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Vaghchhipawala Z, Rojas CM, Senthil-Kumar M, Mysore KS. Agroinoculation and agroinfiltration: simple tools for complex gene function analyses. Methods Mol Biol 2011; 678:65-76. [PMID: 20931373 DOI: 10.1007/978-1-60761-682-5_6] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Agroinoculation, first developed as a simple tool to study plant-virus interactions, is a popular method of choice for functional gene analysis of viral genomes. With the explosive growth of genomic information and the development of advanced vectors to dissect plant gene function, this reliable method of viral gene delivery in plants, has been recruited and morphed into a technique popularly known as agroinfiltration. This technique was developed to examine the effects of transient gene expression, with applications ranging from studies of plant-pathogen interactions, abiotic stresses, a variety of transient expression assays to study protein localization, and protein-protein interactions. We present a brief overview of literature which document both these applications, and then provide simple agroinoculation and agroinfiltration methods being used in our laboratory for functional gene analysis, as well as for fast-forward and reverse genetic screens using virus-induced gene silencing (VIGS).
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52
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Williams D, Norman G, Khoury C, Metcalfe N, Briard J, Laporte A, Sheibani S, Portt L, Mandato CA, Greenwood MT. Evidence for a second messenger function of dUTP during Bax mediated apoptosis of yeast and mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:315-21. [PMID: 21145358 DOI: 10.1016/j.bbamcr.2010.11.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 11/02/2010] [Accepted: 11/29/2010] [Indexed: 01/26/2023]
Abstract
The identification of novel anti-apoptotic sequences has lead to new insights into the mechanisms involved in regulating different forms of programmed cell death. For example, the anti-apoptotic function of free radical scavenging proteins supports the pro-apoptotic function of Reactive Oxygen Species (ROS). Using yeast as a model of eukaryotic mitochondrial apoptosis, we show that a cDNA corresponding to the mitochondrial variant of the human DUT gene (DUT-M) encoding the deoxyuridine triphosphatase (dUTPase) enzyme can prevent apoptosis in yeast in response to internal (Bax expression) and to exogenous (H(2)O(2) and cadmium) stresses. Of interest, cell death was not prevented under culture conditions modeling chronological aging, suggesting that DUT-M only protects dividing cells. The anti-apoptotic function of DUT-M was confirmed by demonstrating that an increase in dUTPase protein levels is sufficient to confer increased resistance to H(2)O(2) in cultured C2C12 mouse skeletal myoblasts. Given that the function of dUTPase is to decrease the levels of dUTP, our results strongly support an emerging role for dUTP as a pro-apoptotic second messenger in the same vein as ROS and ceramide.
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Affiliation(s)
- Drew Williams
- Department of Anatomy and Cell Biology, McGill University. Montreal, Quebec, Canada
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53
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Portt L, Norman G, Clapp C, Greenwood M, Greenwood MT. Anti-apoptosis and cell survival: a review. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:238-59. [PMID: 20969895 DOI: 10.1016/j.bbamcr.2010.10.010] [Citation(s) in RCA: 430] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 10/04/2010] [Accepted: 10/11/2010] [Indexed: 02/08/2023]
Abstract
Type I programmed cell death (PCD) or apoptosis is critical for cellular self-destruction for a variety of processes such as development or the prevention of oncogenic transformation. Alternative forms, including type II (autophagy) and type III (necrotic) represent the other major types of PCD that also serve to trigger cell death. PCD must be tightly controlled since disregulated cell death is involved in the development of a large number of different pathologies. To counter the multitude of processes that are capable of triggering death, cells have devised a large number of cellular processes that serve to prevent inappropriate or premature PCD. These cell survival strategies involve a myriad of coordinated and systematic physiological and genetic changes that serve to ward off death. Here we will discuss the different strategies that are used to prevent cell death and focus on illustrating that although anti-apoptosis and cellular survival serve to counteract PCD, they are nevertheless mechanistically distinct from the processes that regulate cell death.
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Affiliation(s)
- Liam Portt
- Department of Chemistry and Chemical Engineering, Royal Military College, Ontario, Canada
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Laloux G, Deghelt M, de Barsy M, Letesson JJ, De Bolle X. Identification of the essential Brucella melitensis porin Omp2b as a suppressor of Bax-induced cell death in yeast in a genome-wide screening. PLoS One 2010; 5:e13274. [PMID: 20949000 PMCID: PMC2952587 DOI: 10.1371/journal.pone.0013274] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 09/09/2010] [Indexed: 01/08/2023] Open
Abstract
Background Inhibition of apoptosis is one of the mechanisms selected by numerous intracellular pathogenic bacteria to control their host cell. Brucellae, which are the causative agent of a worldwide zoonosis, prevent apoptosis of infected cells, probably to support survival of their replication niche. Methodology/Principal Findings In order to identify Brucella melitensis anti-apoptotic effector candidates, we performed a genome-wide functional screening in yeast. The B. melitensis ORFeome was screened to identify inhibitors of Bax-induced cell death in S. cerevisiae. B. melitensis porin Omp2b, here shown to be essential, prevents Bax lethal effect in yeast, unlike its close paralog Omp2a. Our results based on Omp2b size variants characterization suggest that signal peptide processing is required for Omp2b effect in yeast. Conclusion/Significance We report here the first application to a bacterial genome-wide library of coding sequences of this “yeast-rescue” screening strategy, previously used to highlight several new apoptosis regulators. Our work provides B. melitensis proteins that are candidates for an anti-apoptotic function, and can be tested in mammalian cells in the future. Hypotheses on possible molecular mechanisms of Bax inhibition by the B. melitensis porin Omp2b are discussed.
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Affiliation(s)
- Géraldine Laloux
- Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium
| | - Michaël Deghelt
- Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium
| | - Marie de Barsy
- Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium
| | - Jean-Jacques Letesson
- Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium
| | - Xavier De Bolle
- Research Unit in Molecular Biology, Department of Biology, University of Namur (FUNDP), Namur, Belgium
- * E-mail:
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55
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Cacas JL. Devil inside: does plant programmed cell death involve the endomembrane system? PLANT, CELL & ENVIRONMENT 2010; 33:1453-1473. [PMID: 20082668 DOI: 10.1111/j.1365-3040.2010.02117.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Eukaryotic cells have to constantly cope with environmental cues and integrate developmental signals. Cell survival or death is the only possible outcome. In the field of animal biology, tremendous efforts have been put into the understanding of mechanisms underlying cell fate decision. Distinct organelles have been proven to sense a broad range of stimuli and, if necessary, engage cell death signalling pathway(s). Over the years, forward and reverse genetic screens have uncovered numerous regulators of programmed cell death (PCD) in plants. However, to date, molecular networks are far from being deciphered and, apart from the autophagic compartment, no organelles have been assigned a clear role in the regulation of cellular suicide. The endomembrane system (ES) seems, nevertheless, to harbour a significant number of cell death mediators. In this review, the involvement of this system in the control of plant PCD is discussed in-depth, as well as compared and contrasted with what is known in animal and yeast systems.
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Affiliation(s)
- Jean-Luc Cacas
- Institut de Recherche pour le Développement, Equipe 2, Mécanismes des Résistances, Montpellier Cedex 5, France.
