Molecular structure of bacterial endotoxin (Escherichia coli Re lipopolysaccharide): implications for formation of a novel heterogeneous lattice structure

Abstract

Analyses of crystals of Escherichia coli Re lipopolysaccharide (LPS) formed after storage in 1% triethylamine indicate that the LPS molecules are assembled to form a monolayered structure consisting of a novel heterogeneous lattice structure, the greater part of which is occupied by one kind of lattice (lattice I), corresponding to the acyl chain portion of lipid A, and the remainder is occupied by the other kind of lattice (lattice II), corresponding to the 3‐deoxy‐dmanno‐octulosonic acid (dOclA) dimer and the N‐acetylglucosamine disaccharide of lipid A. X‐ray diffraction reveals that the type of cell is monoclinic (a = 5.53 Å, b = 27.2 Å, c = 6.47 Å , α = 90°, β = 125.8°, γ = 90°). Atomic force microscopy shows that crystals consist of multiple layers; the thickness of a layer corresponds to the b‐axis value, and two types of surface topographies are visualized. One, regarded as the view onto the acyl chain ends, is two‐dimensional arrays of oval bodies that constitute the lattice, with the lattice constants corresponding to the a‐ and c‐axes and the angle of β (lattice I). The other, regarded as the view onto the dOclA dimers, is two‐dimensional arrays of dromedary‐back‐like bodies that constitute the lattice with axes of 9.0 and 10.7 Å and the angle of 65° formed by both axes (lattice II). Based on these results, we present the molecular model of E. coli Re LPS.

Motility and chemotaxis of bacteria-driven microswimmers fabricated using antigen 43-mediated biotin display

“…The extent of the biotin functionalization of the cell surface in this strain could be modulated by varying the expression level of Ag43-BAP and by the availability of biotin in the medium. Yet another advantage of labeling mediated by Ag43 is that its N-terminal protrusion overcomes the LPS layer of the bacterial cell surface, which otherwise limits the accessibility of displayed peptides 42 , 43 , 57 , 58 . As Ag43 can be expressed and exposed on the surface in a brought range of gram negative bacteria, including Salmonella enterica, Burkholderia cepacia, Pseudomonas aeruginosa, Pseudomonas fluorescens, Klebsiella pneumoniae, Enterobacter cloacae and Serratia liquefaciens 40 , 59 , this display system is principally compatible with various biomedical applications of bacteriabots based on these species 60 , 61 .…”

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

“…These observations strongly suggest that LPS and glycosphingolipids are similar in producing stable domains in the membrane as a result of the extensive H bonding between neighboring molecules. Interestingly, the structure proposed for a deep rough LPS from E. coli (328) suggests that the free OH group of 3-OH-myristoyl moieties at the 2 and 3 positions of lipid A are located very close to the inner core sugar moiety at the 6Ј position of the neighboring LPS molecule.…”

Helical Disposition of Proteins and Lipopolysaccharide in the Outer Membrane ofEscherichia coli

“…For example, in artificial membrane vesicles stable islands of LPS persist for days in a "sea of phospholipid," indicating the existence of extremely durable lateral interactions between LPS molecules (59). Also, hexagonal arrays of tightly packed LPS subunits are observed in electron micrographs of crystallized LPS (24,64) and by X-ray crystallography and atomic force microscopy (25). Four forces generate this high degree of organization: van der Waals attractions between fatty acid chains, bridging of LPS molecules by divalent cations, hydrogen bonding, and interactions between the O polysaccharides of neighboring molecules (2,23,27,42).…”