Plays an important role in virulence (PubMed:15213144). A highly abundant outer membrane lipoprotein that controls the distance between the inner and outer membranes. The only protein known to be covalently linked to the peptidoglycan network (PGN). Also non-covalently binds the PGN. The link between the cell outer membrane and PGN contributes to maintenance of the structural and functional integrity of the cell envelope, and maintains the correct distance between the PGN and the outer membrane (By similarity). Homotrimer. Attached via its lipidated N-terminus to the inner leaflet of the outer membrane. Attached to the peptidoglycan network (PGN) via its C-terminus. This gene is probably poorly expressed. The integrity of the cell envelope in a lpp null mutant (double-knockout) is not affected. Belongs to the Lpp family.