1
|
Ding F, Li F, Zhang B. A plastid-targeted heat shock cognate 70-kDa protein confers osmotic stress tolerance by enhancing ROS scavenging capability. FRONTIERS IN PLANT SCIENCE 2022; 13:1012145. [PMID: 36275553 PMCID: PMC9581120 DOI: 10.3389/fpls.2022.1012145] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/12/2022] [Indexed: 06/12/2023]
Abstract
Osmotic stress severely affects plant growth and development, resulting in massive loss of crop quality and quantity worldwide. The 70-kDa heat shock proteins (HSP70s) are highly conserved molecular chaperones that play essential roles in cellular processes including abiotic stress responses. However, whether and how plastid-targeted heat shock cognate 70 kDa protein (cpHSC70-1) participates in plant osmotic stress response remain elusive. Here, we report that the expression of cpHSC70-1 is significantly induced upon osmotic stress treatment. Phenotypic analyses reveal that the plants with cpHSC70-1 deficiency are sensitive to osmotic stress and the plants overexpressing cpHSC70-1 exhibit enhanced tolerance to osmotic stress. Consistently, the expression of the stress-responsive genes is lower in cphsc70-1 mutant but higher in 35S:: cpHSC70-1 lines than that in wild-type plants when challenged with osmotic stress. Further, the cphsc70-1 plants have less APX and SOD activity, and thus more ROS accumulation than the wild type when treated with mannitol, but the opposite is observed in the overexpression lines. Overall, our data reveal that cpHSC70-1 is induced and functions positively in plant response to osmotic stress by promoting the expression of the stress-responsive genes and reducing ROS accumulation.
Collapse
Affiliation(s)
- Feng Ding
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
- School of Landscape and Ecological Engineering, Hebei University of Engineering, Handan, China
| | - Fan Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Binglei Zhang
- School of Landscape and Ecological Engineering, Hebei University of Engineering, Handan, China
| |
Collapse
|
2
|
Leng L, Liang Q, Jiang J, Zhang C, Hao Y, Wang X, Su W. A subclass of HSP70s regulate development and abiotic stress responses in Arabidopsis thaliana. JOURNAL OF PLANT RESEARCH 2017; 130:349-363. [PMID: 28004282 DOI: 10.1007/s10265-016-0900-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 11/14/2016] [Indexed: 05/20/2023]
Abstract
Members of the HSP70 family function as molecular chaperones to maintain cellular homeostasis and help plants cope with environmental stimuli. However, due to functional redundancy and lack of effective chemical inhibitors, our knowledge of functions of individual HSP70s has remained limited. Here, we confirmed a subclass of HSP70s, including HSP70-1, -2, -3, -4, and -5, localized to the cytosol and nucleus in Arabidopsis thaliana. Histochemical analyses of promoter:GUS reporter lines showed that HSP70-1, -2, -3, and -4 genes were widely expressed, but HSP70-5 was not. In addition, individual HSP70 showed not only similar but also distinct transcriptions when treated by different abiotic stresses and phytohormones. No apparent phenotype was observed when individual HSP70 genes were overexpressed or knocked-out/down, but the double mutant hsp70-1 hsp70-4 and triple mutant hsp70-2 hsp70-4 hsp70-5 plants exhibited developmental phenotypes with shortened specific growth periods, curly and round leaves, twisted petioles, thin stems, and short siliques. Moreover, both mutants were hypersensitive to heat, cold, high glucose, salt and osmotic stress, but hyposensitive to abscisic acid. Genes related to flowering, and the cytokinin, brassinosteroid, and abscisic acid signaling pathways were differentially expressed in both mutants. Our studies suggest that, the individual HSP70 possibly performs both redundant and specific functions with the other members in the cytosolic/nuclear HSP70 subclass, and apart from enabling plants to cope with abiotic stresses, this subclass of cytosolic/nuclear HSP70 proteins also participates in diverse developmental processes and signaling pathways.