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56
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Faltin Z, Holland D, Velcheva M, Tsapovetsky M, Roeckel-Drevet P, Handa AK, Abu-Abied M, Friedman-Einat M, Eshdat Y, Perl A. Glutathione peroxidase regulation of reactive oxygen species level is crucial for in vitro plant differentiation. PLANT & CELL PHYSIOLOGY 2010; 51:1151-62. [PMID: 20530511 DOI: 10.1093/pcp/pcq082] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is overexpressed in plants under abiotic and biotic stress conditions that mediate oxidative stress. To study its biological role and its ability to confer stress resistance in plants, we tried to obtain transgenic plants overexpressing citrus (Citrus sinensis) PHGPx (cit-PHGPx). All attempts to obtain regenerated plants expressing this enzyme constitutively failed. However, when the enzyme's catalytic activity was abolished by active site-directed mutagenesis, transgenic plants constitutively expressing inactive cit-PHGPx were successfully regenerated. Constitutive expression of enzymatically active cit-PHGPx could only be obtained when transformation was based on non-regenerative processes. These results indicate that overexpression of the antioxidant enzyme PHGPx interferes with shoot organogenesis and suggests the involvement of reactive oxygen species (ROS) in this process. Using transgenic tobacco (Nicotiana tabacum) leaves obtained from plants transformed with a beta-estradiol-inducible promoter, time-dependent induction of cit-PHGPx expression was employed. A pronounced inhibitory effect of cit-PHGPx on shoot formation was found to be limited to the early stage of the regeneration process. Monitoring the ROS level during regeneration revealed that upon cit-PHGPx induction, the lowest level of ROS correlated with the maximal level of shoot inhibition. Our results clearly demonstrate the essential role of ROS in the early stages of in vitro shoot organogenesis and the possible involvement of PHGPx in maintaining ROS homeostasis at this point.
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Affiliation(s)
- Zehava Faltin
- Institute of Plant Science, Agricultural Research Organization, 50250 Bet Dagan, Israel
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57
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Wang M, Kang M, Guo X, Xu B. Identification and characterization of two phospholipid hydroperoxide glutathione peroxidase genes from Apis cerana cerana. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:75-83. [PMID: 20226266 DOI: 10.1016/j.cbpc.2010.03.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Revised: 03/02/2010] [Accepted: 03/02/2010] [Indexed: 02/01/2023]
Abstract
Phospholipid hydroperoxide glutathione peroxidase (PHGPX) plays a crucial role in maintaining the integrity of membrane by reducing hydroperoxides of phospholipids. Here, we report the identification and characterization of two genes, designated AccGtpx-1 and AccGtpx-2, encoding PHGPX proteins from the Chinese honeybees, Apis cerana cerana. Alignment analysis showed that AccGtpx-1 and AccGtpx-2 shared high similarity with other known PHGPXs, which show similar structure to thioredoxin. These single copy genes showed complex exon-intron structures. The mRNA of AccGtpx-1 was detected in larvae, pupae and adults and that AccGtpx-2 was only found in adult worker bees. Furthermore, the expression of AccGtpx-1 could be induced by H(2)O(2), ultraviolet (UV) light, heat shock (37 degrees C), HgCl(2), imidacloprid, cyhalothrin, pyriproxyfen and methomyl. In contrast, AccGtpx-2 expression could only be induced by UV. These results indicated for the first time that the AccGtpx-1 and AccGtpx-2 genes encoding A. cerana cerana PHGPXs are regulated differently in response to environmental stressors.
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Affiliation(s)
- Mian Wang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, PR China
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58
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AtBAG7, an Arabidopsis Bcl-2-associated athanogene, resides in the endoplasmic reticulum and is involved in the unfolded protein response. Proc Natl Acad Sci U S A 2010; 107:6088-93. [PMID: 20231441 DOI: 10.1073/pnas.0912670107] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Bcl-2-associated athanogene (BAG) family is an evolutionarily conserved, multifunctional group of cochaperones that perform diverse cellular functions ranging from proliferation to growth arrest and cell death in yeast, in mammals, and, as recently observed, in plants. The Arabidopsis genome contains seven homologs of the BAG family, including four with domain organization similar to animal BAGs. In the present study we show that an Arabidopsis BAG, AtBAG7, is a uniquely localized endoplasmic reticulum (ER) BAG that is necessary for the proper maintenance of the unfolded protein response (UPR). AtBAG7 was shown to interact directly in vivo with the molecular chaperone, AtBiP2, by bimolecular fluorescence complementation assays, and the interaction was confirmed by yeast two-hybrid assay. Treatment with an inducer of UPR, tunicamycin, resulted in accelerated cell death of AtBAG7-null mutants. Furthermore, AtBAG7 knockouts were sensitive to known ER stress stimuli, heat and cold. In these knockouts heat sensitivity was reverted successfully to the wild-type phenotype with the addition of the chemical chaperone, tauroursodexycholic acid (TUDCA). Real-time PCR of ER stress proteins indicated that the expression of the heat-shock protein, AtBiP3, is selectively up-regulated in AtBAG7-null mutants upon heat and cold stress. Our results reveal an unexpected diversity of the plant's BAG gene family and suggest that AtBAG7 is an essential component of the UPR during heat and cold tolerance, thus confirming the cytoprotective role of plant BAGs.
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Li T, Liu GL, Duan MX, Liu JY. Radish phospholipid hydroperoxide glutathione peroxidase provides protection against hydroperoxide-mediated injury in mouse 3T3 fibroblasts. BMB Rep 2010; 42:648-54. [PMID: 19874709 DOI: 10.5483/bmbrep.2009.42.10.648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Overexpression of phospholipid hydroperoxide glutathione peroxidase (PHGPx) genes has been reported to play an important role in protecting host cells from oxidative injury in several model systems. A radish phospholipid hydroperoxide glutathione peroxidase (RsPHGPx) known to have high catalytic activity was applied to mouse 3T3 fibroblasts to determine the protective effects of PHGPx against oxidative injury triggered by hydroperoxides such as hydrogen peroxide (H(2)O(2)), tert-butyl hydroperoxide (t-BHP) and phosphatidylcholine hydroperoxide (PCOOH). We observed that preincubation of cells with RsPHGPx significantly increased cell viability, reduced levels of malondialdehyde (MDA), inhibited generation of reactive oxygen species (ROS), and maintained natural cell shapes after treatment with H(2)O(2), t-BHP or PCOOH, indicating that the exogenous RsPHGPx can act as an effective hydroperoxide-scavenger and may also protect target cells from oxidative damage. These results suggest the possibility for use of RsPHGPx as a therapeutic protectant.
