Removes the 1-phosphate group from lipid A species. Absence of phosphate groups in lipid A renders the bacteria resistant to host-derived cationic antimicrobial peptides (CAMP) and allowing it to camouflage itself from the host innate immune response. Bacterial outer membrane biogenesis; LPS lipid A biosynthesis. No longer responds to changes in hemin, decreased removal of 1-phosphate from lipid A species. Accumulates bi-phosphorylated pentaacyl and tetraacyl 1-phosphate lipid A species. Lipopolysaccharide (LPS) from this strain is a mild inducer of the human innate immune response via Toll-like receptor 4 (TLR4) in cultured HEK293 cells; double lpxE-lpxF mutants are more potent than either single mutant. No change in resistance to the cationic antimicrobial peptide (CAMP) polymyxin B. Double lpxE-lpxF mutants accumulate multiple mono- and bi-phosphorylated lipid A species (PubMed:19552698). Unable to colonize rabbit periodontium, a model for periodontal disease (PubMed:24478080). When grown in low hemin conditions the major lipid A species are non-phosphorylated tetraacyl and 4'-phosphate pentaacyl lipid A, while under high hemin conditions the major lipid A species are non-phosphorylated tetraacyl and 1-phosphate tetraacyl lipid A (hemin is protoporphyrin IX containing Fe(3+) with a chloride ligand (CHEBI:50385) involved in the change from healthy to diseased gums).