YhjD is required for LPS transport.

(A) Genetic interaction sub-network (rich medium) involving LPS transport factors. LPS is synthesized at the IM cytoplasmic face, flipped across the bilayer by MsbA, extracted by LptBCFG, and transported to the OM by LptA for final assembly by LptDE. (B) Strain growth in rich liquid medium at 32°C over 24 h. (C) Electron microscopy showing morphological alterations (arrows) in mutant E. coli strains relative to wild-type cells; scale-bar 500 nm. (D) SDS-PAGE immunoblots of marker proteins (I) and silver staining LPS (II). (E) Co-immunoprecipitation of SPA-tagged YhjD with His6-tagged LPS transport component. (F) LPS-binding by immobilized recombinant YhjD (test) and LptA (positive control) but not LolE (negative control). After extensive washing, bound LPS molecules were visualized by SDS-PAGE and silver staining.