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Christopher S Cobbett - One of the best experts on this subject based on the ideXlab platform.

  • phytochelatins and Metallothioneins roles in Heavy Metal Detoxification and homeostasis
    Annual Review of Plant Biology, 2002
    Co-Authors: Christopher S Cobbett, Peter B Goldsbrough
    Abstract:

    ▪ Abstract Among the Heavy Metal-binding ligands in plant cells the phytochelatins (PCs) and Metallothioneins (MTs) are the best characterized. PCs and MTs are different classes of cysteine-rich, Heavy Metal-binding protein molecules. PCs are enzymatically synthesized peptides, whereas MTs are gene-encoded polypeptides. Recently, genes encoding the enzyme PC synthase have been identified in plants and other species while the completion of the Arabidopsis genome sequence has allowed the identification of the entire suite of MT genes in a higher plant. Recent advances in understanding the regulation of PC biosynthesis and MT gene expression and the possible roles of PCs and MTs in Heavy Metal Detoxification and homeostasis are reviewed.

  • Heavy Metal Detoxification in plants phytochelatin biosynthesis and function
    Iubmb Life, 2001
    Co-Authors: Christopher S Cobbett
    Abstract:

    Summary Phytochelatins (PCs) are a family of peptides important in the detoxie cation of Heavy Metals such as cadmium inplants and some microorganisms. PCs are synthesised enzymatically from glutathione. Molecular genetic studies, particularly in the yeast Schizosaccharomycespombeand inthe plant Arabidopsisthaliana,have identieed a number of genes important in the biosynthesis or function of PCs. PC-dee cient mutants of Arabidopsis have conermed boththeroleofglutathioneasthesubstrateforPC biosynthesisand the role of PCs themselves in Heavy Metal detoxie cation in plants. PC synthase genes have been identie ed in Arabidopsis and other plant species as well as in a number of animal species, suggesting PCs play a wider role in Metal detoxie cation than previously anticipated. PC synthesis is regulated at a number of levels, most importantly through the activation of PC synthase by Metal ions. This article reviews recent advances in our understanding of the biosynthesis and function of PCs in plants and other organisms. IUBMBLife, 51: 183‐188, 2001

  • phytochelatins and their roles in Heavy Metal Detoxification
    Plant Physiology, 2000
    Co-Authors: Christopher S Cobbett
    Abstract:

    Plants respond to Heavy Metal toxicity in a variety of different ways. Such responses include immobilization, exclusion, chelation and compartmentalization of the Metal ions, and the expression of more general stress response mechanisms such as ethylene and stress proteins. These mechanisms have

  • phytochelatin biosynthesis and function in Heavy Metal Detoxification
    Current Opinion in Plant Biology, 2000
    Co-Authors: Christopher S Cobbett
    Abstract:

    Plants respond to Heavy-Metal toxicity via a number of mechanisms. One such mechanism involves the chelation of Heavy Metals by a family of peptide ligands, the phytochelatins. Molecular genetic approaches have resulted in important advances in our understanding of phytochelatin biosynthesis. In particular, genes encoding the enzyme phytochelatin synthase have been isolated from plant and yeast species. Unexpectedly, genes with similar sequences to those encoding phytochelatin synthase have been identified in some animal species.

Prabodh Kumar Trivedi - One of the best experts on this subject based on the ideXlab platform.

  • Expression of Ceratophyllum demersum phytochelatin synthase, CdPCS1, in Escherichia coli and Arabidopsis enhances Heavy Metal(loid)s accumulation
    Protoplasma, 2013
    Co-Authors: Devesh Shukla, Ravi Kesari, Manish Tiwari, Sanjay Dwivedi, Rudra Deo Tripathi, Pravendra Nath, Prabodh Kumar Trivedi
    Abstract:

