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Literature summary for 2.1.1.280 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)

Cloned (Comment) Organism
expressed in Escherichia coli Astragalus bisulcatus

Protein Variants

Protein Variants Comment Organism
A184T mutant enzyme gains the ability to methylate L-homocysteine Astragalus bisulcatus
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]

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

Localization

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

Organism

Organism UniProt Comment Textmining
Astragalus bisulcatus P56707
-
-

Source Tissue

Source Tissue Comment Organism Textmining
leaf
-
Astragalus bisulcatus
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
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
-
?
S-adenosyl-L-methionine + L-selenocysteine
-
Astragalus bisulcatus S-adenosyl-L-homocysteine + Se-methyl-L-selenocysteine
-
?

Synonyms

Synonyms Comment Organism
selenocysteine methyltransferase
-
Astragalus bisulcatus
SMT
-
Astragalus bisulcatus