Figure 1.

Lipoprotein maturation and export pathway. Lipoprotein (green) is synthesized in the cytoplasm with the N-terminal SS (red) which targets it for translocation across the IM by the Sec or Tat translocon. The lipoprotein remains anchored in the IM by its SS and Lgt adds a diacylglyceryl moiety to the Cys residue. LspA cleaves the SS and Lnt adds another acyl chain to the newly formed N-terminus. The lipoprotein is then recognized by IM LolCDE complex which powers extraction of the lipoprotein from the IM using the energy of ATP. The lipoprotein is released to the periplasm in a complex with the chaperone LolA. LolA delivers lipoprotein to the OM acceptor protein LolB which inserts it in the inner leaflet of the OM. Empty LolA returns to LolCDE and is recycled. (Online version in colour.)