1 research outputs found
Mechanism of <i>S</i>‑Adenosyl‑l‑methionine <i>C</i>‑Methylation by Cobalamin-dependent Radical <i>S</i>‑Adenosyl‑l‑methionine Methylase in 1‑Amino-2-methylcyclopropanecarboxylic Acid Biosynthesis
The radical S-adenosyl-l-methionine
(SAM)
methylase Orf29 catalyzes the C-methylation of SAM
in the biosynthesis of 1-amino-2-methylcyclopropanecarboxylic acid.
Here, we determined that the methylation product is (4″R)-4″-methyl-SAM. Furthermore, we found that the
5′-deoxyadenosyl radical generated by Orf29 abstracts the pro-R hydrogen atom from the C-4″ position of SAM
to generate the radical intermediate, which reacts with methylcobalamin
to give (4″R)-4″-methyl-SAM. Consequently,
the Orf29-catalyzed C-methylation was confirmed to
proceed with retention of configuration