    Phytochelatin synthase (PCS) gene encoding key enzyme for Heavy Metal Detoxification and accumulation has been characterised from different sources and used to develop a technology for bioremediation. Past efforts provided limited success and contradictory results. Therefore, functional characterisation of PCS gene from new sources into different target systems is considered as an important task in the area of bioremediation. Earlier, we isolated and functionally characterised PCS gene from an aquatic macrophyte Ceratophyllum demersum L., a Metal accumulator aquatic plant. Expression of this gene, CdPCS1 , in tobacco enhanced PC synthesis and Metal accumulation of transgenic tobacco plants. In the present study, we have expressed CdPCS1 in more diverse systems, Escherichia coli and Arabidopsis , and studied growth and Metal accumulation of transgenic organisms. The expression of CdPCS1 in E . coli offered tolerance against cadmium as well as higher accumulation accompanied with PCS1 activity. The expression of CdPCS1 in Arabidopsis showed a significant enhanced accumulation of Heavy Metal(loid)s in aerial parts without significant difference in growth parameters in comparison to wild-type Arabidopsis plants. Our study suggests that CdPCS1 can be utilised for enhancing bioremediation potential of different organisms using biotechnological approaches.

  • genome wide identification of rice class i Metallothionein gene tissue expression patterns and induction in response to Heavy Metal stress
    Functional & Integrative Genomics, 2012
    Co-Authors: Neelam Gautam, Rudra Deo Tripathi, Prabodh Kumar Trivedi, Pankaj Kumar Verma, Shikha Verma, Bijan Adhikari, Debasis Chakrabarty
    Abstract:

    Metallothioneins (MTs) are members of a family of cysteine-rich low molecular weight polypeptides which play an important role in Heavy Metal Detoxification and homeostasis of intracellular Metal ions in plant. Though MT genes from some selected plants have been characterized with respect to their protein sequences, kinetic properties and tissue-specific localization, no detailed study has been carried out in rice. Here, we present genome-wide identification, structural and expression analyses of rice MT gene family. Our analysis suggests presence of 11 class I MT genes in rice genome (Release 7 of the MSU Rice Genome Annotation Project) which are differentially expressed during growth and development, in various tissues and during biotic and abiotic stresses. Our analyses suggest that class I MT proteins in rice differ in tissue localization as well as in Heavy Metal coordination chemistry. We also suggest that some MTs have a predominant role in Detoxification of As (V) in arsenic-tolerant rice cultivars. Our analysis suggests that apart from transcriptional regulation, post-transcriptional alternative splicing in some members of this family takes place during growth and development, in various tissues and during biotic and abiotic stresses.

  • expression of phytochelatin synthase from aquatic macrophyte ceratophyllum demersum l enhances cadmium and arsenic accumulation in tobacco
    Plant Cell Reports, 2012
    Co-Authors: Devesh Shukla, Ravi Kesari, Sanjay Dwivedi, Rudra Deo Tripathi, Pravendra Nath, Seema Mishra, Prabodh Kumar Trivedi
    Abstract:

    Phytochelatin synthase (PCS), the key enzyme involved in Heavy Metal Detoxification and accumulation has been used from various sources to develop transgenic plants for the purpose of phytoremediation. However, some of the earlier studies provided contradictory results. Most of the PCS genes were isolated from plants that are not potential Metal accumulators. In this study, we have isolated PCS gene from Ceratophyllum demersum cv. L. (CdPCS1), a submerged rootless aquatic macrophyte, which is considered as potential accumulator of Heavy Metals. The CdPCS1 cDNA of 1,757 bp encodes a polypeptide of 501 amino acid residues and differs from other known PCS with respect to the presence of a number of cysteine residues known for their interaction with Heavy Metals. Complementation of cad1-3 mutant of Arabidopsis deficient in PC (phytochelatin) biosynthesis by CdPCS1 suggests its role in the synthesis of PCs. Transgenic tobacco plants expressing CdPCS1 showed several-fold increased PC content and precursor non-protein thiols with enhanced accumulation of cadmium (Cd) and arsenic (As) without significant decrease in plant growth. We conclude that CdPCS1 encodes functional PCS and may be part of Metal Detoxification mechanism of the Heavy Metal accumulating plant C. demersum. Heterologous expression of PCS gene from C. demersum complements Arabidopsis cad1-3 mutant and leads to enhanced accumulation of Cd and As in transgenic tobacco.

