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Literature summary extracted from

  • Chen, M.; Zeng, L.; Luo, X.; Mehboob, M.Z.; Ao, T.; Lang, M.
    Identification and functional characterization of a novel selenocysteine methyltransferase from Brassica juncea L. (2019), J. Exp. Bot., 70, 6401-6416 .
    View publication on PubMed

Application

EC Number Application Comment Organism
2.1.1.280 agriculture Brassica juncea SMT demonstrates its potential applications in crop MeSeCys biofortification and phytoremediation of Se pollution Brassica juncea

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.1.1.280 gene SMT, DNA and amino acid sequence determination and analysis, sequence comparisons and phylogenetic analysis and tree, recombinant expression of GFP-tagged enzyme under control of 35S promoter in Nicotiana tabacum, quantitative real-time PCR enzyme expression analysis Brassica juncea

Protein Variants

EC Number Protein Variants Comment Organism
2.1.1.280 additional information overexpression of BjSMT in tobacco substantially enhances tolerance to selenite stress manifested as significantly higher fresh weight, plant height, and chlorophyll content than control plants. Transgenic plants exhibited low glutathione peroxidase activity in response to a lower dose of selenite stress (with a higher dose of selenite stress resulting in a high activity response) compared with the controls. The BjSMT-transformed tobacco plants accumulate a high level of Se upon selenite stress, and the plants also have significantly increased MeSeCys production potential in their leaves Brassica juncea

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
2.1.1.280 Zn2+ the presence of the conserved amino acids in BjSMT at positions Cys248, Cys315, and Cys316 suggests that BjSMT may also coordinate the binding of Zn2+ Brassica juncea

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.1.1.280 S-methyl-L-methionine + L-homocysteine Brassica juncea
-
 L-methionine + S-methyl-L-homocysteine
-
 ?
2.1.1.280 S-methyl-L-methionine + L-selenocysteine Brassica juncea
-
 L-methionine + Se-methyl-L-selenocysteine
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
2.1.1.280 Brassica juncea
-
-
-

Source Tissue

EC Number Source Tissue Comment Organism Textmining
2.1.1.280 leaf
-
 Brassica juncea
-
2.1.1.280 additional information semiquantitative RT-PCR expression analysis of BjSMT transcript accumulation in leaves and roots of Indian mustard plants supplied with 0.04 mM Na2SeO4, 0.04 mM Na2SeO3, and 0.001 mM MgSO4 in the medium, overview Brassica juncea
-
2.1.1.280 root
-
 Brassica juncea
-
2.1.1.280 seedling
-
 Brassica juncea
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.1.1.280 S-methyl-L-methionine + L-homocysteine
-
 Brassica juncea L-methionine + S-methyl-L-homocysteine
-
 ?
2.1.1.280 S-methyl-L-methionine + L-selenocysteine
-
 Brassica juncea L-methionine + Se-methyl-L-selenocysteine
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.1.1.280 BjSMT
-
 Brassica juncea
2.1.1.280 selenocysteine methyltransferase
-
 Brassica juncea
2.1.1.280 SMT
-
 Brassica juncea

Expression

EC Number Organism Comment Expression
2.1.1.280 Brassica juncea BjSMT responds to selenite [Se(IV)] and selenate [Se(VI)] stress in Brassica juncea. BjSMT expression is nearly undetectable in the Brassica juncea plant without Se exposure, but in the plant leaves it can be rapidly and significantly upregulated upon a low level of selenite stress, and enormously upregulated upon selenate treatment up

General Information

EC Number General Information Comment Organism
2.1.1.280 malfunction overexpression of BjSMT in tobacco substantially enhances tolerance to selenite stress manifested as significantly higher fresh weight, plant height, and chlorophyll content than control plants. The BjSMT-transformed tobacco plants accumulate a high level of Se upon selenite stress, and the plants also have significantly increased MeSeCys production potential in their leaves. The enzyme is highly induced by selenite and especially selenate. BjSMT overexpressing plants maintain a higher level of GSH-Px activity and chlorophyll content under severe selenite treatment Brassica juncea
2.1.1.280 additional information the post-secondary structure assembled by conserved Cys207, Cys272, and Cys273 residues is believed to form such a geometrical catalytic pocket which will position the sulfur group of L-homocysteine in close proximity to Thr147, responsible for methyl group transfer by donating a hydrogen bond Brassica juncea
2.1.1.280 physiological function plants can easily absorb and assimilate Se in the form of selenate and selenite through sulfur transport proteins and metabolic pathways and remove it by converting it into volatilized methylated forms. The Se substitution of S in proteins can destroy the molecular function of these proteins, so an increased level of Se is toxic to most organisms. In plants,selenates are reduced and assimilated to organic Se which can be converted to methylselenocysteine (MeSeCys) in addition to selenocysteine (SeCys), selenomethionine (SeMet), and dimethylselenide (DMSe). Selenocysteine methyltransferase (SMT) is the key enzyme responsible for Se-methylselenocysteine (MeSeCys) formation. Brassica juncea is a selenium accumulator. BjSMT also possesses a conserved Thr187 which is involved in transferring a methyl group to L-homocysteine (HoCys) by donating a hydrogen bond, suggesting that BjSMT can methylate both HoCys and SeCys substrates Brassica juncea