JXB Advance Access originally published online on June 18, 2004
Journal of Experimental Botany 2004 55(404):1881-1888; doi:10.1093/jxb/erh151
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
RESEARCH PAPER |
Overproduction of SAT and/or OASTL in transgenic plants: a survey of effects
aszczyk
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawinskiego 5A, 02-106 Warsaw, Poland
* To whom correspondence should be addressed. Fax: +48 22 6584804. E-mail: asirko{at}ibb.waw.pl
Received 21 January 2004; Accepted 15 March 2004
 |
Abstract |
|---|
 Top Abstract IntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
The last steps of cysteine biosynthesis are catalysed by a bi-enzyme complex composed of serine acetyltransferase (SAT) and cysteine synthase, also called O-acetyl-serine (thiol) lyase (OASTL). SAT is responsible for the production of O-acetyl-serine (OAS) from serine and acetyl-coenzyme A, while OASTL catalyses the formation of cysteine from OAS and hydrogen sulphide. Several distinct nuclear genes for SAT and OASTL enzymes exist in plants. Products of these genes are targeted into at least three cellular compartments: cytosol, chloroplasts, and mitochondria. The SAT and OASTL enzymes are strongly evolutionary conserved, both structurally and functionally. Therefore, isoenzymes from various cellular compartments can be substituted, not only by their plant counterparts from the other cellular compartments but also by their bacterial homologues. During the last decade transgenic plants overproducing SAT, OASTL or both enzymes simultaneously were obtained independently by several research groups. These manipulations led not only to the elevated levels of the respective products, namely OAS and cysteine, but also to increased amounts of glutathione and changes in the levels of other metabolites and enzymatic activities. In several cases, the transgenic plants were also shown to be less susceptible to applied abiotic stresses. In this review, all published and some unpublished results from this laboratory related to heterologous overproduction of SAT and OASTL in transgenic plants are discussed and summarized.
Key words: Cysteine synthase, glutathione, serine acetyltransferase, transgenic plants
|
Introduction |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
Regulation of sulphur assimilation is complex and takes place on multiple levels. For the obvious reasons only some of these regulatory mechanisms are common for bacteria and plants. In bacteria, most of the processes responsible for the regulation of sulphur flow from sulphate to cysteine are quite well characterized (Kredich, 1996
). The regulatory mechanisms functioning in plants, especially at the transcriptional level, are not yet fully understood. However, considerable knowledge exists concerning allosteric and metabolic control of sulphate flux. These aspects were recently reviewed, and therefore only the most important elements of the regulatory system described in detail elsewhere (Leustek et al., 2000; Noji and Saito, 2002; Hell, 2003) will be pointed out. Firstly, sulphate transport and assimilation activities are up-regulated by sulphur deprivation and OAS feeding. It is worth emphasizing that OAS appears not only as an intermediate but also as a potential signalling element of the system. Factors directly participating in the regulation have not been identified yet. This regulation takes place at the gene expression level and, at least in the case of adenosine 5'-phosphosulphate reductase (APR), at the level of protein enzymatic activity (Koprivova et al., 2000; Hesse et al., 2003). Secondly, according to the model proposed for Arabidopsis thaliana (Noji et al., 1998) the feedback inhibition of the cytosolic SAT isoform by cysteine plays a central role in regulation of the level of OAS in the cytosol, while the SAT isoforms localized in mitochondria and chloroplasts are insensitive to this inhibition. It is necessary to point out that a discrepancy exists in the literature concerning the cellular localization of the SAT forms sensitive to the feedback inhibition by cysteine (Droux, 2003). This inconsistency can be explained by the species-specific differences, diverse methods of SAT purification and/or by the fact that some SAT isoforms can be phosphorylated by calcium-dependent protein kinases that leads to their insensitivity to feedback inhibition by cysteine (Yoo and Harmon, 1997; Saito, 2000). Thirdly, the other important regulatory circuit is connected with the formation of the bi-enzymatic cysteine synthase complex consisting of SAT and OASTL. This level of regulation is particularly important for an understanding of the consequences of overproduction of the enzymes forming the complex. Therefore, the model proposed previously (Hell and Hillebrand, 2001) will be summarized and the significance of complex formation will be discussed.
Functional complementation of bacterial mutants was used by several research groups as a method of cloning plant cDNAs encoding SAT (Roberts and Wray, 1996; Howarth et al., 1997, 2003; Wirtz and Hell, 2003) and OASTL (Saito et al., 1993; Noji et al., 1994) isoforms or as a method of confirming the specific function of the cloned cDNA (Wirtz and Hell, 2003; Chronis and Krishnan, 2004). The success of such approaches, together with computer analysis of the available structures of SAT and OASTL proteins, indicate that both enzymes are evolutionally conserved and that most of the important steps of cysteine biosynthesis are similar in bacteria and plants. In addition, the bacterial isoforms of SAT and OASTL are active in plants. Heterologous overproduction of enzymes of the sulphate assimilation pathway from organisms that are evolutionary distant might be a good approach to obtain changes in the levels of compounds containing reduced sulphur in plants. It might be expected that such an approach could overcome the intrinsic regulatory mechanisms functioning in plants that are responsible for the tight control of this metabolic trail. Similar effects could be achieved by using the mutated versions of the enzymes that would be insensitive to the plant control mechanisms.