Pauline M Doran - One of the best experts on this subject based on the ideXlab platform.

  • hyperaccumulation of cadmium by hairy roots of thlaspi caerulescens
    Biotechnology and Bioengineering, 2000
    Co-Authors: Tatjana V Nedelkoska, Pauline M Doran
    Abstract:

    Hairy roots were used to investigate cadmium uptake by Thlaspi caerulescens, a Metal hyperaccumulator plant with potential applications in phytoremediation and phytomining. Experiments were carried out in nutrient media under conditions supporting root growth. Accumulation of Cd in short-term (9-h) experiments varied with initial medium pH and increased after treating the roots with H+-ATPase inhibitor. The highest equilibrium Cd content measured in T. caerulescens roots was 62,800 μg g−1 dry weight, or 6.3% dry weight, at a liquid Cd concentration of 3710 ppm. Cd levels in live T. caerulescens roots were 1.5- to 1.7-fold those in hairy roots of nonhyperaccumulator species exposed to the same Cd concentration, but similar to the Cd content of autoclaved T. caerulescens roots. The ability to grow at Cd concentrations of up to 100 ppm clearly distinguished T. caerulescens hairy roots from the nonhyperaccumulators. The specific growth rate of T. caerulescens roots was essentially unaffected by 20 to 50 ppm Cd in the culture medium; in contrast, N. tabacum roots turned dark brown at 20 ppm and growth was negligible. Up to 10,600 μg g−1 dry weight Cd was accumulated by growing T. caerulescens hairy roots. Measurement of Cd levels in whole roots and in the cell wall fraction revealed significant differences in the responses of T. caerulescens and N. tabacum roots to 20 ppm Cd. Most Metal was transported directly into the symplasm of N. tabacum roots within 3 days of exposure; in contrast, T. caerulescens roots stored virtually all of their Cd in the wall fraction for the first 7 to 10 days. This delay in transmembrane uptake may represent an important defensive strategy against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for Heavy Metal Detoxification. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 67: 607–615, 2000.

  • hyperaccumulation of cadmium by hairy roots of thlaspi caerulescens
    Biotechnology and Bioengineering, 2000
    Co-Authors: Tatjana V Nedelkoska, Pauline M Doran
    Abstract:

    Hairy roots were used to investigate cadmium uptake by Thlaspi caerulescens, a Metal hyperaccumulator plant with potential applications in phytoremediation and phytomining. Experiments were carried out in nutrient media under conditions supporting root growth. Accumulation of Cd in short-term (9-h) experiments varied with initial medium pH and increased after treating the roots with H(+)-ATPase inhibitor. The highest equilibrium Cd content measured in T. caerulescens roots was 62,800 microg g(-1) dry weight, or 6.3% dry weight, at a liquid Cd concentration of 3710 ppm. Cd levels in live T. caerulescens roots were 1.5- to 1.7-fold those in hairy roots of nonhyperaccumulator species exposed to the same Cd concentration, but similar to the Cd content of autoclaved T. caerulescens roots. The ability to grow at Cd concentrations of up to 100 ppm clearly distinguished T. caerulescens hairy roots from the nonhyperaccumulators. The specific growth rate of T. caerulescens roots was essentially unaffected by 20 to 50 ppm Cd in the culture medium; in contrast, N. tabacum roots turned dark brown at 20 ppm and growth was negligible. Up to 10,600 microg g(-1) dry weight Cd was accumulated by growing T. caerulescens hairy roots. Measurement of Cd levels in whole roots and in the cell wall fraction revealed significant differences in the responses of T. caerulescens and N. tabacum roots to 20 ppm Cd. Most Metal was transported directly into the symplasm of N. tabacum roots within 3 days of exposure; in contrast, T. caerulescens roots stored virtually all of their Cd in the wall fraction for the first 7 to 10 days. This delay in transmembrane uptake may represent an important defensive strategy against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for Heavy Metal Detoxification.

