Cytosolic Action of Phytochelatin Synthase

Blum, Ralph; Meyer, Katrin C.; Wünschmann, Jana; Lendzian, Klaus J.; Grill, Erwin

doi:10.1104/pp.109.149922

Cited by 67 publications

(68 citation statements)

References 59 publications

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“…), the processing of GS‐isothiocyanate conjugates is hypothesized to be localized in the cytosol where AtPCS1 is active (Blum et al . ). Directly testing the proposed role of AtPCS1 in the PEN2‐dependent pathway will be extremely challenging, not the least because of uncertain concentrations and stabilities of pathway intermediates.…”

Section: Discussionmentioning

confidence: 97%

Expression of Caenorhabditis elegans PCS in the AtPCS1‐deficient Arabidopsis thaliana cad1‐3 mutant separates the metal tolerance and non‐host resistance functions of phytochelatin synthases

Kühnlenz

Westphal

Schmidt

et al. 2015

Plant Cell & Environment

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Phytochelatin synthases (PCS) play key roles in plant metal tolerance. They synthesize small metal-binding peptides, phytochelatins, under conditions of metal excess. Respective mutants are strongly cadmium and arsenic hypersensitive. However, their ubiquitous presence and constitutive expression had long suggested a more general function of PCS besides metal detoxification. Indeed, phytochelatin synthase1 from Arabidopsis thaliana (AtPCS1) was later implicated in non-host resistance. The two different physiological functions may be attributable to the two distinct catalytic activities demonstrated for AtPCS1, that is the dipeptidyl transfer onto an acceptor molecule in phytochelatin synthesis, and the proteolytic deglycylation of glutathione conjugates. In order to test this hypothesis and to possibly separate the two biological roles, we expressed a phylogenetically distant PCS from Caenorhabditis elegans in an AtPCS1 mutant. We confirmed the involvement of AtPCS1 in non-host resistance by showing that plants lacking the functional gene develop a strong cell death phenotype when inoculated with the potato pathogen Phytophthora infestans. Furthermore, we found that the C. elegans gene rescues phytochelatin synthesis and cadmium tolerance, but not the defect in non-host resistance. This strongly suggests that the second enzymatic function of AtPCS1, which remains to be defined in detail, is underlying the plant immunity function.

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Section: Discussionmentioning

confidence: 97%

Expression of Caenorhabditis elegans PCS in the AtPCS1‐deficient Arabidopsis thaliana cad1‐3 mutant separates the metal tolerance and non‐host resistance functions of phytochelatin synthases

Kühnlenz

Westphal

Schmidt

et al. 2015

Plant Cell & Environment

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“…As noted previously, it is possible that PCS has other biochemical roles, in addition to phytochelatin synthesis, for example, turnover of GS‐conjugates (Rea et al . 2004; Blum et al . 2007, 2010; Clemens & Peršoh 2009).…”

Section: Metabolic Functions Of Glutathionementioning

confidence: 99%

Glutathione in plants: an integrated overview

Noctor

Mhamdi

Chaouch

et al. 2011

Plant Cell & Environment

1,309

936

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Plants cannot survive without glutathione (g-glutamylcysteinylglycine) or g-glutamylcysteinecontaining homologues. The reasons why this small molecule is indispensable are not fully understood, but it can be inferred that glutathione has functions in plant development that cannot be performed by other thiols or antioxidants. The known functions of glutathione include roles in biosynthetic pathways, detoxification, antioxidant biochemistry and redox homeostasis. Glutathione can interact in multiple ways with proteins through thiol-disulphide exchange and related processes. Its strategic position between oxidants such as reactive oxygen species and cellular reductants makes the glutathione system perfectly configured for signalling functions. Recent years have witnessed considerable progress in understanding glutathione synthesis, degradation and transport, particularly in relation to cellular redox homeostasis and related signalling under optimal and stress conditions. Here we outline the key recent advances and discuss how alterations in glutathione status, such as those observed during stress, may participate in signal transduction cascades. The discussion highlights some of the issues surrounding the regulation of glutathione contents, the control of glutathione redox potential, and how the functions of glutathione and other thiols are integrated to fine-tune photorespiratory and respiratory metabolism and to modulate phytohormone signalling pathways through appropriate modification of sensitive protein cysteine residues.

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“…(Gong et al 2003), predominantly in the phloem (Mendoza-Cozatl et al 2008), and in zinc sequestration (Tennstedt et al 2009). A second enzymatic activity of PCS as a peptidase has been linked to the catabolism of GS conjugates in plants (Clemens 2006a;Blum et al 2007Blum et al , 2010. Recently, an involvement of AtPCS1 in plant innate immunity was demonstrated (Clay et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…AtPCS2 is characterised by a low and constitutive expression with higher transcript accumulation in roots than in shoots (Cazalé and Clemens 2001). More recently, expression of AtPCS2 has been found to be localized mainly at the root tip (Blum et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of Arabidopsis halleri and Thlaspi caerulescens phytochelatin synthases

Meyer

Peisker

Courbot

et al. 2011

Planta

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The synthesis of phytochelatins (PC) represents a major metal and metalloid detoxification mechanism in various species. PC most likely play a role in the distribution and accumulation of Cd and possibly other metals. However, to date, no studies have investigated the phytochelatin synthase (PCS) genes and their expression in the Cd-hyperaccumulating species. We used functional screens in two yeast species to identify genes expressed by two Cd hyperaccumulators (Arabidopsis halleri and Thlaspi caerulescens) and involved in cellular Cd tolerance. As a result of these screens, PCS genes were identified for both species. PCS1 was in each case the dominating cDNA isolated. The deduced sequences of AhPCS1 and TcPCS1 are very similar to AtPCS1 and their identity is particularly high in the proposed catalytic N-terminal domain. We also identified in A. halleri and T. caerulescens orthologues of AtPCS2 that encode functional PCS. As compared to A. halleri and A. thaliana, T. caerulescens showed the lowest PCS expression. Furthermore, concentrations of PC in Cd-treated roots were the highest in A. thaliana, intermediate in A. halleri and the lowest in T. caerulescens. This mirrors the known capacity of these species to translocate Cd to the shoot, with T. caerulescens being the best translocator. Very low or undetectable concentrations of PC were measured in A. halleri and T. caerulescens shoots, contrary to A. thaliana. These results suggest that extremely efficient alternative Cd sequestration pathways in leaves of Cd hyperaccumulators prevent activation of PC synthase by Cd²⁺ ions.

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Cytosolic Action of Phytochelatin Synthase

Cited by 67 publications

References 59 publications

Expression of Caenorhabditis elegans PCS in the AtPCS1‐deficient Arabidopsis thaliana cad1‐3 mutant separates the metal tolerance and non‐host resistance functions of phytochelatin synthases

Expression of Caenorhabditis elegans PCS in the AtPCS1‐deficient Arabidopsis thaliana cad1‐3 mutant separates the metal tolerance and non‐host resistance functions of phytochelatin synthases

Glutathione in plants: an integrated overview

Isolation and characterization of Arabidopsis halleri and Thlaspi caerulescens phytochelatin synthases

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