title: Trapped lipopolysaccharide and LptD intermediates reveal lipopolysaccharide translocation steps across the Escherichia coli outer membrane.
abstract: Lipopolysaccharide (LPS) is a main component of the outer membrane of Gram-negative bacteria, which is essential for the vitality of most Gram-negative bacteria and plays a critical role for drug resistance. LptD/E complex forms a N-terminal LPS transport slide, a hydrophobic intramembrane hole and the hydrophilic channel of the barrel, for LPS transport, lipid A insertion and core oligosaccharide and O-antigen polysaccharide translocation, respectively. However, there is no direct evidence to confirm that LptD/E transports LPS from the periplasm to the external leaflet of the outer membrane. By replacing LptD residues with an unnatural amino acid p-benzoyl-L-phenyalanine (pBPA) and UV-photo-cross-linking in E.coli, the translocon and LPS intermediates were obtained at the N-terminal domain, the intramembrane hole, the lumenal gate, the lumen of LptD channel, and the extracellular loop 1 and 4, providing the first direct evidence and "snapshots" to reveal LPS translocation steps across the outer membrane.
authors.affiliation: Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Li
authors.affiliation: Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Biomedical Sciences Research Complex, School of Chemistry, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK.
authors.forename: Haohao
authors.initials: H
authors.lastname: Dong
authors.affiliation: Laboratory of Department of Surgery, the First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou, Guangdong, 510080, China.
authors.forename: Wenjian
authors.initials: W
authors.lastname: Wang
authors.affiliation: Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
authors.forename: Changjiang
authors.initials: C
authors.lastname: Dong
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001577:Benzophenones / Q000737:chemistry / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism*; D019081:O Antigens / Q000378:metabolism; D019897:Periplasm / Q000378:metabolism; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D014466:Ultraviolet Rays
chemical_list: C488060:4-benzoylphenylalanine; D001425:Bacterial Outer Membrane Proteins; D001577:Benzophenones; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; C475958:LptD protein, E coli; D019081:O Antigens; D010649:Phenylalanine