The influence of rough lipopolysaccharide structure on molecular interactions with mammalian antimicrobial peptides

Gianluca Bello, Alice Bodin, M. Jayne Lawrence, David Barlow, A. James Mason, Robert D. Barker*, Richard D. Harvey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)
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Abstract

The influence of Escherichia coli rough lipopolysaccharide chemotype on the membrane activity of the mammalian antimicrobial peptides (AMPs) human cathelicidin (LL37) and bovine lactoferricin (LFb) was studied on bilayers using solid state 2H NMR (ssNMR) and on monolayers using the subphase injection technique, Brewster angle microscopy (BAM) and neutron reflectivity (NR). The two AMPs were selected because of their differing biological activities. Chain-deuterated dipalmitoylphosphatidylcholine (d62-DPPC) was added to the LPS samples, to highlight alterations in the system properties caused by the presence of the different LPS chemotypes and upon AMP challenge. Both LPS chemotypes showed a temperature dependent influence on the packing of the DPPC molecules, with a fluidizing effect exerted below the DPPC phase transition temperature (Tm), and an ordering effect observed above the Tm. The magnitude of these effects was influenced by LPS structure; the shorter Rc LPS promoted more ordered lipid packing compared to the longer Ra LPS. These differential ordering effects in turn influenced the penetrative activity of the two peptides, as the perturbation induced by both AMPs to Ra LPS-containing models was greater than that observed in those containing Rc LPS. The NR data suggests that in addition to penetrating into the monolayers, both LL37 and LFb formed a non-interacting layer below the LPS/DPPC monolayer. The overall activity of LL37, which showed a deeper penetration into the model membranes, was more marked than that of LFb, which appeared to localise at the interfacial region, thus providing evidence for the molecular origins of their different biological activities.

Original languageEnglish
Pages (from-to)197-209
Number of pages13
JournalBIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
Volume1858
Issue number2
Early online date17 Nov 2015
DOIs
Publication statusPublished - 1 Feb 2016

Keywords

  • Air/liquid interface
  • Antimicrobial peptides
  • Bilayer
  • Endotoxin
  • Lipopolysaccharide
  • LPS
  • Monolayer
  • Neutron reflectivity
  • ssNMR

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