Collapse
Affiliation(s)
- Linna Leng
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China
| | - Qianqian Liang
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China
| | - Jianjun Jiang
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China
| | - Chi Zhang
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China
| | - Yuhan Hao
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China
| | - Xuelu Wang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wei Su
- State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
| |
Collapse
|
3
|
Tsay LM, Hu SM, Wang C, Lee WS, Lin LJ, Kan LS. Circular Dichroism Measurements on C-Terminal Fragment of Heat Shock Protein from Rat. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.199500063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
|
4
|
Hong JH, Seah SW, Xu J. The root of ABA action in environmental stress response. PLANT CELL REPORTS 2013; 32:971-83. [PMID: 23571661 DOI: 10.1007/s00299-013-1439-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/24/2013] [Accepted: 03/26/2013] [Indexed: 05/05/2023]
Abstract
The growth and development of plants are influenced by the integration of diverse endogenous and environmental signals. Acting as a mediator of extrinsic signals, the stress hormone, abscisic acid (ABA), has been shown to regulate many aspects of plant development in response to unfavourable environmental stresses, allowing the plant to cope and survive in adverse conditions, such as drought, low or high temperature, or high salinity. Here, we summarize recent evidence on the roles of ABA in environmental stress responses in the Arabidopsis root; and on how ABA crosstalks with other phytohormones to modulate root development and growth in Arabidopsis. We also review literature findings showing that, in response to environmental stresses, ABA affects the root system architecture in other plant species, such as rice.
Collapse
Affiliation(s)
- Jing Han Hong
- Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | | | | |
Collapse
|
5
|
Study of receptor-chaperone interactions using the optical technique of spectroscopic ellipsometry. Biophys J 2011; 101:504-11. [PMID: 21767504 DOI: 10.1016/j.bpj.2011.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/07/2011] [Accepted: 06/09/2011] [Indexed: 11/22/2022] Open
Abstract
This work describes a detailed quantitative interaction study between the novel plastidial chaperone receptor OEP61 and isoforms of the chaperone types Hsp70 and Hsp90 using the optical method of total internal reflection ellipsometry (TIRE). The receptor OEP61 was electrostatically immobilized on a gold surface via an intermediate layer of polycations. The TIRE measurements allowed the evaluation of thickness changes in the adsorbed molecular layers as a result of chaperone binding to receptor proteins. Hsp70 chaperone isoforms but not Hsp90 were shown to be capable of binding OEP61. Dynamic TIRE measurements were carried out to evaluate the affinity constants of the above reactions and resulted in clear discrimination between specific and nonspecific binding of chaperones as well as differences in binding properties between the highly similar Hsp70 isoforms.
Collapse
|
6
|
Tominaga H, Coury DA, Amano H, Kakinuma M. Isolation and characterization of a cDNA encoding a heat shock protein 70 from a sterile mutant of Ulva pertusa (Ulvales, Chlorophyta). ECOTOXICOLOGY (LONDON, ENGLAND) 2010; 19:577-588. [PMID: 20111994 DOI: 10.1007/s10646-010-0462-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/11/2010] [Indexed: 05/28/2023]
Abstract
Synthesis and accumulation of molecular chaperones are universal responses found in all cellular organisms when exposed to a variety of unfavorable conditions. Heat shock protein 70 (Hsp70), which is one of the major classes of molecular chaperones, plays a particularly important role in cellular stress responses, and the Hsp70 system is the most intensely studied in higher plants and algae. Therefore, we isolated and characterized a cDNA clone encoding Hsp70 from a sterile strain of Ulva pertusa (Ulvales, Chlorophyta). The sterile U. pertusa Hsp70 (UpHsp70) cDNA consisted of 2,272 nucleotides and had an open reading frame encoding a polypeptide of 663 amino acid (AA) residues with a molecular mass of 71.7 kDa. Amino acid alignment and phylogenetic analysis of Hsp70s from other organisms showed that UpHsp70 was more similar to cytoplasmic Hsp70s from green algae and higher plants (> or =75%) than to those from other algae and microorganisms. Southern blot analysis indicated that the sterile U. pertusa genome had at least four cytoplasmic Hsp70-encoding genes. UpHsp70 mRNA levels were significantly affected by diurnal changes, rapidly increased by high-temperature stress, and gradually increased by exposure to copper, cadmium, and lead. These results suggest that UpHsp70 plays particularly important roles in adaptation to high-temperature conditions and diurnal changes, and is potentially involved in tolerance to heavy metal toxicity.
