. Also, heterologously expressed HSP90C was mainly found in dimers, but tetramers and fewer monomers were detected, as well. HSP90C exhibits a weak ATPase activity with a Km for ATP of approximately 48 microM and a kcat of approximately 0.71 min(-1). This activity was inhibited by the Hsp90-specific inhibitor radicicol. In coimmunoprecipitation experiments, we found that HSP90C interacts with several proteins, among them plastidic HSP70B. The cellular concentration of HSP70B was found to be 2.9 times higher than that of HSP90C, giving a 4.8:1 stoichiometry of HSP70B monomers to HSP90C dimers. The strong inducibility of HSP90C by heat shock implies a role of the chaperone in stress management. Furthermore, its interaction with HSP70B suggests that, similar to their relatives in cytosol and the endoplasmic reticulum, both chaperones might constitute the core of a multichaperone complex involved in the maturation of specific client proteins, e.g. components of signal transduction pathways.
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Affiliation(s)
- Felix Willmund
- Institute of Biology II, Plant Biochemistry, University of Freiburg, D-79104 Freiburg, Germany
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Sangster TA, Queitsch C. The HSP90 chaperone complex, an emerging force in plant development and phenotypic plasticity. CURRENT OPINION IN PLANT BIOLOGY 2005; 8:86-92. [PMID: 15653405 DOI: 10.1016/j.pbi.2004.11.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The essential cellular functions of the molecular chaperone HSP90 have been intensively investigated in fungal and mammalian model systems. Several recent publications have highlighted the importance of this chaperone complex in plant development and responsiveness to external stimuli. In particular, HSP90 is crucial for R-protein-mediated defense against pathogens. Other facets of HSP90 function in plants include its involvement in phenotypic plasticity, developmental stability, and buffering of genetic variation. Plants have emerged as powerful tools that complement other model systems in attempts to extend our knowledge of the myriad impacts of protein folding and chaperone function.
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Affiliation(s)
- Todd A Sangster
- Committee on Genetics, University of Chicago, 920 E. 58th Street. Chicago, Illinois 60637, USA
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Navarro MT, Mariscal V, Macías MI, Fernández E, Galván A. Chlamydomonas reinhardtii strains expressing nitrate reductase under control of the cabII-1 promoter: isolation of chlorate resistant mutants and identification of new loci for nitrate assimilation. PHOTOSYNTHESIS RESEARCH 2005; 83:151-61. [PMID: 16143849 DOI: 10.1007/s11120-004-9297-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Accepted: 04/29/2004] [Indexed: 05/04/2023]
Abstract
The Chlamydomonas reinhardtii strain Tx11-8 is a transgenic alga that bears the nitrate reductase gene (Nia1) under control of the CabII-1 gene promoter (CabII-1-Nia1). Approximately nine copies of the chimeric CabII-1-Nia1 gene were found to be integrated in this strain and to confer a phenotype of chlorate sensitivity in the presence of ammonium. We have used this strain for the isolation of spontaneous chlorate resistant mutants in the presence of ammonium that were found to be defective at loci involved in MoCo metabolism and light-dependent growth in nitrate media. Of a total of 45 mutant strains analyzed first, 44 were affected in the MoCo activity (16 Nit(-), unable to grow in nitrate, and 28 Nit(+), able to grow in nitrate). All the Nit(-) strains lacked MoCo activity. Diploid complementation of Nit(-), MoCo(-) strains with C. reinhardtii MoCo mutants and genetic analysis indicated that some strains were defective at known loci for MoCo biosynthesis, while three strains were defective at two new loci, hereafter named Nit10 and Nit11. The other 28 Nit(+) strains showed almost undetectable MoCo activity or activity was below 20% of the parental strain. Second, only one strain (named 23c(+)) showed MoCo and NR activities comparable to those in the parental strain. Strain 23c(+) seems to be affected in a locus, Nit12, required for growth in nitrate under continuous light. It is proposed that this locus is required for nitrate/chlorate transport activity. In this work, mechanisms of chlorate toxicity are reviewed in the light of our results.
