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ENZYME entry: EC 2.1.1.326

Accepted Name
N-acetyl-demethylphosphinothricin P-methyltransferase.
Alternative Name(s)
P-methylase.
Reaction catalysed
2 S-adenosyl-L-methionine + N-acetyl-demethylphosphinothricin + reduced acceptor <=> S-adenosyl-L-homocysteine + 5'-deoxyadenosine + L-methionine + N-acetyl-phosphinothricin + oxidized acceptor
Cofactor(s)
Iron-sulfur; Methyl(III)cobalamin.
Comment(s)
  • The enzyme was originally characterized from bacteria that produce the tripeptides bialaphos and phosalacine, which inhibit plant and bacterial glutamine synthetases.
  • It is a radical S-adenosyl-L-methionine (SAM) enzyme.
  • According to the proposed mechanism, the reduced iron-sulfur center donates an electron to SAM, resulting in homolytic cleavage of the carbon-sulfur bond to form a 5'-deoxyadenosyl radical that abstracts the hydrogen atom from the P-H bond of the substrate, forming a phosphinate-centered radical.
  • This radical reacts with methylcob(III)alamin to produce the methylated product and cob(II)alamin, which is reduced by an unknown donor to cob(I)alamin.
  • A potential route for restoring the latter back to methylcob(III)alamin is a nucleophilic attack on a second SAM molecule.
  • The enzyme acts in vivo on N-acetyl-demethylphosphinothricin-L- alanyl-L-alanine or N-acetyl-demethylphosphinothricin-L-alanyl-L- leucine, the intermediates in the biosynthesis of bialaphos and phosalacine, respectively.
  • This transformation produces the only example of a carbon-phosphorus- carbon linkage known to occur in nature.
Cross-references
BRENDA2.1.1.326
EC2PDB2.1.1.326
ExplorEnz2.1.1.326
PRIAM enzyme-specific profiles2.1.1.326
KEGG Ligand Database for Enzyme Nomenclature2.1.1.326
IUBMB Enzyme Nomenclature2.1.1.326
IntEnz2.1.1.326
MEDLINEFind literature relating to 2.1.1.326
MetaCyc2.1.1.326

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