title: Bilayer Properties of Lipid A from Various Gram-Negative Bacteria.
abstract: Lipid A is the lipid anchor of a lipopolysaccharide in the outer leaflet of the outer membrane of Gram-negative bacteria. In general, lipid A consists of two phosphorylated N-acetyl glucosamine and several acyl chains that are directly linked to the two sugars. Depending on the bacterial species and environments, the acyl chain number and length vary, and lipid A can be chemically modified with phosphoethanolamine, aminoarabinose, or glycine residues, which are key to bacterial pathogenesis. In this work, homogeneous lipid bilayers of 21 distinct lipid A types from 12 bacterial species are modeled and simulated to investigate the differences and similarities of their membrane properties. In addition, different neutralizing ion types (Ca2+, K+, and Na+) are considered to examine the ion's influence on the membrane properties. The trajectory analysis shows that (1) the area per lipid is mostly correlated to the acyl chain number, and the area per lipid increases as a function of the acyl chain number; (2) the hydrophobic thickness is mainly determined by the average acyl chain length with slight dependence on the acyl chain number, and the hydrophobic thickness generally increases with the average acyl chain length; (3) a good correlation is observed among the area per lipid, hydrophobic thickness, and acyl chain order; and (4) although the influence of neutralizing ion types on the area per lipid and hydrophobic thickness is minimal, Ca2+stays longer on the membrane surface than K+or Na+, consequently leading to lower lateral diffusion and a higher compressibility modulus, which agrees well with available experiments.
authors.affiliation: Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
authors.forename: Seonghoon
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
authors.forename: Dhilon S
authors.initials: DS
authors.lastname: Patel
authors.affiliation: Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
authors.forename: Soohyung
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, Lawrence, Kansas.
authors.forename: Joanna
authors.initials: J
authors.lastname: Slusky
authors.affiliation: Department of Chemical and Biomolecular Engineering and the Biophysics Program, University of Maryland, College Park, Maryland.
authors.forename: Jeffery B
authors.initials: JB
authors.lastname: Klauda
authors.affiliation: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Widmalm
authors.affiliation: Department of Biological Sciences and Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania. Electronic address: wonpil@lehigh.edu.
authors.forename: Wonpil
authors.initials: W
authors.lastname: Im
mesh_terms: D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000737:chemistry* / Q000166:cytology; D008050:Lipid A / Q000737:chemistry* / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D008050:Lipid A; D008051:Lipid Bilayers; D002118:Calcium