|
Significance of the SAT–OASTL complex formation |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
SAT and OASTL enzymes form an enzymatic complex through specific protein–protein interactions. No crystal structure of the SAT–OASTL complex is yet available. The domains of SAT protein responsible for SAT–SAT and SAT–OASTL interactions have been well characterized by deletion mapping and two-hybrid experiments (Bogdanova and Hell, 1997
; Wirtz et al., 2001). On the other hand, despite resolving of the three-dimensional structure of the bacterial OASTL–OASTL dimmer (Burkhard et al., 1998), the sequences responsible for interaction with SAT are not yet identified in OASTL. Mapping of the amino acids responsible for interactions with SAT by deletion analysis of OASTL is quite difficult because of the complex arrangement of the interaction surfaces in the latter protein (Burkhard et al., 1998; Campanini et al., 2003).
The formation of a SAT–OASTL complex plays an important role in the regulation of both enzymatic activities (for recent reviews see Hell et al., 2002; Hell, 2003). OASTL is active only in a free form since it is allosterically inactivated in a complex. By contrast, SAT activity relies on the association with OASTL since free SAT is inactive (Droux et al., 1998; Wirtz et al., 2001). Sulphide stimulates the formation of the complex, while OAS stimulates its dissociation. Recently obtained kinetic data provide clear evidence for a function of the complex as a regulatory switch for the flux of primary sulphur metabolism in the cell (Berkowitz et al., 2002; Hell, 2003). The hypothesis explaining the significance of SAT–OASTL complex formation and its influence on the regulation of the sulphur assimilation pathway has recently been proposed (Hell and Hillebrand, 2001). The most important features of the model are shown in Fig. 1.
|
|
Effects of SAT overproduction |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
Effects of heterologous SAT overproduction, either in the cytosol or in the chloroplasts, indicate that SAT activity is a factor limiting the amount of cysteine and glutathione produced by the plants since, in most transformants, regardless of the targeting compartment and SAT isoform, the contents of non-protein thiols were higher than in the controls. A summary of the published works containing information concerning SAT overproduction in transgenic plants are included in Table 1. It has previously been reported (Creissen et al., 1999
) that tobacco plants overproducing the chloroplast-targeted 
-glutamylcysteine synthase (ECS) had about 3-fold elevated levels of glutathione. Necrotic lesions on the leaves of the transformants were also observed. The authors suggested that such transformants suffered due to a failure of the redox-sensing process in the chloroplasts. It is worth mentioning that most researchers studying the effects of SAT overexpression emphasize that, despite elevated thiol levels, the SAT overproducers did not show any disease-like symptoms and plants had the normal wild-type (wt) phenotype. The lack of necrosis in these transformants might be a result of differences in experimental plant growth conditions (lower light intensities), lower glutathione levels than in ECS-overproducers, or it might indicate the advantage of this approach as a means of obtaining plants with raised levels of glutathione.
|
Overproduction of bacterial SAT
The effects of constitutive overexpression of the Escherichia coli cysE gene, encoding SAT, had been independently studied in two plant species, tobacco and potato. Transgenic potato lines with bacterial SAT targeted to the chloroplasts had increased levels of cysteine and glutathione in leaves, but not in tubers (Harms et al., 2000
). The thiol content was maximally 2-fold higher in the green tissues of the best transgenics than in the control plants. However, neither expression patterns nor activity of cytosolic and chloroplastic OASTL isoforms were influenced by the increased thiols.