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Affiliation(s)
- Tian Li
- Laboratory of Molecular Biology and MOE Laboratory of Protein Science, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, China
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60
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Yamaguchi M, Valliyodan B, Zhang J, Lenoble ME, Yu O, Rogers EE, Nguyen HT, Sharp RE. Regulation of growth response to water stress in the soybean primary root. I. Proteomic analysis reveals region-specific regulation of phenylpropanoid metabolism and control of free iron in the elongation zone. PLANT, CELL & ENVIRONMENT 2010; 33:223-43. [PMID: 19906149 DOI: 10.1111/j.1365-3040.2009.02073.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In water-stressed soybean primary roots, elongation was maintained at well-watered rates in the apical 4 mm (region 1), but was progressively inhibited in the 4-8 mm region (region 2), which exhibits maximum elongation in well-watered roots. These responses are similar to previous results for the maize primary root. To understand these responses in soybean, spatial profiles of soluble protein composition were analysed. Among the changes, the results indicate that region-specific regulation of phenylpropanoid metabolism may contribute to the distinct growth responses in the different regions. Several enzymes related to isoflavonoid biosynthesis increased in abundance in region 1, correlating with a substantial increase of isoflavonoid content in this region which could contribute to growth maintenance via various potential mechanisms. In contrast, caffeoyl-CoA O-methyltransferase, which is involved in lignin synthesis, was highly up-regulated in region 2. This response was associated with enhanced accumulation of lignin, which may be related to the inhibition of growth in this region. Several proteins that increased in abundance in both regions of water-stressed roots were related to protection from oxidative damage. In particular, an increase in the abundance of ferritin proteins effectively sequestered more iron and prevented excess free iron in the elongation zone under water stress.
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Affiliation(s)
- Mineo Yamaguchi
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
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61
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Chen X, Hackett CA, Niks RE, Hedley PE, Booth C, Druka A, Marcel TC, Vels A, Bayer M, Milne I, Morris J, Ramsay L, Marshall D, Cardle L, Waugh R. An eQTL analysis of partial resistance to Puccinia hordei in barley. PLoS One 2010; 5:e8598. [PMID: 20066049 PMCID: PMC2798965 DOI: 10.1371/journal.pone.0008598] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 11/10/2009] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Genetic resistance to barley leaf rust caused by Puccinia hordei involves both R genes and quantitative trait loci. The R genes provide higher but less durable resistance than the quantitative trait loci. Consequently, exploring quantitative or partial resistance has become a favorable alternative for controlling disease. Four quantitative trait loci for partial resistance to leaf rust have been identified in the doubled haploid Steptoe (St)/Morex (Mx) mapping population. Further investigations are required to study the molecular mechanisms underpinning partial resistance and ultimately identify the causal genes. METHODOLOGY/PRINCIPAL FINDINGS We explored partial resistance to barley leaf rust using a genetical genomics approach. We recorded RNA transcript abundance corresponding to each probe on a 15K Agilent custom barley microarray in seedlings from St and Mx and 144 doubled haploid lines of the St/Mx population. A total of 1154 and 1037 genes were, respectively, identified as being P. hordei-responsive among the St and Mx and differentially expressed between P. hordei-infected St and Mx. Normalized ratios from 72 distant-pair hybridisations were used to map the genetic determinants of variation in transcript abundance by expression quantitative trait locus (eQTL) mapping generating 15685 eQTL from 9557 genes. Correlation analysis identified 128 genes that were correlated with resistance, of which 89 had eQTL co-locating with the phenotypic quantitative trait loci (pQTL). Transcript abundance in the parents and conservation of synteny with rice allowed us to prioritise six genes as candidates for Rphq11, the pQTL of largest effect, and highlight one, a phospholipid hydroperoxide glutathione peroxidase (HvPHGPx) for detailed analysis. CONCLUSIONS/SIGNIFICANCE The eQTL approach yielded information that led to the identification of strong candidate genes underlying pQTL for resistance to leaf rust in barley and on the general pathogen response pathway. The dataset will facilitate a systems appraisal of this host-pathogen interaction and, potentially, for other traits measured in this population.
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Affiliation(s)
- Xinwei Chen
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
- * E-mail: (XC); (RW)
| | - Christine A. Hackett
- Biomathematics and Statistics Scotland (BioSS), Scottish Crop Research Institute, Dundee, United Kingdom
| | - Rients E. Niks
- Laboratory of Plant Breeding, Graduate School for Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Peter E. Hedley
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Clare Booth
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Arnis Druka
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Thierry C. Marcel
- Laboratory of Plant Breeding, Graduate School for Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Anton Vels
- Laboratory of Plant Breeding, Graduate School for Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Micha Bayer
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Iain Milne
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Jenny Morris
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Luke Ramsay
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - David Marshall
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Linda Cardle
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
| | - Robbie Waugh
- Genetics Programme, Scottish Crop Research Institute, Dundee, United Kingdom
- * E-mail: (XC); (RW)
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Expressing and functional analysis of mammalian apoptotic regulators in yeast. Cell Death Differ 2009; 17:737-45. [DOI: 10.1038/cdd.2009.177] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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63
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Bax Inhibitor-1, a conserved cell death suppressor, is a key molecular switch downstream from a variety of biotic and abiotic stress signals in plants. Int J Mol Sci 2009; 10:3149-3167. [PMID: 19742129 PMCID: PMC2738916 DOI: 10.3390/ijms10073149] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/06/2009] [Accepted: 07/06/2009] [Indexed: 02/03/2023] Open
Abstract
In Nature plants are constantly challenged by a variety of environmental stresses that could lead to disruptions in cellular homeostasis. Programmed cell death (PCD) is a fundamental cellular process that is often associated with defense responses to pathogens, during development and in response to abiotic stresses in fungi, animals and plants. Although there are many characteristics shared between different types of PCD events, it remains unknown whether a common mechanism drives various types of PCD in eukaryotes. One candidate regulator for such a mechanism is Bax Inhibitor-1 (BI-1), an evolutionary conserved, endoplasmic reticulum (ER)-resident protein that represents an ancient cell death regulator that potentially regulates PCD in all eukaryotes. Recent findings strongly suggested that BI-1 plays an important role in the conserved ER stress response pathway to modulate cell death induction in response to multiple types of cell death signals. As ER stress signaling pathways has been suggested to play important roles not only in the control of ER homeostasis but also in other biological processes such as the response to pathogens and abiotic stress in plants, BI-1 might function to control the convergence point that modulates the level of the “pro-survival and pro-death” signals under multiple stress conditions.
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64
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Chang CCC, Slesak I, Jordá L, Sotnikov A, Melzer M, Miszalski Z, Mullineaux PM, Parker JE, Karpinska B, Karpinski S. Arabidopsis chloroplastic glutathione peroxidases play a role in cross talk between photooxidative stress and immune responses. PLANT PHYSIOLOGY 2009; 150:670-83. [PMID: 19363092 PMCID: PMC2689974 DOI: 10.1104/pp.109.135566] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 04/06/2009] [Indexed: 05/18/2023]
Abstract
Glutathione peroxidases (GPXs; EC 1.11.1.9) are key enzymes of the antioxidant network in plants and animals. In order to investigate the role of antioxidant systems in plant chloroplasts, we generated Arabidopsis (Arabidopsis thaliana) transgenic lines that are depleted specifically in chloroplastic (cp) forms of GPX1 and GPX7. We show that reduced cpGPX expression, either in transgenic lines with lower total cpGPX expression (GPX1 and GPX7) or in a gpx7 insertion mutant, leads to compromised photooxidative stress tolerance but increased basal resistance to virulent bacteria. Depletion of both GPX1 and GPX7 expression also caused alterations in leaf cell and chloroplast morphology. Leaf tissues were characterized by shorter and more rounded palisade cells, irregular spongy mesophyll cells, and larger intercellular air spaces compared with the wild type. Chloroplasts had larger and more abundant starch grains than in wild-type and gpx7 mutant plants. Constitutively reduced cpGPX expression also led to higher foliar ascorbic acid, glutathione, and salicylic acid levels in plants exposed to higher light intensities. Our results suggest partially overlapping functions of GPX1 and GPX7. The data further point to specific changes in the chloroplast ascorbate-glutathione cycle due to reduced cpGPX expression, initiating reactive oxygen species and salicylic acid pathways that affect leaf development, light acclimation, basal defense, and cell death programs. Thus, cpGPXs regulate cellular photooxidative tolerance and immune responses.