Collapse
|
7
|
He Z, Xie R, Wang Y, Zou H, Zhu J, Yu G. Cloning and characterization of a heat shock protein 70 gene, MsHSP70-1, in Medicago sativa. Acta Biochim Biophys Sin (Shanghai) 2008; 40:209-16. [PMID: 18330475 DOI: 10.1111/j.1745-7270.2008.00394.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Some members of the heat shock protein 70 (HSP70) family have important functions in organism development. Here, we identified an alfalfa (Medicago sativa L. cv. Algonquin) HSP70 gene, MsHSP70-1, using cDNA array and reverse transcription-polymerase chain reaction. This gene contains a 1947 bp open reading frame encoding a protein of 649 amino acids. This protein contains all conserved domains, motifs, and characteristic sequences of plant HSP70s. The expression of MsHSP70-1 is enhanced in nodule compared with root, stem, leaf, and flower, and throughout the process of nodule development. Northern hybridization analysis indicated that the expression of MsHSP70-1 in nodule requires the active bacA gene of rhizobia. These results suggested that MsHSP70-1 might play an important role in alfalfa nodule development.
Collapse
Affiliation(s)
- Zhishui He
- National Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | | | | | | | | | | |
Collapse
|
8
|
Suri SS, Dhindsa RS. A heat-activated MAP kinase (HAMK) as a mediator of heat shock response in tobacco cells. PLANT, CELL & ENVIRONMENT 2008; 31:218-26. [PMID: 17996015 DOI: 10.1111/j.1365-3040.2007.01754.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
A heat-activated MAP kinase (HAMK), immunologically related to the extracellular signal-regulated kinase (ERK) super-family of protein kinases, has been identified in BY2 cells of tobacco. The activation of HAMK at 37 degrees C was transient and detected within 2 min and reached a maximum level within 5 min. Ca(2+) chelators and channel blockers, and the known inhibitors of MEK, a MAP kinase kinase, prevented the heat activation of HAMK. This suggests that HAMK activation is part of a heat-triggered MAP kinase cascade that requires Ca(2+) influx. The heat shock protein HSP70 accumulated at 37 degrees C, but not when HAMK activation was prevented with the inhibitors of MEK or with Ca(2+) chelators or channel blockers. As previously shown for heat activation of HAMK, heat-induced accumulation of HSP70 requires membrane fluidization and reorganization of cytoskeleton. We concluded that heat-triggered HAMK cascade might play an essential role in the launching of heat shock response and hsp gene expression in tobacco cells.
Collapse
Affiliation(s)
- Sarabjeet S Suri
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada
| | | |
Collapse
|
9
|
Yan C, Shen H, Li Q, He Z. A novel ABA-hypersensitive mutant in Arabidopsis defines a genetic locus that confers tolerance to xerothermic stress. PLANTA 2006; 224:889-99. [PMID: 16575591 DOI: 10.1007/s00425-006-0272-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2006] [Accepted: 03/10/2006] [Indexed: 05/03/2023]
Abstract
Hot and dry air (harmattan or xerothermic climate) greatly inhibits plant growth, particularly flowering and seed setting of crops. Little is known about the mechanism of plant response to this extreme environmental stress due to the lack of valuable genetic resource. Here, we report the isolation and characteristics of a unique Arabidopsis mutant, hat1 (harmattan tolerant 1), which shows high tolerance to hot and dry air. Under normal growth conditions, the mutant does not differ in morphology and soil drought tolerance compared to the wild type. When subjected to high temperature (42 degrees C) and low humidity (10-15%), however, it could survive up to 6 days, while the wild type (Col-0) died after 24 h. The hat1 mutant also exhibits enhanced tolerance to soil drought, but only under xerothermic conditions. Mutant plants tightly close their stomata to retain water under xerothermic stress, and are more tolerant to high salinity at all developmental stages, accumulating less Na+ and more K+ than wild-type plants during NaCl treatment. Interestingly, hat1 plants are also ABA-hypersensitive. Genetic analysis revealed that the hat1 phenotype is caused by a dominant mutation at a single nuclear locus. Mapping studies indicate that Hat1 is located at an interval of 168 kb on chromosome 5 in which 21 genes are known to be regulated by diverse abiotic stresses. A mutant of this kind, to our knowledge, has not been previously reported. Thus, this report serves as a starting point in the genetic dissection of the plant response to xerothermic stress, and provides physiological and genetic evidence of the existence of a novel abiotic stress response pathway that is also ABA-dependent.