Additional data are available from transgenic tobacco plants. Bacterial SAT, either wild type or its mutated form (mutation changing Met256 into Ile), which is less sensitive to the feedback inhibition by cysteine (Denk and Bock, 1987; Nakamori et al., 1998) had been targeted either to the chloroplasts or to the cytosol (Blaszczyk et al., 1999). As in potato, no obvious phenotypic effects of SAT overproduction were observed in transformants under non-stressed conditions. The following groups of transformants were obtained: (i) RCEM producing chloroplastic mutated SAT; (ii) RCE producing chloroplastic wt SAT; (iii) CEM containing mutated SAT in the cytosol; and (iv) CE producing wt SAT in cytosol. Although the fold of elevation of thiol levels in the leaf tissues varied between the individuals, transformants with the 2–3-fold higher cysteine and glutathione levels could be identified in each group. Moreover, the leaf tissues of the transgenic plants were shown to be more resistant than the control to the oxidative stress generated by hydrogen peroxide, as determined by the level of chlorophyll remaining after the treatment. The increased resistance was observed in plants from all four groups of transformants and was generally correlated with the level of glutathione in the leaves. In subsequent studies (Blaszczyk et al., 2002) the T1 and T2 progeny from one transgenic line selected from each group had been characterized biochemically in more detail. An increased level of non-protein thiols have been found in all SAT overproducers, however, the levels of these compounds was lower in the T2 and T1 generations than in T0 of the same plant lines. The comparative statistical analysis of the plants containing bacterial SAT located in the cytosol to the plants containing bacterial SAT targeted to the chloroplasts was performed (Blaszczyk et al., 1999, 2002). However, only tentative conclusions can be drawn because the number of independent transgenic lines used in this study was rather small and some of the interesting correlations cannot be sufficiently statistically evaluated. Yet, they seem to point out some of the important features of sulphur metabolism in plants and might show the directions for future studies. For example, only in the group of plants producing bacterial SAT in the cytosol (but not in the chloroplasts) was the level of glutathione negatively correlated with sulphate (correlation coefficient –0.71) and total sulphur (correlation coefficient –0.69). It might suggest that there are some limitations in the transport of OAS, cysteine, and glutathione between these compartments and, moreover, what is more speculative, that the cytosolic (but not chloroplastic) glutathione levels are involved in the regulatory circuit influencing the expression of the genes responsible for sulphate transport and assimilation. It has been postulated previously that external glutathione is a negative regulator of sulphate transport (Smith et al., 1997; Bolchi et al., 1999; Vidmar et al., 2000). On the other hand, a positive correlation between cysteine and glutathione levels (correlation coefficient above +0.7) in all SAT overproducers was found, independently of the SAT targeting compartment. It might suggest that the process of glutathione production from cysteine (a two-step reaction catalysed subsequently by ECS and glutathione synthase) can run independently in both cellular compartments or that cysteine is rapidly transported to the compartment where glutathione synthesis takes place. Glutathione can be synthesized in both compartments, cytosol and chloroplasts, and the control of its concentration and redox state is a result of a complex interplay between biosynthesis, utilization, degradation, and transport (Noctor et al., 2002).
Finally, it is worth emphasizing that, in the tobacco SAT overproducers, particularly in the ‘cytosolic’ transformants, elevated OASTL activities were found. Moreover, all transgenic tobacco plants had an increased activity of glutathione-S-transferase and, what is even more interesting and less expected, a moderate but statistically significant increase of the soluble protein contents in their leaf tissues (Blaszczyk et al., 2002).
Overproduction of plant SAT isoforms
Four groups of SAT-overproducing Arabidopsis transformants have been obtained using the gene from watermelon encoding either wt SAT or its mutated allele encoding SAT insensitive to the feedback inhibition by cysteine due to the presence of the mutation changing Gly227 into Cys. The proteins were targeted either to cytosol or to chloroplasts (Noji and Saito, 2002). In watermelon, the product of this gene is localized in the cytosol. In Arabidopsis, its chloroplastic location was achieved due to the fusion with a transit peptide from the small subunit of Rubisco. The constitutive overexpression of the mutated gene for SAT in any of the compartments resulted in an elevated level of OAS and cysteine, however, the overexpression of the wt gene for SAT did not. Interestingly, glutathione contents increased in all four groups of Arabidopsis transformants. The authors explain that this is an indication of an enhanced metabolic flux through cysteine to glutathione in all groups of transgenic plants. Elevation of the glutathione level was higher in the transformants producing SAT encoded by the mutated gene than by the wt gene. Therefore, a significant value of this work is the demonstration in vivo of the importance of the feedback inhibition of SAT activity by cysteine for the regulation of sulphur assimilation (Noji and Saito, 2002).
The strategy of overexpression of a feedback-insensitive SAT was also applied to tobacco by another research group (Wirtz and Hell, 2003). The cDNA encoding SAT A from Arabidopsis thaliana, that was previously shown to be insensitive to the feedback inhibition by cysteine, was constitutively expressed in tobacco with and without the fusion peptide targeting the protein to the plastids. The subsequent analyses were performed on the T1 progeny of the primary transformants. SAT activity was strongly increased in both groups of SAT-overproducers, cytosolic and chloroplastic. The cysteine levels were, on average, elevated 3-fold by cytosolic targeting and 6-fold by plastidic targeting of the Arabidopsis SAT A, while the glutathione levels were, on average, increased 3-fold independently on the type of the transformants (Wirtz and Hell, 2003).
|
Effects of OASTL overproduction |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
Under non-stressed conditions, overproduction of OASTL in plants seems to have less significant effects on the level of the non-cellular thiols than overproduction of SAT. It is not surprising considering the fact, that in pea in vivo, OASTL is present at a huge molar excess over SAT in all compartments (Ruffet et al., 1995
; Droux, 2003). In fact, it is unclear how to explain the observed increase of thiol levels in tobacco OASTL-transformants without modification of the current models. One possibility is that the OASTL/SAT ratio in tobacco might be much lower than in pea. Nevertheless, under stress conditions, OASTL-overproducing transformants contain more thiols and are more tolerant to stress than the control plants suggesting that the increased potential for cysteine synthesis in such conditions still give them an important advantage. The summary of the published works containing information concerning OASTL-overproduction in transgenic plants are included in Table 2.
