Inhibition of Growth of Escherichia coli and of Homoserine O -Transsuccinylase by α-Methylmethionine

Abstract

The methionine analogue, α-methylmethionine, inhibits bacterial growth, but its action is overcome by methionine, homocysteine, and cystathionine. The effect of the analogue on growth is attributed to its ability to mimic methionine as a feed-back inhibitor of the first enzyme specific to methionine biosynthesis. This conclusion is based on the findings that (i) α-methylmethionine inhibits excretion of O -succinylhomoserine, the product of the first enzyme, by a methionine auxotroph unable to convert succinylhomoserine to cystahionine, and that (ii) the enzyme homoserine O -transsuccinylase is inhibited by α-methylmethionine in extracts of Escherichia coli . α-Methylmethionine also inhibits methionyl-ribonucleic acid synthetase in extracts, but this inhibition probably does not affect growth.