Collapse
Affiliation(s)
- Chengshi Yan
- National Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | | | | | | |
Collapse
|
10
|
Wang H, Ng TB. Antifungal peptides, a heat shock protein-like peptide, and a serine-threonine kinase-like protein from Ceylon spinach seeds. Peptides 2004; 25:1209-14. [PMID: 15245882 DOI: 10.1016/j.peptides.2004.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 05/04/2004] [Indexed: 10/26/2022]
Abstract
Two antifungal peptides (designated alpha- and beta-basrubrins) with molecular masses of 4-5 kDa and distinct N-terminal sequences, and a peptide and a protein with N-terminal sequences resembling heat shock protein (hsp) and serine-threonine kinase, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure entailed saline extraction, (NH4)2SO4 precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, and FPLC-gel filtration on a Superdex peptide column. alpha- and beta-basrubrins inhibited mycelial growth in Botrytis cirerea with an IC50 value of 7.5 and 14.7 microM, respectively, Mycosphaerella arachidicola with an IC50 of 12.4 and 6.9 microM, and Fusarium oxysporum with an IC50 of 5.8 and 6.2 microM. Neither alpha-basrubrin nor beta-basrubin exhibited DNase, RNase, lectin or protease activity, indicating that their antifungal action is not due to these activities. HIV-1 reverse transcriptase was inhibited by alpha- and beta-basrubrins with an IC50 of 246 and 370 microM, respectively. Translation in rabbit reticulocyte lysate was inhibited by alpha- and beta-basrubrins with an IC50 of 400 and 100 nM. The heat shock protein-like peptide and serine-threonine kinase-like protein exhibited a molecular mass of 3 and 30 kDa, respectively. They inhibited neither translation in a rabbit reticulocyte system at concentrations up to 50 microM nor HIV-1 reverse transcriptase activity at concentrations up to 400 microM. They did not exert antifungal activity toward B. cinerea, M. arachidicola, and F. oxysporum when tested up to 16 microg. None of the aforementioned proteins demonstrated DNase, RNase, protease or lectin activity.
Collapse
Affiliation(s)
- Hexiang Wang
- Department of Microbiology, College of Biological Science, China Agricultural University, Beijing
| | | |
Collapse
|
11
|
Weber H, Chételat A, Reymond P, Farmer EE. Selective and powerful stress gene expression in Arabidopsis in response to malondialdehyde. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 37:877-88. [PMID: 14996219 DOI: 10.1111/j.1365-313x.2003.02013.x] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The provenance, half-life and biological activity of malondialdehyde (MDA) were investigated in Arabidopsis thaliana. We provide genetic confirmation of the hypothesis that MDA originates from fatty acids containing more than two methylene-linked double bonds, showing that tri-unsaturated fatty acids are the in vivo source of up to 75% of MDA. The abundance of the combined pool of free and reversibly bound MDA did not change dramatically in stress, although a significant increase in the free MDA pool under oxidative conditions was observed. The half-life of infiltrated MDA indicated rapid metabolic turnover/sequestration. Exposure of plants to low levels of MDA using a recently developed protocol powerfully upregulated many genes on a cDNA microarray with a bias towards those implicated in abiotic/environmental stress (e.g. ROF1 and XERO2). Remarkably, and in contrast to the activities of other reactive electrophile species (i.e. small vinyl ketones), none of the pathogenesis-related (PR) genes tested responded to MDA. The use of structural mimics of MDA isomers suggested that the propensity of the molecule to act as a cross-linking/modifying reagent might contribute to the activation of gene expression. Changes in the concentration/localisation of unbound MDA in vivo could strongly affect stress-related transcription.