|
Overproduction of bacterial OASTL
These authors have recently overexpressed the bacterial cysK gene encoding cysteine synthase in tobacco plants. Two types of transgenic tobacco lines were obtained. In CK transformants, bacterial OASTL was targeted to the cytosol and in RCK to the chloroplasts due to the fusion of the product of the cysK gene with the leader peptide from the small subunit of tomato Rubisco (Liszewska and Sirko, 2003
; F Liszewska and A Sirko, unpublished results). The plants had an elevated OASTL activity and an elevated level of non-protein thiols. An important and puzzling observation was the bleaching of the older leaves in young plants of RCK transformants with the highest OASTL activity (Fig. 2). In some individual plants of RCK lines, similar symptoms could be observed during entire plant development. Obviously, the elevation of OASTL activity in the chloroplasts seems to have harmful effects on chlorophyll contents and/or plant metabolism.
|
Finally, the CK lines are also slightly more tolerant than the control to cadmium. The CK seedlings grown for 3 weeks in the presence of 300 µM CdCl2 germinated better and were less yellow and less bleached (contained more chlorophyll) than the seedlings of the control line (F Liszewska and A Sirko, unpublished results). No data concerning the cadmium-tolerance of RCK transformants are yet available.
Overproduction of plant OASTL isoforms
Transgenic tobacco lines producing various isoforms of plant OASTL have been obtained and analysed by several independent research groups.
The Cys1 cDNA from wheat (Triticum aestivum) encoding OASTL was used for tobacco transformation (Youssefian et al., 1993). An elevated OASTL activity was observed in all ‘sense’ transformants, while the ‘antisense’ transformants had OASTL activity on the level of the control plants. The most significant observation of this study was an increased resistance of the transgenic plants to H2S fumigation. One of the transgenic lines was selected for subsequent studies (Youssefian et al., 2001). Despite only a slight increase of non-protein thiols observed in the plants under non-stressed conditions, transformants were significantly more resistant than the controls to the damage caused by SO2 fumigation. Moreover, cysteine and glutathione levels became particularly elevated in these plants upon SO2 exposure. An accumulation of the transcript of Cu/Zn superoxide dismutase (SOD), known to be induced by cysteine or glutathione was observed in the OASTL-overproducers. In addition, the treatment with the substrates for cysteine biosynthesis (sulphite and OAS, combined) resulted in the strong elevation of SOD activity in the OASTL overproducers, but not in the controls. The transgenic plants were also more tolerant to the oxidative damage caused by methyl viologen showing less chlorosis and less electrolyte leakage than the controls (Youssefian et al., 2001).
The cytosolic OASTL A (CS A) cDNA from spinach (Spinacia oleracea) was used for tobacco transformation. The OASTL protein was targeted either to cytosol or to chloroplasts after fusion with a sequence for chloroplast-targeting transit peptide of the small subunit of pea Rubisco (Saito et al., 1994). All transformants had increased OASTL activities, but only a slight elevation of cysteine and glutathione levels, regardless from the targeting compartment for spinach OASTL. However, significantly enhanced cysteine formation was observed in the leaf discs of chloroplastic transformants upon sulphite incubation. These leaf discs were also partially resistant to sulphite toxicity, possibly due to the metabolic detoxification of sulphite by fixing into cysteine. Subsequently, the double transgenic tobacco plants overproducing spinach OASTL in the cytosol and the chloroplasts simultaneously were created by cross-pollination of two single transformants (Noji et al., 2001). Although the contents of cysteine and glutathione was increased in a similar way in all three types of transformants compared with the controls, the double transgenics were more resistant to SO2 and methyl viologen than any of the single transformants.
Additional proof for the important role of increased cysteine availability in the tolerance of plants to cadmium was obtained by using transgenic Arabidopsis plants constitutively overproducing cytosolic OASTL due to the presence of an additional copy of the Atcys-3A gene in their genomes (Dominguez-Solis et al., 2001). Up to a 9-fold overexpression of the Atcys-3A gene from Arabidopsis did not result in increased thiol content under the non-stressed conditions, however, the OASTL overproducers were more tolerant than the controls to the high concentration of cadmium. Interestingly, treatment with 250 µM CdCl2 produced opposite effects in the control and in the transformants, a 30% decrease of reduced glutathione content in wt and an increase of 54% in the OASTL-overproducing plants (Dominguez-Solis et al., 2001). Unfortunately, no data about the phytochelatins contents are available for these plants (Gotor et al., 2003).
