TLR1- and TLR6-independent recognition of bacterial lipopeptides

J Biol Chem. 2006 Apr 7;281(14):9049-57. doi: 10.1074/jbc.M512525200. Epub 2006 Feb 2.

Abstract

Bacterial cell walls contain lipoproteins/peptides, which are strong modulators of the innate immune system. Triacylated lipopeptides are assumed to be recognized by TLR2/TLR1-, whereas diacylated lipopeptides use TLR2/TLR6 heteromers for signaling. Following our initial discovery of TLR6-independent diacylated lipopeptides, we could now characterize di- and triacylated lipopeptides (e.g. Pam(2)C-SK(4), Pam(3)C-GNNDESNISFKEK), which have stimulatory activity in TLR1- and in TLR6-deficient mice. Furthermore, for the first time, we present triacylated lipopeptides with short length ester-bound fatty acids (like PamOct(2)C-SSNASK(4)), which induce no response in TLR1-deficient cells. No differences in the phosphorylation of MAP kinases by lipopeptide analogs having different TLR2-coreceptor usage were observed. Blocking experiments indicated that different TLR2 heteromers recognize their specific lipopeptide ligands independently from each other. In summary, a triacylation pattern is necessary but not sufficient to render a lipopeptide TLR1-dependent, and a diacylation pattern is necessary but not sufficient to render a lipopeptide TLR6-dependent. Contrary to the current model, distinct lipopeptides are recognized by TLR2 in a TLR1- and TLR6-independent manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacteria / chemistry
  • Fatty Acids / metabolism
  • Immunity, Innate
  • Ligands
  • Lipoproteins / chemistry
  • Lipoproteins / metabolism*
  • Mice
  • Mice, Knockout
  • Phosphorylation
  • Signal Transduction
  • Toll-Like Receptor 1 / genetics
  • Toll-Like Receptor 1 / physiology*
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / physiology*
  • Toll-Like Receptor 6 / genetics
  • Toll-Like Receptor 6 / physiology*

Substances

  • Fatty Acids
  • Ligands
  • Lipoproteins
  • Tlr2 protein, mouse
  • Toll-Like Receptor 1
  • Toll-Like Receptor 2
  • Toll-Like Receptor 6