Collapse
Affiliation(s)
- Hans Weber
- Gene Expression Laboratory, Plant Molecular Biology, University of Lausanne, Biology Building, 1015 Lausanne, Switzerland
| | | | | | | |
Collapse
|
12
|
Wolucka BA, Van Montagu M. GDP-mannose 3',5'-epimerase forms GDP-L-gulose, a putative intermediate for the de novo biosynthesis of vitamin C in plants. J Biol Chem 2003; 278:47483-90. [PMID: 12954627 DOI: 10.1074/jbc.m309135200] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite its importance for agriculture, bioindustry, and nutrition, the fundamental process of L-ascorbic acid (vitamin C) biosynthesis in plants is not completely elucidated, and little is known about its regulation. The recently identified GDP-Man 3',5'-epimerase catalyzes a reversible epimerization of GDP-D-mannose that precedes the committed step in the biosynthesis of vitamin C, resulting in the hydrolysis of the highly energetic glycosyl-pyrophosphoryl linkage. Here, we characterize the native and recombinant GDP-Man 3',5'-epimerase of Arabidopsis thaliana. GDP and GDP-D-glucose are potent competitive inhibitors of the enzyme, whereas GDP-L-fucose gives a complex type of inhibition. The epimerase contains a modified version of the NAD binding motif and is inhibited by NAD(P)H and stimulated by NAD(P)+. A feedback inhibition of vitamin C biosynthesis is observed apparently at the level of GDP-Man 3',5'-epimerase. The epimerase catalyzes at least two distinct epimerization reactions and releases, besides the well known GDP-l-galactose, a novel intermediate: GDP-L-gulose. The yield of the epimerization varies and seems to depend on the molecular form of the enzyme. Both recombinant and native enzymes co-purified with a Hsp70 heat-shock protein (Escherichia coli DnaK and A. thaliana Hsc70.3, respectively). We speculate, therefore, that the Hsp70 molecular chaperones might be involved in folding and/or regulation of the epimerase. In summary, the plant epimerase undergoes a complex regulation and could control the carbon flux into the vitamin C pathway in response to the redox state of the cell, stress conditions, and GDP-sugar demand for the cell wall/glycoprotein biosynthesis. Exogenous L-gulose and L-gulono-1,4-lactone serve as direct precursors of l-ascorbic acid in plant cells. We propose an L-gulose pathway for the de novo biosynthesis of vitamin C in plants.
Collapse
Affiliation(s)
- Beata A Wolucka
- Department of Molecular Microbiology, Flanders Interuniversity Institute for Biotechnology (VIB), Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Belgium.
| | | |
Collapse
|
13
|
Chou ML, Fitzpatrick LM, Tu SL, Budziszewski G, Potter-Lewis S, Akita M, Levin JZ, Keegstra K, Li HM. Tic40, a membrane-anchored co-chaperone homolog in the chloroplast protein translocon. EMBO J 2003; 22:2970-80. [PMID: 12805212 PMCID: PMC162133 DOI: 10.1093/emboj/cdg281] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The function of Tic40 during chloroplast protein import was investigated. Tic40 is an inner envelope membrane protein with a large hydrophilic domain located in the stroma. Arabidopsis null mutants of the atTic40 gene were very pale green and grew slowly but were not seedling lethal. Isolated mutant chloroplasts imported precursor proteins at a lower rate than wild-type chloroplasts. Mutant chloroplasts were normal in allowing binding of precursor proteins. However, during subsequent translocation across the inner membrane, fewer precursors were translocated and more precursors were released from the mutant chloroplasts. Cross-linking experiments demonstrated that Tic40 was part of the translocon complex and functioned at the same stage of import as Tic110 and Hsp93, a member of the Hsp100 family of molecular chaperones. Tertiary structure prediction and immunological studies indicated that the C-terminal portion of Tic40 contains a TPR domain followed by a domain with sequence similarity to co-chaperones Sti1p/Hop and Hip. We propose that Tic40 functions as a co-chaperone in the stromal chaperone complex that facilitates protein translocation across the inner membrane.