The cytosolic cysteine synthase gene, RCS1, from rice (Oryza sativa) was introduced into tobacco (Harada et al., 2001). The transgenic plants were shown to be more tolerant to cadmium than the control plants, as explained by the authors, most probably due to higher concentration of sulphur-containing compounds able to detoxify cadmium.
|
Simultaneous overproduction of SAT and OASTL |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
The double tobacco transformants producing two E. coli enzymes, SAT and OASTL, were obtained in this laboratory by super-transformation of the cysE-expressing plants with the cysK-containing construct (Liszewska et al., 2001
; Liszewska and Sirko, 2003). Six independent transgenic lines were obtained, one CEK line, after transformation of the CE-20 line (wt SAT in the cytosol), four CEMK lines, after transformation of the CEM-12 line (mutated SAT in the cytosol), and one RCEK line, after transformation of the RCE-5 line (wt SAT in the chloroplasts). Inefficiency in production of the double transformants with both enzymes targeted to the chloroplasts can be explained by the fact that the levels of acetyl-coenzyme A and other forms of coenzyme A are low in the chloroplasts (Roughan, 1997). Therefore, it is possible that, in RCEK plants, acetyl-coenzyme A becomes limiting for other metabolic reactions in the chloroplasts. A huge excess of bi-enzymatic SAT–OASTL molecules must exist in the chloroplasts of the ‘chloroplastic’ double transformants and it is known that SAT bound in a complex has a strong affinity for its substrates, including acetyl-coenzyme A (Droux et al., 1998).
Simultaneous overexpression of cysE (encoding SAT) and cysK (encoding OASTL A) in tobacco resulted in a higher level of total glutathione in most transgenic plants than the single overexpression of any of the above genes (Liszewska et al., 2001; Liszewska and Sirko, 2003). On average, the double transformants containing Met256Ile SAT and OASTL targeted to the cytosol and wt SAT and OASTL targeted to the chloroplasts had 15–20% more of the total glutathione than the single transformants (Fig. 3). By contrast, CEK plants, containing wt SAT and OASTL targeted to the cytosol did not have more of the total glutathione than the single CK and CE transformants. A simple explanation of these results would be the silencing of the expression of the cysE gene in the CEK line, since rather low SAT activity was detected in these plants (a progeny of a single CEK line). Two possible reasons for such a cessation of expression are possible. First, the ‘chimeric’ promoter (Ni et al., 1995) used for cysE expression in the CE, CEM, and RCE transformants is not stable over future generations. Second, the high SAT activity and excess of thiols (or excess of OAS) produce unfavourable conditions for the plants, particularly when the highly active enzyme is present in the cytosol. Therefore, such plants are under pressure to reduce expression of the transgenes. The expression of the mutated isoform of SAT (Met265Ile) in the cytosol is much less harmful, since this isoform is not only less sensitive to the feedback inhibition by cysteine but also is much less active (Nakamori et al., 1998).
|
|
Concluding remarks |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
Increasing the plants potential for sulphate assimilation into cysteine, and subsequently into glutathione, by the elevation of SAT and OASTL activities and by the elimination/modification of the intrinsic regulatory mechanisms has been a goal for several independent groups. Such plants are important for basic research since they can help understanding of the regulatory aspects of the pathway. They can also be useful from the biotechnological point of view since they can potentially be applied for the phytoremediation of soil and water or might have an environmental advantage in some conditions, for example, they can be more tolerant to stresses. However, it must be kept in mind that glutathione, the most abundant thiol-containing compound, has numerous roles in the cell, not only in sulphur metabolism but also in stress defence and maintaining of the appropriate redox state of the cells. Therefore, plants tightly control its level and have the mechanisms responsible for counteracting the unfavourable changes.
The concept of increasing the sulphur flow in plants through raising the activity of SAT in various cellular compartments of plants agrees with the current model of the cysteine synthase complex and the observation that SAT is limiting for cysteine production. On the other hand, elevation of thiol levels was also achieved in the OASTL-overproducing transformants. This effect is somewhat unexpected, assuming that, in most cellular compartments, the OASTL/SAT ratio is high. It means that all the players involved in the regulation of cysteine biosynthesis in plants are not known and that the current models require adjustment.
|
Acknowledgements |
|---|
Research in our laboratory is supported by KBN (grant no. 6P04A07121) and by the EU Commission through funding of FP5 projects OPTI-2 (QLRT-2000-00103 and QLRT-2001-02928 [NAS]) and PHYTAC (QLRT-2001-00429 and QLRT-2001-02778 [NAS]).
|
Footnotes |
|---|
Abbreviations:
-ECS, -glutamylcysteine synthetase; OAS, O-acetylserine; OASTL, O-acetyl-serine (thiol) lyase (EC 2.5.1.47
[EC]
, previously EC 4.2.99.8
[EC]
); Rubisco, ribulose-1,5-biphosphate carboxylase; SAT, serine acetyltransferase (EC 2.3.1.30
[EC]
); SOD, superoxide dismutase; wt, wild type. |
References |
|---|
|
TopAbstractIntroductionSignificance of the SAT-OASTL...Effects of SAT overproductionEffects of OASTL overproductionSimultaneous overproduction of...Concluding remarksReferences |
|---|
Berkowitz O, Wirtz M, Wolf A, Kuhlmann J, Hell R. 2002. Use of biomolecular interaction analysis to elucidate the regulatory mechanism of the cysteine synthase complex from Arabidopsis thaliana. Journal of Biological Chemistry 277, 30629–30634.
