Reaction participants Show >> << Hide
- Name help_outline L-selenocysteine Identifier CHEBI:57843 Charge 0 Formula C3H7NO2Se InChIKeyhelp_outline ZKZBPNGNEQAJSX-REOHCLBHSA-N SMILEShelp_outline [NH3+][C@@H](C[SeH])C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 3 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline S-methyl-L-methionine Identifier CHEBI:58252 Charge 1 Formula C6H14NO2S InChIKeyhelp_outline YDBYJHTYSHBBAU-YFKPBYRVSA-O SMILEShelp_outline C[S+](C)CC[C@H]([NH3+])C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 3 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,176 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline L-methionine Identifier CHEBI:57844 Charge 0 Formula C5H11NO2S InChIKeyhelp_outline FFEARJCKVFRZRR-BYPYZUCNSA-N SMILEShelp_outline CSCC[C@H]([NH3+])C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 118 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline Se-methyl-L-selenocysteine Identifier CHEBI:58531 Charge 0 Formula C4H9NO2Se InChIKeyhelp_outline XDSSPSLGNGIIHP-VKHMYHEASA-N SMILEShelp_outline C[Se]C[C@H]([NH3+])C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 1 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:26341 | RHEA:26342 | RHEA:26343 | RHEA:26344 | |
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Publications
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Molecular and biochemical characterization of the selenocysteine Se-methyltransferase gene and Se-methylselenocysteine synthesis in broccoli.
Lyi S.M., Heller L.I., Rutzke M., Welch R.M., Kochian L.V., Li L.
Selenium (Se) plays an indispensable role in human nutrition and has been implicated to have important health benefits, including being a cancer preventative agent. While different forms of Se vary in their anticarcinogenic efficacy, Se-methylselenocysteine (SeMSC) has been demonstrated to be one ... >> More
Selenium (Se) plays an indispensable role in human nutrition and has been implicated to have important health benefits, including being a cancer preventative agent. While different forms of Se vary in their anticarcinogenic efficacy, Se-methylselenocysteine (SeMSC) has been demonstrated to be one of the most effective chemopreventative compounds. Broccoli (Brassica oleracea var. italica) is known for its ability to accumulate high levels of Se with the majority of the selenoamino acids in the form of Se-methylselenocysteine. Therefore, it serves as a good model to study the regulation of SeMSC accumulation in plants. A cDNA encoding selenocysteine Se-methyltransferase, the key enzyme responsible for SeMSC formation, was cloned from broccoli using a homocysteine S-methyltransferase gene probe from Arabidopsis (Arabidopsis thaliana). This clone, designated as BoSMT, was functionally expressed in Escherichia coli, and its identity was confirmed by its substrate specificity in the methylation of selenocysteine. The BoSMT gene represents a single copy sequence in the broccoli genome. Examination of BoSMT gene expression and SeMSC accumulation in response to selenate, selenite, and sulfate treatments showed that the BoSMT transcript and SeMSC synthesis were significantly up-regulated in plants exposed to selenate but were low in plants supplied with selenite. Simultaneous treatment of selenate with selenite significantly reduced SeMSC production. In addition, high levels of sulfate suppressed selenate uptake, resulting in a dramatic reduction of BoSMT mRNA level and SeMSC accumulation. Our results reveal that SeMSC accumulation closely correlated with the BoSMT gene expression and the total Se status in tissues and provide important information for maximizing the SeMSC production in this beneficial vegetable plant. << Less
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On the mechanism of selenium tolerance in selenium-accumulating plants. Purification and characterization of a specific selenocysteine methyltransferase from cultured cells of Astragalus bisculatus.
Neuhierl B., Boeck A.
Selected members of the genus Astragalus (Fabaceae) are known for their ability to accumulate high levels of selenium, mainly in the form of Se-methyl-selenocysteine. With the aid of cell cultures we have investigated the molecular basis for selenium tolerance of these plants. It is shown that cul ... >> More
Selected members of the genus Astragalus (Fabaceae) are known for their ability to accumulate high levels of selenium, mainly in the form of Se-methyl-selenocysteine. With the aid of cell cultures we have investigated the molecular basis for selenium tolerance of these plants. It is shown that cultured cells from a selenium-accumulating Astragalus species synthesize Se-methyl-selenocysteine in contrast to those of a non-accumulating species and do not unspecifically incorporate selenium into proteins. The purification and biochemical characterization of a selenocysteine methyltransferase from cultured Astragalus bisculatus cells is described, which does not accept cysteine as a substrate. We propose that this enzyme plays a crucial role in conferring selenium tolerance. << Less
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Biochemical and molecular characterization of the homocysteine S-methyltransferase from broccoli (Brassica oleracea var. italica).
Lyi S.M., Zhou X., Kochian L.V., Li L.
Plants are known for their unique ability to synthesize methionine from S-methylmethionine (SMM) and homocysteine using the enzyme SMM: homocysteine S-methyltransferase (HMT) in the SMM cycle. Two cDNAs exhibiting HMT activity were cloned from broccoli and functionally expressed in E. coli. One cD ... >> More
Plants are known for their unique ability to synthesize methionine from S-methylmethionine (SMM) and homocysteine using the enzyme SMM: homocysteine S-methyltransferase (HMT) in the SMM cycle. Two cDNAs exhibiting HMT activity were cloned from broccoli and functionally expressed in E. coli. One cDNA, that encodes an enzyme with high substrate specificity for homocysteine, was designated as BoHMT1. The other cDNA was the BoSMT gene that we previously characterized and encodes a selenocysteine methyltransferase (Lyi, S.M., Heller, L.I., Rutzke, M., Welch, R.M., Kochian, L.V., Li, L., 2005. Molecular and biochemical characterization of the selenocysteine Se-methyltransferase gene and Se-methylselenocysteine synthesis in broccoli. Plant Physiol. 138, 409-420). Both exist as single gene sequences in the broccoli genome. While BoSMT expression was extremely low or undetectable in broccoli plants unless the plants were exposed to selenium, the BoHMT1 mRNA accumulated in most tissues of the plant except older leaves. In contrast to BoSMT whose expression was dramatically upregulated by treating plants with selenate, the transcript levels of BoHMT1 were not markedly affected in plants exposed to selenium. BoHMT1 expression responded significantly to changes in plant sulfur status. However, its expression was not dramatically affected in plants treated with methionine, SMM, homocysteine, or the heavy metal, cadmium. The differences in the substrate specificity and gene expression in response to changes in plant sulfur and selenium status between BoHMT1 and BoSMT suggest that the enzymes encoded by these two genes play distinct roles in sulfur and selenium metabolism in broccoli. << Less