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Affiliation(s)
- María Teresa Navarro
- Departamento de Ciencias Ambientales, Area de Fisiología Vegetal, Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, Carretera de Utrera, Seville 41013, Spain
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Boccalandro HE, Rossi MC, Saijo Y, Deng XW, Casal JJ. Promotion of photomorphogenesis by COP1. PLANT MOLECULAR BIOLOGY 2004; 56:905-15. [PMID: 15821989 DOI: 10.1007/s11103-004-5919-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 11/06/2004] [Indexed: 05/05/2023]
Abstract
CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) represses photomorphogenesis in darkness by targeting nuclear-localized transcription factors to proteasome-mediated degradation. Upon light exposure, COP1 migrates to the cytosol allowing photomorphogenesis to proceed but the residual nuclear pool down-regulates light signaling mediated by phytochrome A. Here we show that weak alleles of cop1 exhibit reverse photomorphogenic responses i.e. reduced rather than enhanced cotyledon unfolding under red light compared to darkness. Conversely, COP1 overexpressors which de-etiolate poorly under blue or far-red light, showed enhanced photomorphogenesis under red light. The positive relationship between COP1 and photomorphogenic response required phytochrome B. Thus, genetic manipulation of COP1 levels differentially affects phytochrome A- compared to phytochrome B-mediated responses. We hypothesize that COP1 could be involved in degradation of negative regulators of photomorphogenesis or in transcriptional activation, as observed for some E3 ligases in mammalian development.
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Affiliation(s)
- Hernán E Boccalandro
- I.F.E.V.A., Faculty of Agronomy, University of Buenos Aires, Av. San Martín 4453, 1417, Buenos Aires, Argentina
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Schroda M. The Chlamydomonas genome reveals its secrets: chaperone genes and the potential roles of their gene products in the chloroplast. PHOTOSYNTHESIS RESEARCH 2004; 82:221-40. [PMID: 16143837 DOI: 10.1007/s11120-004-2216-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Accepted: 06/11/2004] [Indexed: 05/04/2023]
Abstract
The first draft of the Chlamydomonas nuclear genome was searched for genes potentially encoding members of the five major chaperone families, Hsp100/Clp, Hsp90, Hsp70, Hsp60, the small heat shock proteins, and the Hsp70 and Cpn60 co-chaperones GrpE and Cpn10/20, respectively. This search yielded 34 potential (co-)chaperone genes, among them those 8 that have been reported earlier inChlamydomonas. These 34 genes encode all the (co-)chaperones that have been expected for the different compartments and organelles from genome searches in Arabidopsis, where 74 genes have been described to encode basically the same set of (co-)chaperones. Genome data from Arabidopsis and Chlamydomonas on the five major chaperone families are compared and discussed, with particular emphasis on chloroplast chaperones.
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Affiliation(s)
- Michael Schroda
- Institut für Biologie II/Biochemie, Universität Freiburg, Schänzlestr. 1, 79104, Freiburg, Germany,
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Yang KY, Kim YM, Lee S, Song PS, Soh MS. Overexpression of a mutant basic helix-loop-helix protein HFR1, HFR1-deltaN105, activates a branch pathway of light signaling in Arabidopsis. PLANT PHYSIOLOGY 2003; 133:1630-42. [PMID: 14645731 PMCID: PMC300719 DOI: 10.1104/pp.103.029751] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2003] [Revised: 08/05/2003] [Accepted: 09/13/2003] [Indexed: 05/23/2023]
Abstract
The HFR1, a basic helix-loop-helix protein, is required for a subset of phytochrome A-mediated photoresponses in Arabidopsis. Here, we show that overexpression of the HFR1-deltaN105 mutant, which lacks the N-terminal 105 amino acids, confers exaggerated photoresponses even in darkness. Physiological analysis implied that overexpression of HFR1-deltaN105 activated constitutively a branch pathway of light signaling that mediates a subset of photomorphogenic responses, including germination, de-etiolation, gravitropic hypocotyl growth, blocking of greening, and expression of some light-regulated genes such as CAB, DRT112, PSAE, PSBL, PORA, and XTR7, without affecting the light-responsiveness of anthocyanin accumulation and expression of other light-regulated genes such as CHS and PSBS. Although the end-of-day far-red light response and petiole elongation were suppressed in the HFR1-deltaN105-overexpressing plants, flowering time was not affected by HFR1-deltaN105. In addition, the HFR1-deltaN105-overexpressing plants showed hypersensitive photoresponses in the inhibition of hypocotyl elongation, dependently on phytochrome A, FHY1, and FHY3 under FR light or phyB under R light, respectively. Moreover, our double mutant analysis suggested that the hypersensitive photoresponse is due to functional cooperation between HFR1-deltaN105 and other light-signaling components including HY5, a basic leucine zipper protein. Taken together, our results of gain-of-function approach with HFR1-deltaN105 suggest the existence of a complex and important basic helix-loop-helix protein-mediated transcriptional network controlling a branch pathway of light signaling and provide a useful framework for further genetic dissection of light-signaling network in Arabidopsis.
