Nam7 Hydroxylase Is Responsible for the Formation of the Naphthalenic Ring in the Biosynthesis of Neoansamycins.

Ten new benzenic ansamycins, 5,10-seco-neoansamycins A-J (1-10), were isolated from the nam7-disrupted mutant strain SR201nam1OEΔnam7. These are the benzenic counterparts of the neoansamycins, which provide direct evidence that the putative hydroxylase Nam7 is involved in the formation of naphthalenic ring in neoansamycin biosynthesis and connect benzenic and naphthalenic ansamycins for the first time.