Gang Wang - One of the best experts on this subject based on the ideXlab platform.

  • the glutathione synthesis may be regulated by cadmium induced endogenous ethylene in lycium chinense and overexpression of an ethylene responsive transcription factor gene enhances tolerance to cadmium stress in tobacco
    Molecular Breeding, 2015
    Co-Authors: Chunfeng Guan, Wenzhu Guan, Chao Jin, Gang Wang
    Abstract:

    Glutathione (GSH) plays a pivotal role in Heavy Metal Detoxification. Ethylene is one of the important plant hormones, which plays a critical role in triggering plant responses to different stresses such as cadmium (Cd) stress. Ethylene responsive transcription factor (ERF) belongs to one of the largest plant transcription factor families. ERF is known to be induced by ethylene and thus regulate multiple stress responses through the activation of stress-related genes. Until now, little has been done to explore the relationship among the accumulation of endogenous ethylene, ERF transcript levels and the GSH content in plants under Cd treatment and we will investigate these link. In this study, the gene transcript level of LchERF, LchGSH1 (gene responsible for the first-step GSH biosynthesis) and LchGSHS (gene responsible for the second-step GSH biosynthesis), endogenous ethylene accumulation, GSH content and Cd concentration in Lycium chinense with or without Cd stress treatment were studied. Furthermore, the transgenic tobacco expressing 35S::LchERF which grown under Cd stress condition was also investigated in this study. Our results showed that endogenous ethylene, LchERF, LchGSH1 and LchGSHS gene expression and GSH content can be induced by Cd treatment in L. chinense, however, reduced by co-treatment with 2-aminoethoxyvinlglycine (AVG), an inhibitor of ethylene biosynthesis. The transgenic tobacco expressing 35S::LchERF showed greater tolerance to Cd stress than non-transgenic plants. The expression of NtGSH1 and NtGSHS genes was increased in transgenic tobacco plants compared with non-transgenic plants, indicating that LchERF is associated with the expression level of GSH synthesis related genes in tobacco. Evidence was presented here that under Cd stress, GSH accumulation occurred at least partially via enhanced LchERF gene expression and the ethylene signal transduction pathways might be involved in this accumulation.

  • a gshs like gene from lycium chinense maybe regulated by cadmium induced endogenous salicylic acid and overexpression of this gene enhances tolerance to cadmium stress in arabidopsis
    Plant Cell Reports, 2015
    Co-Authors: Chunfeng Guan, Cuicui Jia, Wenzhu Guan, Chao Jin, Gang Wang
    Abstract:

    A GSHS gene, LcGSHS , was cloned from L. chinense for the first time. Evidence is presented here that endogenous SA accumulation maybe important for the regulation of LcGSHS expression level. Glutathione (GSH) plays a pivotal role in Heavy Metal Detoxification. GSH synthetase (GSHS) catalyzes the rate-limiting step of GSH synthesis in plants. Salicylic acid (SA) is one of the important plant hormones, which plays a critical role in triggering plant responses to different stresses such as cadmium (Cd) stress. Until now, little has been done to explore the relationship among the accumulation of endogenous SA, GSHS transcript levels and the GSH content in plants under Cd treatment and we will investigate this link in this study. The chlorophyll content, transcripts level of LcGSHS gene, endogenous SA accumulation, GSH accumulation and Cd concentration in the leaves of Lycium chinense were studied under different treatment conditions. Endogenous SA, LcGSHS transcript expression and GSH content can be induced by Cd treatment in L. chinense, however, reduced by co-treatment with 2-aminoindan-2-phosphonic acid (AIP), an inhibitor of SA biosynthesis. Strong staining was observed in the leaves of Arabidopsis expressing ProLcGSHS::GUS under Cd stress and the staining was reduced by co-treatment with AIP. The transgenic Arabidopsis expressing ProLcGSHS::LcGSHS also showed greater tolerance to Cd stress than wild types. Evidence was presented here that under Cd stress, GSH accumulation occurred via enhanced LcGSHS gene expression and the SA signaling cascade was involved in this accumulation. Furthermore, the overexpression of LcGSHS in transgenic Arabidopsis resulted in greater tolerance to Cd stress than wild-type lines.