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Affiliation(s)
- Ki-Young Yang
- Kumho Life and Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
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Abstract
The internal programs of plant development are informed in a profound way by environmental light conditions. This review summarizes the contribution of repressor proteins to the light-signaling machinery during seedling development, and discusses the integration of repressors with other, positively acting, light-signaling pathways and auxin and brassinosteroid hormone-signaling pathways. The main focus is placed on the mode of action of the COP/DET/FUS proteins, which were first identified in Arabidopsis but are now emerging in other plants. Their role in regulating protein turnover through ubiquitination is reviewed in light of parallel ongoing investigations of COP/DET/FUS homologues in metazoans and fungi.
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Affiliation(s)
- Tae-Houn Kim
- Department of Botany, The University of Tennessee, Knoxville 37996, USA
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Cao D, Froehlich JE, Zhang H, Cheng CL. The chlorate-resistant and photomorphogenesis-defective mutant cr88 encodes a chloroplast-targeted HSP90. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 33:107-118. [PMID: 12943545 DOI: 10.1046/j.1365-313x.2003.016011.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The cr88 mutant of Arabidopsis is a novel chlorate-resistant mutant that displays long hypocotyls in red light, but not in far red or blue light, and is delayed in the greening process. In cotyledons and young leaves, plastids are less developed compared with those of the wild type. In addition, a subset of light-regulated genes are under-expressed in this mutant. To understand the pleiotropic phenotypes of cr88, we isolated the CR88 gene through map-based cloning. We found that CR88 encodes a chloroplast-targeted 90-kDa heat shock protein (HSP90). The CR88 gene is expressed at highest levels during early post-germination stages and in leaves and reproductive organs. It is constitutively expressed but is also light and heat shock inducible. Chloroplast import experiments showed that the protein is localized to the stroma compartment of the chloroplast. The possible function of an HSP90 in the chloroplast and a plausible explanation of the pleiotropic phenotypes observed in cr88 are discussed.
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Affiliation(s)
- Dongsun Cao
- Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA
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Kim YM, Woo JC, Song PS, Soh MS. HFR1, a phytochrome A-signalling component, acts in a separate pathway from HY5, downstream of COP1 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 30:711-719. [PMID: 12061902 DOI: 10.1046/j.1365-313x.2002.01326.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
HFR1, a basic helix-loop-helix protein, is known to be required for a subset of phytochrome A (phyA)-dependent photoresponses. To investigate the role of HFR1 in light signalling, we have examined the genetic interaction between HFR1 and HY5, a positive regulator of light signalling, and COP1, a repressor of photomorphogenesis. Double mutant analysis suggests that HFR1 mediates phyA-dependent inhibition of hypocotyl elongation independently of HY5. HFR1 was shown to be necessary for a subset of cop1-triggered photomorphogenic phenotypes in the dark, including inhibition of hypocotyl elongation, gravitropic hypocotyl growth, and expression of the light-inducible genes CAB and RBCS. Phenotypic analysis of the triple mutant cop1hy5hfr1 indicated that both HFR1 and HY5 are required for cop1-mediated photomorphogenic seedling development in darkness, consistent with their additive roles in phyA-dependent signalling. Taken together, these results suggest that HFR1 might act downstream of COP1, in a separate pathway from HY5, to mediate photomorphogenesis in Arabidopsis.
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Affiliation(s)
- Young-Mi Kim
- Kumho Life & Environmental Science Laboratory, 1 Oryong-Dong, Buk-Gu, Gwangju 500-712, Republic of Korea
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Crawford NM, Forde BG. Molecular and developmental biology of inorganic nitrogen nutrition. THE ARABIDOPSIS BOOK 2002; 1:e0011. [PMID: 22303192 PMCID: PMC3243300 DOI: 10.1199/tab.0011] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Nigel M. Crawford
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0116
- Corresponding Author, phone/fx: 858/534-1637;
| | - Brian G. Forde
- Department of Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK
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