Unusual effect of hydroxyurea on a strain of E. coli resistant to isohydroxyurea.

SUMMARY In a strain of E. coli resistant to isohydroxyurea (E. coli C600/isoHU), hydroxyurea inhibits protein synthesis prefer entially. This is in contrast to the effects of hydroxyurea in all other systems studied including E. coli C600, in which hy droxyurea inhibits DNA synthesis selectively. A scheme is pro posed to explain the metabolic conversions of hydroxyurea, isohydroxyurea, and hydroxyurethan. It is postulated that in E. coli C600/isoHU hydroxyurea can be converted to isohy droxyurea but that the reverse reaction is blocked.