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Structure of supported bilayers composed of lipopolysaccharides and bacterial phospholipids: raft formation and implications for bacterial resistance.

Publication ,  Journal Article
Tong, J; McIntosh, TJ
Published in: Biophys J
June 2004

Lipopolysaccharide (LPS), the major lipid on the surface of Gram-negative bacteria, plays a key role in bacterial resistance to hydrophobic antibiotics and antimicrobial peptides. Using atomic force microscopy (AFM) we characterized supported bilayers composed of LPSs from two bacterial chemotypes with different sensitivities to such antibiotics and peptides. Rd LPS, from more sensitive "deep rough" mutants, contains only an inner saccharide core, whereas Ra LPS, from "rough" mutants, contains a longer polysaccharide region. A vesicle fusion technique was used to deposit LPS onto either freshly cleaved mica or polyethylenimine-coated mica substrates. The thickness of the supported bilayers measured with contact-mode AFM was 7 nm for Rd LPS and 9 nm for Ra LPS, consistent with previous x-ray diffraction measurements. In water the Ra LPS bilayer surface was more disordered than Rd LPS bilayers, likely due to the greater volume occupied by the longer Ra LPS polysaccharide region. Since deep rough mutants contain bacterial phospholipid (BPL) as well as LPS on their surfaces, we also investigated the organization of Rd LPS/BPL bilayers. Differential scanning calorimetry and x-ray diffraction indicated that incorporation of BPL reduced the phase transition temperature, enthalpy, and average bilayer thickness of Rd LPS. For Rd LPS/BPL mixtures, AFM showed irregularly shaped regions thinner than Rd LPS bilayers by 2 nm (the difference in thickness between Rd LPS and BPL bilayers), whose area increased with increasing BPL concentration. We argue that the increased permeability of deep rough mutants is due to structural modifications caused by BPL to the LPS membrane, in LPS hydrocarbon chain packing and in the formation of BPL-enriched microdomains.

Duke Scholars

Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

June 2004

Volume

86

Issue

6

Start / End Page

3759 / 3771

Location

United States

Related Subject Headings

  • X-Ray Diffraction
  • Polyethylene
  • Phospholipids
  • Microscopy, Atomic Force
  • Membrane Microdomains
  • Lipopolysaccharides
  • Gram-Negative Bacteria
  • Cell Membrane Permeability
  • Calorimetry, Differential Scanning
  • Biophysics
 

Citation

APA
Chicago
ICMJE
MLA
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Tong, J., & McIntosh, T. J. (2004). Structure of supported bilayers composed of lipopolysaccharides and bacterial phospholipids: raft formation and implications for bacterial resistance. Biophys J, 86(6), 3759–3771. https://doi.org/10.1529/biophysj.103.037507
Tong, Jihong, and Thomas J. McIntosh. “Structure of supported bilayers composed of lipopolysaccharides and bacterial phospholipids: raft formation and implications for bacterial resistance.Biophys J 86, no. 6 (June 2004): 3759–71. https://doi.org/10.1529/biophysj.103.037507.
Tong, Jihong, and Thomas J. McIntosh. “Structure of supported bilayers composed of lipopolysaccharides and bacterial phospholipids: raft formation and implications for bacterial resistance.Biophys J, vol. 86, no. 6, June 2004, pp. 3759–71. Pubmed, doi:10.1529/biophysj.103.037507.
Journal cover image

Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

June 2004

Volume

86

Issue

6

Start / End Page

3759 / 3771

Location

United States

Related Subject Headings

  • X-Ray Diffraction
  • Polyethylene
  • Phospholipids
  • Microscopy, Atomic Force
  • Membrane Microdomains
  • Lipopolysaccharides
  • Gram-Negative Bacteria
  • Cell Membrane Permeability
  • Calorimetry, Differential Scanning
  • Biophysics