L-alpha-D-Hep-(1->3)-4-O-phospho-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A (E. coli) + ADP-L-glycero-beta-D-manno-heptose = L-alpha-D-Hep-(1->7)-L-alpha-D-Hep-(1->3)-4-O-phospho-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A (E. coli) + ADP + H(+) — reaction