alpha-D-Glc-(1->3)-L-alpha-D-Hep-(1->3)-4-O-PO3(2-)-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A + ADP-L-glycero-beta-D-manno-heptose = alpha-D-Glc-(1->3)-[L-alpha-D-Hep-(1->7)]-L-alpha-D-Hep-(1->3)-4-O-PO3(2-)-L-alpha-D-Hep-(1->5)-[alpha-Kdo-(2->4)]-alpha-Kdo-(2->6)-lipid A + ADP + H(+) — reaction