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Affiliation(s)
- Christine C C Chang
- Department of Botany, Stockholm University, Frescati 10691 Stockholm, Sweden
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65
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Cheng JS, Yuan YJ. Release of proteins: Insights into oxidative response of Taxus cuspidata cells induced by shear stress. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.molcatb.2008.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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66
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Dong CJ, Yang XD, Liu JY. Enzymatic properties of a recombinant phospholipid hydroperoxide glutathione peroxidase from Momordica charantia and its complementation function in yeast. BIOCHEMISTRY. BIOKHIMIIA 2009; 74:502-508. [PMID: 19538123 DOI: 10.1134/s0006297909050046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The entire encoding region for Momordica charantia phospholipid hydroperoxide glutathione peroxidase (McPHGPx) was cloned into pET-28a(+) vector and expressed in Escherichia coli BL21(DE3). The purified recombinant McPHGPx displayed GSH-dependent peroxidase activity towards phospholipid hydroperoxide, H2O2, and tert-butyl hydroperoxide and had the highest affinity with and catalytic efficiency for phospholipid hydroperoxide. The optimum temperature of the enzyme activity ranged from 40 to 50 degrees C, thus it is a thermostable enzyme compared to other PHGPx enzymes. Furthermore, McPHGPx expression in Saccharomyces cerevisiae PHGPx-deletion mutant rescued the susceptibilities to the oxidation-sensitive polyunsaturated fatty acid (linolenic acid), indicating its PHGPx complementation function in yeast. These results have well documented that McPHGPx functions as a PHGPx in vitro and in vivo and will be beneficial for further functional studies on plant PHGPx enzymes.
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Affiliation(s)
- Chun-Juan Dong
- Laboratory of Molecular Biology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, China
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67
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Susnow N, Zeng L, Margineantu D, Hockenbery DM. Bcl-2 family proteins as regulators of oxidative stress. Semin Cancer Biol 2008. [PMID: 19138742 DOI: 10.1016/j.semcancer.2008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Bcl-2 family of proteins includes pro- and anti-apoptotic factors acting at mitochondrial and microsomal membranes. An impressive body of published studies, using genetic and physical reconstitution experiments in model organisms and cell lines, supports a view of Bcl-2 proteins as the critical arbiters of apoptotic cell death decisions in most circumstances (excepting CD95 death receptor signaling in Type I cells). Evasion of apoptosis is one of the hallmarks of cancer [Hanahan D, Weinberg RA. The hallmarks of cancer. Cell 2000;100:57-70], relevant to tumorigenesis as well as resistance to cytotoxic drugs, and deregulation of Bcl-2 proteins is observed in many cancers [Manion MK, Hockenbery DM. Targeting BCL-2-related proteins in cancer therapy. Cancer Biol Ther. 2003;2:S105-14; Olejniczak ET, Van Sant C, Anderson MG, Wang G, Tahir SK, Sauter G, et al. Integrative genomic analysis of small-cell lung carcinoma reveals correlates of sensitivity to bcl-2 antagonists and uncovers novel chromosomal gains. Mol Cancer Res. 2007;5:331-9]. The rekindled interest in aerobic glycolysis as a cancer trait raises interesting questions as to how metabolic changes in cancer cells are integrated with other essential alterations in cancer, e.g. promotion of angiogenesis and unbridled growth signals. Apoptosis induced by multiple different signals involves loss of mitochondrial homeostasis, in particular, outer mitochondrial membrane integrity, releasing cytochrome c and other proteins from the intermembrane space. This integrative process, controlled by Bcl-2 family proteins, is also influenced by the metabolic state of the cell. In this review, we consider the role of reactive oxygen species, a metabolic by-product, in the mitochondrial pathway of apoptosis, and the relationships between Bcl-2 functions and oxidative stress.
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Affiliation(s)
- Nathan Susnow
- Department of Medicine, University of Washington, Seattle, 98195-6424, United States
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68
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Bcl-2 family proteins as regulators of oxidative stress. Semin Cancer Biol 2008; 19:42-9. [PMID: 19138742 DOI: 10.1016/j.semcancer.2008.12.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 12/13/2008] [Indexed: 12/22/2022]
Abstract
The Bcl-2 family of proteins includes pro- and anti-apoptotic factors acting at mitochondrial and microsomal membranes. An impressive body of published studies, using genetic and physical reconstitution experiments in model organisms and cell lines, supports a view of Bcl-2 proteins as the critical arbiters of apoptotic cell death decisions in most circumstances (excepting CD95 death receptor signaling in Type I cells). Evasion of apoptosis is one of the hallmarks of cancer [Hanahan D, Weinberg RA. The hallmarks of cancer. Cell 2000;100:57-70], relevant to tumorigenesis as well as resistance to cytotoxic drugs, and deregulation of Bcl-2 proteins is observed in many cancers [Manion MK, Hockenbery DM. Targeting BCL-2-related proteins in cancer therapy. Cancer Biol Ther. 2003;2:S105-14; Olejniczak ET, Van Sant C, Anderson MG, Wang G, Tahir SK, Sauter G, et al. Integrative genomic analysis of small-cell lung carcinoma reveals correlates of sensitivity to bcl-2 antagonists and uncovers novel chromosomal gains. Mol Cancer Res. 2007;5:331-9]. The rekindled interest in aerobic glycolysis as a cancer trait raises interesting questions as to how metabolic changes in cancer cells are integrated with other essential alterations in cancer, e.g. promotion of angiogenesis and unbridled growth signals. Apoptosis induced by multiple different signals involves loss of mitochondrial homeostasis, in particular, outer mitochondrial membrane integrity, releasing cytochrome c and other proteins from the intermembrane space. This integrative process, controlled by Bcl-2 family proteins, is also influenced by the metabolic state of the cell. In this review, we consider the role of reactive oxygen species, a metabolic by-product, in the mitochondrial pathway of apoptosis, and the relationships between Bcl-2 functions and oxidative stress.
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69
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The pleiotropic effects of heterologous Bax expression in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1449-65. [DOI: 10.1016/j.bbamcr.2007.12.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 12/14/2007] [Accepted: 12/30/2007] [Indexed: 12/27/2022]
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70
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Williams B, Dickman M. Plant programmed cell death: can't live with it; can't live without it. MOLECULAR PLANT PATHOLOGY 2008; 9:531-44. [PMID: 18705866 PMCID: PMC6640338 DOI: 10.1111/j.1364-3703.2008.00473.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The decision of whether a cell should live or die is fundamental for the wellbeing of all organisms. Despite intense investigation into cell growth and proliferation, only recently has the essential and equally important idea that cells control/programme their own demise for proper maintenance of cellular homeostasis gained recognition. Furthermore, even though research into programmed cell death (PCD) has been an extremely active area of research there are significant gaps in our understanding of the process in plants. In this review, we discuss PCD during plant development and pathogenesis, and compare/contrast this with mammalian apoptosis.