Blaszczyk A, Brodzik R, Sirko A. 1999. Increased resistance to oxidative stress in transgenic tobacco plants overexpressing bacterial serine acetyltransferase. The Plant Journal 20, 237–243.[CrossRef][Web of Science][Medline]
Blaszczyk A, Sirko L, Hawkesford MJ, Sirko A. 2002. Biochemical analysis of transgenic tobacco lines producing bacterial serine acetyltransferase. Plant Science 162, 589–597.[CrossRef][Web of Science]
Bogdanova N, Hell R. 1997. Cysteine synthesis in plants: protein–protein interactions of serine acetyltransferase from Arabidopsis thaliana. The Plant Journal 11, 251–262.[CrossRef][Web of Science][Medline]
Bolchi A, Petrucco S, Tenca PL, Foroni C, Ottonello S. 1999. Coordinate modulation of maize sulphate permease and ATP sulphurylase mRNAs in response to variations in sulphur nutritional status: stereospecific down-regulation by L-cysteine. Plant Molecular Biology 39, 527–537.[CrossRef][Web of Science][Medline]
Burkhard P, Rao GS, Hohenester E, Schnackerz KD, Cook PF, Jansonius JN. 1998. Three-dimensional structure of O-acetylserine sulphhydrylase from Salmonella typhimurium. Journal of Molecular Biology 283, 121–133.[CrossRef][Web of Science][Medline]
Campanini B, Raboni S, Vaccari S, Zhang L, Cook PF, Hazlett TL, Mozzarelli A, Bettati S. 2003. Surface-exposed tryptophan residues are essential for O-acetylserine sulphhydrylase structure, function, and stability. Journal of Biological Chemistry 278, 37511–37519.
Chronis D, Krishnan HB. 2004. Sulphur assimilation in soybean (Glycine max [L.] Merr.): molecular cloning and characterization of a cytosolic isoform of serine acetyltransferase. Planta 218, 417–426.[CrossRef][Web of Science][Medline]
Creissen G, Firmin J, Fryer M, et al. 1999. Elevated glutathione biosynthetic capacity in the chloroplasts of transgenic tobacco plants paradoxically causes increased oxidative stress. The Plant Cell 11, 1277–1292.
Denk D, Bock A. 1987. L-cysteine biosynthesis in Escherichia coli: nucleotide sequence and expression of the serine acetyltransferase (cysE) gene from the wild-type and a cysteine-excreting mutant. Journal of General Microbiology 133, 515–525.
Dominguez-Solis JR, Gutierrez-Alcala G, Vega JM, Romero LC, Gotor C. 2001. The cytosolic O-acetylserine(thiol)lyase gene is regulated by heavy metals and can function in cadmium tolerance. Journal of Biological Chemistry 276, 9297–9302.
Droux M. 2003. Plant serine acetyltransferase: new insights for regulation of sulphur metabolism in plant cells. Plant Physiology and Biochemistry 41, 619–627.[CrossRef][Web of Science]
Droux M, Ruffet ML, Douce R, Job D. 1998. Interactions between serine acetyltransferase and O-acetylserine (thiol) lyase in higher plants—structural and kinetic properties of the free and bound enzymes. European Journal of Biochemistry 255, 235–245.[Web of Science][Medline]
Gotor C, Domingues-Solis JR, Gutierrez-Alcala G, Lopez-Martin MC, Calo L, Romero LC. 2003. Heavy metal regulation of cysteine biosynthesis and sulphur metabolism related to stress in Arabidopsis thaliana trichomes. In: Davidian J-C, Grill D, De Kok LJ, Stulen I, Hawkesford MJ, Schnug E, Rennerberg H, eds. Sulphur transport and assimilation in plants. Regulation, interaction and signaling. Leiden, The Netherlands: Backhuys Publishers, 91–99.
Griffith OW. 1980. Determination of glutathione and glutathione disulfide using glutathione reductase and 2-vinylpyridine. Analytical Biochemistry 106, 207–212.[CrossRef][Web of Science][Medline]
Harada E, Choi YE, Tsuchisaka A, Obata H, Sano H. 2001. Transgenic tobacco plants expressing a rice cysteine synthase gene are tolerant to toxic levels of cadmium. Journal of Plant Physiology 158, 655–661.[CrossRef][Web of Science]
Harms K, von Ballmoos P, Brunold C, Hofgen R, Hesse H. 2000. Expression of a bacterial serine acetyltransferase in transgenic potato plants leads to increased levels of cysteine and glutathione. The Plant Journal 22, 335–343.[CrossRef][Web of Science][Medline]
Hell R. 2003. Metabolic regulation of cysteine synthesis and sulphur assimilation. In: Davidian J-C, Grill D, De Kok LJ, Stulen I, Hawkesford MJ, Schnug E, Rennerberg H, eds. Sulphur transport and assimilation in plants. Regulation, interaction and signaling. Leiden, The Netherlands: Backhuys Publishers, 21–31.