Collapse
Affiliation(s)
- Ming-Lun Chou
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Vignols F, Mouaheb N, Thomas D, Meyer Y. Redox control of Hsp70-Co-chaperone interaction revealed by expression of a thioredoxin-like Arabidopsis protein. J Biol Chem 2003; 278:4516-23. [PMID: 12433921 DOI: 10.1074/jbc.m210080200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
By using a yeast functional complementation assay, we have identified AtTDX, a new Arabidopsis thaliana gene, encoding a two-domain 42-kDa protein. The amino-terminal domain of AtTDX is closely related to the co-chaperone Hsp70-interacting protein HIP, whereas its carboxyl-terminal part contains a thioredoxin domain. Both in vivo and in vitro assays showed that AtTDX is a protein-disulfide reductase. We next found that the HIP domain of AtTDX is capable of interacting with the ATPase domain of Ssb2, a yeast heat-shock protein 70 chaperone. Strikingly, the AtTDX-Ssb2 interaction can be released under oxidative stress, a redox-dependent regulation involving the thioredoxin activity of AtTDX. A mutation inactivating the cysteine 20 of the ATPase domain of Ssb2 was found to stabilize the AtTDX-Ssb2 interaction that becomes redox-insensitive. As cysteine 20 is conserved in virtually all the Hsp70 chaperones, our results suggest that this residue might be more generally the target of redox regulations of chaperone binding activity.
Collapse
Affiliation(s)
- Florence Vignols
- Laboratoire Génome et Développement des Plantes, CNRS, UMR 5096, Université de Perpignan, 52 Avenue de Villeneuve, 66860 Perpignan, France.
| | | | | | | |
Collapse
|
15
|
Larkindale J, Knight MR. Protection against heat stress-induced oxidative damage in Arabidopsis involves calcium, abscisic acid, ethylene, and salicylic acid. PLANT PHYSIOLOGY 2002; 128:682-95. [PMID: 11842171 PMCID: PMC148929 DOI: 10.1104/pp.010320] [Citation(s) in RCA: 410] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2001] [Revised: 08/15/2001] [Accepted: 09/18/2001] [Indexed: 05/18/2023]
Abstract
Plants, in common with all organisms, have evolved mechanisms to cope with the problems caused by high temperatures. We examined specifically the involvement of calcium, abscisic acid (ABA), ethylene, and salicylic acid (SA) in the protection against heat-induced oxidative damage in Arabidopsis. Heat caused increased thiobarbituric acid reactive substance levels (an indicator of oxidative damage to membranes) and reduced survival. Both effects required light and were reduced in plants that had acquired thermotolerance through a mild heat pretreatment. Calcium channel blockers and calmodulin inhibitors increased these effects of heating and added calcium reversed them, implying that protection against heat-induced oxidative damage in Arabidopsis requires calcium and calmodulin. Similar to calcium, SA, 1-aminocyclopropane-1-carboxylic acid (a precursor to ethylene), and ABA added to plants protected them from heat-induced oxidative damage. In addition, the ethylene-insensitive mutant etr-1, the ABA-insensitive mutant abi-1, and a transgenic line expressing nahG (consequently inhibited in SA production) showed increased susceptibility to heat. These data suggest that protection against heat-induced oxidative damage in Arabidopsis also involves ethylene, ABA, and SA. Real time measurements of cytosolic calcium levels during heating in Arabidopsis detected no increases in response to heat per se, but showed transient elevations in response to recovery from heating. The magnitude of these calcium peaks was greater in thermotolerant plants, implying that these calcium signals might play a role in mediating the effects of acquired thermotolerance. Calcium channel blockers and calmodulin inhibitors added solely during the recovery phase suggest that this role for calcium is in protecting against oxidative damage specifically during/after recovery.
Collapse
Affiliation(s)
- Jane Larkindale
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom.
