Evidence Implicating Dimethylsulfoniopropionaldehyde as an Intermediate in Dimethylsulfoniopropionate Biosynthesis

James, Franck; Paquet, Luc; Sparace, Salvatore A.; Gage, Douglas A.; Hanson, Andrew D.

doi:10.1104/pp.108.4.1439

Cited by 48 publications

(52 citation statements)

References 23 publications

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“…This value is consistent with DDH catalyzing DMSP-ald oxidation in vivo, because stromal DMSP-ald levels are probably very low. They may be estimated as 3 to 8 /U,M by assuming a DMSP-ald pool of 0.3 to 0.6 nmol g~] fresh weight (James et al, 1995b), a stromal location for this pool, a chlorophyll content of 3 mg g~J fresh weight (Table II), and a stromal volume of 25 to 35 ju.L mg" 1 chlorophyll (Winter et al, 1993). The enzyme used NAD or NADP as a cofactor, although NAD was strongly preferred; the apparent K m value for NAD was 6.9, compared with 68 /XM for NADP at 3 /U.M DMSP-ald.…”

Section: Localization Of Ddh Within W Biflora Chloroplastsmentioning

confidence: 99%

“…Radiochemical yield was 37%; radiochemical purity was 299% as judged from TLE system 2 and TLC system 1. [metkyl-14C]DMSP-ald iodide (0.41 MBq pmol-') and DMSP-ald iodide were prepared and handled as before (James et al, 1995b) except that the chloroform used was stabilized with amylenes. Fast atom bombardment MS showed that this eliminated the diethylacetal DMSP-ald seen previously with ethanol-stabilized chloroform (James et al, 199513).…”

Section: Preparation Of Chemicals and Radiochemicalsmentioning

confidence: 99%

“…[35S]DMS was trapped in 1-cm discs of filter paper (3MM, Whatman) impregnated with 20 pL of 3% (w/v) HgCl, solution and quantified by scintillation counting (James et al, 1995b …”

Section: Metabolism Of [35s]smm By Lntact Chloroplastsmentioning

confidence: 99%

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Evidence That the Pathway of Dimethylsulfoniopropionate Biosynthesis Begins in the Cytosol and Ends in the Chloroplast

1996

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Section: Localization Of Ddh Within W Biflora Chloroplastsmentioning

confidence: 99%

Section: Preparation Of Chemicals and Radiochemicalsmentioning

confidence: 99%

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Evidence That the Pathway of Dimethylsulfoniopropionate Biosynthesis Begins in the Cytosol and Ends in the Chloroplast

1996

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“…Leaf extracts and phloem exudates were fractionated by passage through 1-mL columns of Dowex-1 (OH Ϫ ) and BioRex-70 (H ϩ ; Bio-Rad) arranged in series; these columns retain, respectively, neutral plus acidic amino acids and S-methylmethionine (SMM; James et al, 1995b). Subsequent separations were by thin-layer chromatography (TLC) system 1 and thin-layer electrophoresis (TLE) system 2 (James et al, 1995b), or by TLC on cellulose plates developed with n-propanol-formic acid-water (20:1:5 [v/v]). Radioactivity was detected by autoradiography and amino acids with ninhydrin.…”

Section: Analysis Of 35 S-labeled Compoundsmentioning

confidence: 99%

“…Leaves were extracted as described previously (James et al, 1995b). Leaf extracts and phloem exudates were fractionated by passage through 1-mL columns of Dowex-1 (OH Ϫ ) and BioRex-70 (H ϩ ; Bio-Rad) arranged in series; these columns retain, respectively, neutral plus acidic amino acids and S-methylmethionine (SMM; James et al, 1995b).…”

Section: Analysis Of 35 S-labeled Compoundsmentioning

confidence: 99%

S-Methylmethionine Plays a Major Role in Phloem Sulfur Transport and Is Synthesized by a Novel Type of Methyltransferase

et al. 1999

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All flowering plants produce S -methylmethionine (SMM) from Met and have a separate mechanism to convert SMM back to Met. The functions of SMM and the reasons for its interconversion with Met are not known. In this study, by using the aphid stylet collection method together with mass spectral and radiolabeling analyses, we established that L -SMM is a major constituent of the phloem sap moving to wheat ears. The SMM level in the phloem ( ‫ف‬ 2% of free amino acids) was 1.5-fold that of glutathione, indicating that SMM could contribute approximately half the sulfur needed for grain protein synthesis. Similarly, L -SMM was a prominently labeled product in phloem exudates obtained by EDTA treatment of detached leaves from plants of the Poaceae, Fabaceae, Asteraceae, Brassicaceae, and Cucurbitaceae that were given L -35 S-Met. cDNA clones for the enzyme that catalyzes SMM synthesis ( S -adenosylMet:Met S -methyltransferase; EC 2.1.1.12) were isolated from Wollastonia biflora , maize, and Arabidopsis. The deduced amino acid sequences revealed the expected methyltransferase domain ( ‫ف‬ 300 residues at the N terminus), plus an 800-residue C-terminal region sharing significant similarity with aminotransferases and other pyridoxal 5 -phosphate-dependent enzymes. These results indicate that SMM has a previously unrecognized but often major role in sulfur transport in flowering plants and that evolution of SMM synthesis in this group involved a gene fusion event. The resulting bipartite enzyme is unlike any other known methyltransferase. INTRODUCTIONPlant Met metabolism differs from that in other organisms by involving S -methylmethionine (SMM). SMM is a ubiquitous constituent of the free amino acid pool in flowering plants, occurring in leaves, roots, and other organs at levels that typically range from 0.5 to 3 mol g Ϫ 1 dry weight, a concentration that is often higher than those of Met or S -adenosylmethionine (AdoMet) (Giovanelli et al., 1980;Mudd and Datko, 1990;Bezzubov and Gessler, 1992). SMM also has been detected as a metabolite of radiolabeled L -Met in all flowering plants tested ( Ͼ 50 species from Ͼ 20 families; Paquet et al., 1995). As shown in Figure 1, SMM is formed from L -Met via the action of AdoMet:Met S -methyltransferase (MMT; EC 2.1.1.12) and can be reconverted to Met by donating a methyl group to L -homocysteine (Hcy) in a reaction catalyzed by Hcy S -methyltransferase (HMT; EC 2.1.1.10; Giovanelli et al., 1980;Mudd and Datko, 1990). The tandem action of MMT and HMT, together with S -adenosyl-L -Hcy hydrolase, constitutes the SMM cycle, which is apparently futile (Mudd and Datko, 1990).As expected from the universality of SMM, MMT activity has been found in many flowering plants (Giovanelli et al., 1980;Mudd and Datko, 1990). It has been purified from leaves of Wollastonia biflora (James et al., 1995a) and from germinating barley (Pimenta et al., 1998), and it is known to have subunits of ‫ف‬ 115 kD. Because this is approximately three times larger than any other small-molecule methyltransferase (F...

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Jaenicke³

1997

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Evidence Implicating Dimethylsulfoniopropionaldehyde as an Intermediate in Dimethylsulfoniopropionate Biosynthesis

Abstract: 3-Dimethylsulfoniopropionate

Cited by 48 publications

References 23 publications

Evidence That the Pathway of Dimethylsulfoniopropionate Biosynthesis Begins in the Cytosol and Ends in the Chloroplast

Evidence That the Pathway of Dimethylsulfoniopropionate Biosynthesis Begins in the Cytosol and Ends in the Chloroplast

S-Methylmethionine Plays a Major Role in Phloem Sulfur Transport and Is Synthesized by a Novel Type of Methyltransferase

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