Hell R, Hillebrand H. 2001. Plant concepts for mineral acquisition and allocation. Current Opinion in Biotechnology 12, 161–168.[CrossRef][Web of Science][Medline]
Hell R, Jost R, Berkowitz O, Wirtz M. 2002. Molecular and biochemical analysis of the enzymes of cysteine biosynthesis in the plant Arabidopsis thaliana. Amino Acids 22, 245–257.[CrossRef][Web of Science][Medline]
Hesse H, Trachsel N, Suter M, Kopriva S, von Ballmoos P, Rennenberg H, Brunold C. 2003. Effect of glucose on assimilatory sulphate reduction in Arabidopsis thaliana roots. Journal of Experimental Botany 54, 1701–1709.
Howarth JR, Dominguez-Solis JR, Gutierrez-Alcala G, Wray JL, Romero LC, Gotor C. 2003. The serine acetyltransferase gene family in Arabidopsis thaliana and the regulation of its expression by cadmium. Plant Molecular Biology 51, 589–598.[CrossRef][Web of Science][Medline]
Howarth JR, Roberts MA, Wray JL. 1997. Cysteine biosynthesis in higher plants: a new member of the Arabidopsis thaliana serine acetyltransferase small gene-family obtained by functional complementation of an Escherichia coli cysteine auxotroph. Biochimica et Biophysica Acta 1350, 123–127.[Medline]
Koprivova A, Suter M, den Camp RO, Brunold C, Kopriva S. 2000. Regulation of sulphate assimilation by nitrogen in Arabidopsis. Plant Physiology 122, 737–746.
Kredich NM. 1996. Biosynthesis of cysteine. In: Umbarger HE, ed. Escherichia coli and Salmonella typhimurium: cellular and molecular biology, 2nd edn, Vol. 1. Washington DC: American Society for Microbiology, 514–427.
Leustek T, Martin MN, Bick J-A, Davis JP. 2000. Pathways and regulation of sulphur metabolism revealed through molecular and genetic studies. Annual Review of Plant Physiology and Plant Molecular Biology 51, 141–165.[CrossRef][Web of Science]
Liszewska F, Blaszczyk A, Sirko A. 2001. Modification of non-protein thiols contents in transgenic tobacco plants producing bacterial enzymes of cysteine biosynthesis pathway. Acta Biochimica Polonica 48, 647–656.[Web of Science][Medline]
Liszewska F, Sirko A. 2003. Analysis of transgenic tobacco lines expressing bacterial cysK gene encoding O-acetylserine (thiol) lyase A. In: Davidian J-C, Grill D, De Kok LJ, Stulen I, Hawkesford MJ, Schnug E, Rennerberg H, eds. Sulphur transport and assimilation in plants. Regulation, interaction and signaling. Leiden: Backhuys Publishers, 269–271.
Nakamori S, Kobayashi SI, Kobayashi C, Takagi H. 1998. Overproduction of L-cysteine and L-cystine by Escherichia coli strains with a genetically altered serine acetyltransferase. Applied and Environmental Microbiology 64, 1607–1611.
Ni M, Cui D, Einstein J, Narasimhulu S, Vergara CE, Gelvin SB. 1995. Strength and tissue specificity of chimeric promoters derived from the octopine and mannopine synthase genes. The Plant Journal 7, 661–676.[CrossRef][Web of Science]
Noctor G, Gomez L, Vanacker H, Foyer CH. 2002. Interactions between biosynthesis, compartmentation and transport in the control of glutathione homeostasis and signalling. Journal of Experimental Botany 53, 1283–1304.
Noji M, Inoue K, Kimura N, Gouda A, Saito K. 1998. Isoform-dependent differences in feedback regulation and subcellular localization of serine acetyltransferase involved in cysteine biosynthesis from Arabidopsis thaliana. Journal of Biological Chemistry 273, 32739–32745.
Noji M, Murakoshi I, Saito K. 1994. Molecular cloning of a cysteine synthase cDNA from Citrullus vulgaris (watermelon) by genetic complementation in an Escherichia coli Cys- auxotroph. Molecular and General Genetics 244, 57–66.
Noji M, Saito K. 2002. Molecular and biochemical analysis of serine acetyltransferase and cysteine synthase towards sulphur metabolic engineering in plants. Amino Acids 22, 231–243.[CrossRef][Web of Science][Medline]
Noji M, Saito M, Nakamura M, Aono M, Saji H, Saito K. 2001. Cysteine synthase overexpression in tobacco confers tolerance to sulphur-containing environmental pollutants. Plant Physiology 126, 973–980.