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Affiliation(s)
- Brett Williams
- Institute for Plant Genomics and Biotechnology, Texas A&M University, Department of Plant Pathology and Microbiology, College Station, TX 77843, USA
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71
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Khoury CM, Yang Z, Li XY, Vignali M, Fields S, Greenwood MT. A TSC22-like motif defines a novel antiapoptotic protein family. FEMS Yeast Res 2008; 8:540-63. [PMID: 18355271 PMCID: PMC2593406 DOI: 10.1111/j.1567-1364.2008.00367.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 01/15/2008] [Accepted: 01/22/2008] [Indexed: 11/28/2022] Open
Abstract
The apoptotic programme is evolutionarily conserved between yeast and metazoan organisms. We have previously identified a number of mammalian cDNAs capable of suppressing the deleterious effects of Bax expression in yeast. We herein report that one such suppressor, named Tsc22((86)), represents the C-terminal 86 amino acids of the previously characterized leucine zipper (LZ) motif-containing transcriptional regulator Tsc22. Employing a genome-wide two-hybrid screen, functional genomics, and deletion mutagenesis approaches, we conclude that Tsc22((86))-mediated antiapoptosis is independent of the LZ motif and is likely independent of effects on gene transcription. Rather, a 16-residue sequence within the conserved 56-residue TSC22 domain is necessary for antiapoptosis. The presence of a similar sequence was used to predict an antiapoptotic role for two yeast proteins, Sno1p and Fyv10p. Overexpression and knock-out experiments were used to validate this prediction. These findings demonstrate the potential of studying heterologous proteins in yeast to uncover novel biological insights into the regulation of apoptosis.
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Affiliation(s)
- Chamel M Khoury
- Department of Medicine, McGill University, Montreal, Quebec, Canada
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72
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Singh A, Grover A. Genetic engineering for heat tolerance in plants. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2008; 14:155-66. [PMID: 23572882 PMCID: PMC3550655 DOI: 10.1007/s12298-008-0014-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
High temperature tolerance has been genetically engineered in plants mainly by over-expressing the heat shock protein genes or indirectly by altering levels of heat shock transcription factor proteins. Apart from heat shock proteins, thermotolerance has also been altered by elevating levels of osmolytes, increasing levels of cell detoxification enzymes and through altering membrane fluidity. It is suggested that Hsps may be directly implicated in thermotolerance as agents that minimize damage to cell proteins. The other three above approaches leading to thermotolerance in transgenic experiments though operate in their own specific ways but indirectly might be aiding in creation of more reductive and energy-rich cellular environment, thereby minimizing the accumulation of damaged proteins. Intervention in protein metabolism such that accumulation of damaged proteins is minimized thus appears to be the main target for genetically-engineering crops against high temperature stress.
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Affiliation(s)
- Amanjot Singh
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110 021 India
| | - Anil Grover
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110 021 India
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73
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Zhao CJ, Wang AR, Shi YJ, Wang LQ, Liu WD, Wang ZH, Lu GD. Identification of defense-related genes in rice responding to challenge by Rhizoctonia solani. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2008; 116:501-16. [PMID: 18075727 DOI: 10.1007/s00122-007-0686-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 11/23/2007] [Indexed: 05/04/2023]
Abstract
Rice sheath blight, caused by Rhizoctonia solani is one of the major diseases of rice. The pathogen infects rice plants directly through stomata or using lobate appressoria and hyphal masses called infection cushions. The infection structures were normally found at 36 h post-inoculation. During infection, the pathogenesis-related genes, PR1b and PBZ1 were induced in rice plants. To identify rice genes induced early in the defense response, suppression subtractive hybridization (SSH) was used to generate a cDNA library enriched for transcripts differentially expressed during infection by R. solani. After differential screening by membrane-based hybridization and subsequent confirmation by reverse Northern blot analysis, selected clones were sequenced. Fifty unique cDNA clones were found and assigned to five different functional categories. Most of the genes were not previously identified as being induced in response to pathogens. We examined expression of 100 rice genes induced by infection with Magnaporthe grisea, Xanthomonas oryzae pv. oryze (Xoo) and X. oryzae pv. oryzicola (Xooc). Twenty-five of them were found to be differentially expressed after the sheath blight infection, suggesting overlap of defense responses to different fungal and bacterial pathogens infection.
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Affiliation(s)
- Chang-Jiang Zhao
- Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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74
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Yang X, Chen H, Xu W, He Z, Ma M. Hyperaccumulation of arsenic by callus, sporophytes and gametophytes of Pteris vittata cultured in vitro. PLANT CELL REPORTS 2007; 26:1889-97. [PMID: 17589853 DOI: 10.1007/s00299-007-0388-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 05/14/2007] [Accepted: 05/15/2007] [Indexed: 05/16/2023]
Abstract
The callus of Pteris vittata was induced from gametophytes generated from spores in vitro, and grew rapidly with periodical medium change. Arsenic tolerance and accumulation of P. vittata callus were compared with those of Arabidopsis thaliana callus. Cell death was not detected in P. vittata callus even at arsenate concentrations up to 2 mM; however, A. thaliana callus died at low (0.2 mM) arsenate concentrations. Meanwhile, P. vittata callus accumulated almost three times more As than A. thaliana callus when exposed to 0.2 mM arsenate. About 60% of the total As was removed when 7.5 g of P. vittata callus was cultured on 150 ml of half-strength MS liquid medium containing 450 microg As for 2 days. Furthermore, P. vittata callus, sporophytes, and gametophytes all grew well under 1 mM of arsenate and accumulated 1,250; 1,150 and 2,180 mg kg(-1 )dry weight As when grown on 2 mM arsenate for 15 or 30 days. The characteristics of non-differentiated cells, large biomass, ease of culture, good synchronization, and excellent As sequestering, make the callus of P. vittata a new ideal system to study the mechanisms of As hyperaccumulation and phytoremediation in As-contaminated groundwater.
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Affiliation(s)
- Xuexi Yang
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China
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75
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Wang Z, Wang F, Duan R, Liu JY. Purification and Physicochemical Characterization of a Recombinant Phospholipid Hydroperoxide Glutathione Peroxidase from Oryza sativa. BMB Rep 2007; 40:412-8. [PMID: 17562293 DOI: 10.5483/bmbrep.2007.40.3.412] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes. In the present work, the entire encoding region for Oryza sativa PHGPx was expressed in Escherichia coli M15, and the purified fusion protein showed a single band with 21.0 kD and pI = 8.5 on SDS- and IFE-PAGE, respectively. Judging from CD and fluorescence spectroscopy, this protein is considered to have a well-ordered structure with 12.2% alpha-helix, 30.7% beta-sheet, 18.5% gamma-turn, and 38.5% random coil. The optimum pH and temperature of the enzyme activity were pH 9.3 and 27 degrees C. The enzyme exhibited the highest affinity and catalytical efficiency to phospholipid hydroperoxide employing GSH or Trx as electron donor. Moreover, the protein displayed higher GSH-dependent activity towards t-Butyl-OOH and H(2)O(2). These results show that OsPHGPx is an enzyme with broad specificity for hydroperoxide substrates and yielded significant insight into the physicochemical properties and the dynamics of OsPHGPx.