Philip A Rea - One of the best experts on this subject based on the ideXlab platform.

  • drosophila abc transporter dmhmt 1 confers tolerance to cadmium dmhmt 1 and its yeast homolog sphmt 1 are not essential for vacuolar phytochelatin sequestration
    Journal of Biological Chemistry, 2009
    Co-Authors: Thanwalee Sooksanguan, Bakhtiyor Yakubov, Volodymyr I Kozlovskyy, Caitlin M Barkume, Kevin J Howe, Theodore W Thannhauser, Michael Rutzke, Jonathan J Hart, Leon V Kochian, Philip A Rea
    Abstract:

    Half-molecule ATP-binding cassette transporters of the HMT-1 (Heavy Metal tolerance factor 1) subfamily are required for Cd2+ tolerance in Schizosaccharomyces pombe, Caenorhabditis elegans, and Chlamydomonas reinhardtii. Based on studies of S. pombe, it has been proposed that SpHMT-1 transports Heavy Metal·phytochelatin (PC) complexes into the vacuolysosomal compartment. PCs are glutathione derivatives synthesized by PC synthases (PCS) in plants, fungi, and C. elegans in response to Heavy Metals. Our previous studies in C. elegans, however, suggested that HMT-1 and PCS-1 do not necessarily act in concert in Metal Detoxification. To further explore this inconsistency, we have gone on to test whether DmHMT-1, an HMT-1 from a new source, Drosophila, whose genome lacks PCS homologs, functions in Heavy Metal Detoxification. In so doing, we show that heterologously expressed DmHMT-1 suppresses the Cd2+ hypersensitivity of S. pombe hmt-1 mutants and localizes to the vacuolar membrane but does not transport Cd·PC complexes. Crucially, similar analyses of S. pombe hmt-1 mutants extend this finding to show that SpHMT-1 itself either does not transport Cd·PC complexes or is not the principal Cd·PC/apoPC transporter. Consistent with this discovery and with our previous suggestion that HMT-1 and PCS-1 do not operate in a simple linear Metal Detoxification pathway, we demonstrate that, unlike PCS-deficient cells, which are hypersensitive to several Heavy Metals, SpHMT-1-deficient cells are hypersensitive to Cd2+, but not to Hg2+ or As3+. These findings significantly change our current understanding of the function of HMT-1 proteins and invoke a PC-independent role for these transporters in Cd2+ Detoxification.

  • a new pathway for Heavy Metal Detoxification in animals phytochelatin synthase is required for cadmium tolerance in caenorhabditis elegans
    Journal of Biological Chemistry, 2001
    Co-Authors: Olena K Vatamaniuk, Elizabeth A Bucher, James T Ward, Philip A Rea
    Abstract:

    Increasing emissions of Heavy Metals such as cadmium, mercury, and arsenic into the environment pose an acute problem for all organisms. Considerations of the biochemical basis of Heavy Metal Detoxification in animals have focused exclusively on two classes of peptides, the thiol tripeptide, glutathione (GSH, γ-Glu-Cys-Gly), and a diverse family of cysteine-rich low molecular weight proteins, the Metallothioneins. Plants and some fungi, however, not only deploy GSH and Metallothioneins for Metal Detoxification but also synthesize another class of Heavy Metal binding peptides termed phytochelatins (PCs) from GSH. Here we show that PC-mediated Heavy Metal Detoxification is not restricted to plants and some fungi but extends to animals by demonstrating that thece-pcs-1 gene of the nematode wormCaenorhabditis elegans encodes a functional PC synthase whose activity is critical for Heavy Metal tolerance in the intact organism.