| | | |
Collapse
|
16
|
Sung DY, Vierling E, Guy CL. Comprehensive expression profile analysis of the Arabidopsis Hsp70 gene family. PLANT PHYSIOLOGY 2001; 126:789-800. [PMID: 11402207 PMCID: PMC111169 DOI: 10.1104/pp.126.2.789] [Citation(s) in RCA: 307] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2000] [Revised: 01/19/2001] [Accepted: 02/22/2001] [Indexed: 05/18/2023]
Abstract
We isolated cDNA clones for two nuclear-encoded, organellar members of the Arabidopsis hsp70 gene family, mtHsc70-2 (AF217458) and cpHsc70-2 (AF217459). Together with the completion of the genome sequence, the hsp70 family in Arabidopsis consists of 14 members unequally distributed among the five chromosomes. To establish detailed expression data of this gene family, a comprehensive reverse transcriptase-polymerase chain reaction analysis for 11 hsp70s was conducted including analysis of organ-specific and developmental expression and expression in response to temperature extremes. All hsp70s showed 2- to 20-fold induction by heat shock treatment except cpHsc70-1 and mtHsc70-1, which were unchanged or repressed. The expression profiles in response to low temperature treatment were more diverse than those evoked by heat shock treatment. Both mitochondrial and all cytosolic members of the family except Hsp70b were strongly induced by low temperature, whereas endoplasmic reticulum and chloroplast members were not induced or were slightly repressed. Developmentally regulated expression of the heat-inducible Hsp70 in mature dry seed and roots in the absence of temperature stress suggests prominent roles in seed maturation and root growth for this member of the hsp70 family. This reverse transcriptase-polymerase chain reaction analysis establishes the complex differential expression pattern for the hsp70s in Arabidopsis that portends specialized functions even among members localized to the same subcellular compartment.
Collapse
Affiliation(s)
- D Y Sung
- Plant Molecular and Cellular Biology Program, Department of Environmental Horticulture, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611-0670, USA
| | | | | |
Collapse
|
17
|
Wu SJ, Wang C. Binding of heptapeptides or unfolded proteins to the chimeric C-terminal domains of 70-kDa heat shock cognate protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 259:449-55. [PMID: 9914526 DOI: 10.1046/j.1432-1327.1999.00073.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Seventy-kDa heat shock cognate protein (hsc70) and its homologs in bacteria, yeast and vertebrates are known to form complexes with S-carboxymethyl-alpha-lactalbumin (CMLA), an unfolded protein; and, this activity has been attributed to its C-terminal 30-kDa domain. Herein, we show that hsc70s isolated from the seeds of mung bean and peas, however, are not effective in complexing with CMLA, and that the 30-kDa domain of Arabidopsis hsc70 (At30) cannot form stable complexes with CMLA either. Moreover, chimeric 30-kDa domains, either composed of rat 18-kDa and Arabidopsis 10-kDa subdomains (R18At10) or with Arabidopsis 18-kDa and rat 10-kDa subdomains (At18R10), were prepared and tested for their ability to complex with CMLA or a heptapeptide FYQLALT. At18R10 cannot complex with both CMLA and FYQLALT. On the other hand, R18At10 is capable of forming complexes with FYQLALT at a level similar to that of the rat 30-kDa domain (R30). R18At10 also forms complexes with CMLA, but the amount of the R18At10/CMLA complexes is much less than that of R30/CMLA. The results imply that the 18-kDa subdomain dictates the binding specificity for heptapeptide, and that the C-terminal 10-kDa subdomain may also provide some selection or restriction for unfolded proteins to form complexes with hsc70.
Collapse
Affiliation(s)
- S J Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | |
Collapse
|
18
|
AnHsp70 antisense gene affects the expression of HSP70/HSC70, the regulation of HSF, and the acquisition of thermotolerance in transgenicArabidopsis thaliana. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf02173200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
19
|
Abstract
A tomato hsc70 genomic clone (Lehsc70-3; Lycopersicon esculentum heat-shock cognate 70-3) was obtained by screening a genomic library with the tomato Lehsc70-2 cDNA. Two restriction fragments of 2.6 and 5 kb, which compose the Lehsc70-3 gene, were subcloned into pBluescriptIIKS+ and analyzed. Transcript mapping reveals that the mature Lehsc70-3 mRNA contains a 122-nt 5' untranslated region (UTR), a coding region of 1956 nt corresponding to a polypeptide of 651 amino acids, an intron of 717 nt and a 3' UTR. Analysis of genomic DNA indicates that Lehsc70-3 is present as a low-copy-number gene. We note that the sequence upstream from the coding region of Lehsc70-3 shares common features with a number of hsc/hsp genes. High-temperature treatment (37 degrees C) caused a twofold increase in the level of the Lehsc70-3 mRNA. However, Lehsc70-3 has also been expressed at substantial levels in tomato vegetative tissues, suggesting a general function of this hsc70 gene in L. esculentum.
Collapse
Affiliation(s)
- S W Sun
- Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan, R.O.C
| | | | | |
Collapse
|