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Affiliation(s)
- Zebin Wang
- Laboratory of Molecular Biology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, P. R. China
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76
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Abstract
Glutathione peroxidases (GPXs, EC 1.11.1.9) were first discovered in mammals as key enzymes involved in scavenging of activated oxygen species (AOS). Their efficient antioxidant activity depends on the presence of the rare amino-acid residue selenocysteine (SeCys) at the catalytic site. Nonselenium GPX-like proteins (NS-GPXs) with a Cys residue instead of SeCys have also been found in most organisms. As SeCys is important for GPX activity, the function of the NS-GPX can be questioned. Here, we highlight the evolutionary link between NS-GPX and seleno-GPX, particularly the evolution of the SeCys incorporation system. We then discuss what is known about the enzymatic activity and physiological functions of NS-GPX. Biochemical studies have shown that NS-GPXs are not true GPXs; notably they reduce AOS using reducing substrates other than glutathione, such as thioredoxin. We provide evidence that, in addition to their inefficient scavenging action, NS-GPXs act as AOS sensors in various signal-transduction pathways.
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77
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Guidetti-Gonzalez S, Freitas-Astúa J, Amaral AMD, Martins NF, Mehta A, Silva MS, Carrer H. Genes associated with hypersensitive response (HR) in the citrus EST database (CitEST). Genet Mol Biol 2007. [DOI: 10.1590/s1415-47572007000500022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | - Juliana Freitas-Astúa
- Embrapa Mandioca e Fruticultura Tropical, Brazil; Instituto Agronômico de Campinas, Brazil
| | | | | | - Angela Mehta
- Embrapa Recursos Genéticos e Biotecnologia, Brazil
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78
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Navrot N, Collin V, Gualberto J, Gelhaye E, Hirasawa M, Rey P, Knaff DB, Issakidis E, Jacquot JP, Rouhier N. Plant glutathione peroxidases are functional peroxiredoxins distributed in several subcellular compartments and regulated during biotic and abiotic stresses. PLANT PHYSIOLOGY 2006; 142:1364-79. [PMID: 17071643 PMCID: PMC1676047 DOI: 10.1104/pp.106.089458] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We provide here an exhaustive overview of the glutathione (GSH) peroxidase (Gpx) family of poplar (Populus trichocarpa). Although these proteins were initially defined as GSH dependent, in fact they use only reduced thioredoxin (Trx) for their regeneration and do not react with GSH or glutaredoxin, constituting a fifth class of peroxiredoxins. The two chloroplastic Gpxs display a marked selectivity toward their electron donors, being exclusively specific for Trxs of the y type for their reduction. In contrast, poplar Gpxs are much less specific with regard to their electron-accepting substrates, reducing hydrogen peroxide and more complex hydroperoxides equally well. Site-directed mutagenesis indicates that the catalytic mechanism and the Trx-mediated recycling process involve only two (cysteine [Cys]-107 and Cys-155) of the three conserved Cys, which form a disulfide bridge with an oxidation-redox midpoint potential of -295 mV. The reduction/formation of this disulfide is detected both by a shift on sodium dodecyl sulfate-polyacrylamide gel electrophoresis or by measuring the intrinsic tryptophan fluorescence of the protein. The six genes identified coding for Gpxs are expressed in various poplar organs, and two of them are localized in the chloroplast, with one colocalizing in mitochondria, suggesting a broad distribution of Gpxs in plant cells. The abundance of some Gpxs is modified in plants subjected to environmental constraints, generally increasing during fungal infection, water deficit, and metal stress, and decreasing during photooxidative stress, showing that Gpx proteins are involved in the response to both biotic and abiotic stress conditions.
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Affiliation(s)
- Nicolas Navrot
- Unité Mixte de Recherche Institut National de la Recherche Agronomique-Université Henri Poincaré 1136, Université Henri Poincaré, 54506 Vandoeuvre cedex, France
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79
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Bounhar Y, Mann KK, Roucou X, LeBlanc AC. Prion protein prevents Bax-mediated cell death in the absence of other Bcl-2 family members inSaccharomyces cerevisiae. FEMS Yeast Res 2006; 6:1204-12. [PMID: 17156017 DOI: 10.1111/j.1567-1364.2006.00122.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Although there is no consensus regarding the normal function of the prion protein, increasing evidence points towards a role in cellular protection against cell death. We have previously shown that prion protein is a potent inhibitor of Bax-induced apoptosis in human primary neurons and in the breast carcinoma MCF-7 cells. Here, we used the yeast Saccharomyces cerevisiae to investigate if the neuroprotective function of prion protein requires other members of the Bcl-2 family given that S. cerevisiae lacks Bcl-2 genes but undergoes a mitochondrial-dependent apoptotic cell death upon exogenous expression of Bax protein. We show that Bax induces cell death and growth inhibition in S. cerevisiae. Prion protein prevents Bax-mediated cell death. Prion protein overcomes Bax-mediated growth arrest in S phase but cannot overcome population growth inhibition because the cells then accumulate in G(2)/M phase. We conclude that prion protein does not require other Bcl-2 family proteins to protect against Bax-mediated cell death.
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Affiliation(s)
- Younes Bounhar
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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80
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Yang XD, Dong CJ, Liu JY. A plant mitochondrial phospholipid hydroperoxide glutathione peroxidase: its precise localization and higher enzymatic activity. PLANT MOLECULAR BIOLOGY 2006; 62:951-62. [PMID: 16944266 DOI: 10.1007/s11103-006-9068-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2006] [Accepted: 07/29/2006] [Indexed: 05/09/2023]
Abstract
A novel cDNA of phospholipid hydroperoxide glutathione peroxidase (PHGPx), which encodes a functional protein capable of complementing the yeast PHGHX-deletion mutant, was recently discovered in radish (Raphanus sativus) and designated as RsPHGPx [Yang X-D, Li W-J, Liu J-Y (2005) Biochim Biophys Acta 1728:199-205]. Sequence alignment suggested that RsPHGPx contains a targeting peptide required for transport to mitochondria, but the experimental evidence for the exact intracellular distribution of RsPHGPx remains to be elucidated. To uncover the cellular localization of plant PHGPx, we first investigated RsPHGPx's intracellular distribution. Western blot analysis of subcellular fractions using the RsPHGPx antiserum clearly indicated the distribution of RsPHGPx in the radish mitochondrial fraction. Furthermore, a construct expressing the RsPHGPx precursor tagged with green fluorescent protein was introduced into tobacco and yeast cells, and the fusion protein was transported into both mitochondria, indicating that RsPHGPx was indeed localized in mitochondria. To explore the biochemical functions of this enzyme, we tested the enzymatic activity of the recombinant RsPHGPx protein. It displayed GSH-dependent peroxidase activity and exhibited the largest affinity to and the highest catalytic efficiency on phosphatidylcholine hydroperoxide, suggesting that phospholipid hydroperoxide is probably the optimum substrate for RsPHGPx. Furthermore, RsPHGPx showed a much higher V (max) value, by two orders of magnitude, than those of all other known plant PHGPxs. Taken together, these results showed evidence for the first time of mitochondrial localization and higher activity of PHGPx in plants and provided a framework for continued studies on the physiological functions of RsPHGPx.
