Assimilatory Sulfate Reduction in C3, C3-C4, and C4 Species of Flaveria

Koprivova, A.

doi:10.1104/pp.127.2.543

Cited by 15 publications

(25 citation statements)

References 21 publications

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“…In plants, sulfate reduction occurs in chloroplasts (Schmidt and Trebst 1969). Consistent with this observation, all plant APS reductases that have been analyzed are targeted to plastids and APS reductase has been shown by immunolocalization to be localized exclusively in plastids Rotte and Leustek 2000;Suter et al 2000;Koprivova et al 2001). As with other nutrient assimilation pathways, sulfate assimilation is an energy intensive process that relies primarily on ATP and reductant generated by photosynthesis.…”

Section: An Overview Of Aps Reductasementioning

confidence: 50%

The role of 5′-adenylylsulfate reductase in controlling sulfate reduction in plants

et al. 2005

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Cysteine is the first organic product of sulfate assimilation and as such is the precursor of all molecules containing reduced sulfur including methionine, glutathione, and their many metabolites. In plants, 5'-adenylylsulfate (APS) reductase is hypothesized to be a key regulatory point in sulfate assimilation and reduction. APS reductase catalyzes the two-electron reduction of APS to sulfite using glutathione as an electron donor. This paper reviews the experimental basis for this hypothesis. In addition, the results of an experiment designed to test the hypothesis by bypassing the endogenous APS reductase and its regulatory mechanisms are described. Two different bacterial assimilatory reductases were expressed in transgenic Zea mays, the thioredoxin-dependent APS reductase from Pseudomonas aeruginosa and the thioredoxin-dependent 3'-phosphoadenylylsulfate reductase from Escherichia coli. Each of them was placed under transcriptional control of the ubiquitin promoter and the protein products were targeted to chloroplasts. The leaves of transgenic Z. mays lines showed significant accumulation of reduced organic thiol compounds including cysteine, gamma-glutamylcysteine, and glutathione; and reduced inorganic forms of sulfur including sulfite and thiosulfate. Both bacterial enzymes appeared to be equally capable of deregulating the assimilative sulfate reduction pathway. The reduced sulfur compounds accumulated to such high levels that the transgenic plants showed evidence of toxicity. The results provide additional evidence that APS reductase is a major control point for sulfate reduction in Z. mays.

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Section: An Overview Of Aps Reductasementioning

confidence: 50%

The role of 5′-adenylylsulfate reductase in controlling sulfate reduction in plants

et al. 2005

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“…, 2009), is 3′‐phosphoadenosine 5′‐phosphosulfate (PAPS), which is formed from APS by APS kinase. The enzymes responsible for the reductive steps, APS reductase and sulfite reductase, are exclusively present in the plastids (Koprivova et al. , 2001; Kopriva et al.…”

Section: Introductionmentioning

confidence: 99%

“…as the last step of synthesis of glucosinolates , is 3¢-phosphoadenosine 5¢-phosphosulfate (PAPS), which is formed from APS by APS kinase. The enzymes responsible for the reductive steps, APS reductase and sulfite reductase, are exclusively present in the plastids (Koprivova et al, 2001;Kopriva et al, 2009), but ATP sulfurylase and APS kinase are localized in both plastids and cytosol (Rotte and Leustek, 2000;Mugford et al, 2009). OAS and cysteine synthesis occurs in plastids, the cytosol and mitochondria.…”

Section: Introductionmentioning

confidence: 99%

Control of sulfur partitioning between primary and secondary metabolism

et al. 2010

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SUMMARYSulfur is an essential nutrient for all organisms. Plants take up most sulfur as inorganic sulfate, reduce it and incorporate it into cysteine during primary sulfate assimilation. However, some of the sulfate is partitioned into the secondary metabolism to synthesize a variety of sulfated compounds. The two pathways of sulfate utilization branch after activation of sulfate to adenosine 5¢-phosphosulfate (APS). Recently we showed that the enzyme APS kinase limits the availability of activated sulfate for the synthesis of sulfated secondary compounds in Arabidopsis. To further dissect the control of sulfur partitioning between the primary and secondary metabolism, we analysed plants in which activities of enzymes that use APS as a substrate were increased or reduced. Reduction in APS kinase activity led to reduced levels of glucosinolates as a major class of sulfated secondary metabolites and an increased concentration of thiols, products of primary reduction. However, over-expression of this gene does not affect the levels of glucosinolates. Over-expression of APS reductase had no effect on glucosinolate levels but did increase thiol levels, but neither glucosinolate nor thiol levels were affected in mutants lacking the APR2 isoform of this enzyme. Measuring the flux through sulfate assimilation using [35 S]sulfate confirmed the larger flow of sulfur to primary assimilation when APS kinase activity was reduced. Thus, at least in Arabidopsis, the interplay between APS reductase and APS kinase is important for sulfur partitioning between the primary and secondary metabolism.

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“…cytosol, plastid, and mitochondria [17]. Sulfate activation, however, takes place in the cytosol and plastids, whereas sulfate reduction is confined to plastids [17,18]. Since sulfite reductase utilizes ferredoxin as an electron donor, the association of sulfate reduction with photosynthesis and plastids might be general for all photosynthetic eukaryotes.…”

Section: Introductionmentioning

confidence: 99%

Sulfate assimilation in eukaryotes: fusions, relocations and lateral transfers

2008

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BackgroundThe sulfate assimilation pathway is present in photosynthetic organisms, fungi, and many bacteria, providing reduced sulfur for the synthesis of cysteine and methionine and a range of other metabolites. In photosynthetic eukaryotes sulfate is reduced in the plastids whereas in aplastidic eukaryotes the pathway is cytosolic. The only known exception is Euglena gracilis, where the pathway is localized in mitochondria. To obtain an insight into the evolution of the sulfate assimilation pathway in eukaryotes and relationships of the differently compartmentalized isoforms we determined the locations of the pathway in lineages for which this was unknown and performed detailed phylogenetic analyses of three enzymes involved in sulfate reduction: ATP sulfurylase (ATPS), adenosine 5'-phosphosulfate reductase (APR) and sulfite reductase (SiR).ResultsThe inheritance of ATPS, APR and the related 3'-phosphoadenosine 5'-phosphosulfate reductase (PAPR) are remarkable, with multiple origins in the lineages that comprise the opisthokonts, different isoforms in chlorophytes and streptophytes, gene fusions with other enzymes of the pathway, evidence a eukaryote to prokaryote lateral gene transfer, changes in substrate specificity and two reversals of cellular location of host- and endosymbiont-originating enzymes. We also found that the ATPS and APR active in the mitochondria of Euglena were inherited from its secondary, green algal plastid.ConclusionOur results reveal a complex history for the enzymes of the sulfate assimilation pathway. Whilst they shed light on the origin of some characterised novelties, such as a recently described novel isoform of APR from Bryophytes and the origin of the pathway active in the mitochondria of Euglenids, the many distinct and novel isoforms identified here represent an excellent resource for detailed biochemical studies of the enzyme structure/function relationships.

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Assimilatory Sulfate Reduction in C3, C3-C4, and C4 Species of Flaveria

Cited by 15 publications

References 21 publications

The role of 5′-adenylylsulfate reductase in controlling sulfate reduction in plants

The role of 5′-adenylylsulfate reductase in controlling sulfate reduction in plants

Control of sulfur partitioning between primary and secondary metabolism

Sulfate assimilation in eukaryotes: fusions, relocations and lateral transfers

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