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Literature summary extracted from

  • Sors, T.G.; Martin, C.P.; Salt, D.E.
    Characterization of selenocysteine methyltransferases from Astragalus species with contrasting selenium accumulation capacity (2009), Plant J., 59, 110-122.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.1.1.280 expressed in Escherichia coli Astragalus bisulcatus

Protein Variants

EC Number Protein Variants Comment Organism
2.1.1.280 A184T mutant enzyme gains the ability to methylate L-homocysteine Astragalus bisulcatus
2.1.1.280 additional information the but lacks the selenocysteine methyltransferase activity in vitro, explaining why little or no detectable levels of Se-methylselenocysteine accumulation are observed in the non-accumulator plant. Sequence analysis reveals that the selenocysteine methyltransferase from all plant that accumulate selenium contain a glycine residue at position 24, whereas the plants that do not accumulate selenium possess an alanine residue. A phenylalanine residue at position 148 in the accumulator selenocysteine methyltransferases is replaced by a tyrosine residue in non-accumulators. Thr334 is common among the Se accumulator species is lacking in the non-accumulator selenocysteine methyltransferase sequences and it appears as a complete deletion of the Thr334 codon of the DNA sequence Astragalus bisulcatus

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.1.1.280 0.37
-
 L-selenocysteine wild-type enzyme Astragalus bisulcatus
2.1.1.280 0.46
-
 L-selenocysteine mutant enzyme A184T Astragalus bisulcatus
2.1.1.280 0.74
-
 L-homocysteine mutant enzyme A184T, wild-type enzyme is not active with L-homocysteine Astragalus bisulcatus

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
2.1.1.280 chloroplast predominantly localized within Astragalus bisulcatus 9507
-

Organism

EC Number Organism UniProt Comment Textmining
2.1.1.280 Astragalus bisulcatus P56707
-
-

Source Tissue

EC Number Source Tissue Comment Organism Textmining
2.1.1.280 leaf
-
 Astragalus bisulcatus
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.1.1.280 S-adenosyl-L-methionine + L-homocysteine no activity with wild-type enzyme. A184T mutant enzyme gains the ability to methylate L-homocysteine Astragalus bisulcatus S-adenosyl-L-homocysteine + L-methionine
-
 ?
2.1.1.280 S-adenosyl-L-methionine + L-selenocysteine
-
 Astragalus bisulcatus S-adenosyl-L-homocysteine + Se-methyl-L-selenocysteine
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.1.1.280 selenocysteine methyltransferase
-
 Astragalus bisulcatus
2.1.1.280 SMT
-
 Astragalus bisulcatus