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Affiliation(s)
- Xiao-Dong Yang
- Laboratory of Molecular Biology and MOE Laboratory of Protein Science, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, China
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81
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Iqbal A, Yabuta Y, Takeda T, Nakano Y, Shigeoka S. Hydroperoxide reduction by thioredoxin-specific glutathione peroxidase isoenzymes of Arabidopsis thaliana. FEBS J 2006; 273:5589-97. [PMID: 17096689 DOI: 10.1111/j.1742-4658.2006.05548.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Arabidopsis thaliana contains eight glutathione peroxidase (GPX) homologs (AtGPX1-8). Four mature GPX isoenzymes with different subcellular distributions, AtGPX1, -2, -5 and -6, were overexpressed in Escherichia coli and characterized. Interestingly, these recombinant proteins were able to reduce H2O2, cumene hydroperoxide, phosphatidylcholine and linoleic acid hydroperoxides using thioredoxin but not glutathione or NADPH as an electron donor. The reduction activities of the recombinant proteins with H2O2 were 2-7 times higher than those with cumene hydroperoxide. Km values for thioredoxin and H2O2 were 2.2-4.0 and 14.0-25.4 microM, respectively. These finding suggest that GPX isoenzymes may function to detoxify H2O2 and organic hydroperoxides using thioredoxin in vivo and may also be involved in regulation of the cellular redox homeostasis by maintaining the thiol/disulfide or NADPH/NADP balance.
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Affiliation(s)
- Aqib Iqbal
- Department of Applied Biological Chemistry, Osaka Prefecture University, Sakai, Japan
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82
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Chen C, Wanduragala S, Becker DF, Dickman MB. Tomato QM-like protein protects Saccharomyces cerevisiae cells against oxidative stress by regulating intracellular proline levels. Appl Environ Microbiol 2006; 72:4001-6. [PMID: 16751508 PMCID: PMC1489650 DOI: 10.1128/aem.02428-05] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Exogenous proline can protect cells of Saccharomyces cerevisiae from oxidative stress. We altered intracellular proline levels by overexpressing the proline dehydrogenase gene (PUT1) of S. cerevisiae. Put1p performs the first enzymatic step of proline degradation in S. cerevisiae. Overexpression of Put1p results in low proline levels and hypersensitivity to oxidants, such as hydrogen peroxide and paraquat. A put1-disrupted yeast mutant deficient in Put1p activity has increased protection from oxidative stress and increased proline levels. Following a conditional life/death screen in yeast, we identified a tomato (Lycopersicon esculentum) gene encoding a QM-like protein (tQM) and found that stable expression of tQM in the Put1p-overexpressing strain conferred protection against oxidative damage from H2O2, paraquat, and heat. This protection was correlated with reactive oxygen species (ROS) reduction and increased proline accumulation. A yeast two-hybrid system assay was used to show that tQM physically interacts with Put1p in yeast, suggesting that tQM is directly involved in modulating proline levels. tQM also can rescue yeast from the lethality mediated by the mammalian proapoptotic protein Bax, through the inhibition of ROS generation. Our results suggest that tQM is a component of various stress response pathways and may function in proline-mediated stress tolerance in plants.
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Affiliation(s)
- Changbin Chen
- Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, 2123 TAMU, College Station, TX 77843, USA
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83
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Yang Z, Khoury C, Jean-Baptiste G, Greenwood MT. Identification of mouse sphingomyelin synthase 1 as a suppressor of Bax-mediated cell death in yeast. FEMS Yeast Res 2006; 6:751-62. [PMID: 16879426 DOI: 10.1111/j.1567-1364.2006.00052.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
We have identified mouse sphingomyelin synthase 1 as a novel suppressor of the growth inhibitory effect of heterologously expressed Bax. Yeast cells expressing sphingomyelin synthase 1 were also found to show an increased resistance to a variety of cytotoxic stimuli including hydrogen peroxide, osmotic stress and elevated temperature. Sphingomyelin synthase 1 functions by catalyzing the conversion of ceramide and phosphatidylcholine to sphingomyelin and diacylglycerol. Ceramide is an antiproliferative and proapoptotic sphingolipid whose level increases in response to a variety of stresses. Consistent with its biochemical function, yeast cells expressing sphingomyelin synthase 1 have an enhanced ability to grow in media containing the cell-permeable C2-ceramide analog as well as the ceramide precursor phytosphingosine. We also show that overexpression of AUR1, a potential yeast functional homolog of sphingomyelin synthase, also protects cells from osmotic stress. Taken together, these results suggest that sphingomyelin synthase 1 likely prevents cell death by counteracting stress-mediated accumulation of endogenous sphingolipids.
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Affiliation(s)
- Zhao Yang
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
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84
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Doukhanina EV, Chen S, van der Zalm E, Godzik A, Reed J, Dickman MB. Identification and Functional Characterization of the BAG Protein Family in Arabidopsis thaliana. J Biol Chem 2006; 281:18793-801. [PMID: 16636050 DOI: 10.1074/jbc.m511794200] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The genes that control mammalian programmed cell death are conserved across wide evolutionary distances. Although plant cells can undergo apoptosis-like cell death, plant homologs of mammalian regulators of apoptosis have, in general, not been found. This is in part due to the lack of primary sequence conservation between animal and putative plant regulators of apoptosis. Thus, alternative approaches beyond sequence similarities are required to find functional plant homologs of apoptosis regulators. Here, we present the results of using advanced bioinformatic tools to uncover the Arabidopsis family of BAG proteins. The mammalian BAG (Bcl-2-associated athanogene) proteins are a family of chaperone regulators that modulate a number of diverse processes ranging from proliferation to growth arrest and cell death. Such proteins are distinguished by a conserved BAG domain that directly interacts with Hsp70 and Hsc70 proteins to regulate their activity. Our searches of the Arabidopsis thaliana genome sequence revealed seven homologs of the BAG protein family. We further show that plant BAG family members are also multifunctional and remarkably similar to their animal counterparts, as they regulate apoptosis-like processes ranging from pathogen attack to abiotic stress and development.
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Affiliation(s)
- Elena V Doukhanina
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583, USA
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85
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Imani J, Baltruschat H, Stein E, Jia G, Vogelsberg J, Kogel KH, Hückelhoven R. Expression of barley BAX Inhibitor-1 in carrots confers resistance to Botrytis cinerea. MOLECULAR PLANT PATHOLOGY 2006; 7:279-84. [PMID: 20507447 DOI: 10.1111/j.1364-3703.2006.00339.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
SUMMARY BAX Inhibitor-1 (BI-1) is a protein that controls heterologous BAX-induced cell death, the hypersensitive reaction and abiotic stress-induced cell death in plants. When over-expressed in epidermal cells of barley, barley BI-1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis. When we expressed barley BI-1 in carrot susceptible to the necrotrophic fungus Botrytis cinerea, we obtained BI-1-mediated resistance to fungus-induced leaf cell death and less fungal spreading on the leaves. Barley BI-1 also mediated resistance to Chalara elegans in carrot roots. The results support the idea that cell death inhibition is an applicable approach to control cell-death-inducing pathogens in crop plants.
