Fig. 1.

LPS transport from the IM to the OM by the trans-envelope complex LptABCDEFG. a LPS is extracted from the periplasmic side of the IM by the ABC transporter LptB₂FG, and is delivered to an IM protein LptC, which forms a complex with LptB₂FG. LptC composes of a single membrane spanning domain and a large periplasmic domain, which forms a periplasmic bridge with LptA and the N-terminal domain of LptD. LPS is then inserted into the OM by LptD/E complex. LPS contains O-antigen, core oligosaccharide, and lipid A components, of which the O-antigen has 4-40 O-antigen repeat units. Ra-LPS, rough LPS, Kdo, 3-deoxy-D-manno-oct-2-ulosonic acid, Hep, L-glycero-D-manno-heptose, Glc, D-glucose, Gal, D-galactose. b Coomassie brilliant blue staining of the purified K. pneumoniae LptB₂FG