Roberts MA, Wray JL. 1996. Cloning and characterization of an Arabidopsis thaliana cDNA clone encoding an organellar isoform of serine acetyltransferase. Plant Molecular Biology 30, 1041–1049.[CrossRef][Web of Science][Medline]
Roughan PG. 1997. Stromal concentrations of coenzyme A and its esters are insufficient to account for rates of chloroplast fatty acid synthesis: evidence for substrate channelling within the chloroplast fatty acid synthase. Biochemistry Journal 327, 267–273.
Ruffet ML, Lebrun M, Droux M, Douce R. 1995. Subcellular distribution of serine acetyltransferase from Pisum sativum and characterization of an Arabidopsis thaliana putative cytosolic isoform. European Journal of Biochemistry 227, 500–509.[Web of Science][Medline]
Saito K. 2000. Regulation of sulphate transport and synthesis of sulphur-containing amino acids. Current Opinion in Plant Biology 3, 188–195.[Web of Science][Medline]
Saito K, Kurosawa M, Tatsuguchi K, Takagi Y, Murakoshi I. 1994. Modulation of cysteine biosynthesis in chloroplasts of transgenic tobacco overexpressing cysteine synthase [O-acetylserine(thiol)-lyase]. Plant Physiology 106, 887–895.[Abstract]
Saito K, Tatsuguchi K, Murakoshi I, Hirano H. 1993. cDNA cloning and expression of cysteine synthase B localized in chloroplasts of Spinacia oleracea. FEBS Letters 324, 247–252.[CrossRef][Web of Science][Medline]
Smith FW, Hawkesford MJ, Ealing PM, Clarkson DT, Vanden Berg PJ, Belcher AR, Warrilow AG. 1997. Regulation of expression of a cDNA from barley roots encoding a high affinity sulphate transporter. The Plant Journal 12, 875–884.[CrossRef][Web of Science][Medline]
Vidmar JJ, Tagmount A, Cathala N, Touraine B, Davidian JE. 2000. Cloning and characterization of a root specific high-affinity sulphate transporter from Arabidopsis thaliana. FEBS Letters 475, 65–69.[CrossRef][Web of Science][Medline]
Wirtz M, Berkowitz O, Droux M, Hell R. 2001. The cysteine synthase complex from plants. Mitochondrial serine acetyltransferase from Arabidopsis thaliana carries a bifunctional domain for catalysis and protein-protein interaction. European Journal of Biochemistry 268, 686–693.[Web of Science][Medline]
Wirtz M, Hell R. 2003. Production of cysteine for bacterial and plant biotechnology: application of cysteine feedback-insensitive isoforms of serine acetyltransferase. Amino Acids 24, 195–203.[Web of Science][Medline]
Yoo B-C, Harmon AC. 1997. Regulation of recombinant soybean serine acetyltransferase by CDPK. Plant Physiology 114, 267.[Web of Science]
Youssefian S, Nakamura M, Orudgev E, Kondo N. 2001. Increased cysteine biosynthesis capacity of transgenic tobacco overexpressing an O-acetylserine(thiol) lyase modifies plant responses to oxidative stress. Plant Physiology 126, 1001–1011.
Youssefian S, Nakamura M, Sano H. 1993. Tobacco plants transformed with the O-acetylserine (thiol) lyase gene of wheat are resistant to toxic levels of hydrogen sulphide gas. The Plant Journal 4, 759–769.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  L. Tabe, M. Wirtz, L. Molvig, M. Droux, and R. Hell Overexpression of serine acetlytransferase produced large increases in O-acetylserine and free cysteine in developing seeds of a grain legume J. Exp. Bot., March 1, 2010; 61(3): 721 - 733. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. H. Haas, C. Heeg, R. Queiroz, A. Bauer, M. Wirtz, and R. Hell Mitochondrial Serine Acetyltransferase Functions as a Pacemaker of Cysteine Synthesis in Plant Cells Plant Physiology, October 1, 2008; 148(2): 1055 - 1067. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Heeg, C. Kruse, R. Jost, M. Gutensohn, T. Ruppert, M. Wirtz, and R. Hell Analysis of the Arabidopsis O-Acetylserine(thiol)lyase Gene Family Demonstrates Compartment-Specific Differences in the Regulation of Cysteine Synthesis PLANT CELL, January 1, 2008; 20(1): 168 - 185. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Wirtz and R. Hell Dominant-Negative Modification Reveals the Regulatory Function of the Multimeric Cysteine Synthase Protein Complex in Transgenic Tobacco PLANT CELL, February 1, 2007; 19(2): 625 - 639. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Liu, B.-C. Yoo, J.-Y. Lee, W. Pan, and A. C. Harmon Calcium-regulated Phosphorylation of Soybean Serine Acetyltransferase in Response to Oxidative Stress J. Biol. Chem., September 15, 2006; 281(37): 27405 - 27415. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Riemenschneider, K. Riedel, R. Hoefgen, J. Papenbrock, and H. Hesse Impact of Reduced O-Acetylserine(thiol)lyase Isoform Contents on Potato Plant Metabolism Plant Physiology, March 1, 2005; 137(3): 892 - 900. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||