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Affiliation(s)
- Jafargholi Imani
- Research Centre for BioSystems, Land Use and Nutrition, Institute of Phytopathology and Applied Zoology, Justus-Liebig-Universität Giessen, Heinrich-Buff Ring 26-32, D-35392 Giessen, Germany
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86
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Curto M, Camafeita E, Lopez JA, Maldonado AM, Rubiales D, Jorrín JV. A proteomic approach to study pea (Pisum sativum) responses to powdery mildew (Erysiphe pisi). Proteomics 2006; 6 Suppl 1:S163-74. [PMID: 16511815 DOI: 10.1002/pmic.200500396] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
As a global approach to gain a better understanding of the mechanisms involved in pea resistance to Erysiphe pisi, changes in the leaf proteome of two pea genotypes differing in their resistance phenotype were analyzed by a combination of 2-DE and MALDI-TOF/TOF MS. Leaf proteins from control non-inoculated and inoculated susceptible (Messire) and resistant (JI2480) plants were resolved by 2-DE, with IEF in the 5-8 pH range and SDS-PAGE on 12% gels. CBB-stained gels revealed the existence of quantitative and qualitative differences between extracts from: (i) non-inoculated leaves of both genotypes (77 spots); (ii) inoculated and non-inoculated Messire leaves (19 spots); and (iii) inoculated and non-inoculated JI2480 leaves (12 spots). Some of the differential spots have been identified, after MALDI-TOF/TOF analysis and database searching, as proteins belonging to several functional categories, including photosynthesis and carbon metabolism, energy production, stress and defense, protein synthesis and degradation and signal transduction. Results are discussed in terms of constitutive and induced elements involved in pea resistance against Erysiphe pisi.
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Affiliation(s)
- Miguel Curto
- Agricultural and Plant Biochemistry Research Group, Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Córdoba, Spain
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87
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Gullner G, Kômíves T. Defense Reactions of Infected Plants: Roles of Glutathione and Glutathione S-Transferase Enzymes. ACTA ACUST UNITED AC 2006. [DOI: 10.1556/aphyt.41.2006.1-2.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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88
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Reekmans R, De Smet K, Chen C, Van Hummelen P, Contreras R. Old yellow enzyme interferes with Bax-induced NADPH loss and lipid peroxidation in yeast. FEMS Yeast Res 2005; 5:711-25. [PMID: 15851100 DOI: 10.1016/j.femsyr.2004.12.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2004] [Revised: 12/29/2004] [Accepted: 12/30/2004] [Indexed: 12/19/2022] Open
Abstract
The yeast transcriptional response to murine Bax expression was compared with the changes induced by H(2)O(2) treatment via microarray technology. Although most of the Bax-responsive genes were also triggered by H(2)O(2) treatment, OYE3, ICY2, MLS1 and BTN2 were validated to have a Bax-specific transcriptional response not shared with the oxidative stress trigger. In knockout experiments, only deletion of OYE3, coding for yeast Old yellow enzyme, attenuated the rate of Bax-induced growth arrest, cell death and NADPH decrease. Lipid peroxidation was completely absent in DeltaOYE3 expressing Bax. However, the absence of OYE3 sensitized yeast cells to H(2)O(2)-induced cell death, and increased the rate of NADPH decrease and lipid peroxidation. Our results clearly indicate that OYE3 interferes with Bax- and H(2)O(2)-induced lipid peroxidation and cell death in Saccharomyces cerevisiae.
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Affiliation(s)
- Rieka Reekmans
- Unit of Fundamental and Applied Molecular Biology, Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Zwijnaarde, Belgium
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89
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Foyer CH, Noctor G. Redox homeostasis and antioxidant signaling: a metabolic interface between stress perception and physiological responses. THE PLANT CELL 2005; 17:1866-75. [PMID: 15987996 PMCID: PMC1167537 DOI: 10.1105/tpc.105.033589] [Citation(s) in RCA: 1453] [Impact Index Per Article: 76.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Christine H Foyer
- Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
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90
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Gratão PL, Polle A, Lea PJ, Azevedo RA. Making the life of heavy metal-stressed plants a little easier. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:481-494. [PMID: 32689149 DOI: 10.1071/fp05016] [Citation(s) in RCA: 445] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Accepted: 04/28/2005] [Indexed: 05/04/2023]
Abstract
The contamination of soils and water with metals has created a major environmental problem, leading to considerable losses in plant productivity and hazardous health effects. Exposure to toxic metals can intensify the production of reactive oxygen species (ROS), which are continuously produced in both unstressed and stressed plants cells. Some of the ROS species are highly toxic and must be detoxified by cellular stress responses, if the plant is to survive and grow. The aim of this review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.
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Affiliation(s)
- Priscila L Gratão
- Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba CEP 13418-900, SP, Brazil
| | - Andrea Polle
- Forstbotanisches Institut, Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Peter J Lea
- Department of Biological Sciences, University of Lancaster, Lancaster LA1 4YQ, United Kingdom
| | - Ricardo A Azevedo
- Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba CEP 13418-900, SP, Brazil
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91
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Foyer CH, Noctor G. Redox homeostasis and antioxidant signaling: a metabolic interface between stress perception and physiological responses. THE PLANT CELL 2005. [PMID: 15987996 DOI: 10.1105/tpc.105.0335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Christine H Foyer
- Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
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92
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Yang XD, Li WJ, Liu JY. Isolation and characterization of a novel PHGPx gene in Raphanus sativus. ACTA ACUST UNITED AC 2005; 1728:199-205. [PMID: 15777688 DOI: 10.1016/j.bbaexp.2005.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 01/30/2005] [Accepted: 02/01/2005] [Indexed: 11/16/2022]
Abstract
A full-length cDNA encoding putative phospholipid hydroperoxide glutathione peroxidase (PHGPx) was cloned from Raphanus sativus. The cDNA, designated RsPHGPx, includes an open reading frame which encodes 197 amino acid residues. The alignment of amino acid sequences showed that RsPHGPx had the highest sequence homology to plant PHGPx and contained an N-terminal extension characteristic of a mitochondrial targeting peptide. Northern blot analysis indicated that RsPHGPx was constitutively and ubiquitously expressed during radish development, and its expression was differently regulated by various stress conditions. The expression of RsPHGPx in a yeast PHGPx-deletion mutant significantly rescued the mutant sensitivity to oxidation-sensitive linolenic acid, just as the yeast PHGPx3 gene did. This suggested that RsPHGPx encodes a functional PHGPx protein.
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Affiliation(s)
- Xiao-Dong Yang
- Laboratory of Molecular Biology and MOE Laboratory of Protein Science, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, P. R. China
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93
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Current awareness on yeast. Yeast 2005; 22:71-8. [PMID: 15685779 DOI: 10.1002/yea.1157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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