Hydroxyurea inhibits also the syntheses of thymine nucleotides and methionine in the cells of Escherichia coli.

Hydroxyurea not only inhibited the reduction of ribonucleotides, but also gave rise to need of exogenous methionine and thymidine for full growth in the cultures of Escherichia coli K12. In vitro the drug inhibited the formation of 5,10-methylenetetrahydrofolate by serine hydroxymethyltransferase in the cell extracts, which suggests that this reaction is a secondary target of hydroxyurea in the cells of E. coli. The syntheses of thymine nucleotides and methionine were also the most sensitive targets of hydroxylamine in the cultures of E. coli.