Sedoheptulose 7-phosphate (S-7-P) can be converted to ADP-L-glycero-β-D-manno-heptose by SepB, SepL, and SepC, involving ADP-sugar in microbial natural product biosynthesis. SepB, an S-7-P isomerase, and SepL, which is involved in the biosynthesis of heptoses in the core region of E. coli LPS, catalyze a four-reaction relay converting S-7-P into ADP-D-glycero-β-D-manno-heptose. Septacidin and its analogs are potential anticancer and pain-relief agents.